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BIOMASS AS A SUSTAINABLE ENERGYSOURCE FOR THE FUTURE

BIOMASS AS ASUSTAINABLE ENERGYSOURCE FOR THEFUTURE

Fundamentals of Conversion Processes

Edited By

WIEBREN DE JONG

J RUUD VAN OMMEN

Copyright copy 2015 by John Wiley amp Sons Inc by the American Institute of Chemical Engineers Inc

Published by John Wiley amp Sons Inc Hoboken New Jersey All rights reserved

Published by John Wiley amp Sons Inc Hoboken New JerseyPublished simultaneously in Canada

No part of this publication may be reproduced stored in a retrieval system or transmitted in any formor by any means electronic mechanical photocopying recording scanning or otherwise except aspermitted under Section 107 or 108 of the 1976 United States Copyright Act without either the priorwritten permission of the Publisher or authorization through payment of the appropriate per-copy feeto the Copyright Clearance Center Inc 222 Rosewood Drive Danvers MA 01923 (978) 750-8400fax (978) 750-4470 or on the web at wwwcopyrightcom Requests to the Publisher for permissionshould be addressed to the Permissions Department John Wiley amp Sons Inc 111 River Street HobokenNJ 07030 (201) 748-6011 fax (201) 748-6008 or online at httpwwwwileycomgopermission

Limit of LiabilityDisclaimer of Warranty While the publisher and author have used their best effortsin preparing this book they make no representations or warranties with respect to the accuracy orcompleteness of the contents of this book and specifically disclaim any implied warranties ofmerchantability or fitness for a particular purpose No warranty may be created or extended by salesrepresentatives or written sales materials The advice and strategies contained herein may not besuitable for your situation You should consult with a professional where appropriate Neither thepublisher nor author shall be liable for any loss of profit or any other commercial damages includingbut not limited to special incidental consequential or other damages

For general information on our other products and services or for technical support please contactour Customer Care Department within the United States at (800) 762-2974 outside the United Statesat (317) 572-3993 or fax (317) 572-4002

Wiley also publishes its books in a variety of electronic formats Some content that appears in printmay not be available in electronic formats For more information about Wiley products visit ourweb site at wwwwileycom

Library of Congress Cataloging-in-Publication Data

Biomass as a sustainable energy source for the future fundamentals of conversion processes edited by Wiebren de Jong and J Ruud van Ommen

pages cmIncludes bibliographical references and indexISBN 978-1-118-30491-4 (cloth)

1 Biomass energy I Jong Wiebren de 1968ndash II Ommen J Ruud van 1973ndashTP339B5474 201466288ndashdc23

2014015277

Printed in the United States of America

10 9 8 7 6 5 4 3 2 1

BIOMASS AS A SUSTAINABLE ENERGYSOURCE FOR THE FUTURE

BIOMASS AS ASUSTAINABLE ENERGYSOURCE FOR THEFUTURE

Fundamentals of Conversion Processes

Edited By

WIEBREN DE JONG

J RUUD VAN OMMEN

Copyright copy 2015 by John Wiley amp Sons Inc by the American Institute of Chemical Engineers Inc

Published by John Wiley amp Sons Inc Hoboken New Jersey All rights reserved

Published by John Wiley amp Sons Inc Hoboken New JerseyPublished simultaneously in Canada

No part of this publication may be reproduced stored in a retrieval system or transmitted in any formor by any means electronic mechanical photocopying recording scanning or otherwise except aspermitted under Section 107 or 108 of the 1976 United States Copyright Act without either the priorwritten permission of the Publisher or authorization through payment of the appropriate per-copy feeto the Copyright Clearance Center Inc 222 Rosewood Drive Danvers MA 01923 (978) 750-8400fax (978) 750-4470 or on the web at wwwcopyrightcom Requests to the Publisher for permissionshould be addressed to the Permissions Department John Wiley amp Sons Inc 111 River Street HobokenNJ 07030 (201) 748-6011 fax (201) 748-6008 or online at httpwwwwileycomgopermission

Limit of LiabilityDisclaimer of Warranty While the publisher and author have used their best effortsin preparing this book they make no representations or warranties with respect to the accuracy orcompleteness of the contents of this book and specifically disclaim any implied warranties ofmerchantability or fitness for a particular purpose No warranty may be created or extended by salesrepresentatives or written sales materials The advice and strategies contained herein may not besuitable for your situation You should consult with a professional where appropriate Neither thepublisher nor author shall be liable for any loss of profit or any other commercial damages includingbut not limited to special incidental consequential or other damages

For general information on our other products and services or for technical support please contactour Customer Care Department within the United States at (800) 762-2974 outside the United Statesat (317) 572-3993 or fax (317) 572-4002

Wiley also publishes its books in a variety of electronic formats Some content that appears in printmay not be available in electronic formats For more information about Wiley products visit ourweb site at wwwwileycom

Library of Congress Cataloging-in-Publication Data

Biomass as a sustainable energy source for the future fundamentals of conversion processes edited by Wiebren de Jong and J Ruud van Ommen

pages cmIncludes bibliographical references and indexISBN 978-1-118-30491-4 (cloth)

1 Biomass energy I Jong Wiebren de 1968ndash II Ommen J Ruud van 1973ndashTP339B5474 201466288ndashdc23

2014015277

Printed in the United States of America

10 9 8 7 6 5 4 3 2 1

BIOMASS AS ASUSTAINABLE ENERGYSOURCE FOR THEFUTURE

Fundamentals of Conversion Processes

Edited By

WIEBREN DE JONG

J RUUD VAN OMMEN

Copyright copy 2015 by John Wiley amp Sons Inc by the American Institute of Chemical Engineers Inc

Published by John Wiley amp Sons Inc Hoboken New Jersey All rights reserved

Published by John Wiley amp Sons Inc Hoboken New JerseyPublished simultaneously in Canada

No part of this publication may be reproduced stored in a retrieval system or transmitted in any formor by any means electronic mechanical photocopying recording scanning or otherwise except aspermitted under Section 107 or 108 of the 1976 United States Copyright Act without either the priorwritten permission of the Publisher or authorization through payment of the appropriate per-copy feeto the Copyright Clearance Center Inc 222 Rosewood Drive Danvers MA 01923 (978) 750-8400fax (978) 750-4470 or on the web at wwwcopyrightcom Requests to the Publisher for permissionshould be addressed to the Permissions Department John Wiley amp Sons Inc 111 River Street HobokenNJ 07030 (201) 748-6011 fax (201) 748-6008 or online at httpwwwwileycomgopermission

Limit of LiabilityDisclaimer of Warranty While the publisher and author have used their best effortsin preparing this book they make no representations or warranties with respect to the accuracy orcompleteness of the contents of this book and specifically disclaim any implied warranties ofmerchantability or fitness for a particular purpose No warranty may be created or extended by salesrepresentatives or written sales materials The advice and strategies contained herein may not besuitable for your situation You should consult with a professional where appropriate Neither thepublisher nor author shall be liable for any loss of profit or any other commercial damages includingbut not limited to special incidental consequential or other damages

For general information on our other products and services or for technical support please contactour Customer Care Department within the United States at (800) 762-2974 outside the United Statesat (317) 572-3993 or fax (317) 572-4002

Wiley also publishes its books in a variety of electronic formats Some content that appears in printmay not be available in electronic formats For more information about Wiley products visit ourweb site at wwwwileycom

Library of Congress Cataloging-in-Publication Data

Biomass as a sustainable energy source for the future fundamentals of conversion processes edited by Wiebren de Jong and J Ruud van Ommen

pages cmIncludes bibliographical references and indexISBN 978-1-118-30491-4 (cloth)

1 Biomass energy I Jong Wiebren de 1968ndash II Ommen J Ruud van 1973ndashTP339B5474 201466288ndashdc23

2014015277

Printed in the United States of America

10 9 8 7 6 5 4 3 2 1

Copyright copy 2015 by John Wiley amp Sons Inc by the American Institute of Chemical Engineers Inc

Published by John Wiley amp Sons Inc Hoboken New Jersey All rights reserved

Published by John Wiley amp Sons Inc Hoboken New JerseyPublished simultaneously in Canada

No part of this publication may be reproduced stored in a retrieval system or transmitted in any formor by any means electronic mechanical photocopying recording scanning or otherwise except aspermitted under Section 107 or 108 of the 1976 United States Copyright Act without either the priorwritten permission of the Publisher or authorization through payment of the appropriate per-copy feeto the Copyright Clearance Center Inc 222 Rosewood Drive Danvers MA 01923 (978) 750-8400fax (978) 750-4470 or on the web at wwwcopyrightcom Requests to the Publisher for permissionshould be addressed to the Permissions Department John Wiley amp Sons Inc 111 River Street HobokenNJ 07030 (201) 748-6011 fax (201) 748-6008 or online at httpwwwwileycomgopermission

Limit of LiabilityDisclaimer of Warranty While the publisher and author have used their best effortsin preparing this book they make no representations or warranties with respect to the accuracy orcompleteness of the contents of this book and specifically disclaim any implied warranties ofmerchantability or fitness for a particular purpose No warranty may be created or extended by salesrepresentatives or written sales materials The advice and strategies contained herein may not besuitable for your situation You should consult with a professional where appropriate Neither thepublisher nor author shall be liable for any loss of profit or any other commercial damages includingbut not limited to special incidental consequential or other damages

For general information on our other products and services or for technical support please contactour Customer Care Department within the United States at (800) 762-2974 outside the United Statesat (317) 572-3993 or fax (317) 572-4002

Wiley also publishes its books in a variety of electronic formats Some content that appears in printmay not be available in electronic formats For more information about Wiley products visit ourweb site at wwwwileycom

Library of Congress Cataloging-in-Publication Data

Biomass as a sustainable energy source for the future fundamentals of conversion processes edited by Wiebren de Jong and J Ruud van Ommen

pages cmIncludes bibliographical references and indexISBN 978-1-118-30491-4 (cloth)

1 Biomass energy I Jong Wiebren de 1968ndash II Ommen J Ruud van 1973ndashTP339B5474 201466288ndashdc23

2014015277

Printed in the United States of America

10 9 8 7 6 5 4 3 2 1

CONTENTS

PREFACE xiii

ACKNOWLEDGMENTS xv

LIST OF CONTRIBUTORS xvii

PART I SOCIAL CONTEXT AND STRUCTURAL BASIS OFBIOMASS AS A RENEWABLE ENERGY SOURCES 1

1 Introduction Socioeconomic Aspects of Biomass Conversion 3Wiebren de Jong and J Ruud van Ommen

11 Energy Supply Economic and Environmental Considerations 412 Ways to Mitigate Threats to a Sustainable Energy Supply 1613 What is Sustainable Supply of Biomass 2014 Resources and Sustainable Potential of Biomass 2515 A Brief Introduction to Multiproduct Biomass Conversion Techniques 29Chapter Summary and Study Guide 30Key Concepts 30Short-Answer Questions 30Problems 32Projects 32Internet References 33References 33

v

2 Biomass Composition Properties and Characterization 36Wiebren de Jong

21 Physicochemical Properties 3722 Main Structural Organic Constituents 4223 Minor Organic Constituents 4524 Inorganic Compounds 4925 Proximate and Ultimate Analysis 5226 Heating Values 5727 Ash Characterization Techniques 59Chapter Summary and Study Guide 61Key Concepts 62Short-Answer Questions 62Problems 63Projects 65Internet References 65References 65

PART II CHEMICAL ENGINEERING PRINCIPLESOF BIOMASS PROCESSING 69

3 Conservation Mass Momentum and Energy Balances 71Wiebren de Jong

31 General Conservation Equation 7332 Conservation of Mass 7433 Conservation of Energy 8034 Conservation of Momentum 90Chapter Summary and Study Guide 92Key Concepts 92Short-Answer Questions 93Problems 93Projects 95Internet Reference 96References 96

4 Transfer Basics of Mass and Heat Transfer 97Dirk JEM Roekaerts

41 Introduction 10042 Transport Terms in the Governing Equations 10043 Radiative Heat Transfer 10344 Convective Heat and Mass Transfer 10845 Transfer of Heat and Mass with Phase Change 110Chapter Summary and Study Guide 124

vi CONTENTS

Key Concepts 124Short-Answer Questions 125Problems 125Projects 127References 128

5 Reactions Thermodynamic Aspects Kinetics and Catalysis 129Martina Fantini Wiebren de Jong and J Ruud van Ommen

51 Reaction Kinetics 13052 Chemical Equilibrium 13853 Catalysis 148Chapter Summary and Study Guide 154Key Concepts 155Short-Answer Questions 155Problems 155Projects 156References 158

6 Reactors Idealized Chemical Reactors 159Lilian de Martiacuten and J Ruud van Ommen

61 Preliminary Concepts 16062 Batch Reactors (BRs) 16363 Steady-State Continuous Stirred Tank Reactors (CSTRs) 16764 Steady-State Plug Flow Reactors (PFRs) 16865 Residence Time and Space Time for Flow Reactors 17366 Deviations from Plug Flow and Perfect Mixing 176Chapter Summary and Study Guide 180Key Concepts 181Short-Answer Questions 181Problems 181Project 182References 183

7 Processes Basics of Process Design 184Johan Grievink Pieter LJ Swinkels and J Ruud van Ommen

71 Scope 18672 Characterization of Biomass Processing 18773 Analyzing the Outside of a Process 18974 Analyzing the Inside of a Process 19275 A Design Procedure for Biomass Conversion Processes 19576 Interface with Supply Chain InputndashOutput Diagram 20177 Division in Subprocesses 20678 Process Design Functional Block Diagram 207

viiCONTENTS

79 Example of Analysis and Evaluation in Process Design 212710 Integrating Process Units into the Functional Network 222711 Application Potential 224Chapter Summary and Study Guide 224Key Concepts 225Short-Answer Questions 225Problems 226Projects 229Internet References 229References 229

PART III BIOMASS CONVERSION TECHNOLOGIES 231

8 Physical Pretreatment of Biomass 233Wiebren de Jong

81 Introduction 23582 Harvesting and Transport 23683 Storage 24184 Washing 24285 Size Reduction 24386 Particle Size Characterization 24787 Screening and Classification 24988 Methods of Moisture Reduction 24989 Compaction Technologies 257810 Sequencing the Pretreatment Steps 261Chapter Summary and Study Guide 261Key Concepts 261Short-Answer Questions 262Problems 263Projects 264Internet References 265References 265

9 Thermochemical Conversion Direct Combustion 268Rob JM Bastiaans and Jeroen A van Oijen

91 Introduction 27092 Fundamental Conversion Processes 27193 Particle Conversion Modes 27394 Combustion Systems 28395 Emissions 288Chapter Summary and Study Guide 294Key Concepts 295Short-Answer Questions 295

viii CONTENTS

Problems 295Projects 296Internet References 296References 297

10 Thermochemical Conversion (Co)gasification andHydrothermal Gasification 298Sascha RA Kersten and Wiebren de Jong

101 What is Gasification A Chemical and Engineering Background 300102 A Short History of Gasification 317103 (Co)gasification Technologies for Dry Biomass 318104 Gasification in an Aqueous Environment Hydrothermal

Biomass Conversion 329105 Gas Cleaning for Biomass Gasification Processes 337Chapter Summary and Study Guide 348Key Concepts 348Short-Answer Questions 349Problems 350Projects 353Internet References 353References 353

11 Thermochemical Conversion An Introductionto Fast Pyrolysis 359Stijn RG Oudenhoven and Sascha RA Kersten

111 Introduction 361112 A First Look at a Liquefaction Process 362113 A First Look at Fast Pyrolysis Oil 363114 Chemistry and Kinetics of Pyrolysis 364115 Processes at the Particle Level 368116 A Closer Look at Pyrolysis Oil 371117 Fast Pyrolysis Processes 374118 Catalytic Pyrolysis 377119 Oil Applications 3781110 Outlook 380Appendix 111 Single-Particle Model (Based on the Model byDi Blasi 1997) 380Chapter Summary and Study Guide 383Key Concepts 383Short-Answer Questions 383Problems 384Projects 384Internet References 385References 385

ixCONTENTS

12 Thermochemical Conversion Torrefaction 388Jaap HA Kiel Arno HH Janssen and Yash Joshi

121 Introduction 388122 Fundamentals of Torrefaction 389123 Advantages of Torrefaction 392124 Torrefaction Technology 392125 Torrefaction An Enabling Technology 397126 The Future of Torrefaction 398Chapter Summary and Study Guide 399Key Concepts 399Short-Answer Questions 399Problems 400Projects 401References 401

13 Biochemical Conversion Biofuels byIndustrial Fermentation 403Maria C Cuellar and Adrie JJ Straathof

131 Introduction 404132 First-Generation Bioethanol Processes 406133 Second-Generation Bioethanol Processes 417134 Butanol 428135 Diesel-like Products 429136 Stoichiometric and Thermodynamic Comparison of

Fermentative Biofuels 432137 Outlook 436Chapter Summary and Study Guide 437Key Concepts 438Short-Answer Questions 438Problems 438Projects 439References 439

14 Biochemical Conversion Anaerobic Digestion 441Robbert Kleerebezem

141 Introduction 442142 Biochemical Fundamentals 443143 Thermodynamic Fundamentals 453144 Process Engineering 454145 Outlook and Discussion 463Chapter Summary and Study Guide 466Key Concepts 466Short-Answer Questions 466Problems 467

x CONTENTS

Project 467References 468

15 Biorefineries Integration of Different Technologies 469Wiebren de Jong

151 What is a Biorefinery and What is the Difference with anOil Refinery 470

152 Types of Biorefineries 474153 Economic Considerations Evaluating Biorefinery Concepts

Basic Methods for Assessing Investments and Cost Prices 481154 Outlook to the Future of Biorefineries 492Chapter Summary and Study Guide 493Key Concepts 493Short-Answer Questions 493Problems 494Projects 497Internet References 500References 500

PART IV END USES 503

16 High-Efficiency Energy Systems withBiomass Gasifiers and Solid Oxide Fuel Cells 505PV Aravind and Ming Liu

161 Introduction 506162 Solid Oxide Fuel Cells 507163 Biomass GasifierndashSOFC Combination 512164 Concluding Remarks 520Chapter Summary and Study Guide 520Key Concepts 521Short-Answer Questions 521Problems 521Projects 522Internet References 522References 523

17 Synthesis Gas Utilization for TransportationFuel Production 525J Ruud van Ommen and Johan Grievink

171 Introduction 526172 FischerndashTropsch Synthesis 527173 Synthetic Natural Gas Synthesis 535174 Methanol Synthesis 537

xiCONTENTS

175 Comparison of the Different Options 538Chapter Summary and Study Guide 540Key Concepts 540Short-Answer Questions 541Problems 541Projects 544Internet References 545References 545

18 Chemistry of Biofuels and Biofuel Additivesfrom Biomass 547Isabel WCE Arends

181 Introduction 548182 Bioethanol and Biodiesel 548183 Conversion of Sugars to Hydrocarbon Fuels 553184 Greenness of the Conversion of Platform Molecules

into Biobased Fuel Additives 557185 Direct Aqueous Reforming of Sugars Leading to a

Range of Alkanes 564186 Future Generations of Biofuel 566Chapter Summary and Study Guide 566Key Concepts 567Short-Answer Questions 567Problems 568Projects 568Internet References 568References 569

INDEX 571

xii CONTENTS

PREFACE

This book deals with bioenergy as a versatile renewable source Ever since thedawn of mankind people have been using wood and other biogenic sources forheating cooking and lighting Trade of biomass came up in historic times (thinkabout the silk route for example) Even industrial iron making via metal reductionwas based on biomass utilization (carbonization) However that very applicationalso led to substantial deforestation which was clear in the United Kingdomand demonstrated that using biomass does not guarantee a sustainable energy sup-ply Therefore the industrial revolution introduced the large-scale application offossil fuel starting with the use of coal

The steam engine became the workhorse of the nineteenth century Coal alsobecame the basis of the chemical industry at that time Oil was initially used for lampsbut later it appeared to be the choice of raw material for petrol and diesel in Otto andDiesel engines respectively Wood and other sources came back into the pictureduring the interbellum period and the Second World War when oil was scarce inparticular on the European continent At that time cars trucks and ships made useof the gas extracted from fixed bed wood gasification installations Also chemicalssupply and materials were increasingly supported by wood-based processes AfterWWII the cheap oil era was entered and such routes were largely abandoned Afterthe oil crises of the 1970s biomass came back into the picture as an energy sourcereinforced by environmental concerns about the use of fossil energy sources due totheir associated CO2 emissions stimulating the greenhouse effect At present biomassis seriously back as part of a sustainable energy mix in combination with materialsand chemicals supply and a wide world of biorefinery options has opened up

The field of biomass to energy supply is multidisciplinary and offers a wealth ofintegration of knowledge to young engineers starting their careers The technologies

xiii

strongly lean on chemical engineering skills but also on physics mechanical engineer-ing and agricultural sciences among others Not only technology issues determine thesuccess of biomass for our energy supply there are many hurdles to be taken into thenontechnical domain such as logistics (trade and handling) infrastructure and politics(subsidies rural development employment generation etc) to name a few

This book is divided into four parts covering broad areas of the field of biomassconversion technology chains Part I starts with the socioeconomic and environmentalcontext and biomass basics It gives insight into the boundary conditions and the playingfield bioenergy supply has Moreover it provides a deeper look into what biomass reallyis Part II covers the chemical engineering basics to provide the engineer with tools tosolve problems in the domain design new biomass-based processes and evaluateconversion subprocesses The tools range from setting up balances evaluating the massand heat transport phenomena thermodynamics and kinetics to reactor and processdesign Part III deals with the study of different biomass conversion processes rangingfrom nonreactive pretreatment via combustion processes gasification hydrothermal pro-cessing pyrolysis and torrefaction to biochemical conversion processes and biorefineryintegration of such technologies Finally Part IV treats the end use of primary biomassconversion products for example power production via fuel cells transportationfuel production (eg via the FischerndashTropsch process) and platform chemicalsproduction via organic chemistry to substitute the conventional petrochemical pathwaysoffered today

We were inspired to write this book by the course ldquoEnergy from Biomassrdquo that wehave been teaching for a number of years in the MSc program of Sustainable EnergyTechnology at Delft University a program that is part of the 3TU cooperation betweenthe technical universities of Delft Eindhoven and Twente After teaching the coursefor some years using the lecture notes prepared by our Eindhoven colleagues RobBastiaans Jeroen van Oijen andMark Prins we thought it would be worthy to furtherimprove the course material Since the students in Sustainable Energy Technologyhave a very diverse background we have devoted Part II of the book to giving thereader enough background in chemical engineering for reading the more specializedchapters This means that this book is useful for everyone with a BSc in anyengineering discipline Apart from students at the MSc level professionals in thebiomass field may also find this book as a knowledgeable source for example fordesigning and evaluating novel biorefinery systems and conversion components

Delft December 2013 WIEBREN DE JONG AND J RUUD VAN OMMEN

He will be like a tree planted by the water that sends out its roots by the stream It doesnot fear when heat comes its leaves are always green It has no worries in a year ofdrought and never fails to bear fruit ndash Bible Jeremiah 178

Biomass is forever ndash Prof David Halldagger

xiv PREFACE

ACKNOWLEDGMENTS

This book would not have been published without the contributions from manypeople First of all we would like to acknowledge all the students that followedour course ldquoEnergy from Biomassrdquo over the years they inspired us to compose thisbook We are very glad that many of our colleagues agreed to contribute chapters tothis book It was great to work with this team of co-authors all bringing in their spe-cific expertise to cover the broad field of energy from biomass A big thanks to all ofyou For some chapters the additional input from others is specifically acknowledgedLikun Ma is kindly acknowledged for his contribution to the examples in Chapter 4Ryan Bogaars for his suggestions concerning Chapter 10 Xiangmei Meng and Onur-sal Yakaboylu for contributing some of the examples of Chapter 10 Richard Eijsbergfor the first generation ethanol process figures and data in Chapter 13 Tim Geraedtsand Elze Oude Lansink for the project in Chapter 15 Fred van Rantwijk for valuableinput and discussions on Chapter 18 and Adrea Fabre for her advices regarding thewritingWe are also grateful for the willingness of many colleagues to review chaptersin order to find mistakes and make suggestions for further improvements Ourreviewers were in alphabetic order Rob Bakker Sune Bengtsson PouyanBoukany Anthony Bridgwater Harry Croezen Lilian de Martiacuten Jorge GasconHans Geerlings Johan Grievink Sef Heijnen Kas Hemmes Paulien Herder TrulsLiliedahl Gabrie Meesters Bart Merci Kyriakos Panopoulos Wolter Prins SinaSartipi Fabrizio Scala Tilman Schildhauer Andrzej Stankiewicz GeorgiosStefanidis Bob Ursem Henk van den Berg Theo van der Meer Jules van Lier Maritvan Lieshout and Stanislav Vassilev A special word of thanks should go to Anneliesvan Diepen When the chapters were complete she made a great effort to harmonizethem for example in figures symbols lay-out and wording She also has caughtnumerous mistakes that were still present in earlier versions We would like to thank

xv

Jan Leen Kloosterman (Director of Education Sustainable Energy Technology SET)for the financial support from the SET program for editorial assistance We would alsolike to thank the people at Wiley for the smooth cooperation during the preparation ofthe manuscript Finally we would like to thank the ones close to usmdashKlarine (WdJ)and Ceciel Fenne and Chris (JRvO)mdashfor their understanding and support during allthe evenings and weekends that the writing and editing took

xvi ACKNOWLEDGMENTS

LIST OF CONTRIBUTORS

PV Aravind Drir Department of Process and Energy Energy TechnologySection Faculty of Mechanical Maritime and Materials Engineering DelftUniversity of Technology Delft the Netherlands

Isabel WCE Arends Profdr Department of Biotechnology Biocatalysis GroupFaculty of Applied Sciences Delft University of Technology Delft theNetherlands

Rob JM Bastiaans Drir Department of Mechanical Engineering CombustionTechnology Section Eindhoven University of Technology Eindhoven theNetherlands

Maria C Cuellar Dr Department of Biotechnology BioProcess EngineeringGroup Faculty of Applied Sciences Delft University of Technology Delft theNetherlands

Martina Fantini Drir Department of Process and Energy Energy TechnologySection Faculty of Mechanical Maritime and Materials Engineering DelftUniversity of Technology Delft the Netherlands

Johan Grievink Prof ir Department of Chemical Engineering Product amp ProcessEngineering Group Faculty of Applied Sciences Delft University of TechnologyDelft the Netherlands

ArnoHH Janssen Ir ECN Biomass amp Energy Efficiency Petten the Netherlands

Wiebren de Jong Drir Department of Process and Energy Energy TechnologySection Faculty of Mechanical Maritime and Materials Engineering DelftUniversity of Technology Delft the Netherlands

xvii

Yash Joshi Ir Department of Process and Energy Energy Technology SectionFaculty of Mechanical Maritime and Materials Engineering Delft University ofTechnology Delft the Netherlands

Sascha RA Kersten Profdrir Sustainable Process Technology Group Facultyof Science and Technology University of Twente Enschede the Netherlands

Jaap HA Kiel Profdrir ECN Biomass amp Energy Efficiency Petten andDepartment of Process and Energy Energy Technology Section Faculty ofMechanical Maritime andMaterials Engineering Delft University of TechnologyDelft the Netherlands

Robbert Kleerebezem Drir Department of Biotechnology EnvironmentalBiotechnology Group Faculty of Applied Sciences Delft University of TechnologyDelft the Netherlands

Ming Liu Drir Department of Process and Energy Energy Technology SectionFaculty of Mechanical Maritime and Materials Engineering Delft University ofTechnology Delft the Netherlands

Lilian de Martiacuten Dr Department of Chemical Engineering Product amp ProcessEngineering Group Faculty of Applied Sciences Delft University of TechnologyDelft the Netherlands

Jeroen A van Oijen Drir Department of Mechanical Engineering CombustionTechnology Section Eindhoven University of Technology Eindhoven theNetherlands

J Ruud van Ommen Drir Department of Chemical Engineering Product ampProcess Engineering Group Faculty of Applied Sciences Delft University ofTechnology Delft the Netherlands

Stijn RG Oudenhoven Ir Sustainable Process Technology Group Faculty ofScience and Technology University of Twente Enschede the Netherlands

Dirk JEM Roekaerts Profdr Department of Process and Energy FluidMechanics Section Faculty of Mechanical Maritime and Materials EngineeringDelft University of Technology Delft the Netherlands

Adrie JJ Straathof Drir Department of Biotechnology BioProcess EngineeringGroup Faculty of Applied Sciences Delft University of Technology Delft theNetherlands

Pieter LJ Swinkels Ir Faculty of Applied Sciences Delft Product amp ProcessDesign Institute Delft University of Technology Delft the Netherlands

xviii LIST OF CONTRIBUTORS

PART I

SOCIAL CONTEXT AND STRUCTURALBASIS OF BIOMASS AS A RENEWABLEENERGY SOURCES

1INTRODUCTION SOCIOECONOMICASPECTS OF BIOMASS CONVERSION

WIEBREN DE JONG1 AND J RUUD VAN OMMEN2

1Department of Process and Energy Energy Technology Section Faculty of MechanicalMaritime and Materials Engineering Delft University of Technology Delft the Netherlands2Department of Chemical Engineering Product amp Process Engineering Group Faculty ofApplied Sciences Delft University of Technology Delft the Netherlands

ACRONYMS

CDM clean development mechanismCFCs chlorofluorocarbonsdLUC direct land use changeGDP gross domestic productGHG greenhouse gasiLUC indirect land use changeJI joint implementationLCA life cycle assessmentLUC land use changeRP ratio reserves-to-production ratio [y]TOE tonnes of oil equivalent(s) (= 4187 GJ)UNFCCC United Nations Framework Convention on Climate Change

Biomass as a Sustainable Energy Source for the Future Fundamentals of Conversion ProcessesFirst Edition Edited by Wiebren de Jong and J Ruud van Ommencopy 2015 American Institute of Chemical Engineers Inc Published 2015 by John Wiley amp Sons Inc

3

11 ENERGY SUPPLY ECONOMIC AND ENVIRONMENTALCONSIDERATIONS

111 Introduction The Importance of Energy Supply

In the past two centuries since the Industrial Revolution in the 1700s that was initiatedby the invention of the steam turbine the world has undergone a drastic change due tothe steeply increased contribution of fossil fuels (coal oil and natural gas) to modernsocietiesrsquo energy supply (McKay 2009) Though the Chinese society already usedcoal for energy supply in approximately 1000 BC and the Romans prior to AD 400(World-Coal-Institute 2005) the first written references indicating its use are fromabout the thirteenth century and beyond (Hubbert 1949) These hydrocarbon fuelsso far have been considered essential as they are comparatively cheap and convenientenergy carriers used for heating cooking lighting and mechanical as well as electricpower production and have been widely used as transportation fuels and feedstocksfor the manufacture of bulk and fine chemicals as well as other materials with a widerange of applications Rapid global population growth expansion of economies andhigher standards have caused an enormous increase in worldwide energy consump-tion which was partly made possible by the supply of cheap fossil fuels

112 Development of Global Energy Demand

Figure 11 shows a scenario toward the year 2030 presented by the oil company BPconcerning population growth in relation to developments in total primary energyutilization and gross domestic product (GDP) The figure shows that global energy

Billion

Rest of

the world

India

China

9

8

7

6

5

4

3

2

1

0

Population

Billion toe

18

15

12

9

6

3

0

Energy

Trillion $2010 PPP

180

150

120

90

60

30

01970 1990 2010 2030 1970 1990 2010 2030 1970 1990 2010 2030

GDP

FIGURE 11 Prospected global growth rates in population energy demand and GDP 1 toe =41868104 MJ (Source Adapted from BP see tinyurlcom7hlmqxn)

4 INTRODUCTION

demand will rise substantially from the current level with an increasing share fromChina and India This rise of the primary energy demand is projected to be larger thanthe population growth and this will cause a stress on the limited global resources Theprojected GDP even increases stronger so it is expected that average living standardsincrease which will result in additional strain on the available resources

113 Sustainability of Energy Supply

One of the major questions in the world arising from the general picture sketched inSection 112 is how mankind can ensure a global sustainable development for the(near) future In this context sustainability of our energy supply is of paramountimportance The key issues are discussed in the following text both from a pointof view of global socioeconomics and ecological sustainability

1131 Socioeconomic Sustainability As one of the most important economicdrivers to secure and improve the living standards of people in the world energysupply security is of crucial value for current and future generations Fossil fuelsrun out sooner or later as can be seen in Figure 12 they are not renewable on anacceptable time scale

This figure depicts the so-called RP ratios for different sources The RP ratio is theratio of the current proven reserves to production level The unit is years and it is ameasure of the expected time a certain fuel source is expected to be available

On a global scale it appears that oil and natural gas reserves will be availablemdashgiven the figures of 2012mdashfor an expected approximately 55 years and coal substan-tially longer (gt100 years) Of course new contributions to the reserves may be

0

50

100

150

200

250

1980 1985 1990 1995 2000 2005 2010 2015

RP

(yea

rs)

Oil

Coal

Natural gas

FIGURE 12 Overview of world (top) and regional (bottom) reserves-to-production (RP)ratios for oil natural gas and coal respectively (end 2012 status) Figures are based on datafrom BP (2013)

5ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

North America

S amp Cent America

Europe amp Eurasia

Middle East

Africa

Asia Pacific

0 20 40 60

RP (years)

80 100 120 140

North America

S amp Cent America

Europe amp Eurasia

Middle East

Africa

Asia Pacific

0

RP (years)

North America

S amp Cent America

Europe amp Eurasia

Middle East amp Africa

Asia Pacific

0 50 100 150 200 250 300RP (years)

50 100 150 200

FIGURE 12 (Continued )

6 INTRODUCTION

discovered in the (near) future but that does not change the inherently limited supplynature of the fossil fuel sources Regionally there are also significant differenceswhich is important in the context of energy policy developments on the differentcontinents

For the price developments of the fossil fuels not only their forecasted availabilityis of importance but also the market development in a landscape highly determined bypolitics Already well before the last resources of a fuel will have been depleted themarket will be severely stressed For the economies in the world fuel cost develop-ment is therefore also a primary point of concern From past developments particu-larly regarding oil it has been shown that substantial fuel price fluctuations (volatility)occur which has an impact on the global economy (eg food prices) that is difficult topredict Supply and demand will determine the price evolution for each fuel sourcebut the development of the market structure is also essential there is a large differencebetween a free market and an oligopoly or monopoly situation In this respect diver-sification of fuel sources with associated differentiation in suppliers is advantageousas it makes societies less prone to price manipulation by eg cartel formation andsudden disruptions of supply (Johansson et al 1993)

Self-sufficiency concerning energy supply is often mentioned as target of countriesfor (longer-term) sustainable economic development However not all countries haveaccess to resources within their territories that are sufficient for such a target othercountries on the other hand have a structural surplus Relief of trade barriers canhelp mitigate this structural discrepancy Also in the context of economic sustaina-bility a good trade balance should be maintained in relation to the energy supplywithin nations

Regarding social sustainability in the context of energy supply reduction of pov-erty should be mentioned first a good supply structure of energy carriers is one of thebasic requirements for such a development next to access to clean drinking water andgood soil for agricultural activity Associated herewith expectedly substantial healthimprovement should result from a good energy supply infrastructure Job creation andmaintenance is another aspect of social sustainability and certain energy supply formscan contribute significantly to this Also maintaining (or improving) societiesrsquo socialcohesion is an aspect that can be impacted by the energy supply structure

1132 Ecological Sustainability The energy supply structure should notcompromise the sound development of our environment both from a local and globalperspective One of the major issues in this respect is global warming which is for themain part attributed to the release of greenhouse gases (GHG) from fossil fuel com-bustion Other issues are related to local emissions of acid rain precursors and partic-ulate matter (PM)

Climate Change the Greenhouse Effect and Greenhouse Gas EmissionReduction The greenhouse effect occurs naturally to a large extent Without thiseffect the Earthrsquos average global temperature would reach only a low minus18C ratherthan the current approximate +15C Water vapor is the largest contributor to thiseffect with a complex role for clouds but also CO2 in the atmosphere plays a

7ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

significant role More than a century ago Arrhenius (1896) already identified thisrole in the Earthrsquos temperature control Ice core studies reveal that on millennial timescales changes in CO2 content recorded are highly correlated with changes in tem-perature although some temperature changes have occurred without a significantCO2 concentration change but the opposite does not appear to have happened(Falkowski et al 2000) Less pronounced roles are played by CH4 N2O (nitrousoxide) and several types of chlorofluorocarbons (CFCs) and SF6 It is the CO2CH4 N2O and CFC concentrations in the atmosphere upon which manrsquos industrial

0

1

Rad

iati

ve

forc

ing (

Wm

2)

350

(a)

300

Car

bon d

ioxid

e (p

pm

)

250

300

350

400

1800 1900

Year

2000

(b)

1500

2000

1000

Met

han

e (p

pb)

500

0

02

04

Rad

iati

ve

forc

ing (

Wm

2)

1000

500

1500

2000

1900

Year

20001800

FIGURE 13 Atmospheric concentrations of CO2 CH4 and N2O over the last 10000 years(large panels) and since 1750 (inset panels) Measurements are shown from ice cores (symbolswith different grey shades for different studies) and atmospheric samples (light grey lines insteep curve part red lines in the original publication) The corresponding radiative forcings(net solar energy flux to the earth) relative to 1750 are shown on the right-hand axes of the largepanels (SourceReproducedwithpermission fromIPCC(2007) figure23 figureSPM1copyIPCC)

8 INTRODUCTION

and household activities have a measurable impact Scientists largely agree on thepoint that in the last few centuries the activities of humans have directly or indirectlycaused the concentrations of the major GHG to increase This is exemplified byFigure 13 The atmospheric CO2 concentration varies to some extent from placeto place and from season to season It has been shown that concentrations are some-what higher in the northern hemisphere than in the southern hemisphere as most of theanthropogenic sources of CO2 are located north of the equator The difference in landsurface covered with forests being more concentrated north of the equator causeslarger seasonal fluctuations due to comparatively shorter growth periods than in thegenerally milder southern hemisphere locations that are under the influence of largeroceanic surfaces

Oscillations of atmospheric CO2 concentrations between about 180 and 280 ppmv

have occurred in the past approximately 480000 years in cycles of 100000 yearsbut it appears now we have abandoned this cycling behavior in a remarkably shorttime frame

Studies at the NASA Goddard Institute for Space Studies in New York (UnitedStates) have shown that over the past few decades the combined warming effectof non-CO2 GHG should have been comparable to that of CO2 alone However whileeach of the GHGmentioned earlier acts to warm the surface of the Earth the long-termclimatic effects of the other GHG differ from those of CO2 Methane eg has anatmospheric lifetime of only about 12 years By comparison newly added CO2 willremain for a time span of tens to thousands of years As a result about 65 of thecarbon dioxide that human activities have generated since the start of the IndustrialRevolution is in the air we breathe today A historical record of the amount ofCO2 in the atmosphere can be found in bubbles of air in arctic ice layers dating backas far as 600000 years The depth of such a layer is a measure of its time of formation

(c)

10000 5000

Time (before 2005)

0

0

01

Rad

iati

ve

forc

ing (

Wm

2)

300

270

Nit

rous

oxid

e (p

pb)

270

240

300

330

1800 1900

Year

2000

FIGURE 13 (Continued )

9ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

Another difference is that the principal anthropogenic sources of methane-bacterialfermentation in rice paddies and in the intestines of cattle are related to food produc-tion and hence are roughly proportional to the number of people on the planetBecause CH4 has such a short atmospheric lifetime the amount that is in the air isa good indicator of how much is being added with time Should the global populationdouble over the next half century the concentration of CH4 could also double but it isnot likely to rise by much more than that This would add at most a few tenths of adegree to the mean temperature of the Earth Future CO2 increases could in contrastwarm the climate by 10C or more

Nitrous oxide (N2O) and CFCs are in some ways more like CO2 in that oncereleased they remain in the atmosphere for a century or more The production ofN2O however is only indirectly dependent on human activities Its principal sourceis a natural one the bacterial removal of nitrogen from soils and although the worldpopulation swells in coming years the amount in the air should increase only slowly

The outlook for many CFCs is even more promising Today the most abundant ofthese man-made compounds freon-11 and freon-12 are being phased out of produc-tion altogether by international agreements because of their damaging effects on strat-ospheric ozone Indeed the concentration of one of these gases freon-11 peaked in1994 and is now in a slow decline that should continue for the next century or so Thefreon-12 concentration has not yet leveled off but is expected to do so within the nextfew years In terms of climatic effects the main threat from CFCs comes from otherlong-lived compounds that may be used to replace the ones that have been phased outand that could also act as GHG Since these possibly harmful replacement gases are asyet present in only small amounts and since as noted earlier projected increases inCH4 and N2O are so much less severe we shall for the rest of this discussion focussolely on the most important anthropogenic GHG CO2

Some experts have estimated that the Earthrsquos average global temperature has alreadyincreased by more than 05C since the mid-1900s due to this human-enhanced green-house effect also impacts on sea level (rising) and snow coverage (tending to decrease)have been investigated the results of which are summarized in Figure 14

Like most other planets and planetoids in the universe the Earth contains a greatdeal of carbon which is slowly and continually transported from the mantle to thecrust and back again in the course of volcanic eruption and subduction phenomenaThe portion that finds itself near the surface is continually exchanged and recycledamong plants animals soil air and oceans In some of these temporary stocks car-bon is more securely held while in others it more readily combines with oxygen in theair to form CO2 In order to predict how atmospheric CO2 levels and climate maychange in the future it is important to understand where carbon is stored and whatits dynamic cycling behavior looks like The carbon reservoirs that are most relevantto global warming are listed in Table 11 with the total amount of carbon that theycontained in 2000

The atmosphere contains approximately 720 Gt C in the form of CO2 currentmeasured atmospheric CO2 concentrations are nearly 400 ppmv The rate of changein this carbon stock not only depends on human activities but also on biogeochemicaland climatological processes and their interactions with the global carbon cycle

10 INTRODUCTION

2 Biomass Composition Properties and Characterization 36Wiebren de Jong

21 Physicochemical Properties 3722 Main Structural Organic Constituents 4223 Minor Organic Constituents 4524 Inorganic Compounds 4925 Proximate and Ultimate Analysis 5226 Heating Values 5727 Ash Characterization Techniques 59Chapter Summary and Study Guide 61Key Concepts 62Short-Answer Questions 62Problems 63Projects 65Internet References 65References 65

PART II CHEMICAL ENGINEERING PRINCIPLESOF BIOMASS PROCESSING 69

3 Conservation Mass Momentum and Energy Balances 71Wiebren de Jong

31 General Conservation Equation 7332 Conservation of Mass 7433 Conservation of Energy 8034 Conservation of Momentum 90Chapter Summary and Study Guide 92Key Concepts 92Short-Answer Questions 93Problems 93Projects 95Internet Reference 96References 96

4 Transfer Basics of Mass and Heat Transfer 97Dirk JEM Roekaerts

41 Introduction 10042 Transport Terms in the Governing Equations 10043 Radiative Heat Transfer 10344 Convective Heat and Mass Transfer 10845 Transfer of Heat and Mass with Phase Change 110Chapter Summary and Study Guide 124

vi CONTENTS

Key Concepts 124Short-Answer Questions 125Problems 125Projects 127References 128

5 Reactions Thermodynamic Aspects Kinetics and Catalysis 129Martina Fantini Wiebren de Jong and J Ruud van Ommen

51 Reaction Kinetics 13052 Chemical Equilibrium 13853 Catalysis 148Chapter Summary and Study Guide 154Key Concepts 155Short-Answer Questions 155Problems 155Projects 156References 158

6 Reactors Idealized Chemical Reactors 159Lilian de Martiacuten and J Ruud van Ommen

61 Preliminary Concepts 16062 Batch Reactors (BRs) 16363 Steady-State Continuous Stirred Tank Reactors (CSTRs) 16764 Steady-State Plug Flow Reactors (PFRs) 16865 Residence Time and Space Time for Flow Reactors 17366 Deviations from Plug Flow and Perfect Mixing 176Chapter Summary and Study Guide 180Key Concepts 181Short-Answer Questions 181Problems 181Project 182References 183

7 Processes Basics of Process Design 184Johan Grievink Pieter LJ Swinkels and J Ruud van Ommen

71 Scope 18672 Characterization of Biomass Processing 18773 Analyzing the Outside of a Process 18974 Analyzing the Inside of a Process 19275 A Design Procedure for Biomass Conversion Processes 19576 Interface with Supply Chain InputndashOutput Diagram 20177 Division in Subprocesses 20678 Process Design Functional Block Diagram 207

viiCONTENTS

79 Example of Analysis and Evaluation in Process Design 212710 Integrating Process Units into the Functional Network 222711 Application Potential 224Chapter Summary and Study Guide 224Key Concepts 225Short-Answer Questions 225Problems 226Projects 229Internet References 229References 229

PART III BIOMASS CONVERSION TECHNOLOGIES 231

8 Physical Pretreatment of Biomass 233Wiebren de Jong

81 Introduction 23582 Harvesting and Transport 23683 Storage 24184 Washing 24285 Size Reduction 24386 Particle Size Characterization 24787 Screening and Classification 24988 Methods of Moisture Reduction 24989 Compaction Technologies 257810 Sequencing the Pretreatment Steps 261Chapter Summary and Study Guide 261Key Concepts 261Short-Answer Questions 262Problems 263Projects 264Internet References 265References 265

9 Thermochemical Conversion Direct Combustion 268Rob JM Bastiaans and Jeroen A van Oijen

91 Introduction 27092 Fundamental Conversion Processes 27193 Particle Conversion Modes 27394 Combustion Systems 28395 Emissions 288Chapter Summary and Study Guide 294Key Concepts 295Short-Answer Questions 295

viii CONTENTS

Problems 295Projects 296Internet References 296References 297

10 Thermochemical Conversion (Co)gasification andHydrothermal Gasification 298Sascha RA Kersten and Wiebren de Jong

101 What is Gasification A Chemical and Engineering Background 300102 A Short History of Gasification 317103 (Co)gasification Technologies for Dry Biomass 318104 Gasification in an Aqueous Environment Hydrothermal

Biomass Conversion 329105 Gas Cleaning for Biomass Gasification Processes 337Chapter Summary and Study Guide 348Key Concepts 348Short-Answer Questions 349Problems 350Projects 353Internet References 353References 353

11 Thermochemical Conversion An Introductionto Fast Pyrolysis 359Stijn RG Oudenhoven and Sascha RA Kersten

111 Introduction 361112 A First Look at a Liquefaction Process 362113 A First Look at Fast Pyrolysis Oil 363114 Chemistry and Kinetics of Pyrolysis 364115 Processes at the Particle Level 368116 A Closer Look at Pyrolysis Oil 371117 Fast Pyrolysis Processes 374118 Catalytic Pyrolysis 377119 Oil Applications 3781110 Outlook 380Appendix 111 Single-Particle Model (Based on the Model byDi Blasi 1997) 380Chapter Summary and Study Guide 383Key Concepts 383Short-Answer Questions 383Problems 384Projects 384Internet References 385References 385

ixCONTENTS

12 Thermochemical Conversion Torrefaction 388Jaap HA Kiel Arno HH Janssen and Yash Joshi

121 Introduction 388122 Fundamentals of Torrefaction 389123 Advantages of Torrefaction 392124 Torrefaction Technology 392125 Torrefaction An Enabling Technology 397126 The Future of Torrefaction 398Chapter Summary and Study Guide 399Key Concepts 399Short-Answer Questions 399Problems 400Projects 401References 401

13 Biochemical Conversion Biofuels byIndustrial Fermentation 403Maria C Cuellar and Adrie JJ Straathof

131 Introduction 404132 First-Generation Bioethanol Processes 406133 Second-Generation Bioethanol Processes 417134 Butanol 428135 Diesel-like Products 429136 Stoichiometric and Thermodynamic Comparison of

Fermentative Biofuels 432137 Outlook 436Chapter Summary and Study Guide 437Key Concepts 438Short-Answer Questions 438Problems 438Projects 439References 439

14 Biochemical Conversion Anaerobic Digestion 441Robbert Kleerebezem

141 Introduction 442142 Biochemical Fundamentals 443143 Thermodynamic Fundamentals 453144 Process Engineering 454145 Outlook and Discussion 463Chapter Summary and Study Guide 466Key Concepts 466Short-Answer Questions 466Problems 467

x CONTENTS

Project 467References 468

15 Biorefineries Integration of Different Technologies 469Wiebren de Jong

151 What is a Biorefinery and What is the Difference with anOil Refinery 470

152 Types of Biorefineries 474153 Economic Considerations Evaluating Biorefinery Concepts

Basic Methods for Assessing Investments and Cost Prices 481154 Outlook to the Future of Biorefineries 492Chapter Summary and Study Guide 493Key Concepts 493Short-Answer Questions 493Problems 494Projects 497Internet References 500References 500

PART IV END USES 503

16 High-Efficiency Energy Systems withBiomass Gasifiers and Solid Oxide Fuel Cells 505PV Aravind and Ming Liu

161 Introduction 506162 Solid Oxide Fuel Cells 507163 Biomass GasifierndashSOFC Combination 512164 Concluding Remarks 520Chapter Summary and Study Guide 520Key Concepts 521Short-Answer Questions 521Problems 521Projects 522Internet References 522References 523

17 Synthesis Gas Utilization for TransportationFuel Production 525J Ruud van Ommen and Johan Grievink

171 Introduction 526172 FischerndashTropsch Synthesis 527173 Synthetic Natural Gas Synthesis 535174 Methanol Synthesis 537

xiCONTENTS

175 Comparison of the Different Options 538Chapter Summary and Study Guide 540Key Concepts 540Short-Answer Questions 541Problems 541Projects 544Internet References 545References 545

18 Chemistry of Biofuels and Biofuel Additivesfrom Biomass 547Isabel WCE Arends

181 Introduction 548182 Bioethanol and Biodiesel 548183 Conversion of Sugars to Hydrocarbon Fuels 553184 Greenness of the Conversion of Platform Molecules

into Biobased Fuel Additives 557185 Direct Aqueous Reforming of Sugars Leading to a

Range of Alkanes 564186 Future Generations of Biofuel 566Chapter Summary and Study Guide 566Key Concepts 567Short-Answer Questions 567Problems 568Projects 568Internet References 568References 569

INDEX 571

xii CONTENTS

PREFACE

This book deals with bioenergy as a versatile renewable source Ever since thedawn of mankind people have been using wood and other biogenic sources forheating cooking and lighting Trade of biomass came up in historic times (thinkabout the silk route for example) Even industrial iron making via metal reductionwas based on biomass utilization (carbonization) However that very applicationalso led to substantial deforestation which was clear in the United Kingdomand demonstrated that using biomass does not guarantee a sustainable energy sup-ply Therefore the industrial revolution introduced the large-scale application offossil fuel starting with the use of coal

The steam engine became the workhorse of the nineteenth century Coal alsobecame the basis of the chemical industry at that time Oil was initially used for lampsbut later it appeared to be the choice of raw material for petrol and diesel in Otto andDiesel engines respectively Wood and other sources came back into the pictureduring the interbellum period and the Second World War when oil was scarce inparticular on the European continent At that time cars trucks and ships made useof the gas extracted from fixed bed wood gasification installations Also chemicalssupply and materials were increasingly supported by wood-based processes AfterWWII the cheap oil era was entered and such routes were largely abandoned Afterthe oil crises of the 1970s biomass came back into the picture as an energy sourcereinforced by environmental concerns about the use of fossil energy sources due totheir associated CO2 emissions stimulating the greenhouse effect At present biomassis seriously back as part of a sustainable energy mix in combination with materialsand chemicals supply and a wide world of biorefinery options has opened up

The field of biomass to energy supply is multidisciplinary and offers a wealth ofintegration of knowledge to young engineers starting their careers The technologies

xiii

strongly lean on chemical engineering skills but also on physics mechanical engineer-ing and agricultural sciences among others Not only technology issues determine thesuccess of biomass for our energy supply there are many hurdles to be taken into thenontechnical domain such as logistics (trade and handling) infrastructure and politics(subsidies rural development employment generation etc) to name a few

This book is divided into four parts covering broad areas of the field of biomassconversion technology chains Part I starts with the socioeconomic and environmentalcontext and biomass basics It gives insight into the boundary conditions and the playingfield bioenergy supply has Moreover it provides a deeper look into what biomass reallyis Part II covers the chemical engineering basics to provide the engineer with tools tosolve problems in the domain design new biomass-based processes and evaluateconversion subprocesses The tools range from setting up balances evaluating the massand heat transport phenomena thermodynamics and kinetics to reactor and processdesign Part III deals with the study of different biomass conversion processes rangingfrom nonreactive pretreatment via combustion processes gasification hydrothermal pro-cessing pyrolysis and torrefaction to biochemical conversion processes and biorefineryintegration of such technologies Finally Part IV treats the end use of primary biomassconversion products for example power production via fuel cells transportationfuel production (eg via the FischerndashTropsch process) and platform chemicalsproduction via organic chemistry to substitute the conventional petrochemical pathwaysoffered today

We were inspired to write this book by the course ldquoEnergy from Biomassrdquo that wehave been teaching for a number of years in the MSc program of Sustainable EnergyTechnology at Delft University a program that is part of the 3TU cooperation betweenthe technical universities of Delft Eindhoven and Twente After teaching the coursefor some years using the lecture notes prepared by our Eindhoven colleagues RobBastiaans Jeroen van Oijen andMark Prins we thought it would be worthy to furtherimprove the course material Since the students in Sustainable Energy Technologyhave a very diverse background we have devoted Part II of the book to giving thereader enough background in chemical engineering for reading the more specializedchapters This means that this book is useful for everyone with a BSc in anyengineering discipline Apart from students at the MSc level professionals in thebiomass field may also find this book as a knowledgeable source for example fordesigning and evaluating novel biorefinery systems and conversion components

Delft December 2013 WIEBREN DE JONG AND J RUUD VAN OMMEN

He will be like a tree planted by the water that sends out its roots by the stream It doesnot fear when heat comes its leaves are always green It has no worries in a year ofdrought and never fails to bear fruit ndash Bible Jeremiah 178

Biomass is forever ndash Prof David Halldagger

xiv PREFACE

ACKNOWLEDGMENTS

This book would not have been published without the contributions from manypeople First of all we would like to acknowledge all the students that followedour course ldquoEnergy from Biomassrdquo over the years they inspired us to compose thisbook We are very glad that many of our colleagues agreed to contribute chapters tothis book It was great to work with this team of co-authors all bringing in their spe-cific expertise to cover the broad field of energy from biomass A big thanks to all ofyou For some chapters the additional input from others is specifically acknowledgedLikun Ma is kindly acknowledged for his contribution to the examples in Chapter 4Ryan Bogaars for his suggestions concerning Chapter 10 Xiangmei Meng and Onur-sal Yakaboylu for contributing some of the examples of Chapter 10 Richard Eijsbergfor the first generation ethanol process figures and data in Chapter 13 Tim Geraedtsand Elze Oude Lansink for the project in Chapter 15 Fred van Rantwijk for valuableinput and discussions on Chapter 18 and Adrea Fabre for her advices regarding thewritingWe are also grateful for the willingness of many colleagues to review chaptersin order to find mistakes and make suggestions for further improvements Ourreviewers were in alphabetic order Rob Bakker Sune Bengtsson PouyanBoukany Anthony Bridgwater Harry Croezen Lilian de Martiacuten Jorge GasconHans Geerlings Johan Grievink Sef Heijnen Kas Hemmes Paulien Herder TrulsLiliedahl Gabrie Meesters Bart Merci Kyriakos Panopoulos Wolter Prins SinaSartipi Fabrizio Scala Tilman Schildhauer Andrzej Stankiewicz GeorgiosStefanidis Bob Ursem Henk van den Berg Theo van der Meer Jules van Lier Maritvan Lieshout and Stanislav Vassilev A special word of thanks should go to Anneliesvan Diepen When the chapters were complete she made a great effort to harmonizethem for example in figures symbols lay-out and wording She also has caughtnumerous mistakes that were still present in earlier versions We would like to thank

xv

Jan Leen Kloosterman (Director of Education Sustainable Energy Technology SET)for the financial support from the SET program for editorial assistance We would alsolike to thank the people at Wiley for the smooth cooperation during the preparation ofthe manuscript Finally we would like to thank the ones close to usmdashKlarine (WdJ)and Ceciel Fenne and Chris (JRvO)mdashfor their understanding and support during allthe evenings and weekends that the writing and editing took

xvi ACKNOWLEDGMENTS

LIST OF CONTRIBUTORS

PV Aravind Drir Department of Process and Energy Energy TechnologySection Faculty of Mechanical Maritime and Materials Engineering DelftUniversity of Technology Delft the Netherlands

Isabel WCE Arends Profdr Department of Biotechnology Biocatalysis GroupFaculty of Applied Sciences Delft University of Technology Delft theNetherlands

Rob JM Bastiaans Drir Department of Mechanical Engineering CombustionTechnology Section Eindhoven University of Technology Eindhoven theNetherlands

Maria C Cuellar Dr Department of Biotechnology BioProcess EngineeringGroup Faculty of Applied Sciences Delft University of Technology Delft theNetherlands

Martina Fantini Drir Department of Process and Energy Energy TechnologySection Faculty of Mechanical Maritime and Materials Engineering DelftUniversity of Technology Delft the Netherlands

Johan Grievink Prof ir Department of Chemical Engineering Product amp ProcessEngineering Group Faculty of Applied Sciences Delft University of TechnologyDelft the Netherlands

ArnoHH Janssen Ir ECN Biomass amp Energy Efficiency Petten the Netherlands

Wiebren de Jong Drir Department of Process and Energy Energy TechnologySection Faculty of Mechanical Maritime and Materials Engineering DelftUniversity of Technology Delft the Netherlands

xvii

Yash Joshi Ir Department of Process and Energy Energy Technology SectionFaculty of Mechanical Maritime and Materials Engineering Delft University ofTechnology Delft the Netherlands

Sascha RA Kersten Profdrir Sustainable Process Technology Group Facultyof Science and Technology University of Twente Enschede the Netherlands

Jaap HA Kiel Profdrir ECN Biomass amp Energy Efficiency Petten andDepartment of Process and Energy Energy Technology Section Faculty ofMechanical Maritime andMaterials Engineering Delft University of TechnologyDelft the Netherlands

Robbert Kleerebezem Drir Department of Biotechnology EnvironmentalBiotechnology Group Faculty of Applied Sciences Delft University of TechnologyDelft the Netherlands

Ming Liu Drir Department of Process and Energy Energy Technology SectionFaculty of Mechanical Maritime and Materials Engineering Delft University ofTechnology Delft the Netherlands

Lilian de Martiacuten Dr Department of Chemical Engineering Product amp ProcessEngineering Group Faculty of Applied Sciences Delft University of TechnologyDelft the Netherlands

Jeroen A van Oijen Drir Department of Mechanical Engineering CombustionTechnology Section Eindhoven University of Technology Eindhoven theNetherlands

J Ruud van Ommen Drir Department of Chemical Engineering Product ampProcess Engineering Group Faculty of Applied Sciences Delft University ofTechnology Delft the Netherlands

Stijn RG Oudenhoven Ir Sustainable Process Technology Group Faculty ofScience and Technology University of Twente Enschede the Netherlands

Dirk JEM Roekaerts Profdr Department of Process and Energy FluidMechanics Section Faculty of Mechanical Maritime and Materials EngineeringDelft University of Technology Delft the Netherlands

Adrie JJ Straathof Drir Department of Biotechnology BioProcess EngineeringGroup Faculty of Applied Sciences Delft University of Technology Delft theNetherlands

Pieter LJ Swinkels Ir Faculty of Applied Sciences Delft Product amp ProcessDesign Institute Delft University of Technology Delft the Netherlands

xviii LIST OF CONTRIBUTORS

PART I

SOCIAL CONTEXT AND STRUCTURALBASIS OF BIOMASS AS A RENEWABLEENERGY SOURCES

1INTRODUCTION SOCIOECONOMICASPECTS OF BIOMASS CONVERSION

WIEBREN DE JONG1 AND J RUUD VAN OMMEN2

1Department of Process and Energy Energy Technology Section Faculty of MechanicalMaritime and Materials Engineering Delft University of Technology Delft the Netherlands2Department of Chemical Engineering Product amp Process Engineering Group Faculty ofApplied Sciences Delft University of Technology Delft the Netherlands

ACRONYMS

CDM clean development mechanismCFCs chlorofluorocarbonsdLUC direct land use changeGDP gross domestic productGHG greenhouse gasiLUC indirect land use changeJI joint implementationLCA life cycle assessmentLUC land use changeRP ratio reserves-to-production ratio [y]TOE tonnes of oil equivalent(s) (= 4187 GJ)UNFCCC United Nations Framework Convention on Climate Change

Biomass as a Sustainable Energy Source for the Future Fundamentals of Conversion ProcessesFirst Edition Edited by Wiebren de Jong and J Ruud van Ommencopy 2015 American Institute of Chemical Engineers Inc Published 2015 by John Wiley amp Sons Inc

3

11 ENERGY SUPPLY ECONOMIC AND ENVIRONMENTALCONSIDERATIONS

111 Introduction The Importance of Energy Supply

In the past two centuries since the Industrial Revolution in the 1700s that was initiatedby the invention of the steam turbine the world has undergone a drastic change due tothe steeply increased contribution of fossil fuels (coal oil and natural gas) to modernsocietiesrsquo energy supply (McKay 2009) Though the Chinese society already usedcoal for energy supply in approximately 1000 BC and the Romans prior to AD 400(World-Coal-Institute 2005) the first written references indicating its use are fromabout the thirteenth century and beyond (Hubbert 1949) These hydrocarbon fuelsso far have been considered essential as they are comparatively cheap and convenientenergy carriers used for heating cooking lighting and mechanical as well as electricpower production and have been widely used as transportation fuels and feedstocksfor the manufacture of bulk and fine chemicals as well as other materials with a widerange of applications Rapid global population growth expansion of economies andhigher standards have caused an enormous increase in worldwide energy consump-tion which was partly made possible by the supply of cheap fossil fuels

112 Development of Global Energy Demand

Figure 11 shows a scenario toward the year 2030 presented by the oil company BPconcerning population growth in relation to developments in total primary energyutilization and gross domestic product (GDP) The figure shows that global energy

Billion

Rest of

the world

India

China

9

8

7

6

5

4

3

2

1

0

Population

Billion toe

18

15

12

9

6

3

0

Energy

Trillion $2010 PPP

180

150

120

90

60

30

01970 1990 2010 2030 1970 1990 2010 2030 1970 1990 2010 2030

GDP

FIGURE 11 Prospected global growth rates in population energy demand and GDP 1 toe =41868104 MJ (Source Adapted from BP see tinyurlcom7hlmqxn)

4 INTRODUCTION

demand will rise substantially from the current level with an increasing share fromChina and India This rise of the primary energy demand is projected to be larger thanthe population growth and this will cause a stress on the limited global resources Theprojected GDP even increases stronger so it is expected that average living standardsincrease which will result in additional strain on the available resources

113 Sustainability of Energy Supply

One of the major questions in the world arising from the general picture sketched inSection 112 is how mankind can ensure a global sustainable development for the(near) future In this context sustainability of our energy supply is of paramountimportance The key issues are discussed in the following text both from a pointof view of global socioeconomics and ecological sustainability

1131 Socioeconomic Sustainability As one of the most important economicdrivers to secure and improve the living standards of people in the world energysupply security is of crucial value for current and future generations Fossil fuelsrun out sooner or later as can be seen in Figure 12 they are not renewable on anacceptable time scale

This figure depicts the so-called RP ratios for different sources The RP ratio is theratio of the current proven reserves to production level The unit is years and it is ameasure of the expected time a certain fuel source is expected to be available

On a global scale it appears that oil and natural gas reserves will be availablemdashgiven the figures of 2012mdashfor an expected approximately 55 years and coal substan-tially longer (gt100 years) Of course new contributions to the reserves may be

0

50

100

150

200

250

1980 1985 1990 1995 2000 2005 2010 2015

RP

(yea

rs)

Oil

Coal

Natural gas

FIGURE 12 Overview of world (top) and regional (bottom) reserves-to-production (RP)ratios for oil natural gas and coal respectively (end 2012 status) Figures are based on datafrom BP (2013)

5ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

North America

S amp Cent America

Europe amp Eurasia

Middle East

Africa

Asia Pacific

0 20 40 60

RP (years)

80 100 120 140

North America

S amp Cent America

Europe amp Eurasia

Middle East

Africa

Asia Pacific

0

RP (years)

North America

S amp Cent America

Europe amp Eurasia

Middle East amp Africa

Asia Pacific

0 50 100 150 200 250 300RP (years)

50 100 150 200

FIGURE 12 (Continued )

6 INTRODUCTION

discovered in the (near) future but that does not change the inherently limited supplynature of the fossil fuel sources Regionally there are also significant differenceswhich is important in the context of energy policy developments on the differentcontinents

For the price developments of the fossil fuels not only their forecasted availabilityis of importance but also the market development in a landscape highly determined bypolitics Already well before the last resources of a fuel will have been depleted themarket will be severely stressed For the economies in the world fuel cost develop-ment is therefore also a primary point of concern From past developments particu-larly regarding oil it has been shown that substantial fuel price fluctuations (volatility)occur which has an impact on the global economy (eg food prices) that is difficult topredict Supply and demand will determine the price evolution for each fuel sourcebut the development of the market structure is also essential there is a large differencebetween a free market and an oligopoly or monopoly situation In this respect diver-sification of fuel sources with associated differentiation in suppliers is advantageousas it makes societies less prone to price manipulation by eg cartel formation andsudden disruptions of supply (Johansson et al 1993)

Self-sufficiency concerning energy supply is often mentioned as target of countriesfor (longer-term) sustainable economic development However not all countries haveaccess to resources within their territories that are sufficient for such a target othercountries on the other hand have a structural surplus Relief of trade barriers canhelp mitigate this structural discrepancy Also in the context of economic sustaina-bility a good trade balance should be maintained in relation to the energy supplywithin nations

Regarding social sustainability in the context of energy supply reduction of pov-erty should be mentioned first a good supply structure of energy carriers is one of thebasic requirements for such a development next to access to clean drinking water andgood soil for agricultural activity Associated herewith expectedly substantial healthimprovement should result from a good energy supply infrastructure Job creation andmaintenance is another aspect of social sustainability and certain energy supply formscan contribute significantly to this Also maintaining (or improving) societiesrsquo socialcohesion is an aspect that can be impacted by the energy supply structure

1132 Ecological Sustainability The energy supply structure should notcompromise the sound development of our environment both from a local and globalperspective One of the major issues in this respect is global warming which is for themain part attributed to the release of greenhouse gases (GHG) from fossil fuel com-bustion Other issues are related to local emissions of acid rain precursors and partic-ulate matter (PM)

Climate Change the Greenhouse Effect and Greenhouse Gas EmissionReduction The greenhouse effect occurs naturally to a large extent Without thiseffect the Earthrsquos average global temperature would reach only a low minus18C ratherthan the current approximate +15C Water vapor is the largest contributor to thiseffect with a complex role for clouds but also CO2 in the atmosphere plays a

7ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

significant role More than a century ago Arrhenius (1896) already identified thisrole in the Earthrsquos temperature control Ice core studies reveal that on millennial timescales changes in CO2 content recorded are highly correlated with changes in tem-perature although some temperature changes have occurred without a significantCO2 concentration change but the opposite does not appear to have happened(Falkowski et al 2000) Less pronounced roles are played by CH4 N2O (nitrousoxide) and several types of chlorofluorocarbons (CFCs) and SF6 It is the CO2CH4 N2O and CFC concentrations in the atmosphere upon which manrsquos industrial

0

1

Rad

iati

ve

forc

ing (

Wm

2)

350

(a)

300

Car

bon d

ioxid

e (p

pm

)

250

300

350

400

1800 1900

Year

2000

(b)

1500

2000

1000

Met

han

e (p

pb)

500

0

02

04

Rad

iati

ve

forc

ing (

Wm

2)

1000

500

1500

2000

1900

Year

20001800

FIGURE 13 Atmospheric concentrations of CO2 CH4 and N2O over the last 10000 years(large panels) and since 1750 (inset panels) Measurements are shown from ice cores (symbolswith different grey shades for different studies) and atmospheric samples (light grey lines insteep curve part red lines in the original publication) The corresponding radiative forcings(net solar energy flux to the earth) relative to 1750 are shown on the right-hand axes of the largepanels (SourceReproducedwithpermission fromIPCC(2007) figure23 figureSPM1copyIPCC)

8 INTRODUCTION

and household activities have a measurable impact Scientists largely agree on thepoint that in the last few centuries the activities of humans have directly or indirectlycaused the concentrations of the major GHG to increase This is exemplified byFigure 13 The atmospheric CO2 concentration varies to some extent from placeto place and from season to season It has been shown that concentrations are some-what higher in the northern hemisphere than in the southern hemisphere as most of theanthropogenic sources of CO2 are located north of the equator The difference in landsurface covered with forests being more concentrated north of the equator causeslarger seasonal fluctuations due to comparatively shorter growth periods than in thegenerally milder southern hemisphere locations that are under the influence of largeroceanic surfaces

Oscillations of atmospheric CO2 concentrations between about 180 and 280 ppmv

have occurred in the past approximately 480000 years in cycles of 100000 yearsbut it appears now we have abandoned this cycling behavior in a remarkably shorttime frame

Studies at the NASA Goddard Institute for Space Studies in New York (UnitedStates) have shown that over the past few decades the combined warming effectof non-CO2 GHG should have been comparable to that of CO2 alone However whileeach of the GHGmentioned earlier acts to warm the surface of the Earth the long-termclimatic effects of the other GHG differ from those of CO2 Methane eg has anatmospheric lifetime of only about 12 years By comparison newly added CO2 willremain for a time span of tens to thousands of years As a result about 65 of thecarbon dioxide that human activities have generated since the start of the IndustrialRevolution is in the air we breathe today A historical record of the amount ofCO2 in the atmosphere can be found in bubbles of air in arctic ice layers dating backas far as 600000 years The depth of such a layer is a measure of its time of formation

(c)

10000 5000

Time (before 2005)

0

0

01

Rad

iati

ve

forc

ing (

Wm

2)

300

270

Nit

rous

oxid

e (p

pb)

270

240

300

330

1800 1900

Year

2000

FIGURE 13 (Continued )

9ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

Another difference is that the principal anthropogenic sources of methane-bacterialfermentation in rice paddies and in the intestines of cattle are related to food produc-tion and hence are roughly proportional to the number of people on the planetBecause CH4 has such a short atmospheric lifetime the amount that is in the air isa good indicator of how much is being added with time Should the global populationdouble over the next half century the concentration of CH4 could also double but it isnot likely to rise by much more than that This would add at most a few tenths of adegree to the mean temperature of the Earth Future CO2 increases could in contrastwarm the climate by 10C or more

Nitrous oxide (N2O) and CFCs are in some ways more like CO2 in that oncereleased they remain in the atmosphere for a century or more The production ofN2O however is only indirectly dependent on human activities Its principal sourceis a natural one the bacterial removal of nitrogen from soils and although the worldpopulation swells in coming years the amount in the air should increase only slowly

The outlook for many CFCs is even more promising Today the most abundant ofthese man-made compounds freon-11 and freon-12 are being phased out of produc-tion altogether by international agreements because of their damaging effects on strat-ospheric ozone Indeed the concentration of one of these gases freon-11 peaked in1994 and is now in a slow decline that should continue for the next century or so Thefreon-12 concentration has not yet leveled off but is expected to do so within the nextfew years In terms of climatic effects the main threat from CFCs comes from otherlong-lived compounds that may be used to replace the ones that have been phased outand that could also act as GHG Since these possibly harmful replacement gases are asyet present in only small amounts and since as noted earlier projected increases inCH4 and N2O are so much less severe we shall for the rest of this discussion focussolely on the most important anthropogenic GHG CO2

Some experts have estimated that the Earthrsquos average global temperature has alreadyincreased by more than 05C since the mid-1900s due to this human-enhanced green-house effect also impacts on sea level (rising) and snow coverage (tending to decrease)have been investigated the results of which are summarized in Figure 14

Like most other planets and planetoids in the universe the Earth contains a greatdeal of carbon which is slowly and continually transported from the mantle to thecrust and back again in the course of volcanic eruption and subduction phenomenaThe portion that finds itself near the surface is continually exchanged and recycledamong plants animals soil air and oceans In some of these temporary stocks car-bon is more securely held while in others it more readily combines with oxygen in theair to form CO2 In order to predict how atmospheric CO2 levels and climate maychange in the future it is important to understand where carbon is stored and whatits dynamic cycling behavior looks like The carbon reservoirs that are most relevantto global warming are listed in Table 11 with the total amount of carbon that theycontained in 2000

The atmosphere contains approximately 720 Gt C in the form of CO2 currentmeasured atmospheric CO2 concentrations are nearly 400 ppmv The rate of changein this carbon stock not only depends on human activities but also on biogeochemicaland climatological processes and their interactions with the global carbon cycle

10 INTRODUCTION

Key Concepts 124Short-Answer Questions 125Problems 125Projects 127References 128

5 Reactions Thermodynamic Aspects Kinetics and Catalysis 129Martina Fantini Wiebren de Jong and J Ruud van Ommen

51 Reaction Kinetics 13052 Chemical Equilibrium 13853 Catalysis 148Chapter Summary and Study Guide 154Key Concepts 155Short-Answer Questions 155Problems 155Projects 156References 158

6 Reactors Idealized Chemical Reactors 159Lilian de Martiacuten and J Ruud van Ommen

61 Preliminary Concepts 16062 Batch Reactors (BRs) 16363 Steady-State Continuous Stirred Tank Reactors (CSTRs) 16764 Steady-State Plug Flow Reactors (PFRs) 16865 Residence Time and Space Time for Flow Reactors 17366 Deviations from Plug Flow and Perfect Mixing 176Chapter Summary and Study Guide 180Key Concepts 181Short-Answer Questions 181Problems 181Project 182References 183

7 Processes Basics of Process Design 184Johan Grievink Pieter LJ Swinkels and J Ruud van Ommen

71 Scope 18672 Characterization of Biomass Processing 18773 Analyzing the Outside of a Process 18974 Analyzing the Inside of a Process 19275 A Design Procedure for Biomass Conversion Processes 19576 Interface with Supply Chain InputndashOutput Diagram 20177 Division in Subprocesses 20678 Process Design Functional Block Diagram 207

viiCONTENTS

79 Example of Analysis and Evaluation in Process Design 212710 Integrating Process Units into the Functional Network 222711 Application Potential 224Chapter Summary and Study Guide 224Key Concepts 225Short-Answer Questions 225Problems 226Projects 229Internet References 229References 229

PART III BIOMASS CONVERSION TECHNOLOGIES 231

8 Physical Pretreatment of Biomass 233Wiebren de Jong

81 Introduction 23582 Harvesting and Transport 23683 Storage 24184 Washing 24285 Size Reduction 24386 Particle Size Characterization 24787 Screening and Classification 24988 Methods of Moisture Reduction 24989 Compaction Technologies 257810 Sequencing the Pretreatment Steps 261Chapter Summary and Study Guide 261Key Concepts 261Short-Answer Questions 262Problems 263Projects 264Internet References 265References 265

9 Thermochemical Conversion Direct Combustion 268Rob JM Bastiaans and Jeroen A van Oijen

91 Introduction 27092 Fundamental Conversion Processes 27193 Particle Conversion Modes 27394 Combustion Systems 28395 Emissions 288Chapter Summary and Study Guide 294Key Concepts 295Short-Answer Questions 295

viii CONTENTS

Problems 295Projects 296Internet References 296References 297

10 Thermochemical Conversion (Co)gasification andHydrothermal Gasification 298Sascha RA Kersten and Wiebren de Jong

101 What is Gasification A Chemical and Engineering Background 300102 A Short History of Gasification 317103 (Co)gasification Technologies for Dry Biomass 318104 Gasification in an Aqueous Environment Hydrothermal

Biomass Conversion 329105 Gas Cleaning for Biomass Gasification Processes 337Chapter Summary and Study Guide 348Key Concepts 348Short-Answer Questions 349Problems 350Projects 353Internet References 353References 353

11 Thermochemical Conversion An Introductionto Fast Pyrolysis 359Stijn RG Oudenhoven and Sascha RA Kersten

111 Introduction 361112 A First Look at a Liquefaction Process 362113 A First Look at Fast Pyrolysis Oil 363114 Chemistry and Kinetics of Pyrolysis 364115 Processes at the Particle Level 368116 A Closer Look at Pyrolysis Oil 371117 Fast Pyrolysis Processes 374118 Catalytic Pyrolysis 377119 Oil Applications 3781110 Outlook 380Appendix 111 Single-Particle Model (Based on the Model byDi Blasi 1997) 380Chapter Summary and Study Guide 383Key Concepts 383Short-Answer Questions 383Problems 384Projects 384Internet References 385References 385

ixCONTENTS

12 Thermochemical Conversion Torrefaction 388Jaap HA Kiel Arno HH Janssen and Yash Joshi

121 Introduction 388122 Fundamentals of Torrefaction 389123 Advantages of Torrefaction 392124 Torrefaction Technology 392125 Torrefaction An Enabling Technology 397126 The Future of Torrefaction 398Chapter Summary and Study Guide 399Key Concepts 399Short-Answer Questions 399Problems 400Projects 401References 401

13 Biochemical Conversion Biofuels byIndustrial Fermentation 403Maria C Cuellar and Adrie JJ Straathof

131 Introduction 404132 First-Generation Bioethanol Processes 406133 Second-Generation Bioethanol Processes 417134 Butanol 428135 Diesel-like Products 429136 Stoichiometric and Thermodynamic Comparison of

Fermentative Biofuels 432137 Outlook 436Chapter Summary and Study Guide 437Key Concepts 438Short-Answer Questions 438Problems 438Projects 439References 439

14 Biochemical Conversion Anaerobic Digestion 441Robbert Kleerebezem

141 Introduction 442142 Biochemical Fundamentals 443143 Thermodynamic Fundamentals 453144 Process Engineering 454145 Outlook and Discussion 463Chapter Summary and Study Guide 466Key Concepts 466Short-Answer Questions 466Problems 467

x CONTENTS

Project 467References 468

15 Biorefineries Integration of Different Technologies 469Wiebren de Jong

151 What is a Biorefinery and What is the Difference with anOil Refinery 470

152 Types of Biorefineries 474153 Economic Considerations Evaluating Biorefinery Concepts

Basic Methods for Assessing Investments and Cost Prices 481154 Outlook to the Future of Biorefineries 492Chapter Summary and Study Guide 493Key Concepts 493Short-Answer Questions 493Problems 494Projects 497Internet References 500References 500

PART IV END USES 503

16 High-Efficiency Energy Systems withBiomass Gasifiers and Solid Oxide Fuel Cells 505PV Aravind and Ming Liu

161 Introduction 506162 Solid Oxide Fuel Cells 507163 Biomass GasifierndashSOFC Combination 512164 Concluding Remarks 520Chapter Summary and Study Guide 520Key Concepts 521Short-Answer Questions 521Problems 521Projects 522Internet References 522References 523

17 Synthesis Gas Utilization for TransportationFuel Production 525J Ruud van Ommen and Johan Grievink

171 Introduction 526172 FischerndashTropsch Synthesis 527173 Synthetic Natural Gas Synthesis 535174 Methanol Synthesis 537

xiCONTENTS

175 Comparison of the Different Options 538Chapter Summary and Study Guide 540Key Concepts 540Short-Answer Questions 541Problems 541Projects 544Internet References 545References 545

18 Chemistry of Biofuels and Biofuel Additivesfrom Biomass 547Isabel WCE Arends

181 Introduction 548182 Bioethanol and Biodiesel 548183 Conversion of Sugars to Hydrocarbon Fuels 553184 Greenness of the Conversion of Platform Molecules

into Biobased Fuel Additives 557185 Direct Aqueous Reforming of Sugars Leading to a

Range of Alkanes 564186 Future Generations of Biofuel 566Chapter Summary and Study Guide 566Key Concepts 567Short-Answer Questions 567Problems 568Projects 568Internet References 568References 569

INDEX 571

xii CONTENTS

PREFACE

This book deals with bioenergy as a versatile renewable source Ever since thedawn of mankind people have been using wood and other biogenic sources forheating cooking and lighting Trade of biomass came up in historic times (thinkabout the silk route for example) Even industrial iron making via metal reductionwas based on biomass utilization (carbonization) However that very applicationalso led to substantial deforestation which was clear in the United Kingdomand demonstrated that using biomass does not guarantee a sustainable energy sup-ply Therefore the industrial revolution introduced the large-scale application offossil fuel starting with the use of coal

The steam engine became the workhorse of the nineteenth century Coal alsobecame the basis of the chemical industry at that time Oil was initially used for lampsbut later it appeared to be the choice of raw material for petrol and diesel in Otto andDiesel engines respectively Wood and other sources came back into the pictureduring the interbellum period and the Second World War when oil was scarce inparticular on the European continent At that time cars trucks and ships made useof the gas extracted from fixed bed wood gasification installations Also chemicalssupply and materials were increasingly supported by wood-based processes AfterWWII the cheap oil era was entered and such routes were largely abandoned Afterthe oil crises of the 1970s biomass came back into the picture as an energy sourcereinforced by environmental concerns about the use of fossil energy sources due totheir associated CO2 emissions stimulating the greenhouse effect At present biomassis seriously back as part of a sustainable energy mix in combination with materialsand chemicals supply and a wide world of biorefinery options has opened up

The field of biomass to energy supply is multidisciplinary and offers a wealth ofintegration of knowledge to young engineers starting their careers The technologies

xiii

strongly lean on chemical engineering skills but also on physics mechanical engineer-ing and agricultural sciences among others Not only technology issues determine thesuccess of biomass for our energy supply there are many hurdles to be taken into thenontechnical domain such as logistics (trade and handling) infrastructure and politics(subsidies rural development employment generation etc) to name a few

This book is divided into four parts covering broad areas of the field of biomassconversion technology chains Part I starts with the socioeconomic and environmentalcontext and biomass basics It gives insight into the boundary conditions and the playingfield bioenergy supply has Moreover it provides a deeper look into what biomass reallyis Part II covers the chemical engineering basics to provide the engineer with tools tosolve problems in the domain design new biomass-based processes and evaluateconversion subprocesses The tools range from setting up balances evaluating the massand heat transport phenomena thermodynamics and kinetics to reactor and processdesign Part III deals with the study of different biomass conversion processes rangingfrom nonreactive pretreatment via combustion processes gasification hydrothermal pro-cessing pyrolysis and torrefaction to biochemical conversion processes and biorefineryintegration of such technologies Finally Part IV treats the end use of primary biomassconversion products for example power production via fuel cells transportationfuel production (eg via the FischerndashTropsch process) and platform chemicalsproduction via organic chemistry to substitute the conventional petrochemical pathwaysoffered today

We were inspired to write this book by the course ldquoEnergy from Biomassrdquo that wehave been teaching for a number of years in the MSc program of Sustainable EnergyTechnology at Delft University a program that is part of the 3TU cooperation betweenthe technical universities of Delft Eindhoven and Twente After teaching the coursefor some years using the lecture notes prepared by our Eindhoven colleagues RobBastiaans Jeroen van Oijen andMark Prins we thought it would be worthy to furtherimprove the course material Since the students in Sustainable Energy Technologyhave a very diverse background we have devoted Part II of the book to giving thereader enough background in chemical engineering for reading the more specializedchapters This means that this book is useful for everyone with a BSc in anyengineering discipline Apart from students at the MSc level professionals in thebiomass field may also find this book as a knowledgeable source for example fordesigning and evaluating novel biorefinery systems and conversion components

Delft December 2013 WIEBREN DE JONG AND J RUUD VAN OMMEN

He will be like a tree planted by the water that sends out its roots by the stream It doesnot fear when heat comes its leaves are always green It has no worries in a year ofdrought and never fails to bear fruit ndash Bible Jeremiah 178

Biomass is forever ndash Prof David Halldagger

xiv PREFACE

ACKNOWLEDGMENTS

This book would not have been published without the contributions from manypeople First of all we would like to acknowledge all the students that followedour course ldquoEnergy from Biomassrdquo over the years they inspired us to compose thisbook We are very glad that many of our colleagues agreed to contribute chapters tothis book It was great to work with this team of co-authors all bringing in their spe-cific expertise to cover the broad field of energy from biomass A big thanks to all ofyou For some chapters the additional input from others is specifically acknowledgedLikun Ma is kindly acknowledged for his contribution to the examples in Chapter 4Ryan Bogaars for his suggestions concerning Chapter 10 Xiangmei Meng and Onur-sal Yakaboylu for contributing some of the examples of Chapter 10 Richard Eijsbergfor the first generation ethanol process figures and data in Chapter 13 Tim Geraedtsand Elze Oude Lansink for the project in Chapter 15 Fred van Rantwijk for valuableinput and discussions on Chapter 18 and Adrea Fabre for her advices regarding thewritingWe are also grateful for the willingness of many colleagues to review chaptersin order to find mistakes and make suggestions for further improvements Ourreviewers were in alphabetic order Rob Bakker Sune Bengtsson PouyanBoukany Anthony Bridgwater Harry Croezen Lilian de Martiacuten Jorge GasconHans Geerlings Johan Grievink Sef Heijnen Kas Hemmes Paulien Herder TrulsLiliedahl Gabrie Meesters Bart Merci Kyriakos Panopoulos Wolter Prins SinaSartipi Fabrizio Scala Tilman Schildhauer Andrzej Stankiewicz GeorgiosStefanidis Bob Ursem Henk van den Berg Theo van der Meer Jules van Lier Maritvan Lieshout and Stanislav Vassilev A special word of thanks should go to Anneliesvan Diepen When the chapters were complete she made a great effort to harmonizethem for example in figures symbols lay-out and wording She also has caughtnumerous mistakes that were still present in earlier versions We would like to thank

xv

Jan Leen Kloosterman (Director of Education Sustainable Energy Technology SET)for the financial support from the SET program for editorial assistance We would alsolike to thank the people at Wiley for the smooth cooperation during the preparation ofthe manuscript Finally we would like to thank the ones close to usmdashKlarine (WdJ)and Ceciel Fenne and Chris (JRvO)mdashfor their understanding and support during allthe evenings and weekends that the writing and editing took

xvi ACKNOWLEDGMENTS

LIST OF CONTRIBUTORS

PV Aravind Drir Department of Process and Energy Energy TechnologySection Faculty of Mechanical Maritime and Materials Engineering DelftUniversity of Technology Delft the Netherlands

Isabel WCE Arends Profdr Department of Biotechnology Biocatalysis GroupFaculty of Applied Sciences Delft University of Technology Delft theNetherlands

Rob JM Bastiaans Drir Department of Mechanical Engineering CombustionTechnology Section Eindhoven University of Technology Eindhoven theNetherlands

Maria C Cuellar Dr Department of Biotechnology BioProcess EngineeringGroup Faculty of Applied Sciences Delft University of Technology Delft theNetherlands

Martina Fantini Drir Department of Process and Energy Energy TechnologySection Faculty of Mechanical Maritime and Materials Engineering DelftUniversity of Technology Delft the Netherlands

Johan Grievink Prof ir Department of Chemical Engineering Product amp ProcessEngineering Group Faculty of Applied Sciences Delft University of TechnologyDelft the Netherlands

ArnoHH Janssen Ir ECN Biomass amp Energy Efficiency Petten the Netherlands

Wiebren de Jong Drir Department of Process and Energy Energy TechnologySection Faculty of Mechanical Maritime and Materials Engineering DelftUniversity of Technology Delft the Netherlands

xvii

Yash Joshi Ir Department of Process and Energy Energy Technology SectionFaculty of Mechanical Maritime and Materials Engineering Delft University ofTechnology Delft the Netherlands

Sascha RA Kersten Profdrir Sustainable Process Technology Group Facultyof Science and Technology University of Twente Enschede the Netherlands

Jaap HA Kiel Profdrir ECN Biomass amp Energy Efficiency Petten andDepartment of Process and Energy Energy Technology Section Faculty ofMechanical Maritime andMaterials Engineering Delft University of TechnologyDelft the Netherlands

Robbert Kleerebezem Drir Department of Biotechnology EnvironmentalBiotechnology Group Faculty of Applied Sciences Delft University of TechnologyDelft the Netherlands

Ming Liu Drir Department of Process and Energy Energy Technology SectionFaculty of Mechanical Maritime and Materials Engineering Delft University ofTechnology Delft the Netherlands

Lilian de Martiacuten Dr Department of Chemical Engineering Product amp ProcessEngineering Group Faculty of Applied Sciences Delft University of TechnologyDelft the Netherlands

Jeroen A van Oijen Drir Department of Mechanical Engineering CombustionTechnology Section Eindhoven University of Technology Eindhoven theNetherlands

J Ruud van Ommen Drir Department of Chemical Engineering Product ampProcess Engineering Group Faculty of Applied Sciences Delft University ofTechnology Delft the Netherlands

Stijn RG Oudenhoven Ir Sustainable Process Technology Group Faculty ofScience and Technology University of Twente Enschede the Netherlands

Dirk JEM Roekaerts Profdr Department of Process and Energy FluidMechanics Section Faculty of Mechanical Maritime and Materials EngineeringDelft University of Technology Delft the Netherlands

Adrie JJ Straathof Drir Department of Biotechnology BioProcess EngineeringGroup Faculty of Applied Sciences Delft University of Technology Delft theNetherlands

Pieter LJ Swinkels Ir Faculty of Applied Sciences Delft Product amp ProcessDesign Institute Delft University of Technology Delft the Netherlands

xviii LIST OF CONTRIBUTORS

PART I

SOCIAL CONTEXT AND STRUCTURALBASIS OF BIOMASS AS A RENEWABLEENERGY SOURCES

1INTRODUCTION SOCIOECONOMICASPECTS OF BIOMASS CONVERSION

WIEBREN DE JONG1 AND J RUUD VAN OMMEN2

1Department of Process and Energy Energy Technology Section Faculty of MechanicalMaritime and Materials Engineering Delft University of Technology Delft the Netherlands2Department of Chemical Engineering Product amp Process Engineering Group Faculty ofApplied Sciences Delft University of Technology Delft the Netherlands

ACRONYMS

CDM clean development mechanismCFCs chlorofluorocarbonsdLUC direct land use changeGDP gross domestic productGHG greenhouse gasiLUC indirect land use changeJI joint implementationLCA life cycle assessmentLUC land use changeRP ratio reserves-to-production ratio [y]TOE tonnes of oil equivalent(s) (= 4187 GJ)UNFCCC United Nations Framework Convention on Climate Change

Biomass as a Sustainable Energy Source for the Future Fundamentals of Conversion ProcessesFirst Edition Edited by Wiebren de Jong and J Ruud van Ommencopy 2015 American Institute of Chemical Engineers Inc Published 2015 by John Wiley amp Sons Inc

3

11 ENERGY SUPPLY ECONOMIC AND ENVIRONMENTALCONSIDERATIONS

111 Introduction The Importance of Energy Supply

In the past two centuries since the Industrial Revolution in the 1700s that was initiatedby the invention of the steam turbine the world has undergone a drastic change due tothe steeply increased contribution of fossil fuels (coal oil and natural gas) to modernsocietiesrsquo energy supply (McKay 2009) Though the Chinese society already usedcoal for energy supply in approximately 1000 BC and the Romans prior to AD 400(World-Coal-Institute 2005) the first written references indicating its use are fromabout the thirteenth century and beyond (Hubbert 1949) These hydrocarbon fuelsso far have been considered essential as they are comparatively cheap and convenientenergy carriers used for heating cooking lighting and mechanical as well as electricpower production and have been widely used as transportation fuels and feedstocksfor the manufacture of bulk and fine chemicals as well as other materials with a widerange of applications Rapid global population growth expansion of economies andhigher standards have caused an enormous increase in worldwide energy consump-tion which was partly made possible by the supply of cheap fossil fuels

112 Development of Global Energy Demand

Figure 11 shows a scenario toward the year 2030 presented by the oil company BPconcerning population growth in relation to developments in total primary energyutilization and gross domestic product (GDP) The figure shows that global energy

Billion

Rest of

the world

India

China

9

8

7

6

5

4

3

2

1

0

Population

Billion toe

18

15

12

9

6

3

0

Energy

Trillion $2010 PPP

180

150

120

90

60

30

01970 1990 2010 2030 1970 1990 2010 2030 1970 1990 2010 2030

GDP

FIGURE 11 Prospected global growth rates in population energy demand and GDP 1 toe =41868104 MJ (Source Adapted from BP see tinyurlcom7hlmqxn)

4 INTRODUCTION

demand will rise substantially from the current level with an increasing share fromChina and India This rise of the primary energy demand is projected to be larger thanthe population growth and this will cause a stress on the limited global resources Theprojected GDP even increases stronger so it is expected that average living standardsincrease which will result in additional strain on the available resources

113 Sustainability of Energy Supply

One of the major questions in the world arising from the general picture sketched inSection 112 is how mankind can ensure a global sustainable development for the(near) future In this context sustainability of our energy supply is of paramountimportance The key issues are discussed in the following text both from a pointof view of global socioeconomics and ecological sustainability

1131 Socioeconomic Sustainability As one of the most important economicdrivers to secure and improve the living standards of people in the world energysupply security is of crucial value for current and future generations Fossil fuelsrun out sooner or later as can be seen in Figure 12 they are not renewable on anacceptable time scale

This figure depicts the so-called RP ratios for different sources The RP ratio is theratio of the current proven reserves to production level The unit is years and it is ameasure of the expected time a certain fuel source is expected to be available

On a global scale it appears that oil and natural gas reserves will be availablemdashgiven the figures of 2012mdashfor an expected approximately 55 years and coal substan-tially longer (gt100 years) Of course new contributions to the reserves may be

0

50

100

150

200

250

1980 1985 1990 1995 2000 2005 2010 2015

RP

(yea

rs)

Oil

Coal

Natural gas

FIGURE 12 Overview of world (top) and regional (bottom) reserves-to-production (RP)ratios for oil natural gas and coal respectively (end 2012 status) Figures are based on datafrom BP (2013)

5ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

North America

S amp Cent America

Europe amp Eurasia

Middle East

Africa

Asia Pacific

0 20 40 60

RP (years)

80 100 120 140

North America

S amp Cent America

Europe amp Eurasia

Middle East

Africa

Asia Pacific

0

RP (years)

North America

S amp Cent America

Europe amp Eurasia

Middle East amp Africa

Asia Pacific

0 50 100 150 200 250 300RP (years)

50 100 150 200

FIGURE 12 (Continued )

6 INTRODUCTION

discovered in the (near) future but that does not change the inherently limited supplynature of the fossil fuel sources Regionally there are also significant differenceswhich is important in the context of energy policy developments on the differentcontinents

For the price developments of the fossil fuels not only their forecasted availabilityis of importance but also the market development in a landscape highly determined bypolitics Already well before the last resources of a fuel will have been depleted themarket will be severely stressed For the economies in the world fuel cost develop-ment is therefore also a primary point of concern From past developments particu-larly regarding oil it has been shown that substantial fuel price fluctuations (volatility)occur which has an impact on the global economy (eg food prices) that is difficult topredict Supply and demand will determine the price evolution for each fuel sourcebut the development of the market structure is also essential there is a large differencebetween a free market and an oligopoly or monopoly situation In this respect diver-sification of fuel sources with associated differentiation in suppliers is advantageousas it makes societies less prone to price manipulation by eg cartel formation andsudden disruptions of supply (Johansson et al 1993)

Self-sufficiency concerning energy supply is often mentioned as target of countriesfor (longer-term) sustainable economic development However not all countries haveaccess to resources within their territories that are sufficient for such a target othercountries on the other hand have a structural surplus Relief of trade barriers canhelp mitigate this structural discrepancy Also in the context of economic sustaina-bility a good trade balance should be maintained in relation to the energy supplywithin nations

Regarding social sustainability in the context of energy supply reduction of pov-erty should be mentioned first a good supply structure of energy carriers is one of thebasic requirements for such a development next to access to clean drinking water andgood soil for agricultural activity Associated herewith expectedly substantial healthimprovement should result from a good energy supply infrastructure Job creation andmaintenance is another aspect of social sustainability and certain energy supply formscan contribute significantly to this Also maintaining (or improving) societiesrsquo socialcohesion is an aspect that can be impacted by the energy supply structure

1132 Ecological Sustainability The energy supply structure should notcompromise the sound development of our environment both from a local and globalperspective One of the major issues in this respect is global warming which is for themain part attributed to the release of greenhouse gases (GHG) from fossil fuel com-bustion Other issues are related to local emissions of acid rain precursors and partic-ulate matter (PM)

Climate Change the Greenhouse Effect and Greenhouse Gas EmissionReduction The greenhouse effect occurs naturally to a large extent Without thiseffect the Earthrsquos average global temperature would reach only a low minus18C ratherthan the current approximate +15C Water vapor is the largest contributor to thiseffect with a complex role for clouds but also CO2 in the atmosphere plays a

7ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

significant role More than a century ago Arrhenius (1896) already identified thisrole in the Earthrsquos temperature control Ice core studies reveal that on millennial timescales changes in CO2 content recorded are highly correlated with changes in tem-perature although some temperature changes have occurred without a significantCO2 concentration change but the opposite does not appear to have happened(Falkowski et al 2000) Less pronounced roles are played by CH4 N2O (nitrousoxide) and several types of chlorofluorocarbons (CFCs) and SF6 It is the CO2CH4 N2O and CFC concentrations in the atmosphere upon which manrsquos industrial

0

1

Rad

iati

ve

forc

ing (

Wm

2)

350

(a)

300

Car

bon d

ioxid

e (p

pm

)

250

300

350

400

1800 1900

Year

2000

(b)

1500

2000

1000

Met

han

e (p

pb)

500

0

02

04

Rad

iati

ve

forc

ing (

Wm

2)

1000

500

1500

2000

1900

Year

20001800

FIGURE 13 Atmospheric concentrations of CO2 CH4 and N2O over the last 10000 years(large panels) and since 1750 (inset panels) Measurements are shown from ice cores (symbolswith different grey shades for different studies) and atmospheric samples (light grey lines insteep curve part red lines in the original publication) The corresponding radiative forcings(net solar energy flux to the earth) relative to 1750 are shown on the right-hand axes of the largepanels (SourceReproducedwithpermission fromIPCC(2007) figure23 figureSPM1copyIPCC)

8 INTRODUCTION

and household activities have a measurable impact Scientists largely agree on thepoint that in the last few centuries the activities of humans have directly or indirectlycaused the concentrations of the major GHG to increase This is exemplified byFigure 13 The atmospheric CO2 concentration varies to some extent from placeto place and from season to season It has been shown that concentrations are some-what higher in the northern hemisphere than in the southern hemisphere as most of theanthropogenic sources of CO2 are located north of the equator The difference in landsurface covered with forests being more concentrated north of the equator causeslarger seasonal fluctuations due to comparatively shorter growth periods than in thegenerally milder southern hemisphere locations that are under the influence of largeroceanic surfaces

Oscillations of atmospheric CO2 concentrations between about 180 and 280 ppmv

have occurred in the past approximately 480000 years in cycles of 100000 yearsbut it appears now we have abandoned this cycling behavior in a remarkably shorttime frame

Studies at the NASA Goddard Institute for Space Studies in New York (UnitedStates) have shown that over the past few decades the combined warming effectof non-CO2 GHG should have been comparable to that of CO2 alone However whileeach of the GHGmentioned earlier acts to warm the surface of the Earth the long-termclimatic effects of the other GHG differ from those of CO2 Methane eg has anatmospheric lifetime of only about 12 years By comparison newly added CO2 willremain for a time span of tens to thousands of years As a result about 65 of thecarbon dioxide that human activities have generated since the start of the IndustrialRevolution is in the air we breathe today A historical record of the amount ofCO2 in the atmosphere can be found in bubbles of air in arctic ice layers dating backas far as 600000 years The depth of such a layer is a measure of its time of formation

(c)

10000 5000

Time (before 2005)

0

0

01

Rad

iati

ve

forc

ing (

Wm

2)

300

270

Nit

rous

oxid

e (p

pb)

270

240

300

330

1800 1900

Year

2000

FIGURE 13 (Continued )

9ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

Another difference is that the principal anthropogenic sources of methane-bacterialfermentation in rice paddies and in the intestines of cattle are related to food produc-tion and hence are roughly proportional to the number of people on the planetBecause CH4 has such a short atmospheric lifetime the amount that is in the air isa good indicator of how much is being added with time Should the global populationdouble over the next half century the concentration of CH4 could also double but it isnot likely to rise by much more than that This would add at most a few tenths of adegree to the mean temperature of the Earth Future CO2 increases could in contrastwarm the climate by 10C or more

Nitrous oxide (N2O) and CFCs are in some ways more like CO2 in that oncereleased they remain in the atmosphere for a century or more The production ofN2O however is only indirectly dependent on human activities Its principal sourceis a natural one the bacterial removal of nitrogen from soils and although the worldpopulation swells in coming years the amount in the air should increase only slowly

The outlook for many CFCs is even more promising Today the most abundant ofthese man-made compounds freon-11 and freon-12 are being phased out of produc-tion altogether by international agreements because of their damaging effects on strat-ospheric ozone Indeed the concentration of one of these gases freon-11 peaked in1994 and is now in a slow decline that should continue for the next century or so Thefreon-12 concentration has not yet leveled off but is expected to do so within the nextfew years In terms of climatic effects the main threat from CFCs comes from otherlong-lived compounds that may be used to replace the ones that have been phased outand that could also act as GHG Since these possibly harmful replacement gases are asyet present in only small amounts and since as noted earlier projected increases inCH4 and N2O are so much less severe we shall for the rest of this discussion focussolely on the most important anthropogenic GHG CO2

Some experts have estimated that the Earthrsquos average global temperature has alreadyincreased by more than 05C since the mid-1900s due to this human-enhanced green-house effect also impacts on sea level (rising) and snow coverage (tending to decrease)have been investigated the results of which are summarized in Figure 14

Like most other planets and planetoids in the universe the Earth contains a greatdeal of carbon which is slowly and continually transported from the mantle to thecrust and back again in the course of volcanic eruption and subduction phenomenaThe portion that finds itself near the surface is continually exchanged and recycledamong plants animals soil air and oceans In some of these temporary stocks car-bon is more securely held while in others it more readily combines with oxygen in theair to form CO2 In order to predict how atmospheric CO2 levels and climate maychange in the future it is important to understand where carbon is stored and whatits dynamic cycling behavior looks like The carbon reservoirs that are most relevantto global warming are listed in Table 11 with the total amount of carbon that theycontained in 2000

The atmosphere contains approximately 720 Gt C in the form of CO2 currentmeasured atmospheric CO2 concentrations are nearly 400 ppmv The rate of changein this carbon stock not only depends on human activities but also on biogeochemicaland climatological processes and their interactions with the global carbon cycle

10 INTRODUCTION

79 Example of Analysis and Evaluation in Process Design 212710 Integrating Process Units into the Functional Network 222711 Application Potential 224Chapter Summary and Study Guide 224Key Concepts 225Short-Answer Questions 225Problems 226Projects 229Internet References 229References 229

PART III BIOMASS CONVERSION TECHNOLOGIES 231

8 Physical Pretreatment of Biomass 233Wiebren de Jong

81 Introduction 23582 Harvesting and Transport 23683 Storage 24184 Washing 24285 Size Reduction 24386 Particle Size Characterization 24787 Screening and Classification 24988 Methods of Moisture Reduction 24989 Compaction Technologies 257810 Sequencing the Pretreatment Steps 261Chapter Summary and Study Guide 261Key Concepts 261Short-Answer Questions 262Problems 263Projects 264Internet References 265References 265

9 Thermochemical Conversion Direct Combustion 268Rob JM Bastiaans and Jeroen A van Oijen

91 Introduction 27092 Fundamental Conversion Processes 27193 Particle Conversion Modes 27394 Combustion Systems 28395 Emissions 288Chapter Summary and Study Guide 294Key Concepts 295Short-Answer Questions 295

viii CONTENTS

Problems 295Projects 296Internet References 296References 297

10 Thermochemical Conversion (Co)gasification andHydrothermal Gasification 298Sascha RA Kersten and Wiebren de Jong

101 What is Gasification A Chemical and Engineering Background 300102 A Short History of Gasification 317103 (Co)gasification Technologies for Dry Biomass 318104 Gasification in an Aqueous Environment Hydrothermal

Biomass Conversion 329105 Gas Cleaning for Biomass Gasification Processes 337Chapter Summary and Study Guide 348Key Concepts 348Short-Answer Questions 349Problems 350Projects 353Internet References 353References 353

11 Thermochemical Conversion An Introductionto Fast Pyrolysis 359Stijn RG Oudenhoven and Sascha RA Kersten

111 Introduction 361112 A First Look at a Liquefaction Process 362113 A First Look at Fast Pyrolysis Oil 363114 Chemistry and Kinetics of Pyrolysis 364115 Processes at the Particle Level 368116 A Closer Look at Pyrolysis Oil 371117 Fast Pyrolysis Processes 374118 Catalytic Pyrolysis 377119 Oil Applications 3781110 Outlook 380Appendix 111 Single-Particle Model (Based on the Model byDi Blasi 1997) 380Chapter Summary and Study Guide 383Key Concepts 383Short-Answer Questions 383Problems 384Projects 384Internet References 385References 385

ixCONTENTS

12 Thermochemical Conversion Torrefaction 388Jaap HA Kiel Arno HH Janssen and Yash Joshi

121 Introduction 388122 Fundamentals of Torrefaction 389123 Advantages of Torrefaction 392124 Torrefaction Technology 392125 Torrefaction An Enabling Technology 397126 The Future of Torrefaction 398Chapter Summary and Study Guide 399Key Concepts 399Short-Answer Questions 399Problems 400Projects 401References 401

13 Biochemical Conversion Biofuels byIndustrial Fermentation 403Maria C Cuellar and Adrie JJ Straathof

131 Introduction 404132 First-Generation Bioethanol Processes 406133 Second-Generation Bioethanol Processes 417134 Butanol 428135 Diesel-like Products 429136 Stoichiometric and Thermodynamic Comparison of

Fermentative Biofuels 432137 Outlook 436Chapter Summary and Study Guide 437Key Concepts 438Short-Answer Questions 438Problems 438Projects 439References 439

14 Biochemical Conversion Anaerobic Digestion 441Robbert Kleerebezem

141 Introduction 442142 Biochemical Fundamentals 443143 Thermodynamic Fundamentals 453144 Process Engineering 454145 Outlook and Discussion 463Chapter Summary and Study Guide 466Key Concepts 466Short-Answer Questions 466Problems 467

x CONTENTS

Project 467References 468

15 Biorefineries Integration of Different Technologies 469Wiebren de Jong

151 What is a Biorefinery and What is the Difference with anOil Refinery 470

152 Types of Biorefineries 474153 Economic Considerations Evaluating Biorefinery Concepts

Basic Methods for Assessing Investments and Cost Prices 481154 Outlook to the Future of Biorefineries 492Chapter Summary and Study Guide 493Key Concepts 493Short-Answer Questions 493Problems 494Projects 497Internet References 500References 500

PART IV END USES 503

16 High-Efficiency Energy Systems withBiomass Gasifiers and Solid Oxide Fuel Cells 505PV Aravind and Ming Liu

161 Introduction 506162 Solid Oxide Fuel Cells 507163 Biomass GasifierndashSOFC Combination 512164 Concluding Remarks 520Chapter Summary and Study Guide 520Key Concepts 521Short-Answer Questions 521Problems 521Projects 522Internet References 522References 523

17 Synthesis Gas Utilization for TransportationFuel Production 525J Ruud van Ommen and Johan Grievink

171 Introduction 526172 FischerndashTropsch Synthesis 527173 Synthetic Natural Gas Synthesis 535174 Methanol Synthesis 537

xiCONTENTS

175 Comparison of the Different Options 538Chapter Summary and Study Guide 540Key Concepts 540Short-Answer Questions 541Problems 541Projects 544Internet References 545References 545

18 Chemistry of Biofuels and Biofuel Additivesfrom Biomass 547Isabel WCE Arends

181 Introduction 548182 Bioethanol and Biodiesel 548183 Conversion of Sugars to Hydrocarbon Fuels 553184 Greenness of the Conversion of Platform Molecules

into Biobased Fuel Additives 557185 Direct Aqueous Reforming of Sugars Leading to a

Range of Alkanes 564186 Future Generations of Biofuel 566Chapter Summary and Study Guide 566Key Concepts 567Short-Answer Questions 567Problems 568Projects 568Internet References 568References 569

INDEX 571

xii CONTENTS

PREFACE

This book deals with bioenergy as a versatile renewable source Ever since thedawn of mankind people have been using wood and other biogenic sources forheating cooking and lighting Trade of biomass came up in historic times (thinkabout the silk route for example) Even industrial iron making via metal reductionwas based on biomass utilization (carbonization) However that very applicationalso led to substantial deforestation which was clear in the United Kingdomand demonstrated that using biomass does not guarantee a sustainable energy sup-ply Therefore the industrial revolution introduced the large-scale application offossil fuel starting with the use of coal

The steam engine became the workhorse of the nineteenth century Coal alsobecame the basis of the chemical industry at that time Oil was initially used for lampsbut later it appeared to be the choice of raw material for petrol and diesel in Otto andDiesel engines respectively Wood and other sources came back into the pictureduring the interbellum period and the Second World War when oil was scarce inparticular on the European continent At that time cars trucks and ships made useof the gas extracted from fixed bed wood gasification installations Also chemicalssupply and materials were increasingly supported by wood-based processes AfterWWII the cheap oil era was entered and such routes were largely abandoned Afterthe oil crises of the 1970s biomass came back into the picture as an energy sourcereinforced by environmental concerns about the use of fossil energy sources due totheir associated CO2 emissions stimulating the greenhouse effect At present biomassis seriously back as part of a sustainable energy mix in combination with materialsand chemicals supply and a wide world of biorefinery options has opened up

The field of biomass to energy supply is multidisciplinary and offers a wealth ofintegration of knowledge to young engineers starting their careers The technologies

xiii

strongly lean on chemical engineering skills but also on physics mechanical engineer-ing and agricultural sciences among others Not only technology issues determine thesuccess of biomass for our energy supply there are many hurdles to be taken into thenontechnical domain such as logistics (trade and handling) infrastructure and politics(subsidies rural development employment generation etc) to name a few

This book is divided into four parts covering broad areas of the field of biomassconversion technology chains Part I starts with the socioeconomic and environmentalcontext and biomass basics It gives insight into the boundary conditions and the playingfield bioenergy supply has Moreover it provides a deeper look into what biomass reallyis Part II covers the chemical engineering basics to provide the engineer with tools tosolve problems in the domain design new biomass-based processes and evaluateconversion subprocesses The tools range from setting up balances evaluating the massand heat transport phenomena thermodynamics and kinetics to reactor and processdesign Part III deals with the study of different biomass conversion processes rangingfrom nonreactive pretreatment via combustion processes gasification hydrothermal pro-cessing pyrolysis and torrefaction to biochemical conversion processes and biorefineryintegration of such technologies Finally Part IV treats the end use of primary biomassconversion products for example power production via fuel cells transportationfuel production (eg via the FischerndashTropsch process) and platform chemicalsproduction via organic chemistry to substitute the conventional petrochemical pathwaysoffered today

We were inspired to write this book by the course ldquoEnergy from Biomassrdquo that wehave been teaching for a number of years in the MSc program of Sustainable EnergyTechnology at Delft University a program that is part of the 3TU cooperation betweenthe technical universities of Delft Eindhoven and Twente After teaching the coursefor some years using the lecture notes prepared by our Eindhoven colleagues RobBastiaans Jeroen van Oijen andMark Prins we thought it would be worthy to furtherimprove the course material Since the students in Sustainable Energy Technologyhave a very diverse background we have devoted Part II of the book to giving thereader enough background in chemical engineering for reading the more specializedchapters This means that this book is useful for everyone with a BSc in anyengineering discipline Apart from students at the MSc level professionals in thebiomass field may also find this book as a knowledgeable source for example fordesigning and evaluating novel biorefinery systems and conversion components

Delft December 2013 WIEBREN DE JONG AND J RUUD VAN OMMEN

He will be like a tree planted by the water that sends out its roots by the stream It doesnot fear when heat comes its leaves are always green It has no worries in a year ofdrought and never fails to bear fruit ndash Bible Jeremiah 178

Biomass is forever ndash Prof David Halldagger

xiv PREFACE

ACKNOWLEDGMENTS

This book would not have been published without the contributions from manypeople First of all we would like to acknowledge all the students that followedour course ldquoEnergy from Biomassrdquo over the years they inspired us to compose thisbook We are very glad that many of our colleagues agreed to contribute chapters tothis book It was great to work with this team of co-authors all bringing in their spe-cific expertise to cover the broad field of energy from biomass A big thanks to all ofyou For some chapters the additional input from others is specifically acknowledgedLikun Ma is kindly acknowledged for his contribution to the examples in Chapter 4Ryan Bogaars for his suggestions concerning Chapter 10 Xiangmei Meng and Onur-sal Yakaboylu for contributing some of the examples of Chapter 10 Richard Eijsbergfor the first generation ethanol process figures and data in Chapter 13 Tim Geraedtsand Elze Oude Lansink for the project in Chapter 15 Fred van Rantwijk for valuableinput and discussions on Chapter 18 and Adrea Fabre for her advices regarding thewritingWe are also grateful for the willingness of many colleagues to review chaptersin order to find mistakes and make suggestions for further improvements Ourreviewers were in alphabetic order Rob Bakker Sune Bengtsson PouyanBoukany Anthony Bridgwater Harry Croezen Lilian de Martiacuten Jorge GasconHans Geerlings Johan Grievink Sef Heijnen Kas Hemmes Paulien Herder TrulsLiliedahl Gabrie Meesters Bart Merci Kyriakos Panopoulos Wolter Prins SinaSartipi Fabrizio Scala Tilman Schildhauer Andrzej Stankiewicz GeorgiosStefanidis Bob Ursem Henk van den Berg Theo van der Meer Jules van Lier Maritvan Lieshout and Stanislav Vassilev A special word of thanks should go to Anneliesvan Diepen When the chapters were complete she made a great effort to harmonizethem for example in figures symbols lay-out and wording She also has caughtnumerous mistakes that were still present in earlier versions We would like to thank

xv

Jan Leen Kloosterman (Director of Education Sustainable Energy Technology SET)for the financial support from the SET program for editorial assistance We would alsolike to thank the people at Wiley for the smooth cooperation during the preparation ofthe manuscript Finally we would like to thank the ones close to usmdashKlarine (WdJ)and Ceciel Fenne and Chris (JRvO)mdashfor their understanding and support during allthe evenings and weekends that the writing and editing took

xvi ACKNOWLEDGMENTS

LIST OF CONTRIBUTORS

PV Aravind Drir Department of Process and Energy Energy TechnologySection Faculty of Mechanical Maritime and Materials Engineering DelftUniversity of Technology Delft the Netherlands

Isabel WCE Arends Profdr Department of Biotechnology Biocatalysis GroupFaculty of Applied Sciences Delft University of Technology Delft theNetherlands

Rob JM Bastiaans Drir Department of Mechanical Engineering CombustionTechnology Section Eindhoven University of Technology Eindhoven theNetherlands

Maria C Cuellar Dr Department of Biotechnology BioProcess EngineeringGroup Faculty of Applied Sciences Delft University of Technology Delft theNetherlands

Martina Fantini Drir Department of Process and Energy Energy TechnologySection Faculty of Mechanical Maritime and Materials Engineering DelftUniversity of Technology Delft the Netherlands

Johan Grievink Prof ir Department of Chemical Engineering Product amp ProcessEngineering Group Faculty of Applied Sciences Delft University of TechnologyDelft the Netherlands

ArnoHH Janssen Ir ECN Biomass amp Energy Efficiency Petten the Netherlands

Wiebren de Jong Drir Department of Process and Energy Energy TechnologySection Faculty of Mechanical Maritime and Materials Engineering DelftUniversity of Technology Delft the Netherlands

xvii

Yash Joshi Ir Department of Process and Energy Energy Technology SectionFaculty of Mechanical Maritime and Materials Engineering Delft University ofTechnology Delft the Netherlands

Sascha RA Kersten Profdrir Sustainable Process Technology Group Facultyof Science and Technology University of Twente Enschede the Netherlands

Jaap HA Kiel Profdrir ECN Biomass amp Energy Efficiency Petten andDepartment of Process and Energy Energy Technology Section Faculty ofMechanical Maritime andMaterials Engineering Delft University of TechnologyDelft the Netherlands

Robbert Kleerebezem Drir Department of Biotechnology EnvironmentalBiotechnology Group Faculty of Applied Sciences Delft University of TechnologyDelft the Netherlands

Ming Liu Drir Department of Process and Energy Energy Technology SectionFaculty of Mechanical Maritime and Materials Engineering Delft University ofTechnology Delft the Netherlands

Lilian de Martiacuten Dr Department of Chemical Engineering Product amp ProcessEngineering Group Faculty of Applied Sciences Delft University of TechnologyDelft the Netherlands

Jeroen A van Oijen Drir Department of Mechanical Engineering CombustionTechnology Section Eindhoven University of Technology Eindhoven theNetherlands

J Ruud van Ommen Drir Department of Chemical Engineering Product ampProcess Engineering Group Faculty of Applied Sciences Delft University ofTechnology Delft the Netherlands

Stijn RG Oudenhoven Ir Sustainable Process Technology Group Faculty ofScience and Technology University of Twente Enschede the Netherlands

Dirk JEM Roekaerts Profdr Department of Process and Energy FluidMechanics Section Faculty of Mechanical Maritime and Materials EngineeringDelft University of Technology Delft the Netherlands

Adrie JJ Straathof Drir Department of Biotechnology BioProcess EngineeringGroup Faculty of Applied Sciences Delft University of Technology Delft theNetherlands

Pieter LJ Swinkels Ir Faculty of Applied Sciences Delft Product amp ProcessDesign Institute Delft University of Technology Delft the Netherlands

xviii LIST OF CONTRIBUTORS

PART I

SOCIAL CONTEXT AND STRUCTURALBASIS OF BIOMASS AS A RENEWABLEENERGY SOURCES

1INTRODUCTION SOCIOECONOMICASPECTS OF BIOMASS CONVERSION

WIEBREN DE JONG1 AND J RUUD VAN OMMEN2

1Department of Process and Energy Energy Technology Section Faculty of MechanicalMaritime and Materials Engineering Delft University of Technology Delft the Netherlands2Department of Chemical Engineering Product amp Process Engineering Group Faculty ofApplied Sciences Delft University of Technology Delft the Netherlands

ACRONYMS

CDM clean development mechanismCFCs chlorofluorocarbonsdLUC direct land use changeGDP gross domestic productGHG greenhouse gasiLUC indirect land use changeJI joint implementationLCA life cycle assessmentLUC land use changeRP ratio reserves-to-production ratio [y]TOE tonnes of oil equivalent(s) (= 4187 GJ)UNFCCC United Nations Framework Convention on Climate Change

Biomass as a Sustainable Energy Source for the Future Fundamentals of Conversion ProcessesFirst Edition Edited by Wiebren de Jong and J Ruud van Ommencopy 2015 American Institute of Chemical Engineers Inc Published 2015 by John Wiley amp Sons Inc

3

11 ENERGY SUPPLY ECONOMIC AND ENVIRONMENTALCONSIDERATIONS

111 Introduction The Importance of Energy Supply

In the past two centuries since the Industrial Revolution in the 1700s that was initiatedby the invention of the steam turbine the world has undergone a drastic change due tothe steeply increased contribution of fossil fuels (coal oil and natural gas) to modernsocietiesrsquo energy supply (McKay 2009) Though the Chinese society already usedcoal for energy supply in approximately 1000 BC and the Romans prior to AD 400(World-Coal-Institute 2005) the first written references indicating its use are fromabout the thirteenth century and beyond (Hubbert 1949) These hydrocarbon fuelsso far have been considered essential as they are comparatively cheap and convenientenergy carriers used for heating cooking lighting and mechanical as well as electricpower production and have been widely used as transportation fuels and feedstocksfor the manufacture of bulk and fine chemicals as well as other materials with a widerange of applications Rapid global population growth expansion of economies andhigher standards have caused an enormous increase in worldwide energy consump-tion which was partly made possible by the supply of cheap fossil fuels

112 Development of Global Energy Demand

Figure 11 shows a scenario toward the year 2030 presented by the oil company BPconcerning population growth in relation to developments in total primary energyutilization and gross domestic product (GDP) The figure shows that global energy

Billion

Rest of

the world

India

China

9

8

7

6

5

4

3

2

1

0

Population

Billion toe

18

15

12

9

6

3

0

Energy

Trillion $2010 PPP

180

150

120

90

60

30

01970 1990 2010 2030 1970 1990 2010 2030 1970 1990 2010 2030

GDP

FIGURE 11 Prospected global growth rates in population energy demand and GDP 1 toe =41868104 MJ (Source Adapted from BP see tinyurlcom7hlmqxn)

4 INTRODUCTION

demand will rise substantially from the current level with an increasing share fromChina and India This rise of the primary energy demand is projected to be larger thanthe population growth and this will cause a stress on the limited global resources Theprojected GDP even increases stronger so it is expected that average living standardsincrease which will result in additional strain on the available resources

113 Sustainability of Energy Supply

One of the major questions in the world arising from the general picture sketched inSection 112 is how mankind can ensure a global sustainable development for the(near) future In this context sustainability of our energy supply is of paramountimportance The key issues are discussed in the following text both from a pointof view of global socioeconomics and ecological sustainability

1131 Socioeconomic Sustainability As one of the most important economicdrivers to secure and improve the living standards of people in the world energysupply security is of crucial value for current and future generations Fossil fuelsrun out sooner or later as can be seen in Figure 12 they are not renewable on anacceptable time scale

This figure depicts the so-called RP ratios for different sources The RP ratio is theratio of the current proven reserves to production level The unit is years and it is ameasure of the expected time a certain fuel source is expected to be available

On a global scale it appears that oil and natural gas reserves will be availablemdashgiven the figures of 2012mdashfor an expected approximately 55 years and coal substan-tially longer (gt100 years) Of course new contributions to the reserves may be

0

50

100

150

200

250

1980 1985 1990 1995 2000 2005 2010 2015

RP

(yea

rs)

Oil

Coal

Natural gas

FIGURE 12 Overview of world (top) and regional (bottom) reserves-to-production (RP)ratios for oil natural gas and coal respectively (end 2012 status) Figures are based on datafrom BP (2013)

5ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

North America

S amp Cent America

Europe amp Eurasia

Middle East

Africa

Asia Pacific

0 20 40 60

RP (years)

80 100 120 140

North America

S amp Cent America

Europe amp Eurasia

Middle East

Africa

Asia Pacific

0

RP (years)

North America

S amp Cent America

Europe amp Eurasia

Middle East amp Africa

Asia Pacific

0 50 100 150 200 250 300RP (years)

50 100 150 200

FIGURE 12 (Continued )

6 INTRODUCTION

discovered in the (near) future but that does not change the inherently limited supplynature of the fossil fuel sources Regionally there are also significant differenceswhich is important in the context of energy policy developments on the differentcontinents

For the price developments of the fossil fuels not only their forecasted availabilityis of importance but also the market development in a landscape highly determined bypolitics Already well before the last resources of a fuel will have been depleted themarket will be severely stressed For the economies in the world fuel cost develop-ment is therefore also a primary point of concern From past developments particu-larly regarding oil it has been shown that substantial fuel price fluctuations (volatility)occur which has an impact on the global economy (eg food prices) that is difficult topredict Supply and demand will determine the price evolution for each fuel sourcebut the development of the market structure is also essential there is a large differencebetween a free market and an oligopoly or monopoly situation In this respect diver-sification of fuel sources with associated differentiation in suppliers is advantageousas it makes societies less prone to price manipulation by eg cartel formation andsudden disruptions of supply (Johansson et al 1993)

Self-sufficiency concerning energy supply is often mentioned as target of countriesfor (longer-term) sustainable economic development However not all countries haveaccess to resources within their territories that are sufficient for such a target othercountries on the other hand have a structural surplus Relief of trade barriers canhelp mitigate this structural discrepancy Also in the context of economic sustaina-bility a good trade balance should be maintained in relation to the energy supplywithin nations

Regarding social sustainability in the context of energy supply reduction of pov-erty should be mentioned first a good supply structure of energy carriers is one of thebasic requirements for such a development next to access to clean drinking water andgood soil for agricultural activity Associated herewith expectedly substantial healthimprovement should result from a good energy supply infrastructure Job creation andmaintenance is another aspect of social sustainability and certain energy supply formscan contribute significantly to this Also maintaining (or improving) societiesrsquo socialcohesion is an aspect that can be impacted by the energy supply structure

1132 Ecological Sustainability The energy supply structure should notcompromise the sound development of our environment both from a local and globalperspective One of the major issues in this respect is global warming which is for themain part attributed to the release of greenhouse gases (GHG) from fossil fuel com-bustion Other issues are related to local emissions of acid rain precursors and partic-ulate matter (PM)

Climate Change the Greenhouse Effect and Greenhouse Gas EmissionReduction The greenhouse effect occurs naturally to a large extent Without thiseffect the Earthrsquos average global temperature would reach only a low minus18C ratherthan the current approximate +15C Water vapor is the largest contributor to thiseffect with a complex role for clouds but also CO2 in the atmosphere plays a

7ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

significant role More than a century ago Arrhenius (1896) already identified thisrole in the Earthrsquos temperature control Ice core studies reveal that on millennial timescales changes in CO2 content recorded are highly correlated with changes in tem-perature although some temperature changes have occurred without a significantCO2 concentration change but the opposite does not appear to have happened(Falkowski et al 2000) Less pronounced roles are played by CH4 N2O (nitrousoxide) and several types of chlorofluorocarbons (CFCs) and SF6 It is the CO2CH4 N2O and CFC concentrations in the atmosphere upon which manrsquos industrial

0

1

Rad

iati

ve

forc

ing (

Wm

2)

350

(a)

300

Car

bon d

ioxid

e (p

pm

)

250

300

350

400

1800 1900

Year

2000

(b)

1500

2000

1000

Met

han

e (p

pb)

500

0

02

04

Rad

iati

ve

forc

ing (

Wm

2)

1000

500

1500

2000

1900

Year

20001800

FIGURE 13 Atmospheric concentrations of CO2 CH4 and N2O over the last 10000 years(large panels) and since 1750 (inset panels) Measurements are shown from ice cores (symbolswith different grey shades for different studies) and atmospheric samples (light grey lines insteep curve part red lines in the original publication) The corresponding radiative forcings(net solar energy flux to the earth) relative to 1750 are shown on the right-hand axes of the largepanels (SourceReproducedwithpermission fromIPCC(2007) figure23 figureSPM1copyIPCC)

8 INTRODUCTION

and household activities have a measurable impact Scientists largely agree on thepoint that in the last few centuries the activities of humans have directly or indirectlycaused the concentrations of the major GHG to increase This is exemplified byFigure 13 The atmospheric CO2 concentration varies to some extent from placeto place and from season to season It has been shown that concentrations are some-what higher in the northern hemisphere than in the southern hemisphere as most of theanthropogenic sources of CO2 are located north of the equator The difference in landsurface covered with forests being more concentrated north of the equator causeslarger seasonal fluctuations due to comparatively shorter growth periods than in thegenerally milder southern hemisphere locations that are under the influence of largeroceanic surfaces

Oscillations of atmospheric CO2 concentrations between about 180 and 280 ppmv

have occurred in the past approximately 480000 years in cycles of 100000 yearsbut it appears now we have abandoned this cycling behavior in a remarkably shorttime frame

Studies at the NASA Goddard Institute for Space Studies in New York (UnitedStates) have shown that over the past few decades the combined warming effectof non-CO2 GHG should have been comparable to that of CO2 alone However whileeach of the GHGmentioned earlier acts to warm the surface of the Earth the long-termclimatic effects of the other GHG differ from those of CO2 Methane eg has anatmospheric lifetime of only about 12 years By comparison newly added CO2 willremain for a time span of tens to thousands of years As a result about 65 of thecarbon dioxide that human activities have generated since the start of the IndustrialRevolution is in the air we breathe today A historical record of the amount ofCO2 in the atmosphere can be found in bubbles of air in arctic ice layers dating backas far as 600000 years The depth of such a layer is a measure of its time of formation

(c)

10000 5000

Time (before 2005)

0

0

01

Rad

iati

ve

forc

ing (

Wm

2)

300

270

Nit

rous

oxid

e (p

pb)

270

240

300

330

1800 1900

Year

2000

FIGURE 13 (Continued )

9ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

Another difference is that the principal anthropogenic sources of methane-bacterialfermentation in rice paddies and in the intestines of cattle are related to food produc-tion and hence are roughly proportional to the number of people on the planetBecause CH4 has such a short atmospheric lifetime the amount that is in the air isa good indicator of how much is being added with time Should the global populationdouble over the next half century the concentration of CH4 could also double but it isnot likely to rise by much more than that This would add at most a few tenths of adegree to the mean temperature of the Earth Future CO2 increases could in contrastwarm the climate by 10C or more

Nitrous oxide (N2O) and CFCs are in some ways more like CO2 in that oncereleased they remain in the atmosphere for a century or more The production ofN2O however is only indirectly dependent on human activities Its principal sourceis a natural one the bacterial removal of nitrogen from soils and although the worldpopulation swells in coming years the amount in the air should increase only slowly

The outlook for many CFCs is even more promising Today the most abundant ofthese man-made compounds freon-11 and freon-12 are being phased out of produc-tion altogether by international agreements because of their damaging effects on strat-ospheric ozone Indeed the concentration of one of these gases freon-11 peaked in1994 and is now in a slow decline that should continue for the next century or so Thefreon-12 concentration has not yet leveled off but is expected to do so within the nextfew years In terms of climatic effects the main threat from CFCs comes from otherlong-lived compounds that may be used to replace the ones that have been phased outand that could also act as GHG Since these possibly harmful replacement gases are asyet present in only small amounts and since as noted earlier projected increases inCH4 and N2O are so much less severe we shall for the rest of this discussion focussolely on the most important anthropogenic GHG CO2

Some experts have estimated that the Earthrsquos average global temperature has alreadyincreased by more than 05C since the mid-1900s due to this human-enhanced green-house effect also impacts on sea level (rising) and snow coverage (tending to decrease)have been investigated the results of which are summarized in Figure 14

Like most other planets and planetoids in the universe the Earth contains a greatdeal of carbon which is slowly and continually transported from the mantle to thecrust and back again in the course of volcanic eruption and subduction phenomenaThe portion that finds itself near the surface is continually exchanged and recycledamong plants animals soil air and oceans In some of these temporary stocks car-bon is more securely held while in others it more readily combines with oxygen in theair to form CO2 In order to predict how atmospheric CO2 levels and climate maychange in the future it is important to understand where carbon is stored and whatits dynamic cycling behavior looks like The carbon reservoirs that are most relevantto global warming are listed in Table 11 with the total amount of carbon that theycontained in 2000

The atmosphere contains approximately 720 Gt C in the form of CO2 currentmeasured atmospheric CO2 concentrations are nearly 400 ppmv The rate of changein this carbon stock not only depends on human activities but also on biogeochemicaland climatological processes and their interactions with the global carbon cycle

10 INTRODUCTION

Problems 295Projects 296Internet References 296References 297

10 Thermochemical Conversion (Co)gasification andHydrothermal Gasification 298Sascha RA Kersten and Wiebren de Jong

101 What is Gasification A Chemical and Engineering Background 300102 A Short History of Gasification 317103 (Co)gasification Technologies for Dry Biomass 318104 Gasification in an Aqueous Environment Hydrothermal

Biomass Conversion 329105 Gas Cleaning for Biomass Gasification Processes 337Chapter Summary and Study Guide 348Key Concepts 348Short-Answer Questions 349Problems 350Projects 353Internet References 353References 353

11 Thermochemical Conversion An Introductionto Fast Pyrolysis 359Stijn RG Oudenhoven and Sascha RA Kersten

111 Introduction 361112 A First Look at a Liquefaction Process 362113 A First Look at Fast Pyrolysis Oil 363114 Chemistry and Kinetics of Pyrolysis 364115 Processes at the Particle Level 368116 A Closer Look at Pyrolysis Oil 371117 Fast Pyrolysis Processes 374118 Catalytic Pyrolysis 377119 Oil Applications 3781110 Outlook 380Appendix 111 Single-Particle Model (Based on the Model byDi Blasi 1997) 380Chapter Summary and Study Guide 383Key Concepts 383Short-Answer Questions 383Problems 384Projects 384Internet References 385References 385

ixCONTENTS

12 Thermochemical Conversion Torrefaction 388Jaap HA Kiel Arno HH Janssen and Yash Joshi

121 Introduction 388122 Fundamentals of Torrefaction 389123 Advantages of Torrefaction 392124 Torrefaction Technology 392125 Torrefaction An Enabling Technology 397126 The Future of Torrefaction 398Chapter Summary and Study Guide 399Key Concepts 399Short-Answer Questions 399Problems 400Projects 401References 401

13 Biochemical Conversion Biofuels byIndustrial Fermentation 403Maria C Cuellar and Adrie JJ Straathof

131 Introduction 404132 First-Generation Bioethanol Processes 406133 Second-Generation Bioethanol Processes 417134 Butanol 428135 Diesel-like Products 429136 Stoichiometric and Thermodynamic Comparison of

Fermentative Biofuels 432137 Outlook 436Chapter Summary and Study Guide 437Key Concepts 438Short-Answer Questions 438Problems 438Projects 439References 439

14 Biochemical Conversion Anaerobic Digestion 441Robbert Kleerebezem

141 Introduction 442142 Biochemical Fundamentals 443143 Thermodynamic Fundamentals 453144 Process Engineering 454145 Outlook and Discussion 463Chapter Summary and Study Guide 466Key Concepts 466Short-Answer Questions 466Problems 467

x CONTENTS

Project 467References 468

15 Biorefineries Integration of Different Technologies 469Wiebren de Jong

151 What is a Biorefinery and What is the Difference with anOil Refinery 470

152 Types of Biorefineries 474153 Economic Considerations Evaluating Biorefinery Concepts

Basic Methods for Assessing Investments and Cost Prices 481154 Outlook to the Future of Biorefineries 492Chapter Summary and Study Guide 493Key Concepts 493Short-Answer Questions 493Problems 494Projects 497Internet References 500References 500

PART IV END USES 503

16 High-Efficiency Energy Systems withBiomass Gasifiers and Solid Oxide Fuel Cells 505PV Aravind and Ming Liu

161 Introduction 506162 Solid Oxide Fuel Cells 507163 Biomass GasifierndashSOFC Combination 512164 Concluding Remarks 520Chapter Summary and Study Guide 520Key Concepts 521Short-Answer Questions 521Problems 521Projects 522Internet References 522References 523

17 Synthesis Gas Utilization for TransportationFuel Production 525J Ruud van Ommen and Johan Grievink

171 Introduction 526172 FischerndashTropsch Synthesis 527173 Synthetic Natural Gas Synthesis 535174 Methanol Synthesis 537

xiCONTENTS

175 Comparison of the Different Options 538Chapter Summary and Study Guide 540Key Concepts 540Short-Answer Questions 541Problems 541Projects 544Internet References 545References 545

18 Chemistry of Biofuels and Biofuel Additivesfrom Biomass 547Isabel WCE Arends

181 Introduction 548182 Bioethanol and Biodiesel 548183 Conversion of Sugars to Hydrocarbon Fuels 553184 Greenness of the Conversion of Platform Molecules

into Biobased Fuel Additives 557185 Direct Aqueous Reforming of Sugars Leading to a

Range of Alkanes 564186 Future Generations of Biofuel 566Chapter Summary and Study Guide 566Key Concepts 567Short-Answer Questions 567Problems 568Projects 568Internet References 568References 569

INDEX 571

xii CONTENTS

PREFACE

This book deals with bioenergy as a versatile renewable source Ever since thedawn of mankind people have been using wood and other biogenic sources forheating cooking and lighting Trade of biomass came up in historic times (thinkabout the silk route for example) Even industrial iron making via metal reductionwas based on biomass utilization (carbonization) However that very applicationalso led to substantial deforestation which was clear in the United Kingdomand demonstrated that using biomass does not guarantee a sustainable energy sup-ply Therefore the industrial revolution introduced the large-scale application offossil fuel starting with the use of coal

The steam engine became the workhorse of the nineteenth century Coal alsobecame the basis of the chemical industry at that time Oil was initially used for lampsbut later it appeared to be the choice of raw material for petrol and diesel in Otto andDiesel engines respectively Wood and other sources came back into the pictureduring the interbellum period and the Second World War when oil was scarce inparticular on the European continent At that time cars trucks and ships made useof the gas extracted from fixed bed wood gasification installations Also chemicalssupply and materials were increasingly supported by wood-based processes AfterWWII the cheap oil era was entered and such routes were largely abandoned Afterthe oil crises of the 1970s biomass came back into the picture as an energy sourcereinforced by environmental concerns about the use of fossil energy sources due totheir associated CO2 emissions stimulating the greenhouse effect At present biomassis seriously back as part of a sustainable energy mix in combination with materialsand chemicals supply and a wide world of biorefinery options has opened up

The field of biomass to energy supply is multidisciplinary and offers a wealth ofintegration of knowledge to young engineers starting their careers The technologies

xiii

strongly lean on chemical engineering skills but also on physics mechanical engineer-ing and agricultural sciences among others Not only technology issues determine thesuccess of biomass for our energy supply there are many hurdles to be taken into thenontechnical domain such as logistics (trade and handling) infrastructure and politics(subsidies rural development employment generation etc) to name a few

This book is divided into four parts covering broad areas of the field of biomassconversion technology chains Part I starts with the socioeconomic and environmentalcontext and biomass basics It gives insight into the boundary conditions and the playingfield bioenergy supply has Moreover it provides a deeper look into what biomass reallyis Part II covers the chemical engineering basics to provide the engineer with tools tosolve problems in the domain design new biomass-based processes and evaluateconversion subprocesses The tools range from setting up balances evaluating the massand heat transport phenomena thermodynamics and kinetics to reactor and processdesign Part III deals with the study of different biomass conversion processes rangingfrom nonreactive pretreatment via combustion processes gasification hydrothermal pro-cessing pyrolysis and torrefaction to biochemical conversion processes and biorefineryintegration of such technologies Finally Part IV treats the end use of primary biomassconversion products for example power production via fuel cells transportationfuel production (eg via the FischerndashTropsch process) and platform chemicalsproduction via organic chemistry to substitute the conventional petrochemical pathwaysoffered today

We were inspired to write this book by the course ldquoEnergy from Biomassrdquo that wehave been teaching for a number of years in the MSc program of Sustainable EnergyTechnology at Delft University a program that is part of the 3TU cooperation betweenthe technical universities of Delft Eindhoven and Twente After teaching the coursefor some years using the lecture notes prepared by our Eindhoven colleagues RobBastiaans Jeroen van Oijen andMark Prins we thought it would be worthy to furtherimprove the course material Since the students in Sustainable Energy Technologyhave a very diverse background we have devoted Part II of the book to giving thereader enough background in chemical engineering for reading the more specializedchapters This means that this book is useful for everyone with a BSc in anyengineering discipline Apart from students at the MSc level professionals in thebiomass field may also find this book as a knowledgeable source for example fordesigning and evaluating novel biorefinery systems and conversion components

Delft December 2013 WIEBREN DE JONG AND J RUUD VAN OMMEN

He will be like a tree planted by the water that sends out its roots by the stream It doesnot fear when heat comes its leaves are always green It has no worries in a year ofdrought and never fails to bear fruit ndash Bible Jeremiah 178

Biomass is forever ndash Prof David Halldagger

xiv PREFACE

ACKNOWLEDGMENTS

This book would not have been published without the contributions from manypeople First of all we would like to acknowledge all the students that followedour course ldquoEnergy from Biomassrdquo over the years they inspired us to compose thisbook We are very glad that many of our colleagues agreed to contribute chapters tothis book It was great to work with this team of co-authors all bringing in their spe-cific expertise to cover the broad field of energy from biomass A big thanks to all ofyou For some chapters the additional input from others is specifically acknowledgedLikun Ma is kindly acknowledged for his contribution to the examples in Chapter 4Ryan Bogaars for his suggestions concerning Chapter 10 Xiangmei Meng and Onur-sal Yakaboylu for contributing some of the examples of Chapter 10 Richard Eijsbergfor the first generation ethanol process figures and data in Chapter 13 Tim Geraedtsand Elze Oude Lansink for the project in Chapter 15 Fred van Rantwijk for valuableinput and discussions on Chapter 18 and Adrea Fabre for her advices regarding thewritingWe are also grateful for the willingness of many colleagues to review chaptersin order to find mistakes and make suggestions for further improvements Ourreviewers were in alphabetic order Rob Bakker Sune Bengtsson PouyanBoukany Anthony Bridgwater Harry Croezen Lilian de Martiacuten Jorge GasconHans Geerlings Johan Grievink Sef Heijnen Kas Hemmes Paulien Herder TrulsLiliedahl Gabrie Meesters Bart Merci Kyriakos Panopoulos Wolter Prins SinaSartipi Fabrizio Scala Tilman Schildhauer Andrzej Stankiewicz GeorgiosStefanidis Bob Ursem Henk van den Berg Theo van der Meer Jules van Lier Maritvan Lieshout and Stanislav Vassilev A special word of thanks should go to Anneliesvan Diepen When the chapters were complete she made a great effort to harmonizethem for example in figures symbols lay-out and wording She also has caughtnumerous mistakes that were still present in earlier versions We would like to thank

xv

Jan Leen Kloosterman (Director of Education Sustainable Energy Technology SET)for the financial support from the SET program for editorial assistance We would alsolike to thank the people at Wiley for the smooth cooperation during the preparation ofthe manuscript Finally we would like to thank the ones close to usmdashKlarine (WdJ)and Ceciel Fenne and Chris (JRvO)mdashfor their understanding and support during allthe evenings and weekends that the writing and editing took

xvi ACKNOWLEDGMENTS

LIST OF CONTRIBUTORS

PV Aravind Drir Department of Process and Energy Energy TechnologySection Faculty of Mechanical Maritime and Materials Engineering DelftUniversity of Technology Delft the Netherlands

Isabel WCE Arends Profdr Department of Biotechnology Biocatalysis GroupFaculty of Applied Sciences Delft University of Technology Delft theNetherlands

Rob JM Bastiaans Drir Department of Mechanical Engineering CombustionTechnology Section Eindhoven University of Technology Eindhoven theNetherlands

Maria C Cuellar Dr Department of Biotechnology BioProcess EngineeringGroup Faculty of Applied Sciences Delft University of Technology Delft theNetherlands

Martina Fantini Drir Department of Process and Energy Energy TechnologySection Faculty of Mechanical Maritime and Materials Engineering DelftUniversity of Technology Delft the Netherlands

Johan Grievink Prof ir Department of Chemical Engineering Product amp ProcessEngineering Group Faculty of Applied Sciences Delft University of TechnologyDelft the Netherlands

ArnoHH Janssen Ir ECN Biomass amp Energy Efficiency Petten the Netherlands

Wiebren de Jong Drir Department of Process and Energy Energy TechnologySection Faculty of Mechanical Maritime and Materials Engineering DelftUniversity of Technology Delft the Netherlands

xvii

Yash Joshi Ir Department of Process and Energy Energy Technology SectionFaculty of Mechanical Maritime and Materials Engineering Delft University ofTechnology Delft the Netherlands

Sascha RA Kersten Profdrir Sustainable Process Technology Group Facultyof Science and Technology University of Twente Enschede the Netherlands

Jaap HA Kiel Profdrir ECN Biomass amp Energy Efficiency Petten andDepartment of Process and Energy Energy Technology Section Faculty ofMechanical Maritime andMaterials Engineering Delft University of TechnologyDelft the Netherlands

Robbert Kleerebezem Drir Department of Biotechnology EnvironmentalBiotechnology Group Faculty of Applied Sciences Delft University of TechnologyDelft the Netherlands

Ming Liu Drir Department of Process and Energy Energy Technology SectionFaculty of Mechanical Maritime and Materials Engineering Delft University ofTechnology Delft the Netherlands

Lilian de Martiacuten Dr Department of Chemical Engineering Product amp ProcessEngineering Group Faculty of Applied Sciences Delft University of TechnologyDelft the Netherlands

Jeroen A van Oijen Drir Department of Mechanical Engineering CombustionTechnology Section Eindhoven University of Technology Eindhoven theNetherlands

J Ruud van Ommen Drir Department of Chemical Engineering Product ampProcess Engineering Group Faculty of Applied Sciences Delft University ofTechnology Delft the Netherlands

Stijn RG Oudenhoven Ir Sustainable Process Technology Group Faculty ofScience and Technology University of Twente Enschede the Netherlands

Dirk JEM Roekaerts Profdr Department of Process and Energy FluidMechanics Section Faculty of Mechanical Maritime and Materials EngineeringDelft University of Technology Delft the Netherlands

Adrie JJ Straathof Drir Department of Biotechnology BioProcess EngineeringGroup Faculty of Applied Sciences Delft University of Technology Delft theNetherlands

Pieter LJ Swinkels Ir Faculty of Applied Sciences Delft Product amp ProcessDesign Institute Delft University of Technology Delft the Netherlands

xviii LIST OF CONTRIBUTORS

PART I

SOCIAL CONTEXT AND STRUCTURALBASIS OF BIOMASS AS A RENEWABLEENERGY SOURCES

1INTRODUCTION SOCIOECONOMICASPECTS OF BIOMASS CONVERSION

WIEBREN DE JONG1 AND J RUUD VAN OMMEN2

1Department of Process and Energy Energy Technology Section Faculty of MechanicalMaritime and Materials Engineering Delft University of Technology Delft the Netherlands2Department of Chemical Engineering Product amp Process Engineering Group Faculty ofApplied Sciences Delft University of Technology Delft the Netherlands

ACRONYMS

CDM clean development mechanismCFCs chlorofluorocarbonsdLUC direct land use changeGDP gross domestic productGHG greenhouse gasiLUC indirect land use changeJI joint implementationLCA life cycle assessmentLUC land use changeRP ratio reserves-to-production ratio [y]TOE tonnes of oil equivalent(s) (= 4187 GJ)UNFCCC United Nations Framework Convention on Climate Change

Biomass as a Sustainable Energy Source for the Future Fundamentals of Conversion ProcessesFirst Edition Edited by Wiebren de Jong and J Ruud van Ommencopy 2015 American Institute of Chemical Engineers Inc Published 2015 by John Wiley amp Sons Inc

3

11 ENERGY SUPPLY ECONOMIC AND ENVIRONMENTALCONSIDERATIONS

111 Introduction The Importance of Energy Supply

In the past two centuries since the Industrial Revolution in the 1700s that was initiatedby the invention of the steam turbine the world has undergone a drastic change due tothe steeply increased contribution of fossil fuels (coal oil and natural gas) to modernsocietiesrsquo energy supply (McKay 2009) Though the Chinese society already usedcoal for energy supply in approximately 1000 BC and the Romans prior to AD 400(World-Coal-Institute 2005) the first written references indicating its use are fromabout the thirteenth century and beyond (Hubbert 1949) These hydrocarbon fuelsso far have been considered essential as they are comparatively cheap and convenientenergy carriers used for heating cooking lighting and mechanical as well as electricpower production and have been widely used as transportation fuels and feedstocksfor the manufacture of bulk and fine chemicals as well as other materials with a widerange of applications Rapid global population growth expansion of economies andhigher standards have caused an enormous increase in worldwide energy consump-tion which was partly made possible by the supply of cheap fossil fuels

112 Development of Global Energy Demand

Figure 11 shows a scenario toward the year 2030 presented by the oil company BPconcerning population growth in relation to developments in total primary energyutilization and gross domestic product (GDP) The figure shows that global energy

Billion

Rest of

the world

India

China

9

8

7

6

5

4

3

2

1

0

Population

Billion toe

18

15

12

9

6

3

0

Energy

Trillion $2010 PPP

180

150

120

90

60

30

01970 1990 2010 2030 1970 1990 2010 2030 1970 1990 2010 2030

GDP

FIGURE 11 Prospected global growth rates in population energy demand and GDP 1 toe =41868104 MJ (Source Adapted from BP see tinyurlcom7hlmqxn)

4 INTRODUCTION

demand will rise substantially from the current level with an increasing share fromChina and India This rise of the primary energy demand is projected to be larger thanthe population growth and this will cause a stress on the limited global resources Theprojected GDP even increases stronger so it is expected that average living standardsincrease which will result in additional strain on the available resources

113 Sustainability of Energy Supply

One of the major questions in the world arising from the general picture sketched inSection 112 is how mankind can ensure a global sustainable development for the(near) future In this context sustainability of our energy supply is of paramountimportance The key issues are discussed in the following text both from a pointof view of global socioeconomics and ecological sustainability

1131 Socioeconomic Sustainability As one of the most important economicdrivers to secure and improve the living standards of people in the world energysupply security is of crucial value for current and future generations Fossil fuelsrun out sooner or later as can be seen in Figure 12 they are not renewable on anacceptable time scale

This figure depicts the so-called RP ratios for different sources The RP ratio is theratio of the current proven reserves to production level The unit is years and it is ameasure of the expected time a certain fuel source is expected to be available

On a global scale it appears that oil and natural gas reserves will be availablemdashgiven the figures of 2012mdashfor an expected approximately 55 years and coal substan-tially longer (gt100 years) Of course new contributions to the reserves may be

0

50

100

150

200

250

1980 1985 1990 1995 2000 2005 2010 2015

RP

(yea

rs)

Oil

Coal

Natural gas

FIGURE 12 Overview of world (top) and regional (bottom) reserves-to-production (RP)ratios for oil natural gas and coal respectively (end 2012 status) Figures are based on datafrom BP (2013)

5ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

North America

S amp Cent America

Europe amp Eurasia

Middle East

Africa

Asia Pacific

0 20 40 60

RP (years)

80 100 120 140

North America

S amp Cent America

Europe amp Eurasia

Middle East

Africa

Asia Pacific

0

RP (years)

North America

S amp Cent America

Europe amp Eurasia

Middle East amp Africa

Asia Pacific

0 50 100 150 200 250 300RP (years)

50 100 150 200

FIGURE 12 (Continued )

6 INTRODUCTION

discovered in the (near) future but that does not change the inherently limited supplynature of the fossil fuel sources Regionally there are also significant differenceswhich is important in the context of energy policy developments on the differentcontinents

For the price developments of the fossil fuels not only their forecasted availabilityis of importance but also the market development in a landscape highly determined bypolitics Already well before the last resources of a fuel will have been depleted themarket will be severely stressed For the economies in the world fuel cost develop-ment is therefore also a primary point of concern From past developments particu-larly regarding oil it has been shown that substantial fuel price fluctuations (volatility)occur which has an impact on the global economy (eg food prices) that is difficult topredict Supply and demand will determine the price evolution for each fuel sourcebut the development of the market structure is also essential there is a large differencebetween a free market and an oligopoly or monopoly situation In this respect diver-sification of fuel sources with associated differentiation in suppliers is advantageousas it makes societies less prone to price manipulation by eg cartel formation andsudden disruptions of supply (Johansson et al 1993)

Self-sufficiency concerning energy supply is often mentioned as target of countriesfor (longer-term) sustainable economic development However not all countries haveaccess to resources within their territories that are sufficient for such a target othercountries on the other hand have a structural surplus Relief of trade barriers canhelp mitigate this structural discrepancy Also in the context of economic sustaina-bility a good trade balance should be maintained in relation to the energy supplywithin nations

Regarding social sustainability in the context of energy supply reduction of pov-erty should be mentioned first a good supply structure of energy carriers is one of thebasic requirements for such a development next to access to clean drinking water andgood soil for agricultural activity Associated herewith expectedly substantial healthimprovement should result from a good energy supply infrastructure Job creation andmaintenance is another aspect of social sustainability and certain energy supply formscan contribute significantly to this Also maintaining (or improving) societiesrsquo socialcohesion is an aspect that can be impacted by the energy supply structure

1132 Ecological Sustainability The energy supply structure should notcompromise the sound development of our environment both from a local and globalperspective One of the major issues in this respect is global warming which is for themain part attributed to the release of greenhouse gases (GHG) from fossil fuel com-bustion Other issues are related to local emissions of acid rain precursors and partic-ulate matter (PM)

Climate Change the Greenhouse Effect and Greenhouse Gas EmissionReduction The greenhouse effect occurs naturally to a large extent Without thiseffect the Earthrsquos average global temperature would reach only a low minus18C ratherthan the current approximate +15C Water vapor is the largest contributor to thiseffect with a complex role for clouds but also CO2 in the atmosphere plays a

7ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

significant role More than a century ago Arrhenius (1896) already identified thisrole in the Earthrsquos temperature control Ice core studies reveal that on millennial timescales changes in CO2 content recorded are highly correlated with changes in tem-perature although some temperature changes have occurred without a significantCO2 concentration change but the opposite does not appear to have happened(Falkowski et al 2000) Less pronounced roles are played by CH4 N2O (nitrousoxide) and several types of chlorofluorocarbons (CFCs) and SF6 It is the CO2CH4 N2O and CFC concentrations in the atmosphere upon which manrsquos industrial

0

1

Rad

iati

ve

forc

ing (

Wm

2)

350

(a)

300

Car

bon d

ioxid

e (p

pm

)

250

300

350

400

1800 1900

Year

2000

(b)

1500

2000

1000

Met

han

e (p

pb)

500

0

02

04

Rad

iati

ve

forc

ing (

Wm

2)

1000

500

1500

2000

1900

Year

20001800

FIGURE 13 Atmospheric concentrations of CO2 CH4 and N2O over the last 10000 years(large panels) and since 1750 (inset panels) Measurements are shown from ice cores (symbolswith different grey shades for different studies) and atmospheric samples (light grey lines insteep curve part red lines in the original publication) The corresponding radiative forcings(net solar energy flux to the earth) relative to 1750 are shown on the right-hand axes of the largepanels (SourceReproducedwithpermission fromIPCC(2007) figure23 figureSPM1copyIPCC)

8 INTRODUCTION

and household activities have a measurable impact Scientists largely agree on thepoint that in the last few centuries the activities of humans have directly or indirectlycaused the concentrations of the major GHG to increase This is exemplified byFigure 13 The atmospheric CO2 concentration varies to some extent from placeto place and from season to season It has been shown that concentrations are some-what higher in the northern hemisphere than in the southern hemisphere as most of theanthropogenic sources of CO2 are located north of the equator The difference in landsurface covered with forests being more concentrated north of the equator causeslarger seasonal fluctuations due to comparatively shorter growth periods than in thegenerally milder southern hemisphere locations that are under the influence of largeroceanic surfaces

Oscillations of atmospheric CO2 concentrations between about 180 and 280 ppmv

have occurred in the past approximately 480000 years in cycles of 100000 yearsbut it appears now we have abandoned this cycling behavior in a remarkably shorttime frame

Studies at the NASA Goddard Institute for Space Studies in New York (UnitedStates) have shown that over the past few decades the combined warming effectof non-CO2 GHG should have been comparable to that of CO2 alone However whileeach of the GHGmentioned earlier acts to warm the surface of the Earth the long-termclimatic effects of the other GHG differ from those of CO2 Methane eg has anatmospheric lifetime of only about 12 years By comparison newly added CO2 willremain for a time span of tens to thousands of years As a result about 65 of thecarbon dioxide that human activities have generated since the start of the IndustrialRevolution is in the air we breathe today A historical record of the amount ofCO2 in the atmosphere can be found in bubbles of air in arctic ice layers dating backas far as 600000 years The depth of such a layer is a measure of its time of formation

(c)

10000 5000

Time (before 2005)

0

0

01

Rad

iati

ve

forc

ing (

Wm

2)

300

270

Nit

rous

oxid

e (p

pb)

270

240

300

330

1800 1900

Year

2000

FIGURE 13 (Continued )

9ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

Another difference is that the principal anthropogenic sources of methane-bacterialfermentation in rice paddies and in the intestines of cattle are related to food produc-tion and hence are roughly proportional to the number of people on the planetBecause CH4 has such a short atmospheric lifetime the amount that is in the air isa good indicator of how much is being added with time Should the global populationdouble over the next half century the concentration of CH4 could also double but it isnot likely to rise by much more than that This would add at most a few tenths of adegree to the mean temperature of the Earth Future CO2 increases could in contrastwarm the climate by 10C or more

Nitrous oxide (N2O) and CFCs are in some ways more like CO2 in that oncereleased they remain in the atmosphere for a century or more The production ofN2O however is only indirectly dependent on human activities Its principal sourceis a natural one the bacterial removal of nitrogen from soils and although the worldpopulation swells in coming years the amount in the air should increase only slowly

The outlook for many CFCs is even more promising Today the most abundant ofthese man-made compounds freon-11 and freon-12 are being phased out of produc-tion altogether by international agreements because of their damaging effects on strat-ospheric ozone Indeed the concentration of one of these gases freon-11 peaked in1994 and is now in a slow decline that should continue for the next century or so Thefreon-12 concentration has not yet leveled off but is expected to do so within the nextfew years In terms of climatic effects the main threat from CFCs comes from otherlong-lived compounds that may be used to replace the ones that have been phased outand that could also act as GHG Since these possibly harmful replacement gases are asyet present in only small amounts and since as noted earlier projected increases inCH4 and N2O are so much less severe we shall for the rest of this discussion focussolely on the most important anthropogenic GHG CO2

Some experts have estimated that the Earthrsquos average global temperature has alreadyincreased by more than 05C since the mid-1900s due to this human-enhanced green-house effect also impacts on sea level (rising) and snow coverage (tending to decrease)have been investigated the results of which are summarized in Figure 14

Like most other planets and planetoids in the universe the Earth contains a greatdeal of carbon which is slowly and continually transported from the mantle to thecrust and back again in the course of volcanic eruption and subduction phenomenaThe portion that finds itself near the surface is continually exchanged and recycledamong plants animals soil air and oceans In some of these temporary stocks car-bon is more securely held while in others it more readily combines with oxygen in theair to form CO2 In order to predict how atmospheric CO2 levels and climate maychange in the future it is important to understand where carbon is stored and whatits dynamic cycling behavior looks like The carbon reservoirs that are most relevantto global warming are listed in Table 11 with the total amount of carbon that theycontained in 2000

The atmosphere contains approximately 720 Gt C in the form of CO2 currentmeasured atmospheric CO2 concentrations are nearly 400 ppmv The rate of changein this carbon stock not only depends on human activities but also on biogeochemicaland climatological processes and their interactions with the global carbon cycle

10 INTRODUCTION

12 Thermochemical Conversion Torrefaction 388Jaap HA Kiel Arno HH Janssen and Yash Joshi

121 Introduction 388122 Fundamentals of Torrefaction 389123 Advantages of Torrefaction 392124 Torrefaction Technology 392125 Torrefaction An Enabling Technology 397126 The Future of Torrefaction 398Chapter Summary and Study Guide 399Key Concepts 399Short-Answer Questions 399Problems 400Projects 401References 401

13 Biochemical Conversion Biofuels byIndustrial Fermentation 403Maria C Cuellar and Adrie JJ Straathof

131 Introduction 404132 First-Generation Bioethanol Processes 406133 Second-Generation Bioethanol Processes 417134 Butanol 428135 Diesel-like Products 429136 Stoichiometric and Thermodynamic Comparison of

Fermentative Biofuels 432137 Outlook 436Chapter Summary and Study Guide 437Key Concepts 438Short-Answer Questions 438Problems 438Projects 439References 439

14 Biochemical Conversion Anaerobic Digestion 441Robbert Kleerebezem

141 Introduction 442142 Biochemical Fundamentals 443143 Thermodynamic Fundamentals 453144 Process Engineering 454145 Outlook and Discussion 463Chapter Summary and Study Guide 466Key Concepts 466Short-Answer Questions 466Problems 467

x CONTENTS

Project 467References 468

15 Biorefineries Integration of Different Technologies 469Wiebren de Jong

151 What is a Biorefinery and What is the Difference with anOil Refinery 470

152 Types of Biorefineries 474153 Economic Considerations Evaluating Biorefinery Concepts

Basic Methods for Assessing Investments and Cost Prices 481154 Outlook to the Future of Biorefineries 492Chapter Summary and Study Guide 493Key Concepts 493Short-Answer Questions 493Problems 494Projects 497Internet References 500References 500

PART IV END USES 503

16 High-Efficiency Energy Systems withBiomass Gasifiers and Solid Oxide Fuel Cells 505PV Aravind and Ming Liu

161 Introduction 506162 Solid Oxide Fuel Cells 507163 Biomass GasifierndashSOFC Combination 512164 Concluding Remarks 520Chapter Summary and Study Guide 520Key Concepts 521Short-Answer Questions 521Problems 521Projects 522Internet References 522References 523

17 Synthesis Gas Utilization for TransportationFuel Production 525J Ruud van Ommen and Johan Grievink

171 Introduction 526172 FischerndashTropsch Synthesis 527173 Synthetic Natural Gas Synthesis 535174 Methanol Synthesis 537

xiCONTENTS

175 Comparison of the Different Options 538Chapter Summary and Study Guide 540Key Concepts 540Short-Answer Questions 541Problems 541Projects 544Internet References 545References 545

18 Chemistry of Biofuels and Biofuel Additivesfrom Biomass 547Isabel WCE Arends

181 Introduction 548182 Bioethanol and Biodiesel 548183 Conversion of Sugars to Hydrocarbon Fuels 553184 Greenness of the Conversion of Platform Molecules

into Biobased Fuel Additives 557185 Direct Aqueous Reforming of Sugars Leading to a

Range of Alkanes 564186 Future Generations of Biofuel 566Chapter Summary and Study Guide 566Key Concepts 567Short-Answer Questions 567Problems 568Projects 568Internet References 568References 569

INDEX 571

xii CONTENTS

PREFACE

This book deals with bioenergy as a versatile renewable source Ever since thedawn of mankind people have been using wood and other biogenic sources forheating cooking and lighting Trade of biomass came up in historic times (thinkabout the silk route for example) Even industrial iron making via metal reductionwas based on biomass utilization (carbonization) However that very applicationalso led to substantial deforestation which was clear in the United Kingdomand demonstrated that using biomass does not guarantee a sustainable energy sup-ply Therefore the industrial revolution introduced the large-scale application offossil fuel starting with the use of coal

The steam engine became the workhorse of the nineteenth century Coal alsobecame the basis of the chemical industry at that time Oil was initially used for lampsbut later it appeared to be the choice of raw material for petrol and diesel in Otto andDiesel engines respectively Wood and other sources came back into the pictureduring the interbellum period and the Second World War when oil was scarce inparticular on the European continent At that time cars trucks and ships made useof the gas extracted from fixed bed wood gasification installations Also chemicalssupply and materials were increasingly supported by wood-based processes AfterWWII the cheap oil era was entered and such routes were largely abandoned Afterthe oil crises of the 1970s biomass came back into the picture as an energy sourcereinforced by environmental concerns about the use of fossil energy sources due totheir associated CO2 emissions stimulating the greenhouse effect At present biomassis seriously back as part of a sustainable energy mix in combination with materialsand chemicals supply and a wide world of biorefinery options has opened up

The field of biomass to energy supply is multidisciplinary and offers a wealth ofintegration of knowledge to young engineers starting their careers The technologies

xiii

strongly lean on chemical engineering skills but also on physics mechanical engineer-ing and agricultural sciences among others Not only technology issues determine thesuccess of biomass for our energy supply there are many hurdles to be taken into thenontechnical domain such as logistics (trade and handling) infrastructure and politics(subsidies rural development employment generation etc) to name a few

This book is divided into four parts covering broad areas of the field of biomassconversion technology chains Part I starts with the socioeconomic and environmentalcontext and biomass basics It gives insight into the boundary conditions and the playingfield bioenergy supply has Moreover it provides a deeper look into what biomass reallyis Part II covers the chemical engineering basics to provide the engineer with tools tosolve problems in the domain design new biomass-based processes and evaluateconversion subprocesses The tools range from setting up balances evaluating the massand heat transport phenomena thermodynamics and kinetics to reactor and processdesign Part III deals with the study of different biomass conversion processes rangingfrom nonreactive pretreatment via combustion processes gasification hydrothermal pro-cessing pyrolysis and torrefaction to biochemical conversion processes and biorefineryintegration of such technologies Finally Part IV treats the end use of primary biomassconversion products for example power production via fuel cells transportationfuel production (eg via the FischerndashTropsch process) and platform chemicalsproduction via organic chemistry to substitute the conventional petrochemical pathwaysoffered today

We were inspired to write this book by the course ldquoEnergy from Biomassrdquo that wehave been teaching for a number of years in the MSc program of Sustainable EnergyTechnology at Delft University a program that is part of the 3TU cooperation betweenthe technical universities of Delft Eindhoven and Twente After teaching the coursefor some years using the lecture notes prepared by our Eindhoven colleagues RobBastiaans Jeroen van Oijen andMark Prins we thought it would be worthy to furtherimprove the course material Since the students in Sustainable Energy Technologyhave a very diverse background we have devoted Part II of the book to giving thereader enough background in chemical engineering for reading the more specializedchapters This means that this book is useful for everyone with a BSc in anyengineering discipline Apart from students at the MSc level professionals in thebiomass field may also find this book as a knowledgeable source for example fordesigning and evaluating novel biorefinery systems and conversion components

Delft December 2013 WIEBREN DE JONG AND J RUUD VAN OMMEN

He will be like a tree planted by the water that sends out its roots by the stream It doesnot fear when heat comes its leaves are always green It has no worries in a year ofdrought and never fails to bear fruit ndash Bible Jeremiah 178

Biomass is forever ndash Prof David Halldagger

xiv PREFACE

ACKNOWLEDGMENTS

This book would not have been published without the contributions from manypeople First of all we would like to acknowledge all the students that followedour course ldquoEnergy from Biomassrdquo over the years they inspired us to compose thisbook We are very glad that many of our colleagues agreed to contribute chapters tothis book It was great to work with this team of co-authors all bringing in their spe-cific expertise to cover the broad field of energy from biomass A big thanks to all ofyou For some chapters the additional input from others is specifically acknowledgedLikun Ma is kindly acknowledged for his contribution to the examples in Chapter 4Ryan Bogaars for his suggestions concerning Chapter 10 Xiangmei Meng and Onur-sal Yakaboylu for contributing some of the examples of Chapter 10 Richard Eijsbergfor the first generation ethanol process figures and data in Chapter 13 Tim Geraedtsand Elze Oude Lansink for the project in Chapter 15 Fred van Rantwijk for valuableinput and discussions on Chapter 18 and Adrea Fabre for her advices regarding thewritingWe are also grateful for the willingness of many colleagues to review chaptersin order to find mistakes and make suggestions for further improvements Ourreviewers were in alphabetic order Rob Bakker Sune Bengtsson PouyanBoukany Anthony Bridgwater Harry Croezen Lilian de Martiacuten Jorge GasconHans Geerlings Johan Grievink Sef Heijnen Kas Hemmes Paulien Herder TrulsLiliedahl Gabrie Meesters Bart Merci Kyriakos Panopoulos Wolter Prins SinaSartipi Fabrizio Scala Tilman Schildhauer Andrzej Stankiewicz GeorgiosStefanidis Bob Ursem Henk van den Berg Theo van der Meer Jules van Lier Maritvan Lieshout and Stanislav Vassilev A special word of thanks should go to Anneliesvan Diepen When the chapters were complete she made a great effort to harmonizethem for example in figures symbols lay-out and wording She also has caughtnumerous mistakes that were still present in earlier versions We would like to thank

xv

Jan Leen Kloosterman (Director of Education Sustainable Energy Technology SET)for the financial support from the SET program for editorial assistance We would alsolike to thank the people at Wiley for the smooth cooperation during the preparation ofthe manuscript Finally we would like to thank the ones close to usmdashKlarine (WdJ)and Ceciel Fenne and Chris (JRvO)mdashfor their understanding and support during allthe evenings and weekends that the writing and editing took

xvi ACKNOWLEDGMENTS

LIST OF CONTRIBUTORS

PV Aravind Drir Department of Process and Energy Energy TechnologySection Faculty of Mechanical Maritime and Materials Engineering DelftUniversity of Technology Delft the Netherlands

Isabel WCE Arends Profdr Department of Biotechnology Biocatalysis GroupFaculty of Applied Sciences Delft University of Technology Delft theNetherlands

Rob JM Bastiaans Drir Department of Mechanical Engineering CombustionTechnology Section Eindhoven University of Technology Eindhoven theNetherlands

Maria C Cuellar Dr Department of Biotechnology BioProcess EngineeringGroup Faculty of Applied Sciences Delft University of Technology Delft theNetherlands

Martina Fantini Drir Department of Process and Energy Energy TechnologySection Faculty of Mechanical Maritime and Materials Engineering DelftUniversity of Technology Delft the Netherlands

Johan Grievink Prof ir Department of Chemical Engineering Product amp ProcessEngineering Group Faculty of Applied Sciences Delft University of TechnologyDelft the Netherlands

ArnoHH Janssen Ir ECN Biomass amp Energy Efficiency Petten the Netherlands

Wiebren de Jong Drir Department of Process and Energy Energy TechnologySection Faculty of Mechanical Maritime and Materials Engineering DelftUniversity of Technology Delft the Netherlands

xvii

Yash Joshi Ir Department of Process and Energy Energy Technology SectionFaculty of Mechanical Maritime and Materials Engineering Delft University ofTechnology Delft the Netherlands

Sascha RA Kersten Profdrir Sustainable Process Technology Group Facultyof Science and Technology University of Twente Enschede the Netherlands

Jaap HA Kiel Profdrir ECN Biomass amp Energy Efficiency Petten andDepartment of Process and Energy Energy Technology Section Faculty ofMechanical Maritime andMaterials Engineering Delft University of TechnologyDelft the Netherlands

Robbert Kleerebezem Drir Department of Biotechnology EnvironmentalBiotechnology Group Faculty of Applied Sciences Delft University of TechnologyDelft the Netherlands

Ming Liu Drir Department of Process and Energy Energy Technology SectionFaculty of Mechanical Maritime and Materials Engineering Delft University ofTechnology Delft the Netherlands

Lilian de Martiacuten Dr Department of Chemical Engineering Product amp ProcessEngineering Group Faculty of Applied Sciences Delft University of TechnologyDelft the Netherlands

Jeroen A van Oijen Drir Department of Mechanical Engineering CombustionTechnology Section Eindhoven University of Technology Eindhoven theNetherlands

J Ruud van Ommen Drir Department of Chemical Engineering Product ampProcess Engineering Group Faculty of Applied Sciences Delft University ofTechnology Delft the Netherlands

Stijn RG Oudenhoven Ir Sustainable Process Technology Group Faculty ofScience and Technology University of Twente Enschede the Netherlands

Dirk JEM Roekaerts Profdr Department of Process and Energy FluidMechanics Section Faculty of Mechanical Maritime and Materials EngineeringDelft University of Technology Delft the Netherlands

Adrie JJ Straathof Drir Department of Biotechnology BioProcess EngineeringGroup Faculty of Applied Sciences Delft University of Technology Delft theNetherlands

Pieter LJ Swinkels Ir Faculty of Applied Sciences Delft Product amp ProcessDesign Institute Delft University of Technology Delft the Netherlands

xviii LIST OF CONTRIBUTORS

PART I

SOCIAL CONTEXT AND STRUCTURALBASIS OF BIOMASS AS A RENEWABLEENERGY SOURCES

1INTRODUCTION SOCIOECONOMICASPECTS OF BIOMASS CONVERSION

WIEBREN DE JONG1 AND J RUUD VAN OMMEN2

1Department of Process and Energy Energy Technology Section Faculty of MechanicalMaritime and Materials Engineering Delft University of Technology Delft the Netherlands2Department of Chemical Engineering Product amp Process Engineering Group Faculty ofApplied Sciences Delft University of Technology Delft the Netherlands

ACRONYMS

CDM clean development mechanismCFCs chlorofluorocarbonsdLUC direct land use changeGDP gross domestic productGHG greenhouse gasiLUC indirect land use changeJI joint implementationLCA life cycle assessmentLUC land use changeRP ratio reserves-to-production ratio [y]TOE tonnes of oil equivalent(s) (= 4187 GJ)UNFCCC United Nations Framework Convention on Climate Change

Biomass as a Sustainable Energy Source for the Future Fundamentals of Conversion ProcessesFirst Edition Edited by Wiebren de Jong and J Ruud van Ommencopy 2015 American Institute of Chemical Engineers Inc Published 2015 by John Wiley amp Sons Inc

3

11 ENERGY SUPPLY ECONOMIC AND ENVIRONMENTALCONSIDERATIONS

111 Introduction The Importance of Energy Supply

In the past two centuries since the Industrial Revolution in the 1700s that was initiatedby the invention of the steam turbine the world has undergone a drastic change due tothe steeply increased contribution of fossil fuels (coal oil and natural gas) to modernsocietiesrsquo energy supply (McKay 2009) Though the Chinese society already usedcoal for energy supply in approximately 1000 BC and the Romans prior to AD 400(World-Coal-Institute 2005) the first written references indicating its use are fromabout the thirteenth century and beyond (Hubbert 1949) These hydrocarbon fuelsso far have been considered essential as they are comparatively cheap and convenientenergy carriers used for heating cooking lighting and mechanical as well as electricpower production and have been widely used as transportation fuels and feedstocksfor the manufacture of bulk and fine chemicals as well as other materials with a widerange of applications Rapid global population growth expansion of economies andhigher standards have caused an enormous increase in worldwide energy consump-tion which was partly made possible by the supply of cheap fossil fuels

112 Development of Global Energy Demand

Figure 11 shows a scenario toward the year 2030 presented by the oil company BPconcerning population growth in relation to developments in total primary energyutilization and gross domestic product (GDP) The figure shows that global energy

Billion

Rest of

the world

India

China

9

8

7

6

5

4

3

2

1

0

Population

Billion toe

18

15

12

9

6

3

0

Energy

Trillion $2010 PPP

180

150

120

90

60

30

01970 1990 2010 2030 1970 1990 2010 2030 1970 1990 2010 2030

GDP

FIGURE 11 Prospected global growth rates in population energy demand and GDP 1 toe =41868104 MJ (Source Adapted from BP see tinyurlcom7hlmqxn)

4 INTRODUCTION

demand will rise substantially from the current level with an increasing share fromChina and India This rise of the primary energy demand is projected to be larger thanthe population growth and this will cause a stress on the limited global resources Theprojected GDP even increases stronger so it is expected that average living standardsincrease which will result in additional strain on the available resources

113 Sustainability of Energy Supply

One of the major questions in the world arising from the general picture sketched inSection 112 is how mankind can ensure a global sustainable development for the(near) future In this context sustainability of our energy supply is of paramountimportance The key issues are discussed in the following text both from a pointof view of global socioeconomics and ecological sustainability

1131 Socioeconomic Sustainability As one of the most important economicdrivers to secure and improve the living standards of people in the world energysupply security is of crucial value for current and future generations Fossil fuelsrun out sooner or later as can be seen in Figure 12 they are not renewable on anacceptable time scale

This figure depicts the so-called RP ratios for different sources The RP ratio is theratio of the current proven reserves to production level The unit is years and it is ameasure of the expected time a certain fuel source is expected to be available

On a global scale it appears that oil and natural gas reserves will be availablemdashgiven the figures of 2012mdashfor an expected approximately 55 years and coal substan-tially longer (gt100 years) Of course new contributions to the reserves may be

0

50

100

150

200

250

1980 1985 1990 1995 2000 2005 2010 2015

RP

(yea

rs)

Oil

Coal

Natural gas

FIGURE 12 Overview of world (top) and regional (bottom) reserves-to-production (RP)ratios for oil natural gas and coal respectively (end 2012 status) Figures are based on datafrom BP (2013)

5ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

North America

S amp Cent America

Europe amp Eurasia

Middle East

Africa

Asia Pacific

0 20 40 60

RP (years)

80 100 120 140

North America

S amp Cent America

Europe amp Eurasia

Middle East

Africa

Asia Pacific

0

RP (years)

North America

S amp Cent America

Europe amp Eurasia

Middle East amp Africa

Asia Pacific

0 50 100 150 200 250 300RP (years)

50 100 150 200

FIGURE 12 (Continued )

6 INTRODUCTION

discovered in the (near) future but that does not change the inherently limited supplynature of the fossil fuel sources Regionally there are also significant differenceswhich is important in the context of energy policy developments on the differentcontinents

For the price developments of the fossil fuels not only their forecasted availabilityis of importance but also the market development in a landscape highly determined bypolitics Already well before the last resources of a fuel will have been depleted themarket will be severely stressed For the economies in the world fuel cost develop-ment is therefore also a primary point of concern From past developments particu-larly regarding oil it has been shown that substantial fuel price fluctuations (volatility)occur which has an impact on the global economy (eg food prices) that is difficult topredict Supply and demand will determine the price evolution for each fuel sourcebut the development of the market structure is also essential there is a large differencebetween a free market and an oligopoly or monopoly situation In this respect diver-sification of fuel sources with associated differentiation in suppliers is advantageousas it makes societies less prone to price manipulation by eg cartel formation andsudden disruptions of supply (Johansson et al 1993)

Self-sufficiency concerning energy supply is often mentioned as target of countriesfor (longer-term) sustainable economic development However not all countries haveaccess to resources within their territories that are sufficient for such a target othercountries on the other hand have a structural surplus Relief of trade barriers canhelp mitigate this structural discrepancy Also in the context of economic sustaina-bility a good trade balance should be maintained in relation to the energy supplywithin nations

Regarding social sustainability in the context of energy supply reduction of pov-erty should be mentioned first a good supply structure of energy carriers is one of thebasic requirements for such a development next to access to clean drinking water andgood soil for agricultural activity Associated herewith expectedly substantial healthimprovement should result from a good energy supply infrastructure Job creation andmaintenance is another aspect of social sustainability and certain energy supply formscan contribute significantly to this Also maintaining (or improving) societiesrsquo socialcohesion is an aspect that can be impacted by the energy supply structure

1132 Ecological Sustainability The energy supply structure should notcompromise the sound development of our environment both from a local and globalperspective One of the major issues in this respect is global warming which is for themain part attributed to the release of greenhouse gases (GHG) from fossil fuel com-bustion Other issues are related to local emissions of acid rain precursors and partic-ulate matter (PM)

Climate Change the Greenhouse Effect and Greenhouse Gas EmissionReduction The greenhouse effect occurs naturally to a large extent Without thiseffect the Earthrsquos average global temperature would reach only a low minus18C ratherthan the current approximate +15C Water vapor is the largest contributor to thiseffect with a complex role for clouds but also CO2 in the atmosphere plays a

7ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

significant role More than a century ago Arrhenius (1896) already identified thisrole in the Earthrsquos temperature control Ice core studies reveal that on millennial timescales changes in CO2 content recorded are highly correlated with changes in tem-perature although some temperature changes have occurred without a significantCO2 concentration change but the opposite does not appear to have happened(Falkowski et al 2000) Less pronounced roles are played by CH4 N2O (nitrousoxide) and several types of chlorofluorocarbons (CFCs) and SF6 It is the CO2CH4 N2O and CFC concentrations in the atmosphere upon which manrsquos industrial

0

1

Rad

iati

ve

forc

ing (

Wm

2)

350

(a)

300

Car

bon d

ioxid

e (p

pm

)

250

300

350

400

1800 1900

Year

2000

(b)

1500

2000

1000

Met

han

e (p

pb)

500

0

02

04

Rad

iati

ve

forc

ing (

Wm

2)

1000

500

1500

2000

1900

Year

20001800

FIGURE 13 Atmospheric concentrations of CO2 CH4 and N2O over the last 10000 years(large panels) and since 1750 (inset panels) Measurements are shown from ice cores (symbolswith different grey shades for different studies) and atmospheric samples (light grey lines insteep curve part red lines in the original publication) The corresponding radiative forcings(net solar energy flux to the earth) relative to 1750 are shown on the right-hand axes of the largepanels (SourceReproducedwithpermission fromIPCC(2007) figure23 figureSPM1copyIPCC)

8 INTRODUCTION

and household activities have a measurable impact Scientists largely agree on thepoint that in the last few centuries the activities of humans have directly or indirectlycaused the concentrations of the major GHG to increase This is exemplified byFigure 13 The atmospheric CO2 concentration varies to some extent from placeto place and from season to season It has been shown that concentrations are some-what higher in the northern hemisphere than in the southern hemisphere as most of theanthropogenic sources of CO2 are located north of the equator The difference in landsurface covered with forests being more concentrated north of the equator causeslarger seasonal fluctuations due to comparatively shorter growth periods than in thegenerally milder southern hemisphere locations that are under the influence of largeroceanic surfaces

Oscillations of atmospheric CO2 concentrations between about 180 and 280 ppmv

have occurred in the past approximately 480000 years in cycles of 100000 yearsbut it appears now we have abandoned this cycling behavior in a remarkably shorttime frame

Studies at the NASA Goddard Institute for Space Studies in New York (UnitedStates) have shown that over the past few decades the combined warming effectof non-CO2 GHG should have been comparable to that of CO2 alone However whileeach of the GHGmentioned earlier acts to warm the surface of the Earth the long-termclimatic effects of the other GHG differ from those of CO2 Methane eg has anatmospheric lifetime of only about 12 years By comparison newly added CO2 willremain for a time span of tens to thousands of years As a result about 65 of thecarbon dioxide that human activities have generated since the start of the IndustrialRevolution is in the air we breathe today A historical record of the amount ofCO2 in the atmosphere can be found in bubbles of air in arctic ice layers dating backas far as 600000 years The depth of such a layer is a measure of its time of formation

(c)

10000 5000

Time (before 2005)

0

0

01

Rad

iati

ve

forc

ing (

Wm

2)

300

270

Nit

rous

oxid

e (p

pb)

270

240

300

330

1800 1900

Year

2000

FIGURE 13 (Continued )

9ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

Another difference is that the principal anthropogenic sources of methane-bacterialfermentation in rice paddies and in the intestines of cattle are related to food produc-tion and hence are roughly proportional to the number of people on the planetBecause CH4 has such a short atmospheric lifetime the amount that is in the air isa good indicator of how much is being added with time Should the global populationdouble over the next half century the concentration of CH4 could also double but it isnot likely to rise by much more than that This would add at most a few tenths of adegree to the mean temperature of the Earth Future CO2 increases could in contrastwarm the climate by 10C or more

Nitrous oxide (N2O) and CFCs are in some ways more like CO2 in that oncereleased they remain in the atmosphere for a century or more The production ofN2O however is only indirectly dependent on human activities Its principal sourceis a natural one the bacterial removal of nitrogen from soils and although the worldpopulation swells in coming years the amount in the air should increase only slowly

The outlook for many CFCs is even more promising Today the most abundant ofthese man-made compounds freon-11 and freon-12 are being phased out of produc-tion altogether by international agreements because of their damaging effects on strat-ospheric ozone Indeed the concentration of one of these gases freon-11 peaked in1994 and is now in a slow decline that should continue for the next century or so Thefreon-12 concentration has not yet leveled off but is expected to do so within the nextfew years In terms of climatic effects the main threat from CFCs comes from otherlong-lived compounds that may be used to replace the ones that have been phased outand that could also act as GHG Since these possibly harmful replacement gases are asyet present in only small amounts and since as noted earlier projected increases inCH4 and N2O are so much less severe we shall for the rest of this discussion focussolely on the most important anthropogenic GHG CO2

Some experts have estimated that the Earthrsquos average global temperature has alreadyincreased by more than 05C since the mid-1900s due to this human-enhanced green-house effect also impacts on sea level (rising) and snow coverage (tending to decrease)have been investigated the results of which are summarized in Figure 14

Like most other planets and planetoids in the universe the Earth contains a greatdeal of carbon which is slowly and continually transported from the mantle to thecrust and back again in the course of volcanic eruption and subduction phenomenaThe portion that finds itself near the surface is continually exchanged and recycledamong plants animals soil air and oceans In some of these temporary stocks car-bon is more securely held while in others it more readily combines with oxygen in theair to form CO2 In order to predict how atmospheric CO2 levels and climate maychange in the future it is important to understand where carbon is stored and whatits dynamic cycling behavior looks like The carbon reservoirs that are most relevantto global warming are listed in Table 11 with the total amount of carbon that theycontained in 2000

The atmosphere contains approximately 720 Gt C in the form of CO2 currentmeasured atmospheric CO2 concentrations are nearly 400 ppmv The rate of changein this carbon stock not only depends on human activities but also on biogeochemicaland climatological processes and their interactions with the global carbon cycle

10 INTRODUCTION

Project 467References 468

15 Biorefineries Integration of Different Technologies 469Wiebren de Jong

151 What is a Biorefinery and What is the Difference with anOil Refinery 470

152 Types of Biorefineries 474153 Economic Considerations Evaluating Biorefinery Concepts

Basic Methods for Assessing Investments and Cost Prices 481154 Outlook to the Future of Biorefineries 492Chapter Summary and Study Guide 493Key Concepts 493Short-Answer Questions 493Problems 494Projects 497Internet References 500References 500

PART IV END USES 503

16 High-Efficiency Energy Systems withBiomass Gasifiers and Solid Oxide Fuel Cells 505PV Aravind and Ming Liu

161 Introduction 506162 Solid Oxide Fuel Cells 507163 Biomass GasifierndashSOFC Combination 512164 Concluding Remarks 520Chapter Summary and Study Guide 520Key Concepts 521Short-Answer Questions 521Problems 521Projects 522Internet References 522References 523

17 Synthesis Gas Utilization for TransportationFuel Production 525J Ruud van Ommen and Johan Grievink

171 Introduction 526172 FischerndashTropsch Synthesis 527173 Synthetic Natural Gas Synthesis 535174 Methanol Synthesis 537

xiCONTENTS

175 Comparison of the Different Options 538Chapter Summary and Study Guide 540Key Concepts 540Short-Answer Questions 541Problems 541Projects 544Internet References 545References 545

18 Chemistry of Biofuels and Biofuel Additivesfrom Biomass 547Isabel WCE Arends

181 Introduction 548182 Bioethanol and Biodiesel 548183 Conversion of Sugars to Hydrocarbon Fuels 553184 Greenness of the Conversion of Platform Molecules

into Biobased Fuel Additives 557185 Direct Aqueous Reforming of Sugars Leading to a

Range of Alkanes 564186 Future Generations of Biofuel 566Chapter Summary and Study Guide 566Key Concepts 567Short-Answer Questions 567Problems 568Projects 568Internet References 568References 569

INDEX 571

xii CONTENTS

PREFACE

This book deals with bioenergy as a versatile renewable source Ever since thedawn of mankind people have been using wood and other biogenic sources forheating cooking and lighting Trade of biomass came up in historic times (thinkabout the silk route for example) Even industrial iron making via metal reductionwas based on biomass utilization (carbonization) However that very applicationalso led to substantial deforestation which was clear in the United Kingdomand demonstrated that using biomass does not guarantee a sustainable energy sup-ply Therefore the industrial revolution introduced the large-scale application offossil fuel starting with the use of coal

The steam engine became the workhorse of the nineteenth century Coal alsobecame the basis of the chemical industry at that time Oil was initially used for lampsbut later it appeared to be the choice of raw material for petrol and diesel in Otto andDiesel engines respectively Wood and other sources came back into the pictureduring the interbellum period and the Second World War when oil was scarce inparticular on the European continent At that time cars trucks and ships made useof the gas extracted from fixed bed wood gasification installations Also chemicalssupply and materials were increasingly supported by wood-based processes AfterWWII the cheap oil era was entered and such routes were largely abandoned Afterthe oil crises of the 1970s biomass came back into the picture as an energy sourcereinforced by environmental concerns about the use of fossil energy sources due totheir associated CO2 emissions stimulating the greenhouse effect At present biomassis seriously back as part of a sustainable energy mix in combination with materialsand chemicals supply and a wide world of biorefinery options has opened up

The field of biomass to energy supply is multidisciplinary and offers a wealth ofintegration of knowledge to young engineers starting their careers The technologies

xiii

strongly lean on chemical engineering skills but also on physics mechanical engineer-ing and agricultural sciences among others Not only technology issues determine thesuccess of biomass for our energy supply there are many hurdles to be taken into thenontechnical domain such as logistics (trade and handling) infrastructure and politics(subsidies rural development employment generation etc) to name a few

This book is divided into four parts covering broad areas of the field of biomassconversion technology chains Part I starts with the socioeconomic and environmentalcontext and biomass basics It gives insight into the boundary conditions and the playingfield bioenergy supply has Moreover it provides a deeper look into what biomass reallyis Part II covers the chemical engineering basics to provide the engineer with tools tosolve problems in the domain design new biomass-based processes and evaluateconversion subprocesses The tools range from setting up balances evaluating the massand heat transport phenomena thermodynamics and kinetics to reactor and processdesign Part III deals with the study of different biomass conversion processes rangingfrom nonreactive pretreatment via combustion processes gasification hydrothermal pro-cessing pyrolysis and torrefaction to biochemical conversion processes and biorefineryintegration of such technologies Finally Part IV treats the end use of primary biomassconversion products for example power production via fuel cells transportationfuel production (eg via the FischerndashTropsch process) and platform chemicalsproduction via organic chemistry to substitute the conventional petrochemical pathwaysoffered today

We were inspired to write this book by the course ldquoEnergy from Biomassrdquo that wehave been teaching for a number of years in the MSc program of Sustainable EnergyTechnology at Delft University a program that is part of the 3TU cooperation betweenthe technical universities of Delft Eindhoven and Twente After teaching the coursefor some years using the lecture notes prepared by our Eindhoven colleagues RobBastiaans Jeroen van Oijen andMark Prins we thought it would be worthy to furtherimprove the course material Since the students in Sustainable Energy Technologyhave a very diverse background we have devoted Part II of the book to giving thereader enough background in chemical engineering for reading the more specializedchapters This means that this book is useful for everyone with a BSc in anyengineering discipline Apart from students at the MSc level professionals in thebiomass field may also find this book as a knowledgeable source for example fordesigning and evaluating novel biorefinery systems and conversion components

Delft December 2013 WIEBREN DE JONG AND J RUUD VAN OMMEN

He will be like a tree planted by the water that sends out its roots by the stream It doesnot fear when heat comes its leaves are always green It has no worries in a year ofdrought and never fails to bear fruit ndash Bible Jeremiah 178

Biomass is forever ndash Prof David Halldagger

xiv PREFACE

ACKNOWLEDGMENTS

This book would not have been published without the contributions from manypeople First of all we would like to acknowledge all the students that followedour course ldquoEnergy from Biomassrdquo over the years they inspired us to compose thisbook We are very glad that many of our colleagues agreed to contribute chapters tothis book It was great to work with this team of co-authors all bringing in their spe-cific expertise to cover the broad field of energy from biomass A big thanks to all ofyou For some chapters the additional input from others is specifically acknowledgedLikun Ma is kindly acknowledged for his contribution to the examples in Chapter 4Ryan Bogaars for his suggestions concerning Chapter 10 Xiangmei Meng and Onur-sal Yakaboylu for contributing some of the examples of Chapter 10 Richard Eijsbergfor the first generation ethanol process figures and data in Chapter 13 Tim Geraedtsand Elze Oude Lansink for the project in Chapter 15 Fred van Rantwijk for valuableinput and discussions on Chapter 18 and Adrea Fabre for her advices regarding thewritingWe are also grateful for the willingness of many colleagues to review chaptersin order to find mistakes and make suggestions for further improvements Ourreviewers were in alphabetic order Rob Bakker Sune Bengtsson PouyanBoukany Anthony Bridgwater Harry Croezen Lilian de Martiacuten Jorge GasconHans Geerlings Johan Grievink Sef Heijnen Kas Hemmes Paulien Herder TrulsLiliedahl Gabrie Meesters Bart Merci Kyriakos Panopoulos Wolter Prins SinaSartipi Fabrizio Scala Tilman Schildhauer Andrzej Stankiewicz GeorgiosStefanidis Bob Ursem Henk van den Berg Theo van der Meer Jules van Lier Maritvan Lieshout and Stanislav Vassilev A special word of thanks should go to Anneliesvan Diepen When the chapters were complete she made a great effort to harmonizethem for example in figures symbols lay-out and wording She also has caughtnumerous mistakes that were still present in earlier versions We would like to thank

xv

Jan Leen Kloosterman (Director of Education Sustainable Energy Technology SET)for the financial support from the SET program for editorial assistance We would alsolike to thank the people at Wiley for the smooth cooperation during the preparation ofthe manuscript Finally we would like to thank the ones close to usmdashKlarine (WdJ)and Ceciel Fenne and Chris (JRvO)mdashfor their understanding and support during allthe evenings and weekends that the writing and editing took

xvi ACKNOWLEDGMENTS

LIST OF CONTRIBUTORS

PV Aravind Drir Department of Process and Energy Energy TechnologySection Faculty of Mechanical Maritime and Materials Engineering DelftUniversity of Technology Delft the Netherlands

Isabel WCE Arends Profdr Department of Biotechnology Biocatalysis GroupFaculty of Applied Sciences Delft University of Technology Delft theNetherlands

Rob JM Bastiaans Drir Department of Mechanical Engineering CombustionTechnology Section Eindhoven University of Technology Eindhoven theNetherlands

Maria C Cuellar Dr Department of Biotechnology BioProcess EngineeringGroup Faculty of Applied Sciences Delft University of Technology Delft theNetherlands

Martina Fantini Drir Department of Process and Energy Energy TechnologySection Faculty of Mechanical Maritime and Materials Engineering DelftUniversity of Technology Delft the Netherlands

Johan Grievink Prof ir Department of Chemical Engineering Product amp ProcessEngineering Group Faculty of Applied Sciences Delft University of TechnologyDelft the Netherlands

ArnoHH Janssen Ir ECN Biomass amp Energy Efficiency Petten the Netherlands

Wiebren de Jong Drir Department of Process and Energy Energy TechnologySection Faculty of Mechanical Maritime and Materials Engineering DelftUniversity of Technology Delft the Netherlands

xvii

Yash Joshi Ir Department of Process and Energy Energy Technology SectionFaculty of Mechanical Maritime and Materials Engineering Delft University ofTechnology Delft the Netherlands

Sascha RA Kersten Profdrir Sustainable Process Technology Group Facultyof Science and Technology University of Twente Enschede the Netherlands

Jaap HA Kiel Profdrir ECN Biomass amp Energy Efficiency Petten andDepartment of Process and Energy Energy Technology Section Faculty ofMechanical Maritime andMaterials Engineering Delft University of TechnologyDelft the Netherlands

Robbert Kleerebezem Drir Department of Biotechnology EnvironmentalBiotechnology Group Faculty of Applied Sciences Delft University of TechnologyDelft the Netherlands

Ming Liu Drir Department of Process and Energy Energy Technology SectionFaculty of Mechanical Maritime and Materials Engineering Delft University ofTechnology Delft the Netherlands

Lilian de Martiacuten Dr Department of Chemical Engineering Product amp ProcessEngineering Group Faculty of Applied Sciences Delft University of TechnologyDelft the Netherlands

Jeroen A van Oijen Drir Department of Mechanical Engineering CombustionTechnology Section Eindhoven University of Technology Eindhoven theNetherlands

J Ruud van Ommen Drir Department of Chemical Engineering Product ampProcess Engineering Group Faculty of Applied Sciences Delft University ofTechnology Delft the Netherlands

Stijn RG Oudenhoven Ir Sustainable Process Technology Group Faculty ofScience and Technology University of Twente Enschede the Netherlands

Dirk JEM Roekaerts Profdr Department of Process and Energy FluidMechanics Section Faculty of Mechanical Maritime and Materials EngineeringDelft University of Technology Delft the Netherlands

Adrie JJ Straathof Drir Department of Biotechnology BioProcess EngineeringGroup Faculty of Applied Sciences Delft University of Technology Delft theNetherlands

Pieter LJ Swinkels Ir Faculty of Applied Sciences Delft Product amp ProcessDesign Institute Delft University of Technology Delft the Netherlands

xviii LIST OF CONTRIBUTORS

PART I

SOCIAL CONTEXT AND STRUCTURALBASIS OF BIOMASS AS A RENEWABLEENERGY SOURCES

1INTRODUCTION SOCIOECONOMICASPECTS OF BIOMASS CONVERSION

WIEBREN DE JONG1 AND J RUUD VAN OMMEN2

1Department of Process and Energy Energy Technology Section Faculty of MechanicalMaritime and Materials Engineering Delft University of Technology Delft the Netherlands2Department of Chemical Engineering Product amp Process Engineering Group Faculty ofApplied Sciences Delft University of Technology Delft the Netherlands

ACRONYMS

CDM clean development mechanismCFCs chlorofluorocarbonsdLUC direct land use changeGDP gross domestic productGHG greenhouse gasiLUC indirect land use changeJI joint implementationLCA life cycle assessmentLUC land use changeRP ratio reserves-to-production ratio [y]TOE tonnes of oil equivalent(s) (= 4187 GJ)UNFCCC United Nations Framework Convention on Climate Change

Biomass as a Sustainable Energy Source for the Future Fundamentals of Conversion ProcessesFirst Edition Edited by Wiebren de Jong and J Ruud van Ommencopy 2015 American Institute of Chemical Engineers Inc Published 2015 by John Wiley amp Sons Inc

3

11 ENERGY SUPPLY ECONOMIC AND ENVIRONMENTALCONSIDERATIONS

111 Introduction The Importance of Energy Supply

In the past two centuries since the Industrial Revolution in the 1700s that was initiatedby the invention of the steam turbine the world has undergone a drastic change due tothe steeply increased contribution of fossil fuels (coal oil and natural gas) to modernsocietiesrsquo energy supply (McKay 2009) Though the Chinese society already usedcoal for energy supply in approximately 1000 BC and the Romans prior to AD 400(World-Coal-Institute 2005) the first written references indicating its use are fromabout the thirteenth century and beyond (Hubbert 1949) These hydrocarbon fuelsso far have been considered essential as they are comparatively cheap and convenientenergy carriers used for heating cooking lighting and mechanical as well as electricpower production and have been widely used as transportation fuels and feedstocksfor the manufacture of bulk and fine chemicals as well as other materials with a widerange of applications Rapid global population growth expansion of economies andhigher standards have caused an enormous increase in worldwide energy consump-tion which was partly made possible by the supply of cheap fossil fuels

112 Development of Global Energy Demand

Figure 11 shows a scenario toward the year 2030 presented by the oil company BPconcerning population growth in relation to developments in total primary energyutilization and gross domestic product (GDP) The figure shows that global energy

Billion

Rest of

the world

India

China

9

8

7

6

5

4

3

2

1

0

Population

Billion toe

18

15

12

9

6

3

0

Energy

Trillion $2010 PPP

180

150

120

90

60

30

01970 1990 2010 2030 1970 1990 2010 2030 1970 1990 2010 2030

GDP

FIGURE 11 Prospected global growth rates in population energy demand and GDP 1 toe =41868104 MJ (Source Adapted from BP see tinyurlcom7hlmqxn)

4 INTRODUCTION

demand will rise substantially from the current level with an increasing share fromChina and India This rise of the primary energy demand is projected to be larger thanthe population growth and this will cause a stress on the limited global resources Theprojected GDP even increases stronger so it is expected that average living standardsincrease which will result in additional strain on the available resources

113 Sustainability of Energy Supply

One of the major questions in the world arising from the general picture sketched inSection 112 is how mankind can ensure a global sustainable development for the(near) future In this context sustainability of our energy supply is of paramountimportance The key issues are discussed in the following text both from a pointof view of global socioeconomics and ecological sustainability

1131 Socioeconomic Sustainability As one of the most important economicdrivers to secure and improve the living standards of people in the world energysupply security is of crucial value for current and future generations Fossil fuelsrun out sooner or later as can be seen in Figure 12 they are not renewable on anacceptable time scale

This figure depicts the so-called RP ratios for different sources The RP ratio is theratio of the current proven reserves to production level The unit is years and it is ameasure of the expected time a certain fuel source is expected to be available

On a global scale it appears that oil and natural gas reserves will be availablemdashgiven the figures of 2012mdashfor an expected approximately 55 years and coal substan-tially longer (gt100 years) Of course new contributions to the reserves may be

0

50

100

150

200

250

1980 1985 1990 1995 2000 2005 2010 2015

RP

(yea

rs)

Oil

Coal

Natural gas

FIGURE 12 Overview of world (top) and regional (bottom) reserves-to-production (RP)ratios for oil natural gas and coal respectively (end 2012 status) Figures are based on datafrom BP (2013)

5ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

North America

S amp Cent America

Europe amp Eurasia

Middle East

Africa

Asia Pacific

0 20 40 60

RP (years)

80 100 120 140

North America

S amp Cent America

Europe amp Eurasia

Middle East

Africa

Asia Pacific

0

RP (years)

North America

S amp Cent America

Europe amp Eurasia

Middle East amp Africa

Asia Pacific

0 50 100 150 200 250 300RP (years)

50 100 150 200

FIGURE 12 (Continued )

6 INTRODUCTION

discovered in the (near) future but that does not change the inherently limited supplynature of the fossil fuel sources Regionally there are also significant differenceswhich is important in the context of energy policy developments on the differentcontinents

For the price developments of the fossil fuels not only their forecasted availabilityis of importance but also the market development in a landscape highly determined bypolitics Already well before the last resources of a fuel will have been depleted themarket will be severely stressed For the economies in the world fuel cost develop-ment is therefore also a primary point of concern From past developments particu-larly regarding oil it has been shown that substantial fuel price fluctuations (volatility)occur which has an impact on the global economy (eg food prices) that is difficult topredict Supply and demand will determine the price evolution for each fuel sourcebut the development of the market structure is also essential there is a large differencebetween a free market and an oligopoly or monopoly situation In this respect diver-sification of fuel sources with associated differentiation in suppliers is advantageousas it makes societies less prone to price manipulation by eg cartel formation andsudden disruptions of supply (Johansson et al 1993)

Self-sufficiency concerning energy supply is often mentioned as target of countriesfor (longer-term) sustainable economic development However not all countries haveaccess to resources within their territories that are sufficient for such a target othercountries on the other hand have a structural surplus Relief of trade barriers canhelp mitigate this structural discrepancy Also in the context of economic sustaina-bility a good trade balance should be maintained in relation to the energy supplywithin nations

Regarding social sustainability in the context of energy supply reduction of pov-erty should be mentioned first a good supply structure of energy carriers is one of thebasic requirements for such a development next to access to clean drinking water andgood soil for agricultural activity Associated herewith expectedly substantial healthimprovement should result from a good energy supply infrastructure Job creation andmaintenance is another aspect of social sustainability and certain energy supply formscan contribute significantly to this Also maintaining (or improving) societiesrsquo socialcohesion is an aspect that can be impacted by the energy supply structure

1132 Ecological Sustainability The energy supply structure should notcompromise the sound development of our environment both from a local and globalperspective One of the major issues in this respect is global warming which is for themain part attributed to the release of greenhouse gases (GHG) from fossil fuel com-bustion Other issues are related to local emissions of acid rain precursors and partic-ulate matter (PM)

Climate Change the Greenhouse Effect and Greenhouse Gas EmissionReduction The greenhouse effect occurs naturally to a large extent Without thiseffect the Earthrsquos average global temperature would reach only a low minus18C ratherthan the current approximate +15C Water vapor is the largest contributor to thiseffect with a complex role for clouds but also CO2 in the atmosphere plays a

7ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

significant role More than a century ago Arrhenius (1896) already identified thisrole in the Earthrsquos temperature control Ice core studies reveal that on millennial timescales changes in CO2 content recorded are highly correlated with changes in tem-perature although some temperature changes have occurred without a significantCO2 concentration change but the opposite does not appear to have happened(Falkowski et al 2000) Less pronounced roles are played by CH4 N2O (nitrousoxide) and several types of chlorofluorocarbons (CFCs) and SF6 It is the CO2CH4 N2O and CFC concentrations in the atmosphere upon which manrsquos industrial

0

1

Rad

iati

ve

forc

ing (

Wm

2)

350

(a)

300

Car

bon d

ioxid

e (p

pm

)

250

300

350

400

1800 1900

Year

2000

(b)

1500

2000

1000

Met

han

e (p

pb)

500

0

02

04

Rad

iati

ve

forc

ing (

Wm

2)

1000

500

1500

2000

1900

Year

20001800

FIGURE 13 Atmospheric concentrations of CO2 CH4 and N2O over the last 10000 years(large panels) and since 1750 (inset panels) Measurements are shown from ice cores (symbolswith different grey shades for different studies) and atmospheric samples (light grey lines insteep curve part red lines in the original publication) The corresponding radiative forcings(net solar energy flux to the earth) relative to 1750 are shown on the right-hand axes of the largepanels (SourceReproducedwithpermission fromIPCC(2007) figure23 figureSPM1copyIPCC)

8 INTRODUCTION

and household activities have a measurable impact Scientists largely agree on thepoint that in the last few centuries the activities of humans have directly or indirectlycaused the concentrations of the major GHG to increase This is exemplified byFigure 13 The atmospheric CO2 concentration varies to some extent from placeto place and from season to season It has been shown that concentrations are some-what higher in the northern hemisphere than in the southern hemisphere as most of theanthropogenic sources of CO2 are located north of the equator The difference in landsurface covered with forests being more concentrated north of the equator causeslarger seasonal fluctuations due to comparatively shorter growth periods than in thegenerally milder southern hemisphere locations that are under the influence of largeroceanic surfaces

Oscillations of atmospheric CO2 concentrations between about 180 and 280 ppmv

have occurred in the past approximately 480000 years in cycles of 100000 yearsbut it appears now we have abandoned this cycling behavior in a remarkably shorttime frame

Studies at the NASA Goddard Institute for Space Studies in New York (UnitedStates) have shown that over the past few decades the combined warming effectof non-CO2 GHG should have been comparable to that of CO2 alone However whileeach of the GHGmentioned earlier acts to warm the surface of the Earth the long-termclimatic effects of the other GHG differ from those of CO2 Methane eg has anatmospheric lifetime of only about 12 years By comparison newly added CO2 willremain for a time span of tens to thousands of years As a result about 65 of thecarbon dioxide that human activities have generated since the start of the IndustrialRevolution is in the air we breathe today A historical record of the amount ofCO2 in the atmosphere can be found in bubbles of air in arctic ice layers dating backas far as 600000 years The depth of such a layer is a measure of its time of formation

(c)

10000 5000

Time (before 2005)

0

0

01

Rad

iati

ve

forc

ing (

Wm

2)

300

270

Nit

rous

oxid

e (p

pb)

270

240

300

330

1800 1900

Year

2000

FIGURE 13 (Continued )

9ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

Another difference is that the principal anthropogenic sources of methane-bacterialfermentation in rice paddies and in the intestines of cattle are related to food produc-tion and hence are roughly proportional to the number of people on the planetBecause CH4 has such a short atmospheric lifetime the amount that is in the air isa good indicator of how much is being added with time Should the global populationdouble over the next half century the concentration of CH4 could also double but it isnot likely to rise by much more than that This would add at most a few tenths of adegree to the mean temperature of the Earth Future CO2 increases could in contrastwarm the climate by 10C or more

Nitrous oxide (N2O) and CFCs are in some ways more like CO2 in that oncereleased they remain in the atmosphere for a century or more The production ofN2O however is only indirectly dependent on human activities Its principal sourceis a natural one the bacterial removal of nitrogen from soils and although the worldpopulation swells in coming years the amount in the air should increase only slowly

The outlook for many CFCs is even more promising Today the most abundant ofthese man-made compounds freon-11 and freon-12 are being phased out of produc-tion altogether by international agreements because of their damaging effects on strat-ospheric ozone Indeed the concentration of one of these gases freon-11 peaked in1994 and is now in a slow decline that should continue for the next century or so Thefreon-12 concentration has not yet leveled off but is expected to do so within the nextfew years In terms of climatic effects the main threat from CFCs comes from otherlong-lived compounds that may be used to replace the ones that have been phased outand that could also act as GHG Since these possibly harmful replacement gases are asyet present in only small amounts and since as noted earlier projected increases inCH4 and N2O are so much less severe we shall for the rest of this discussion focussolely on the most important anthropogenic GHG CO2

Some experts have estimated that the Earthrsquos average global temperature has alreadyincreased by more than 05C since the mid-1900s due to this human-enhanced green-house effect also impacts on sea level (rising) and snow coverage (tending to decrease)have been investigated the results of which are summarized in Figure 14

Like most other planets and planetoids in the universe the Earth contains a greatdeal of carbon which is slowly and continually transported from the mantle to thecrust and back again in the course of volcanic eruption and subduction phenomenaThe portion that finds itself near the surface is continually exchanged and recycledamong plants animals soil air and oceans In some of these temporary stocks car-bon is more securely held while in others it more readily combines with oxygen in theair to form CO2 In order to predict how atmospheric CO2 levels and climate maychange in the future it is important to understand where carbon is stored and whatits dynamic cycling behavior looks like The carbon reservoirs that are most relevantto global warming are listed in Table 11 with the total amount of carbon that theycontained in 2000

The atmosphere contains approximately 720 Gt C in the form of CO2 currentmeasured atmospheric CO2 concentrations are nearly 400 ppmv The rate of changein this carbon stock not only depends on human activities but also on biogeochemicaland climatological processes and their interactions with the global carbon cycle

10 INTRODUCTION

175 Comparison of the Different Options 538Chapter Summary and Study Guide 540Key Concepts 540Short-Answer Questions 541Problems 541Projects 544Internet References 545References 545

18 Chemistry of Biofuels and Biofuel Additivesfrom Biomass 547Isabel WCE Arends

181 Introduction 548182 Bioethanol and Biodiesel 548183 Conversion of Sugars to Hydrocarbon Fuels 553184 Greenness of the Conversion of Platform Molecules

into Biobased Fuel Additives 557185 Direct Aqueous Reforming of Sugars Leading to a

Range of Alkanes 564186 Future Generations of Biofuel 566Chapter Summary and Study Guide 566Key Concepts 567Short-Answer Questions 567Problems 568Projects 568Internet References 568References 569

INDEX 571

xii CONTENTS

PREFACE

This book deals with bioenergy as a versatile renewable source Ever since thedawn of mankind people have been using wood and other biogenic sources forheating cooking and lighting Trade of biomass came up in historic times (thinkabout the silk route for example) Even industrial iron making via metal reductionwas based on biomass utilization (carbonization) However that very applicationalso led to substantial deforestation which was clear in the United Kingdomand demonstrated that using biomass does not guarantee a sustainable energy sup-ply Therefore the industrial revolution introduced the large-scale application offossil fuel starting with the use of coal

The steam engine became the workhorse of the nineteenth century Coal alsobecame the basis of the chemical industry at that time Oil was initially used for lampsbut later it appeared to be the choice of raw material for petrol and diesel in Otto andDiesel engines respectively Wood and other sources came back into the pictureduring the interbellum period and the Second World War when oil was scarce inparticular on the European continent At that time cars trucks and ships made useof the gas extracted from fixed bed wood gasification installations Also chemicalssupply and materials were increasingly supported by wood-based processes AfterWWII the cheap oil era was entered and such routes were largely abandoned Afterthe oil crises of the 1970s biomass came back into the picture as an energy sourcereinforced by environmental concerns about the use of fossil energy sources due totheir associated CO2 emissions stimulating the greenhouse effect At present biomassis seriously back as part of a sustainable energy mix in combination with materialsand chemicals supply and a wide world of biorefinery options has opened up

The field of biomass to energy supply is multidisciplinary and offers a wealth ofintegration of knowledge to young engineers starting their careers The technologies

xiii

strongly lean on chemical engineering skills but also on physics mechanical engineer-ing and agricultural sciences among others Not only technology issues determine thesuccess of biomass for our energy supply there are many hurdles to be taken into thenontechnical domain such as logistics (trade and handling) infrastructure and politics(subsidies rural development employment generation etc) to name a few

This book is divided into four parts covering broad areas of the field of biomassconversion technology chains Part I starts with the socioeconomic and environmentalcontext and biomass basics It gives insight into the boundary conditions and the playingfield bioenergy supply has Moreover it provides a deeper look into what biomass reallyis Part II covers the chemical engineering basics to provide the engineer with tools tosolve problems in the domain design new biomass-based processes and evaluateconversion subprocesses The tools range from setting up balances evaluating the massand heat transport phenomena thermodynamics and kinetics to reactor and processdesign Part III deals with the study of different biomass conversion processes rangingfrom nonreactive pretreatment via combustion processes gasification hydrothermal pro-cessing pyrolysis and torrefaction to biochemical conversion processes and biorefineryintegration of such technologies Finally Part IV treats the end use of primary biomassconversion products for example power production via fuel cells transportationfuel production (eg via the FischerndashTropsch process) and platform chemicalsproduction via organic chemistry to substitute the conventional petrochemical pathwaysoffered today

We were inspired to write this book by the course ldquoEnergy from Biomassrdquo that wehave been teaching for a number of years in the MSc program of Sustainable EnergyTechnology at Delft University a program that is part of the 3TU cooperation betweenthe technical universities of Delft Eindhoven and Twente After teaching the coursefor some years using the lecture notes prepared by our Eindhoven colleagues RobBastiaans Jeroen van Oijen andMark Prins we thought it would be worthy to furtherimprove the course material Since the students in Sustainable Energy Technologyhave a very diverse background we have devoted Part II of the book to giving thereader enough background in chemical engineering for reading the more specializedchapters This means that this book is useful for everyone with a BSc in anyengineering discipline Apart from students at the MSc level professionals in thebiomass field may also find this book as a knowledgeable source for example fordesigning and evaluating novel biorefinery systems and conversion components

Delft December 2013 WIEBREN DE JONG AND J RUUD VAN OMMEN

He will be like a tree planted by the water that sends out its roots by the stream It doesnot fear when heat comes its leaves are always green It has no worries in a year ofdrought and never fails to bear fruit ndash Bible Jeremiah 178

Biomass is forever ndash Prof David Halldagger

xiv PREFACE

ACKNOWLEDGMENTS

This book would not have been published without the contributions from manypeople First of all we would like to acknowledge all the students that followedour course ldquoEnergy from Biomassrdquo over the years they inspired us to compose thisbook We are very glad that many of our colleagues agreed to contribute chapters tothis book It was great to work with this team of co-authors all bringing in their spe-cific expertise to cover the broad field of energy from biomass A big thanks to all ofyou For some chapters the additional input from others is specifically acknowledgedLikun Ma is kindly acknowledged for his contribution to the examples in Chapter 4Ryan Bogaars for his suggestions concerning Chapter 10 Xiangmei Meng and Onur-sal Yakaboylu for contributing some of the examples of Chapter 10 Richard Eijsbergfor the first generation ethanol process figures and data in Chapter 13 Tim Geraedtsand Elze Oude Lansink for the project in Chapter 15 Fred van Rantwijk for valuableinput and discussions on Chapter 18 and Adrea Fabre for her advices regarding thewritingWe are also grateful for the willingness of many colleagues to review chaptersin order to find mistakes and make suggestions for further improvements Ourreviewers were in alphabetic order Rob Bakker Sune Bengtsson PouyanBoukany Anthony Bridgwater Harry Croezen Lilian de Martiacuten Jorge GasconHans Geerlings Johan Grievink Sef Heijnen Kas Hemmes Paulien Herder TrulsLiliedahl Gabrie Meesters Bart Merci Kyriakos Panopoulos Wolter Prins SinaSartipi Fabrizio Scala Tilman Schildhauer Andrzej Stankiewicz GeorgiosStefanidis Bob Ursem Henk van den Berg Theo van der Meer Jules van Lier Maritvan Lieshout and Stanislav Vassilev A special word of thanks should go to Anneliesvan Diepen When the chapters were complete she made a great effort to harmonizethem for example in figures symbols lay-out and wording She also has caughtnumerous mistakes that were still present in earlier versions We would like to thank

xv

Jan Leen Kloosterman (Director of Education Sustainable Energy Technology SET)for the financial support from the SET program for editorial assistance We would alsolike to thank the people at Wiley for the smooth cooperation during the preparation ofthe manuscript Finally we would like to thank the ones close to usmdashKlarine (WdJ)and Ceciel Fenne and Chris (JRvO)mdashfor their understanding and support during allthe evenings and weekends that the writing and editing took

xvi ACKNOWLEDGMENTS

LIST OF CONTRIBUTORS

PV Aravind Drir Department of Process and Energy Energy TechnologySection Faculty of Mechanical Maritime and Materials Engineering DelftUniversity of Technology Delft the Netherlands

Isabel WCE Arends Profdr Department of Biotechnology Biocatalysis GroupFaculty of Applied Sciences Delft University of Technology Delft theNetherlands

Rob JM Bastiaans Drir Department of Mechanical Engineering CombustionTechnology Section Eindhoven University of Technology Eindhoven theNetherlands

Maria C Cuellar Dr Department of Biotechnology BioProcess EngineeringGroup Faculty of Applied Sciences Delft University of Technology Delft theNetherlands

Martina Fantini Drir Department of Process and Energy Energy TechnologySection Faculty of Mechanical Maritime and Materials Engineering DelftUniversity of Technology Delft the Netherlands

Johan Grievink Prof ir Department of Chemical Engineering Product amp ProcessEngineering Group Faculty of Applied Sciences Delft University of TechnologyDelft the Netherlands

ArnoHH Janssen Ir ECN Biomass amp Energy Efficiency Petten the Netherlands

Wiebren de Jong Drir Department of Process and Energy Energy TechnologySection Faculty of Mechanical Maritime and Materials Engineering DelftUniversity of Technology Delft the Netherlands

xvii

Yash Joshi Ir Department of Process and Energy Energy Technology SectionFaculty of Mechanical Maritime and Materials Engineering Delft University ofTechnology Delft the Netherlands

Sascha RA Kersten Profdrir Sustainable Process Technology Group Facultyof Science and Technology University of Twente Enschede the Netherlands

Jaap HA Kiel Profdrir ECN Biomass amp Energy Efficiency Petten andDepartment of Process and Energy Energy Technology Section Faculty ofMechanical Maritime andMaterials Engineering Delft University of TechnologyDelft the Netherlands

Robbert Kleerebezem Drir Department of Biotechnology EnvironmentalBiotechnology Group Faculty of Applied Sciences Delft University of TechnologyDelft the Netherlands

Ming Liu Drir Department of Process and Energy Energy Technology SectionFaculty of Mechanical Maritime and Materials Engineering Delft University ofTechnology Delft the Netherlands

Lilian de Martiacuten Dr Department of Chemical Engineering Product amp ProcessEngineering Group Faculty of Applied Sciences Delft University of TechnologyDelft the Netherlands

Jeroen A van Oijen Drir Department of Mechanical Engineering CombustionTechnology Section Eindhoven University of Technology Eindhoven theNetherlands

J Ruud van Ommen Drir Department of Chemical Engineering Product ampProcess Engineering Group Faculty of Applied Sciences Delft University ofTechnology Delft the Netherlands

Stijn RG Oudenhoven Ir Sustainable Process Technology Group Faculty ofScience and Technology University of Twente Enschede the Netherlands

Dirk JEM Roekaerts Profdr Department of Process and Energy FluidMechanics Section Faculty of Mechanical Maritime and Materials EngineeringDelft University of Technology Delft the Netherlands

Adrie JJ Straathof Drir Department of Biotechnology BioProcess EngineeringGroup Faculty of Applied Sciences Delft University of Technology Delft theNetherlands

Pieter LJ Swinkels Ir Faculty of Applied Sciences Delft Product amp ProcessDesign Institute Delft University of Technology Delft the Netherlands

xviii LIST OF CONTRIBUTORS

PART I

SOCIAL CONTEXT AND STRUCTURALBASIS OF BIOMASS AS A RENEWABLEENERGY SOURCES

1INTRODUCTION SOCIOECONOMICASPECTS OF BIOMASS CONVERSION

WIEBREN DE JONG1 AND J RUUD VAN OMMEN2

1Department of Process and Energy Energy Technology Section Faculty of MechanicalMaritime and Materials Engineering Delft University of Technology Delft the Netherlands2Department of Chemical Engineering Product amp Process Engineering Group Faculty ofApplied Sciences Delft University of Technology Delft the Netherlands

ACRONYMS

CDM clean development mechanismCFCs chlorofluorocarbonsdLUC direct land use changeGDP gross domestic productGHG greenhouse gasiLUC indirect land use changeJI joint implementationLCA life cycle assessmentLUC land use changeRP ratio reserves-to-production ratio [y]TOE tonnes of oil equivalent(s) (= 4187 GJ)UNFCCC United Nations Framework Convention on Climate Change

Biomass as a Sustainable Energy Source for the Future Fundamentals of Conversion ProcessesFirst Edition Edited by Wiebren de Jong and J Ruud van Ommencopy 2015 American Institute of Chemical Engineers Inc Published 2015 by John Wiley amp Sons Inc

3

11 ENERGY SUPPLY ECONOMIC AND ENVIRONMENTALCONSIDERATIONS

111 Introduction The Importance of Energy Supply

In the past two centuries since the Industrial Revolution in the 1700s that was initiatedby the invention of the steam turbine the world has undergone a drastic change due tothe steeply increased contribution of fossil fuels (coal oil and natural gas) to modernsocietiesrsquo energy supply (McKay 2009) Though the Chinese society already usedcoal for energy supply in approximately 1000 BC and the Romans prior to AD 400(World-Coal-Institute 2005) the first written references indicating its use are fromabout the thirteenth century and beyond (Hubbert 1949) These hydrocarbon fuelsso far have been considered essential as they are comparatively cheap and convenientenergy carriers used for heating cooking lighting and mechanical as well as electricpower production and have been widely used as transportation fuels and feedstocksfor the manufacture of bulk and fine chemicals as well as other materials with a widerange of applications Rapid global population growth expansion of economies andhigher standards have caused an enormous increase in worldwide energy consump-tion which was partly made possible by the supply of cheap fossil fuels

112 Development of Global Energy Demand

Figure 11 shows a scenario toward the year 2030 presented by the oil company BPconcerning population growth in relation to developments in total primary energyutilization and gross domestic product (GDP) The figure shows that global energy

Billion

Rest of

the world

India

China

9

8

7

6

5

4

3

2

1

0

Population

Billion toe

18

15

12

9

6

3

0

Energy

Trillion $2010 PPP

180

150

120

90

60

30

01970 1990 2010 2030 1970 1990 2010 2030 1970 1990 2010 2030

GDP

FIGURE 11 Prospected global growth rates in population energy demand and GDP 1 toe =41868104 MJ (Source Adapted from BP see tinyurlcom7hlmqxn)

4 INTRODUCTION

demand will rise substantially from the current level with an increasing share fromChina and India This rise of the primary energy demand is projected to be larger thanthe population growth and this will cause a stress on the limited global resources Theprojected GDP even increases stronger so it is expected that average living standardsincrease which will result in additional strain on the available resources

113 Sustainability of Energy Supply

One of the major questions in the world arising from the general picture sketched inSection 112 is how mankind can ensure a global sustainable development for the(near) future In this context sustainability of our energy supply is of paramountimportance The key issues are discussed in the following text both from a pointof view of global socioeconomics and ecological sustainability

1131 Socioeconomic Sustainability As one of the most important economicdrivers to secure and improve the living standards of people in the world energysupply security is of crucial value for current and future generations Fossil fuelsrun out sooner or later as can be seen in Figure 12 they are not renewable on anacceptable time scale

This figure depicts the so-called RP ratios for different sources The RP ratio is theratio of the current proven reserves to production level The unit is years and it is ameasure of the expected time a certain fuel source is expected to be available

On a global scale it appears that oil and natural gas reserves will be availablemdashgiven the figures of 2012mdashfor an expected approximately 55 years and coal substan-tially longer (gt100 years) Of course new contributions to the reserves may be

0

50

100

150

200

250

1980 1985 1990 1995 2000 2005 2010 2015

RP

(yea

rs)

Oil

Coal

Natural gas

FIGURE 12 Overview of world (top) and regional (bottom) reserves-to-production (RP)ratios for oil natural gas and coal respectively (end 2012 status) Figures are based on datafrom BP (2013)

5ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

North America

S amp Cent America

Europe amp Eurasia

Middle East

Africa

Asia Pacific

0 20 40 60

RP (years)

80 100 120 140

North America

S amp Cent America

Europe amp Eurasia

Middle East

Africa

Asia Pacific

0

RP (years)

North America

S amp Cent America

Europe amp Eurasia

Middle East amp Africa

Asia Pacific

0 50 100 150 200 250 300RP (years)

50 100 150 200

FIGURE 12 (Continued )

6 INTRODUCTION

discovered in the (near) future but that does not change the inherently limited supplynature of the fossil fuel sources Regionally there are also significant differenceswhich is important in the context of energy policy developments on the differentcontinents

For the price developments of the fossil fuels not only their forecasted availabilityis of importance but also the market development in a landscape highly determined bypolitics Already well before the last resources of a fuel will have been depleted themarket will be severely stressed For the economies in the world fuel cost develop-ment is therefore also a primary point of concern From past developments particu-larly regarding oil it has been shown that substantial fuel price fluctuations (volatility)occur which has an impact on the global economy (eg food prices) that is difficult topredict Supply and demand will determine the price evolution for each fuel sourcebut the development of the market structure is also essential there is a large differencebetween a free market and an oligopoly or monopoly situation In this respect diver-sification of fuel sources with associated differentiation in suppliers is advantageousas it makes societies less prone to price manipulation by eg cartel formation andsudden disruptions of supply (Johansson et al 1993)

Self-sufficiency concerning energy supply is often mentioned as target of countriesfor (longer-term) sustainable economic development However not all countries haveaccess to resources within their territories that are sufficient for such a target othercountries on the other hand have a structural surplus Relief of trade barriers canhelp mitigate this structural discrepancy Also in the context of economic sustaina-bility a good trade balance should be maintained in relation to the energy supplywithin nations

Regarding social sustainability in the context of energy supply reduction of pov-erty should be mentioned first a good supply structure of energy carriers is one of thebasic requirements for such a development next to access to clean drinking water andgood soil for agricultural activity Associated herewith expectedly substantial healthimprovement should result from a good energy supply infrastructure Job creation andmaintenance is another aspect of social sustainability and certain energy supply formscan contribute significantly to this Also maintaining (or improving) societiesrsquo socialcohesion is an aspect that can be impacted by the energy supply structure

1132 Ecological Sustainability The energy supply structure should notcompromise the sound development of our environment both from a local and globalperspective One of the major issues in this respect is global warming which is for themain part attributed to the release of greenhouse gases (GHG) from fossil fuel com-bustion Other issues are related to local emissions of acid rain precursors and partic-ulate matter (PM)

Climate Change the Greenhouse Effect and Greenhouse Gas EmissionReduction The greenhouse effect occurs naturally to a large extent Without thiseffect the Earthrsquos average global temperature would reach only a low minus18C ratherthan the current approximate +15C Water vapor is the largest contributor to thiseffect with a complex role for clouds but also CO2 in the atmosphere plays a

7ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

significant role More than a century ago Arrhenius (1896) already identified thisrole in the Earthrsquos temperature control Ice core studies reveal that on millennial timescales changes in CO2 content recorded are highly correlated with changes in tem-perature although some temperature changes have occurred without a significantCO2 concentration change but the opposite does not appear to have happened(Falkowski et al 2000) Less pronounced roles are played by CH4 N2O (nitrousoxide) and several types of chlorofluorocarbons (CFCs) and SF6 It is the CO2CH4 N2O and CFC concentrations in the atmosphere upon which manrsquos industrial

0

1

Rad

iati

ve

forc

ing (

Wm

2)

350

(a)

300

Car

bon d

ioxid

e (p

pm

)

250

300

350

400

1800 1900

Year

2000

(b)

1500

2000

1000

Met

han

e (p

pb)

500

0

02

04

Rad

iati

ve

forc

ing (

Wm

2)

1000

500

1500

2000

1900

Year

20001800

FIGURE 13 Atmospheric concentrations of CO2 CH4 and N2O over the last 10000 years(large panels) and since 1750 (inset panels) Measurements are shown from ice cores (symbolswith different grey shades for different studies) and atmospheric samples (light grey lines insteep curve part red lines in the original publication) The corresponding radiative forcings(net solar energy flux to the earth) relative to 1750 are shown on the right-hand axes of the largepanels (SourceReproducedwithpermission fromIPCC(2007) figure23 figureSPM1copyIPCC)

8 INTRODUCTION

and household activities have a measurable impact Scientists largely agree on thepoint that in the last few centuries the activities of humans have directly or indirectlycaused the concentrations of the major GHG to increase This is exemplified byFigure 13 The atmospheric CO2 concentration varies to some extent from placeto place and from season to season It has been shown that concentrations are some-what higher in the northern hemisphere than in the southern hemisphere as most of theanthropogenic sources of CO2 are located north of the equator The difference in landsurface covered with forests being more concentrated north of the equator causeslarger seasonal fluctuations due to comparatively shorter growth periods than in thegenerally milder southern hemisphere locations that are under the influence of largeroceanic surfaces

Oscillations of atmospheric CO2 concentrations between about 180 and 280 ppmv

have occurred in the past approximately 480000 years in cycles of 100000 yearsbut it appears now we have abandoned this cycling behavior in a remarkably shorttime frame

Studies at the NASA Goddard Institute for Space Studies in New York (UnitedStates) have shown that over the past few decades the combined warming effectof non-CO2 GHG should have been comparable to that of CO2 alone However whileeach of the GHGmentioned earlier acts to warm the surface of the Earth the long-termclimatic effects of the other GHG differ from those of CO2 Methane eg has anatmospheric lifetime of only about 12 years By comparison newly added CO2 willremain for a time span of tens to thousands of years As a result about 65 of thecarbon dioxide that human activities have generated since the start of the IndustrialRevolution is in the air we breathe today A historical record of the amount ofCO2 in the atmosphere can be found in bubbles of air in arctic ice layers dating backas far as 600000 years The depth of such a layer is a measure of its time of formation

(c)

10000 5000

Time (before 2005)

0

0

01

Rad

iati

ve

forc

ing (

Wm

2)

300

270

Nit

rous

oxid

e (p

pb)

270

240

300

330

1800 1900

Year

2000

FIGURE 13 (Continued )

9ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

Another difference is that the principal anthropogenic sources of methane-bacterialfermentation in rice paddies and in the intestines of cattle are related to food produc-tion and hence are roughly proportional to the number of people on the planetBecause CH4 has such a short atmospheric lifetime the amount that is in the air isa good indicator of how much is being added with time Should the global populationdouble over the next half century the concentration of CH4 could also double but it isnot likely to rise by much more than that This would add at most a few tenths of adegree to the mean temperature of the Earth Future CO2 increases could in contrastwarm the climate by 10C or more

Nitrous oxide (N2O) and CFCs are in some ways more like CO2 in that oncereleased they remain in the atmosphere for a century or more The production ofN2O however is only indirectly dependent on human activities Its principal sourceis a natural one the bacterial removal of nitrogen from soils and although the worldpopulation swells in coming years the amount in the air should increase only slowly

The outlook for many CFCs is even more promising Today the most abundant ofthese man-made compounds freon-11 and freon-12 are being phased out of produc-tion altogether by international agreements because of their damaging effects on strat-ospheric ozone Indeed the concentration of one of these gases freon-11 peaked in1994 and is now in a slow decline that should continue for the next century or so Thefreon-12 concentration has not yet leveled off but is expected to do so within the nextfew years In terms of climatic effects the main threat from CFCs comes from otherlong-lived compounds that may be used to replace the ones that have been phased outand that could also act as GHG Since these possibly harmful replacement gases are asyet present in only small amounts and since as noted earlier projected increases inCH4 and N2O are so much less severe we shall for the rest of this discussion focussolely on the most important anthropogenic GHG CO2

Some experts have estimated that the Earthrsquos average global temperature has alreadyincreased by more than 05C since the mid-1900s due to this human-enhanced green-house effect also impacts on sea level (rising) and snow coverage (tending to decrease)have been investigated the results of which are summarized in Figure 14

Like most other planets and planetoids in the universe the Earth contains a greatdeal of carbon which is slowly and continually transported from the mantle to thecrust and back again in the course of volcanic eruption and subduction phenomenaThe portion that finds itself near the surface is continually exchanged and recycledamong plants animals soil air and oceans In some of these temporary stocks car-bon is more securely held while in others it more readily combines with oxygen in theair to form CO2 In order to predict how atmospheric CO2 levels and climate maychange in the future it is important to understand where carbon is stored and whatits dynamic cycling behavior looks like The carbon reservoirs that are most relevantto global warming are listed in Table 11 with the total amount of carbon that theycontained in 2000

The atmosphere contains approximately 720 Gt C in the form of CO2 currentmeasured atmospheric CO2 concentrations are nearly 400 ppmv The rate of changein this carbon stock not only depends on human activities but also on biogeochemicaland climatological processes and their interactions with the global carbon cycle

10 INTRODUCTION

PREFACE

This book deals with bioenergy as a versatile renewable source Ever since thedawn of mankind people have been using wood and other biogenic sources forheating cooking and lighting Trade of biomass came up in historic times (thinkabout the silk route for example) Even industrial iron making via metal reductionwas based on biomass utilization (carbonization) However that very applicationalso led to substantial deforestation which was clear in the United Kingdomand demonstrated that using biomass does not guarantee a sustainable energy sup-ply Therefore the industrial revolution introduced the large-scale application offossil fuel starting with the use of coal

The steam engine became the workhorse of the nineteenth century Coal alsobecame the basis of the chemical industry at that time Oil was initially used for lampsbut later it appeared to be the choice of raw material for petrol and diesel in Otto andDiesel engines respectively Wood and other sources came back into the pictureduring the interbellum period and the Second World War when oil was scarce inparticular on the European continent At that time cars trucks and ships made useof the gas extracted from fixed bed wood gasification installations Also chemicalssupply and materials were increasingly supported by wood-based processes AfterWWII the cheap oil era was entered and such routes were largely abandoned Afterthe oil crises of the 1970s biomass came back into the picture as an energy sourcereinforced by environmental concerns about the use of fossil energy sources due totheir associated CO2 emissions stimulating the greenhouse effect At present biomassis seriously back as part of a sustainable energy mix in combination with materialsand chemicals supply and a wide world of biorefinery options has opened up

The field of biomass to energy supply is multidisciplinary and offers a wealth ofintegration of knowledge to young engineers starting their careers The technologies

xiii

strongly lean on chemical engineering skills but also on physics mechanical engineer-ing and agricultural sciences among others Not only technology issues determine thesuccess of biomass for our energy supply there are many hurdles to be taken into thenontechnical domain such as logistics (trade and handling) infrastructure and politics(subsidies rural development employment generation etc) to name a few

This book is divided into four parts covering broad areas of the field of biomassconversion technology chains Part I starts with the socioeconomic and environmentalcontext and biomass basics It gives insight into the boundary conditions and the playingfield bioenergy supply has Moreover it provides a deeper look into what biomass reallyis Part II covers the chemical engineering basics to provide the engineer with tools tosolve problems in the domain design new biomass-based processes and evaluateconversion subprocesses The tools range from setting up balances evaluating the massand heat transport phenomena thermodynamics and kinetics to reactor and processdesign Part III deals with the study of different biomass conversion processes rangingfrom nonreactive pretreatment via combustion processes gasification hydrothermal pro-cessing pyrolysis and torrefaction to biochemical conversion processes and biorefineryintegration of such technologies Finally Part IV treats the end use of primary biomassconversion products for example power production via fuel cells transportationfuel production (eg via the FischerndashTropsch process) and platform chemicalsproduction via organic chemistry to substitute the conventional petrochemical pathwaysoffered today

We were inspired to write this book by the course ldquoEnergy from Biomassrdquo that wehave been teaching for a number of years in the MSc program of Sustainable EnergyTechnology at Delft University a program that is part of the 3TU cooperation betweenthe technical universities of Delft Eindhoven and Twente After teaching the coursefor some years using the lecture notes prepared by our Eindhoven colleagues RobBastiaans Jeroen van Oijen andMark Prins we thought it would be worthy to furtherimprove the course material Since the students in Sustainable Energy Technologyhave a very diverse background we have devoted Part II of the book to giving thereader enough background in chemical engineering for reading the more specializedchapters This means that this book is useful for everyone with a BSc in anyengineering discipline Apart from students at the MSc level professionals in thebiomass field may also find this book as a knowledgeable source for example fordesigning and evaluating novel biorefinery systems and conversion components

Delft December 2013 WIEBREN DE JONG AND J RUUD VAN OMMEN

He will be like a tree planted by the water that sends out its roots by the stream It doesnot fear when heat comes its leaves are always green It has no worries in a year ofdrought and never fails to bear fruit ndash Bible Jeremiah 178

Biomass is forever ndash Prof David Halldagger

xiv PREFACE

ACKNOWLEDGMENTS

This book would not have been published without the contributions from manypeople First of all we would like to acknowledge all the students that followedour course ldquoEnergy from Biomassrdquo over the years they inspired us to compose thisbook We are very glad that many of our colleagues agreed to contribute chapters tothis book It was great to work with this team of co-authors all bringing in their spe-cific expertise to cover the broad field of energy from biomass A big thanks to all ofyou For some chapters the additional input from others is specifically acknowledgedLikun Ma is kindly acknowledged for his contribution to the examples in Chapter 4Ryan Bogaars for his suggestions concerning Chapter 10 Xiangmei Meng and Onur-sal Yakaboylu for contributing some of the examples of Chapter 10 Richard Eijsbergfor the first generation ethanol process figures and data in Chapter 13 Tim Geraedtsand Elze Oude Lansink for the project in Chapter 15 Fred van Rantwijk for valuableinput and discussions on Chapter 18 and Adrea Fabre for her advices regarding thewritingWe are also grateful for the willingness of many colleagues to review chaptersin order to find mistakes and make suggestions for further improvements Ourreviewers were in alphabetic order Rob Bakker Sune Bengtsson PouyanBoukany Anthony Bridgwater Harry Croezen Lilian de Martiacuten Jorge GasconHans Geerlings Johan Grievink Sef Heijnen Kas Hemmes Paulien Herder TrulsLiliedahl Gabrie Meesters Bart Merci Kyriakos Panopoulos Wolter Prins SinaSartipi Fabrizio Scala Tilman Schildhauer Andrzej Stankiewicz GeorgiosStefanidis Bob Ursem Henk van den Berg Theo van der Meer Jules van Lier Maritvan Lieshout and Stanislav Vassilev A special word of thanks should go to Anneliesvan Diepen When the chapters were complete she made a great effort to harmonizethem for example in figures symbols lay-out and wording She also has caughtnumerous mistakes that were still present in earlier versions We would like to thank

xv

Jan Leen Kloosterman (Director of Education Sustainable Energy Technology SET)for the financial support from the SET program for editorial assistance We would alsolike to thank the people at Wiley for the smooth cooperation during the preparation ofthe manuscript Finally we would like to thank the ones close to usmdashKlarine (WdJ)and Ceciel Fenne and Chris (JRvO)mdashfor their understanding and support during allthe evenings and weekends that the writing and editing took

xvi ACKNOWLEDGMENTS

LIST OF CONTRIBUTORS

PV Aravind Drir Department of Process and Energy Energy TechnologySection Faculty of Mechanical Maritime and Materials Engineering DelftUniversity of Technology Delft the Netherlands

Isabel WCE Arends Profdr Department of Biotechnology Biocatalysis GroupFaculty of Applied Sciences Delft University of Technology Delft theNetherlands

Rob JM Bastiaans Drir Department of Mechanical Engineering CombustionTechnology Section Eindhoven University of Technology Eindhoven theNetherlands

Maria C Cuellar Dr Department of Biotechnology BioProcess EngineeringGroup Faculty of Applied Sciences Delft University of Technology Delft theNetherlands

Martina Fantini Drir Department of Process and Energy Energy TechnologySection Faculty of Mechanical Maritime and Materials Engineering DelftUniversity of Technology Delft the Netherlands

Johan Grievink Prof ir Department of Chemical Engineering Product amp ProcessEngineering Group Faculty of Applied Sciences Delft University of TechnologyDelft the Netherlands

ArnoHH Janssen Ir ECN Biomass amp Energy Efficiency Petten the Netherlands

Wiebren de Jong Drir Department of Process and Energy Energy TechnologySection Faculty of Mechanical Maritime and Materials Engineering DelftUniversity of Technology Delft the Netherlands

xvii

Yash Joshi Ir Department of Process and Energy Energy Technology SectionFaculty of Mechanical Maritime and Materials Engineering Delft University ofTechnology Delft the Netherlands

Sascha RA Kersten Profdrir Sustainable Process Technology Group Facultyof Science and Technology University of Twente Enschede the Netherlands

Jaap HA Kiel Profdrir ECN Biomass amp Energy Efficiency Petten andDepartment of Process and Energy Energy Technology Section Faculty ofMechanical Maritime andMaterials Engineering Delft University of TechnologyDelft the Netherlands

Robbert Kleerebezem Drir Department of Biotechnology EnvironmentalBiotechnology Group Faculty of Applied Sciences Delft University of TechnologyDelft the Netherlands

Ming Liu Drir Department of Process and Energy Energy Technology SectionFaculty of Mechanical Maritime and Materials Engineering Delft University ofTechnology Delft the Netherlands

Lilian de Martiacuten Dr Department of Chemical Engineering Product amp ProcessEngineering Group Faculty of Applied Sciences Delft University of TechnologyDelft the Netherlands

Jeroen A van Oijen Drir Department of Mechanical Engineering CombustionTechnology Section Eindhoven University of Technology Eindhoven theNetherlands

J Ruud van Ommen Drir Department of Chemical Engineering Product ampProcess Engineering Group Faculty of Applied Sciences Delft University ofTechnology Delft the Netherlands

Stijn RG Oudenhoven Ir Sustainable Process Technology Group Faculty ofScience and Technology University of Twente Enschede the Netherlands

Dirk JEM Roekaerts Profdr Department of Process and Energy FluidMechanics Section Faculty of Mechanical Maritime and Materials EngineeringDelft University of Technology Delft the Netherlands

Adrie JJ Straathof Drir Department of Biotechnology BioProcess EngineeringGroup Faculty of Applied Sciences Delft University of Technology Delft theNetherlands

Pieter LJ Swinkels Ir Faculty of Applied Sciences Delft Product amp ProcessDesign Institute Delft University of Technology Delft the Netherlands

xviii LIST OF CONTRIBUTORS

PART I

SOCIAL CONTEXT AND STRUCTURALBASIS OF BIOMASS AS A RENEWABLEENERGY SOURCES

1INTRODUCTION SOCIOECONOMICASPECTS OF BIOMASS CONVERSION

WIEBREN DE JONG1 AND J RUUD VAN OMMEN2

1Department of Process and Energy Energy Technology Section Faculty of MechanicalMaritime and Materials Engineering Delft University of Technology Delft the Netherlands2Department of Chemical Engineering Product amp Process Engineering Group Faculty ofApplied Sciences Delft University of Technology Delft the Netherlands

ACRONYMS

CDM clean development mechanismCFCs chlorofluorocarbonsdLUC direct land use changeGDP gross domestic productGHG greenhouse gasiLUC indirect land use changeJI joint implementationLCA life cycle assessmentLUC land use changeRP ratio reserves-to-production ratio [y]TOE tonnes of oil equivalent(s) (= 4187 GJ)UNFCCC United Nations Framework Convention on Climate Change

Biomass as a Sustainable Energy Source for the Future Fundamentals of Conversion ProcessesFirst Edition Edited by Wiebren de Jong and J Ruud van Ommencopy 2015 American Institute of Chemical Engineers Inc Published 2015 by John Wiley amp Sons Inc

3

11 ENERGY SUPPLY ECONOMIC AND ENVIRONMENTALCONSIDERATIONS

111 Introduction The Importance of Energy Supply

In the past two centuries since the Industrial Revolution in the 1700s that was initiatedby the invention of the steam turbine the world has undergone a drastic change due tothe steeply increased contribution of fossil fuels (coal oil and natural gas) to modernsocietiesrsquo energy supply (McKay 2009) Though the Chinese society already usedcoal for energy supply in approximately 1000 BC and the Romans prior to AD 400(World-Coal-Institute 2005) the first written references indicating its use are fromabout the thirteenth century and beyond (Hubbert 1949) These hydrocarbon fuelsso far have been considered essential as they are comparatively cheap and convenientenergy carriers used for heating cooking lighting and mechanical as well as electricpower production and have been widely used as transportation fuels and feedstocksfor the manufacture of bulk and fine chemicals as well as other materials with a widerange of applications Rapid global population growth expansion of economies andhigher standards have caused an enormous increase in worldwide energy consump-tion which was partly made possible by the supply of cheap fossil fuels

112 Development of Global Energy Demand

Figure 11 shows a scenario toward the year 2030 presented by the oil company BPconcerning population growth in relation to developments in total primary energyutilization and gross domestic product (GDP) The figure shows that global energy

Billion

Rest of

the world

India

China

9

8

7

6

5

4

3

2

1

0

Population

Billion toe

18

15

12

9

6

3

0

Energy

Trillion $2010 PPP

180

150

120

90

60

30

01970 1990 2010 2030 1970 1990 2010 2030 1970 1990 2010 2030

GDP

FIGURE 11 Prospected global growth rates in population energy demand and GDP 1 toe =41868104 MJ (Source Adapted from BP see tinyurlcom7hlmqxn)

4 INTRODUCTION

demand will rise substantially from the current level with an increasing share fromChina and India This rise of the primary energy demand is projected to be larger thanthe population growth and this will cause a stress on the limited global resources Theprojected GDP even increases stronger so it is expected that average living standardsincrease which will result in additional strain on the available resources

113 Sustainability of Energy Supply

One of the major questions in the world arising from the general picture sketched inSection 112 is how mankind can ensure a global sustainable development for the(near) future In this context sustainability of our energy supply is of paramountimportance The key issues are discussed in the following text both from a pointof view of global socioeconomics and ecological sustainability

1131 Socioeconomic Sustainability As one of the most important economicdrivers to secure and improve the living standards of people in the world energysupply security is of crucial value for current and future generations Fossil fuelsrun out sooner or later as can be seen in Figure 12 they are not renewable on anacceptable time scale

This figure depicts the so-called RP ratios for different sources The RP ratio is theratio of the current proven reserves to production level The unit is years and it is ameasure of the expected time a certain fuel source is expected to be available

On a global scale it appears that oil and natural gas reserves will be availablemdashgiven the figures of 2012mdashfor an expected approximately 55 years and coal substan-tially longer (gt100 years) Of course new contributions to the reserves may be

0

50

100

150

200

250

1980 1985 1990 1995 2000 2005 2010 2015

RP

(yea

rs)

Oil

Coal

Natural gas

FIGURE 12 Overview of world (top) and regional (bottom) reserves-to-production (RP)ratios for oil natural gas and coal respectively (end 2012 status) Figures are based on datafrom BP (2013)

5ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

North America

S amp Cent America

Europe amp Eurasia

Middle East

Africa

Asia Pacific

0 20 40 60

RP (years)

80 100 120 140

North America

S amp Cent America

Europe amp Eurasia

Middle East

Africa

Asia Pacific

0

RP (years)

North America

S amp Cent America

Europe amp Eurasia

Middle East amp Africa

Asia Pacific

0 50 100 150 200 250 300RP (years)

50 100 150 200

FIGURE 12 (Continued )

6 INTRODUCTION

discovered in the (near) future but that does not change the inherently limited supplynature of the fossil fuel sources Regionally there are also significant differenceswhich is important in the context of energy policy developments on the differentcontinents

For the price developments of the fossil fuels not only their forecasted availabilityis of importance but also the market development in a landscape highly determined bypolitics Already well before the last resources of a fuel will have been depleted themarket will be severely stressed For the economies in the world fuel cost develop-ment is therefore also a primary point of concern From past developments particu-larly regarding oil it has been shown that substantial fuel price fluctuations (volatility)occur which has an impact on the global economy (eg food prices) that is difficult topredict Supply and demand will determine the price evolution for each fuel sourcebut the development of the market structure is also essential there is a large differencebetween a free market and an oligopoly or monopoly situation In this respect diver-sification of fuel sources with associated differentiation in suppliers is advantageousas it makes societies less prone to price manipulation by eg cartel formation andsudden disruptions of supply (Johansson et al 1993)

Self-sufficiency concerning energy supply is often mentioned as target of countriesfor (longer-term) sustainable economic development However not all countries haveaccess to resources within their territories that are sufficient for such a target othercountries on the other hand have a structural surplus Relief of trade barriers canhelp mitigate this structural discrepancy Also in the context of economic sustaina-bility a good trade balance should be maintained in relation to the energy supplywithin nations

Regarding social sustainability in the context of energy supply reduction of pov-erty should be mentioned first a good supply structure of energy carriers is one of thebasic requirements for such a development next to access to clean drinking water andgood soil for agricultural activity Associated herewith expectedly substantial healthimprovement should result from a good energy supply infrastructure Job creation andmaintenance is another aspect of social sustainability and certain energy supply formscan contribute significantly to this Also maintaining (or improving) societiesrsquo socialcohesion is an aspect that can be impacted by the energy supply structure

1132 Ecological Sustainability The energy supply structure should notcompromise the sound development of our environment both from a local and globalperspective One of the major issues in this respect is global warming which is for themain part attributed to the release of greenhouse gases (GHG) from fossil fuel com-bustion Other issues are related to local emissions of acid rain precursors and partic-ulate matter (PM)

Climate Change the Greenhouse Effect and Greenhouse Gas EmissionReduction The greenhouse effect occurs naturally to a large extent Without thiseffect the Earthrsquos average global temperature would reach only a low minus18C ratherthan the current approximate +15C Water vapor is the largest contributor to thiseffect with a complex role for clouds but also CO2 in the atmosphere plays a

7ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

significant role More than a century ago Arrhenius (1896) already identified thisrole in the Earthrsquos temperature control Ice core studies reveal that on millennial timescales changes in CO2 content recorded are highly correlated with changes in tem-perature although some temperature changes have occurred without a significantCO2 concentration change but the opposite does not appear to have happened(Falkowski et al 2000) Less pronounced roles are played by CH4 N2O (nitrousoxide) and several types of chlorofluorocarbons (CFCs) and SF6 It is the CO2CH4 N2O and CFC concentrations in the atmosphere upon which manrsquos industrial

0

1

Rad

iati

ve

forc

ing (

Wm

2)

350

(a)

300

Car

bon d

ioxid

e (p

pm

)

250

300

350

400

1800 1900

Year

2000

(b)

1500

2000

1000

Met

han

e (p

pb)

500

0

02

04

Rad

iati

ve

forc

ing (

Wm

2)

1000

500

1500

2000

1900

Year

20001800

FIGURE 13 Atmospheric concentrations of CO2 CH4 and N2O over the last 10000 years(large panels) and since 1750 (inset panels) Measurements are shown from ice cores (symbolswith different grey shades for different studies) and atmospheric samples (light grey lines insteep curve part red lines in the original publication) The corresponding radiative forcings(net solar energy flux to the earth) relative to 1750 are shown on the right-hand axes of the largepanels (SourceReproducedwithpermission fromIPCC(2007) figure23 figureSPM1copyIPCC)

8 INTRODUCTION

and household activities have a measurable impact Scientists largely agree on thepoint that in the last few centuries the activities of humans have directly or indirectlycaused the concentrations of the major GHG to increase This is exemplified byFigure 13 The atmospheric CO2 concentration varies to some extent from placeto place and from season to season It has been shown that concentrations are some-what higher in the northern hemisphere than in the southern hemisphere as most of theanthropogenic sources of CO2 are located north of the equator The difference in landsurface covered with forests being more concentrated north of the equator causeslarger seasonal fluctuations due to comparatively shorter growth periods than in thegenerally milder southern hemisphere locations that are under the influence of largeroceanic surfaces

Oscillations of atmospheric CO2 concentrations between about 180 and 280 ppmv

have occurred in the past approximately 480000 years in cycles of 100000 yearsbut it appears now we have abandoned this cycling behavior in a remarkably shorttime frame

Studies at the NASA Goddard Institute for Space Studies in New York (UnitedStates) have shown that over the past few decades the combined warming effectof non-CO2 GHG should have been comparable to that of CO2 alone However whileeach of the GHGmentioned earlier acts to warm the surface of the Earth the long-termclimatic effects of the other GHG differ from those of CO2 Methane eg has anatmospheric lifetime of only about 12 years By comparison newly added CO2 willremain for a time span of tens to thousands of years As a result about 65 of thecarbon dioxide that human activities have generated since the start of the IndustrialRevolution is in the air we breathe today A historical record of the amount ofCO2 in the atmosphere can be found in bubbles of air in arctic ice layers dating backas far as 600000 years The depth of such a layer is a measure of its time of formation

(c)

10000 5000

Time (before 2005)

0

0

01

Rad

iati

ve

forc

ing (

Wm

2)

300

270

Nit

rous

oxid

e (p

pb)

270

240

300

330

1800 1900

Year

2000

FIGURE 13 (Continued )

9ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

Another difference is that the principal anthropogenic sources of methane-bacterialfermentation in rice paddies and in the intestines of cattle are related to food produc-tion and hence are roughly proportional to the number of people on the planetBecause CH4 has such a short atmospheric lifetime the amount that is in the air isa good indicator of how much is being added with time Should the global populationdouble over the next half century the concentration of CH4 could also double but it isnot likely to rise by much more than that This would add at most a few tenths of adegree to the mean temperature of the Earth Future CO2 increases could in contrastwarm the climate by 10C or more

Nitrous oxide (N2O) and CFCs are in some ways more like CO2 in that oncereleased they remain in the atmosphere for a century or more The production ofN2O however is only indirectly dependent on human activities Its principal sourceis a natural one the bacterial removal of nitrogen from soils and although the worldpopulation swells in coming years the amount in the air should increase only slowly

The outlook for many CFCs is even more promising Today the most abundant ofthese man-made compounds freon-11 and freon-12 are being phased out of produc-tion altogether by international agreements because of their damaging effects on strat-ospheric ozone Indeed the concentration of one of these gases freon-11 peaked in1994 and is now in a slow decline that should continue for the next century or so Thefreon-12 concentration has not yet leveled off but is expected to do so within the nextfew years In terms of climatic effects the main threat from CFCs comes from otherlong-lived compounds that may be used to replace the ones that have been phased outand that could also act as GHG Since these possibly harmful replacement gases are asyet present in only small amounts and since as noted earlier projected increases inCH4 and N2O are so much less severe we shall for the rest of this discussion focussolely on the most important anthropogenic GHG CO2

Some experts have estimated that the Earthrsquos average global temperature has alreadyincreased by more than 05C since the mid-1900s due to this human-enhanced green-house effect also impacts on sea level (rising) and snow coverage (tending to decrease)have been investigated the results of which are summarized in Figure 14

Like most other planets and planetoids in the universe the Earth contains a greatdeal of carbon which is slowly and continually transported from the mantle to thecrust and back again in the course of volcanic eruption and subduction phenomenaThe portion that finds itself near the surface is continually exchanged and recycledamong plants animals soil air and oceans In some of these temporary stocks car-bon is more securely held while in others it more readily combines with oxygen in theair to form CO2 In order to predict how atmospheric CO2 levels and climate maychange in the future it is important to understand where carbon is stored and whatits dynamic cycling behavior looks like The carbon reservoirs that are most relevantto global warming are listed in Table 11 with the total amount of carbon that theycontained in 2000

The atmosphere contains approximately 720 Gt C in the form of CO2 currentmeasured atmospheric CO2 concentrations are nearly 400 ppmv The rate of changein this carbon stock not only depends on human activities but also on biogeochemicaland climatological processes and their interactions with the global carbon cycle

10 INTRODUCTION

strongly lean on chemical engineering skills but also on physics mechanical engineer-ing and agricultural sciences among others Not only technology issues determine thesuccess of biomass for our energy supply there are many hurdles to be taken into thenontechnical domain such as logistics (trade and handling) infrastructure and politics(subsidies rural development employment generation etc) to name a few

This book is divided into four parts covering broad areas of the field of biomassconversion technology chains Part I starts with the socioeconomic and environmentalcontext and biomass basics It gives insight into the boundary conditions and the playingfield bioenergy supply has Moreover it provides a deeper look into what biomass reallyis Part II covers the chemical engineering basics to provide the engineer with tools tosolve problems in the domain design new biomass-based processes and evaluateconversion subprocesses The tools range from setting up balances evaluating the massand heat transport phenomena thermodynamics and kinetics to reactor and processdesign Part III deals with the study of different biomass conversion processes rangingfrom nonreactive pretreatment via combustion processes gasification hydrothermal pro-cessing pyrolysis and torrefaction to biochemical conversion processes and biorefineryintegration of such technologies Finally Part IV treats the end use of primary biomassconversion products for example power production via fuel cells transportationfuel production (eg via the FischerndashTropsch process) and platform chemicalsproduction via organic chemistry to substitute the conventional petrochemical pathwaysoffered today

We were inspired to write this book by the course ldquoEnergy from Biomassrdquo that wehave been teaching for a number of years in the MSc program of Sustainable EnergyTechnology at Delft University a program that is part of the 3TU cooperation betweenthe technical universities of Delft Eindhoven and Twente After teaching the coursefor some years using the lecture notes prepared by our Eindhoven colleagues RobBastiaans Jeroen van Oijen andMark Prins we thought it would be worthy to furtherimprove the course material Since the students in Sustainable Energy Technologyhave a very diverse background we have devoted Part II of the book to giving thereader enough background in chemical engineering for reading the more specializedchapters This means that this book is useful for everyone with a BSc in anyengineering discipline Apart from students at the MSc level professionals in thebiomass field may also find this book as a knowledgeable source for example fordesigning and evaluating novel biorefinery systems and conversion components

Delft December 2013 WIEBREN DE JONG AND J RUUD VAN OMMEN

He will be like a tree planted by the water that sends out its roots by the stream It doesnot fear when heat comes its leaves are always green It has no worries in a year ofdrought and never fails to bear fruit ndash Bible Jeremiah 178

Biomass is forever ndash Prof David Halldagger

xiv PREFACE

ACKNOWLEDGMENTS

This book would not have been published without the contributions from manypeople First of all we would like to acknowledge all the students that followedour course ldquoEnergy from Biomassrdquo over the years they inspired us to compose thisbook We are very glad that many of our colleagues agreed to contribute chapters tothis book It was great to work with this team of co-authors all bringing in their spe-cific expertise to cover the broad field of energy from biomass A big thanks to all ofyou For some chapters the additional input from others is specifically acknowledgedLikun Ma is kindly acknowledged for his contribution to the examples in Chapter 4Ryan Bogaars for his suggestions concerning Chapter 10 Xiangmei Meng and Onur-sal Yakaboylu for contributing some of the examples of Chapter 10 Richard Eijsbergfor the first generation ethanol process figures and data in Chapter 13 Tim Geraedtsand Elze Oude Lansink for the project in Chapter 15 Fred van Rantwijk for valuableinput and discussions on Chapter 18 and Adrea Fabre for her advices regarding thewritingWe are also grateful for the willingness of many colleagues to review chaptersin order to find mistakes and make suggestions for further improvements Ourreviewers were in alphabetic order Rob Bakker Sune Bengtsson PouyanBoukany Anthony Bridgwater Harry Croezen Lilian de Martiacuten Jorge GasconHans Geerlings Johan Grievink Sef Heijnen Kas Hemmes Paulien Herder TrulsLiliedahl Gabrie Meesters Bart Merci Kyriakos Panopoulos Wolter Prins SinaSartipi Fabrizio Scala Tilman Schildhauer Andrzej Stankiewicz GeorgiosStefanidis Bob Ursem Henk van den Berg Theo van der Meer Jules van Lier Maritvan Lieshout and Stanislav Vassilev A special word of thanks should go to Anneliesvan Diepen When the chapters were complete she made a great effort to harmonizethem for example in figures symbols lay-out and wording She also has caughtnumerous mistakes that were still present in earlier versions We would like to thank

xv

Jan Leen Kloosterman (Director of Education Sustainable Energy Technology SET)for the financial support from the SET program for editorial assistance We would alsolike to thank the people at Wiley for the smooth cooperation during the preparation ofthe manuscript Finally we would like to thank the ones close to usmdashKlarine (WdJ)and Ceciel Fenne and Chris (JRvO)mdashfor their understanding and support during allthe evenings and weekends that the writing and editing took

xvi ACKNOWLEDGMENTS

LIST OF CONTRIBUTORS

PV Aravind Drir Department of Process and Energy Energy TechnologySection Faculty of Mechanical Maritime and Materials Engineering DelftUniversity of Technology Delft the Netherlands

Isabel WCE Arends Profdr Department of Biotechnology Biocatalysis GroupFaculty of Applied Sciences Delft University of Technology Delft theNetherlands

Rob JM Bastiaans Drir Department of Mechanical Engineering CombustionTechnology Section Eindhoven University of Technology Eindhoven theNetherlands

Maria C Cuellar Dr Department of Biotechnology BioProcess EngineeringGroup Faculty of Applied Sciences Delft University of Technology Delft theNetherlands

Martina Fantini Drir Department of Process and Energy Energy TechnologySection Faculty of Mechanical Maritime and Materials Engineering DelftUniversity of Technology Delft the Netherlands

Johan Grievink Prof ir Department of Chemical Engineering Product amp ProcessEngineering Group Faculty of Applied Sciences Delft University of TechnologyDelft the Netherlands

ArnoHH Janssen Ir ECN Biomass amp Energy Efficiency Petten the Netherlands

Wiebren de Jong Drir Department of Process and Energy Energy TechnologySection Faculty of Mechanical Maritime and Materials Engineering DelftUniversity of Technology Delft the Netherlands

xvii

Yash Joshi Ir Department of Process and Energy Energy Technology SectionFaculty of Mechanical Maritime and Materials Engineering Delft University ofTechnology Delft the Netherlands

Sascha RA Kersten Profdrir Sustainable Process Technology Group Facultyof Science and Technology University of Twente Enschede the Netherlands

Jaap HA Kiel Profdrir ECN Biomass amp Energy Efficiency Petten andDepartment of Process and Energy Energy Technology Section Faculty ofMechanical Maritime andMaterials Engineering Delft University of TechnologyDelft the Netherlands

Robbert Kleerebezem Drir Department of Biotechnology EnvironmentalBiotechnology Group Faculty of Applied Sciences Delft University of TechnologyDelft the Netherlands

Ming Liu Drir Department of Process and Energy Energy Technology SectionFaculty of Mechanical Maritime and Materials Engineering Delft University ofTechnology Delft the Netherlands

Lilian de Martiacuten Dr Department of Chemical Engineering Product amp ProcessEngineering Group Faculty of Applied Sciences Delft University of TechnologyDelft the Netherlands

Jeroen A van Oijen Drir Department of Mechanical Engineering CombustionTechnology Section Eindhoven University of Technology Eindhoven theNetherlands

J Ruud van Ommen Drir Department of Chemical Engineering Product ampProcess Engineering Group Faculty of Applied Sciences Delft University ofTechnology Delft the Netherlands

Stijn RG Oudenhoven Ir Sustainable Process Technology Group Faculty ofScience and Technology University of Twente Enschede the Netherlands

Dirk JEM Roekaerts Profdr Department of Process and Energy FluidMechanics Section Faculty of Mechanical Maritime and Materials EngineeringDelft University of Technology Delft the Netherlands

Adrie JJ Straathof Drir Department of Biotechnology BioProcess EngineeringGroup Faculty of Applied Sciences Delft University of Technology Delft theNetherlands

Pieter LJ Swinkels Ir Faculty of Applied Sciences Delft Product amp ProcessDesign Institute Delft University of Technology Delft the Netherlands

xviii LIST OF CONTRIBUTORS

PART I

SOCIAL CONTEXT AND STRUCTURALBASIS OF BIOMASS AS A RENEWABLEENERGY SOURCES

1INTRODUCTION SOCIOECONOMICASPECTS OF BIOMASS CONVERSION

WIEBREN DE JONG1 AND J RUUD VAN OMMEN2

1Department of Process and Energy Energy Technology Section Faculty of MechanicalMaritime and Materials Engineering Delft University of Technology Delft the Netherlands2Department of Chemical Engineering Product amp Process Engineering Group Faculty ofApplied Sciences Delft University of Technology Delft the Netherlands

ACRONYMS

CDM clean development mechanismCFCs chlorofluorocarbonsdLUC direct land use changeGDP gross domestic productGHG greenhouse gasiLUC indirect land use changeJI joint implementationLCA life cycle assessmentLUC land use changeRP ratio reserves-to-production ratio [y]TOE tonnes of oil equivalent(s) (= 4187 GJ)UNFCCC United Nations Framework Convention on Climate Change

Biomass as a Sustainable Energy Source for the Future Fundamentals of Conversion ProcessesFirst Edition Edited by Wiebren de Jong and J Ruud van Ommencopy 2015 American Institute of Chemical Engineers Inc Published 2015 by John Wiley amp Sons Inc

3

11 ENERGY SUPPLY ECONOMIC AND ENVIRONMENTALCONSIDERATIONS

111 Introduction The Importance of Energy Supply

In the past two centuries since the Industrial Revolution in the 1700s that was initiatedby the invention of the steam turbine the world has undergone a drastic change due tothe steeply increased contribution of fossil fuels (coal oil and natural gas) to modernsocietiesrsquo energy supply (McKay 2009) Though the Chinese society already usedcoal for energy supply in approximately 1000 BC and the Romans prior to AD 400(World-Coal-Institute 2005) the first written references indicating its use are fromabout the thirteenth century and beyond (Hubbert 1949) These hydrocarbon fuelsso far have been considered essential as they are comparatively cheap and convenientenergy carriers used for heating cooking lighting and mechanical as well as electricpower production and have been widely used as transportation fuels and feedstocksfor the manufacture of bulk and fine chemicals as well as other materials with a widerange of applications Rapid global population growth expansion of economies andhigher standards have caused an enormous increase in worldwide energy consump-tion which was partly made possible by the supply of cheap fossil fuels

112 Development of Global Energy Demand

Figure 11 shows a scenario toward the year 2030 presented by the oil company BPconcerning population growth in relation to developments in total primary energyutilization and gross domestic product (GDP) The figure shows that global energy

Billion

Rest of

the world

India

China

9

8

7

6

5

4

3

2

1

0

Population

Billion toe

18

15

12

9

6

3

0

Energy

Trillion $2010 PPP

180

150

120

90

60

30

01970 1990 2010 2030 1970 1990 2010 2030 1970 1990 2010 2030

GDP

FIGURE 11 Prospected global growth rates in population energy demand and GDP 1 toe =41868104 MJ (Source Adapted from BP see tinyurlcom7hlmqxn)

4 INTRODUCTION

demand will rise substantially from the current level with an increasing share fromChina and India This rise of the primary energy demand is projected to be larger thanthe population growth and this will cause a stress on the limited global resources Theprojected GDP even increases stronger so it is expected that average living standardsincrease which will result in additional strain on the available resources

113 Sustainability of Energy Supply

One of the major questions in the world arising from the general picture sketched inSection 112 is how mankind can ensure a global sustainable development for the(near) future In this context sustainability of our energy supply is of paramountimportance The key issues are discussed in the following text both from a pointof view of global socioeconomics and ecological sustainability

1131 Socioeconomic Sustainability As one of the most important economicdrivers to secure and improve the living standards of people in the world energysupply security is of crucial value for current and future generations Fossil fuelsrun out sooner or later as can be seen in Figure 12 they are not renewable on anacceptable time scale

This figure depicts the so-called RP ratios for different sources The RP ratio is theratio of the current proven reserves to production level The unit is years and it is ameasure of the expected time a certain fuel source is expected to be available

On a global scale it appears that oil and natural gas reserves will be availablemdashgiven the figures of 2012mdashfor an expected approximately 55 years and coal substan-tially longer (gt100 years) Of course new contributions to the reserves may be

0

50

100

150

200

250

1980 1985 1990 1995 2000 2005 2010 2015

RP

(yea

rs)

Oil

Coal

Natural gas

FIGURE 12 Overview of world (top) and regional (bottom) reserves-to-production (RP)ratios for oil natural gas and coal respectively (end 2012 status) Figures are based on datafrom BP (2013)

5ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

North America

S amp Cent America

Europe amp Eurasia

Middle East

Africa

Asia Pacific

0 20 40 60

RP (years)

80 100 120 140

North America

S amp Cent America

Europe amp Eurasia

Middle East

Africa

Asia Pacific

0

RP (years)

North America

S amp Cent America

Europe amp Eurasia

Middle East amp Africa

Asia Pacific

0 50 100 150 200 250 300RP (years)

50 100 150 200

FIGURE 12 (Continued )

6 INTRODUCTION

discovered in the (near) future but that does not change the inherently limited supplynature of the fossil fuel sources Regionally there are also significant differenceswhich is important in the context of energy policy developments on the differentcontinents

For the price developments of the fossil fuels not only their forecasted availabilityis of importance but also the market development in a landscape highly determined bypolitics Already well before the last resources of a fuel will have been depleted themarket will be severely stressed For the economies in the world fuel cost develop-ment is therefore also a primary point of concern From past developments particu-larly regarding oil it has been shown that substantial fuel price fluctuations (volatility)occur which has an impact on the global economy (eg food prices) that is difficult topredict Supply and demand will determine the price evolution for each fuel sourcebut the development of the market structure is also essential there is a large differencebetween a free market and an oligopoly or monopoly situation In this respect diver-sification of fuel sources with associated differentiation in suppliers is advantageousas it makes societies less prone to price manipulation by eg cartel formation andsudden disruptions of supply (Johansson et al 1993)

Self-sufficiency concerning energy supply is often mentioned as target of countriesfor (longer-term) sustainable economic development However not all countries haveaccess to resources within their territories that are sufficient for such a target othercountries on the other hand have a structural surplus Relief of trade barriers canhelp mitigate this structural discrepancy Also in the context of economic sustaina-bility a good trade balance should be maintained in relation to the energy supplywithin nations

Regarding social sustainability in the context of energy supply reduction of pov-erty should be mentioned first a good supply structure of energy carriers is one of thebasic requirements for such a development next to access to clean drinking water andgood soil for agricultural activity Associated herewith expectedly substantial healthimprovement should result from a good energy supply infrastructure Job creation andmaintenance is another aspect of social sustainability and certain energy supply formscan contribute significantly to this Also maintaining (or improving) societiesrsquo socialcohesion is an aspect that can be impacted by the energy supply structure

1132 Ecological Sustainability The energy supply structure should notcompromise the sound development of our environment both from a local and globalperspective One of the major issues in this respect is global warming which is for themain part attributed to the release of greenhouse gases (GHG) from fossil fuel com-bustion Other issues are related to local emissions of acid rain precursors and partic-ulate matter (PM)

Climate Change the Greenhouse Effect and Greenhouse Gas EmissionReduction The greenhouse effect occurs naturally to a large extent Without thiseffect the Earthrsquos average global temperature would reach only a low minus18C ratherthan the current approximate +15C Water vapor is the largest contributor to thiseffect with a complex role for clouds but also CO2 in the atmosphere plays a

7ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

significant role More than a century ago Arrhenius (1896) already identified thisrole in the Earthrsquos temperature control Ice core studies reveal that on millennial timescales changes in CO2 content recorded are highly correlated with changes in tem-perature although some temperature changes have occurred without a significantCO2 concentration change but the opposite does not appear to have happened(Falkowski et al 2000) Less pronounced roles are played by CH4 N2O (nitrousoxide) and several types of chlorofluorocarbons (CFCs) and SF6 It is the CO2CH4 N2O and CFC concentrations in the atmosphere upon which manrsquos industrial

0

1

Rad

iati

ve

forc

ing (

Wm

2)

350

(a)

300

Car

bon d

ioxid

e (p

pm

)

250

300

350

400

1800 1900

Year

2000

(b)

1500

2000

1000

Met

han

e (p

pb)

500

0

02

04

Rad

iati

ve

forc

ing (

Wm

2)

1000

500

1500

2000

1900

Year

20001800

FIGURE 13 Atmospheric concentrations of CO2 CH4 and N2O over the last 10000 years(large panels) and since 1750 (inset panels) Measurements are shown from ice cores (symbolswith different grey shades for different studies) and atmospheric samples (light grey lines insteep curve part red lines in the original publication) The corresponding radiative forcings(net solar energy flux to the earth) relative to 1750 are shown on the right-hand axes of the largepanels (SourceReproducedwithpermission fromIPCC(2007) figure23 figureSPM1copyIPCC)

8 INTRODUCTION

and household activities have a measurable impact Scientists largely agree on thepoint that in the last few centuries the activities of humans have directly or indirectlycaused the concentrations of the major GHG to increase This is exemplified byFigure 13 The atmospheric CO2 concentration varies to some extent from placeto place and from season to season It has been shown that concentrations are some-what higher in the northern hemisphere than in the southern hemisphere as most of theanthropogenic sources of CO2 are located north of the equator The difference in landsurface covered with forests being more concentrated north of the equator causeslarger seasonal fluctuations due to comparatively shorter growth periods than in thegenerally milder southern hemisphere locations that are under the influence of largeroceanic surfaces

Oscillations of atmospheric CO2 concentrations between about 180 and 280 ppmv

have occurred in the past approximately 480000 years in cycles of 100000 yearsbut it appears now we have abandoned this cycling behavior in a remarkably shorttime frame

Studies at the NASA Goddard Institute for Space Studies in New York (UnitedStates) have shown that over the past few decades the combined warming effectof non-CO2 GHG should have been comparable to that of CO2 alone However whileeach of the GHGmentioned earlier acts to warm the surface of the Earth the long-termclimatic effects of the other GHG differ from those of CO2 Methane eg has anatmospheric lifetime of only about 12 years By comparison newly added CO2 willremain for a time span of tens to thousands of years As a result about 65 of thecarbon dioxide that human activities have generated since the start of the IndustrialRevolution is in the air we breathe today A historical record of the amount ofCO2 in the atmosphere can be found in bubbles of air in arctic ice layers dating backas far as 600000 years The depth of such a layer is a measure of its time of formation

(c)

10000 5000

Time (before 2005)

0

0

01

Rad

iati

ve

forc

ing (

Wm

2)

300

270

Nit

rous

oxid

e (p

pb)

270

240

300

330

1800 1900

Year

2000

FIGURE 13 (Continued )

9ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

Another difference is that the principal anthropogenic sources of methane-bacterialfermentation in rice paddies and in the intestines of cattle are related to food produc-tion and hence are roughly proportional to the number of people on the planetBecause CH4 has such a short atmospheric lifetime the amount that is in the air isa good indicator of how much is being added with time Should the global populationdouble over the next half century the concentration of CH4 could also double but it isnot likely to rise by much more than that This would add at most a few tenths of adegree to the mean temperature of the Earth Future CO2 increases could in contrastwarm the climate by 10C or more

Nitrous oxide (N2O) and CFCs are in some ways more like CO2 in that oncereleased they remain in the atmosphere for a century or more The production ofN2O however is only indirectly dependent on human activities Its principal sourceis a natural one the bacterial removal of nitrogen from soils and although the worldpopulation swells in coming years the amount in the air should increase only slowly

The outlook for many CFCs is even more promising Today the most abundant ofthese man-made compounds freon-11 and freon-12 are being phased out of produc-tion altogether by international agreements because of their damaging effects on strat-ospheric ozone Indeed the concentration of one of these gases freon-11 peaked in1994 and is now in a slow decline that should continue for the next century or so Thefreon-12 concentration has not yet leveled off but is expected to do so within the nextfew years In terms of climatic effects the main threat from CFCs comes from otherlong-lived compounds that may be used to replace the ones that have been phased outand that could also act as GHG Since these possibly harmful replacement gases are asyet present in only small amounts and since as noted earlier projected increases inCH4 and N2O are so much less severe we shall for the rest of this discussion focussolely on the most important anthropogenic GHG CO2

Some experts have estimated that the Earthrsquos average global temperature has alreadyincreased by more than 05C since the mid-1900s due to this human-enhanced green-house effect also impacts on sea level (rising) and snow coverage (tending to decrease)have been investigated the results of which are summarized in Figure 14

Like most other planets and planetoids in the universe the Earth contains a greatdeal of carbon which is slowly and continually transported from the mantle to thecrust and back again in the course of volcanic eruption and subduction phenomenaThe portion that finds itself near the surface is continually exchanged and recycledamong plants animals soil air and oceans In some of these temporary stocks car-bon is more securely held while in others it more readily combines with oxygen in theair to form CO2 In order to predict how atmospheric CO2 levels and climate maychange in the future it is important to understand where carbon is stored and whatits dynamic cycling behavior looks like The carbon reservoirs that are most relevantto global warming are listed in Table 11 with the total amount of carbon that theycontained in 2000

The atmosphere contains approximately 720 Gt C in the form of CO2 currentmeasured atmospheric CO2 concentrations are nearly 400 ppmv The rate of changein this carbon stock not only depends on human activities but also on biogeochemicaland climatological processes and their interactions with the global carbon cycle

10 INTRODUCTION

ACKNOWLEDGMENTS

This book would not have been published without the contributions from manypeople First of all we would like to acknowledge all the students that followedour course ldquoEnergy from Biomassrdquo over the years they inspired us to compose thisbook We are very glad that many of our colleagues agreed to contribute chapters tothis book It was great to work with this team of co-authors all bringing in their spe-cific expertise to cover the broad field of energy from biomass A big thanks to all ofyou For some chapters the additional input from others is specifically acknowledgedLikun Ma is kindly acknowledged for his contribution to the examples in Chapter 4Ryan Bogaars for his suggestions concerning Chapter 10 Xiangmei Meng and Onur-sal Yakaboylu for contributing some of the examples of Chapter 10 Richard Eijsbergfor the first generation ethanol process figures and data in Chapter 13 Tim Geraedtsand Elze Oude Lansink for the project in Chapter 15 Fred van Rantwijk for valuableinput and discussions on Chapter 18 and Adrea Fabre for her advices regarding thewritingWe are also grateful for the willingness of many colleagues to review chaptersin order to find mistakes and make suggestions for further improvements Ourreviewers were in alphabetic order Rob Bakker Sune Bengtsson PouyanBoukany Anthony Bridgwater Harry Croezen Lilian de Martiacuten Jorge GasconHans Geerlings Johan Grievink Sef Heijnen Kas Hemmes Paulien Herder TrulsLiliedahl Gabrie Meesters Bart Merci Kyriakos Panopoulos Wolter Prins SinaSartipi Fabrizio Scala Tilman Schildhauer Andrzej Stankiewicz GeorgiosStefanidis Bob Ursem Henk van den Berg Theo van der Meer Jules van Lier Maritvan Lieshout and Stanislav Vassilev A special word of thanks should go to Anneliesvan Diepen When the chapters were complete she made a great effort to harmonizethem for example in figures symbols lay-out and wording She also has caughtnumerous mistakes that were still present in earlier versions We would like to thank

xv

Jan Leen Kloosterman (Director of Education Sustainable Energy Technology SET)for the financial support from the SET program for editorial assistance We would alsolike to thank the people at Wiley for the smooth cooperation during the preparation ofthe manuscript Finally we would like to thank the ones close to usmdashKlarine (WdJ)and Ceciel Fenne and Chris (JRvO)mdashfor their understanding and support during allthe evenings and weekends that the writing and editing took

xvi ACKNOWLEDGMENTS

LIST OF CONTRIBUTORS

PV Aravind Drir Department of Process and Energy Energy TechnologySection Faculty of Mechanical Maritime and Materials Engineering DelftUniversity of Technology Delft the Netherlands

Isabel WCE Arends Profdr Department of Biotechnology Biocatalysis GroupFaculty of Applied Sciences Delft University of Technology Delft theNetherlands

Rob JM Bastiaans Drir Department of Mechanical Engineering CombustionTechnology Section Eindhoven University of Technology Eindhoven theNetherlands

Maria C Cuellar Dr Department of Biotechnology BioProcess EngineeringGroup Faculty of Applied Sciences Delft University of Technology Delft theNetherlands

Martina Fantini Drir Department of Process and Energy Energy TechnologySection Faculty of Mechanical Maritime and Materials Engineering DelftUniversity of Technology Delft the Netherlands

Johan Grievink Prof ir Department of Chemical Engineering Product amp ProcessEngineering Group Faculty of Applied Sciences Delft University of TechnologyDelft the Netherlands

ArnoHH Janssen Ir ECN Biomass amp Energy Efficiency Petten the Netherlands

Wiebren de Jong Drir Department of Process and Energy Energy TechnologySection Faculty of Mechanical Maritime and Materials Engineering DelftUniversity of Technology Delft the Netherlands

xvii

Yash Joshi Ir Department of Process and Energy Energy Technology SectionFaculty of Mechanical Maritime and Materials Engineering Delft University ofTechnology Delft the Netherlands

Sascha RA Kersten Profdrir Sustainable Process Technology Group Facultyof Science and Technology University of Twente Enschede the Netherlands

Jaap HA Kiel Profdrir ECN Biomass amp Energy Efficiency Petten andDepartment of Process and Energy Energy Technology Section Faculty ofMechanical Maritime andMaterials Engineering Delft University of TechnologyDelft the Netherlands

Robbert Kleerebezem Drir Department of Biotechnology EnvironmentalBiotechnology Group Faculty of Applied Sciences Delft University of TechnologyDelft the Netherlands

Ming Liu Drir Department of Process and Energy Energy Technology SectionFaculty of Mechanical Maritime and Materials Engineering Delft University ofTechnology Delft the Netherlands

Lilian de Martiacuten Dr Department of Chemical Engineering Product amp ProcessEngineering Group Faculty of Applied Sciences Delft University of TechnologyDelft the Netherlands

Jeroen A van Oijen Drir Department of Mechanical Engineering CombustionTechnology Section Eindhoven University of Technology Eindhoven theNetherlands

J Ruud van Ommen Drir Department of Chemical Engineering Product ampProcess Engineering Group Faculty of Applied Sciences Delft University ofTechnology Delft the Netherlands

Stijn RG Oudenhoven Ir Sustainable Process Technology Group Faculty ofScience and Technology University of Twente Enschede the Netherlands

Dirk JEM Roekaerts Profdr Department of Process and Energy FluidMechanics Section Faculty of Mechanical Maritime and Materials EngineeringDelft University of Technology Delft the Netherlands

Adrie JJ Straathof Drir Department of Biotechnology BioProcess EngineeringGroup Faculty of Applied Sciences Delft University of Technology Delft theNetherlands

Pieter LJ Swinkels Ir Faculty of Applied Sciences Delft Product amp ProcessDesign Institute Delft University of Technology Delft the Netherlands

xviii LIST OF CONTRIBUTORS

PART I

SOCIAL CONTEXT AND STRUCTURALBASIS OF BIOMASS AS A RENEWABLEENERGY SOURCES

1INTRODUCTION SOCIOECONOMICASPECTS OF BIOMASS CONVERSION

WIEBREN DE JONG1 AND J RUUD VAN OMMEN2

1Department of Process and Energy Energy Technology Section Faculty of MechanicalMaritime and Materials Engineering Delft University of Technology Delft the Netherlands2Department of Chemical Engineering Product amp Process Engineering Group Faculty ofApplied Sciences Delft University of Technology Delft the Netherlands

ACRONYMS

CDM clean development mechanismCFCs chlorofluorocarbonsdLUC direct land use changeGDP gross domestic productGHG greenhouse gasiLUC indirect land use changeJI joint implementationLCA life cycle assessmentLUC land use changeRP ratio reserves-to-production ratio [y]TOE tonnes of oil equivalent(s) (= 4187 GJ)UNFCCC United Nations Framework Convention on Climate Change

Biomass as a Sustainable Energy Source for the Future Fundamentals of Conversion ProcessesFirst Edition Edited by Wiebren de Jong and J Ruud van Ommencopy 2015 American Institute of Chemical Engineers Inc Published 2015 by John Wiley amp Sons Inc

3

11 ENERGY SUPPLY ECONOMIC AND ENVIRONMENTALCONSIDERATIONS

111 Introduction The Importance of Energy Supply

In the past two centuries since the Industrial Revolution in the 1700s that was initiatedby the invention of the steam turbine the world has undergone a drastic change due tothe steeply increased contribution of fossil fuels (coal oil and natural gas) to modernsocietiesrsquo energy supply (McKay 2009) Though the Chinese society already usedcoal for energy supply in approximately 1000 BC and the Romans prior to AD 400(World-Coal-Institute 2005) the first written references indicating its use are fromabout the thirteenth century and beyond (Hubbert 1949) These hydrocarbon fuelsso far have been considered essential as they are comparatively cheap and convenientenergy carriers used for heating cooking lighting and mechanical as well as electricpower production and have been widely used as transportation fuels and feedstocksfor the manufacture of bulk and fine chemicals as well as other materials with a widerange of applications Rapid global population growth expansion of economies andhigher standards have caused an enormous increase in worldwide energy consump-tion which was partly made possible by the supply of cheap fossil fuels

112 Development of Global Energy Demand

Figure 11 shows a scenario toward the year 2030 presented by the oil company BPconcerning population growth in relation to developments in total primary energyutilization and gross domestic product (GDP) The figure shows that global energy

Billion

Rest of

the world

India

China

9

8

7

6

5

4

3

2

1

0

Population

Billion toe

18

15

12

9

6

3

0

Energy

Trillion $2010 PPP

180

150

120

90

60

30

01970 1990 2010 2030 1970 1990 2010 2030 1970 1990 2010 2030

GDP

FIGURE 11 Prospected global growth rates in population energy demand and GDP 1 toe =41868104 MJ (Source Adapted from BP see tinyurlcom7hlmqxn)

4 INTRODUCTION

demand will rise substantially from the current level with an increasing share fromChina and India This rise of the primary energy demand is projected to be larger thanthe population growth and this will cause a stress on the limited global resources Theprojected GDP even increases stronger so it is expected that average living standardsincrease which will result in additional strain on the available resources

113 Sustainability of Energy Supply

One of the major questions in the world arising from the general picture sketched inSection 112 is how mankind can ensure a global sustainable development for the(near) future In this context sustainability of our energy supply is of paramountimportance The key issues are discussed in the following text both from a pointof view of global socioeconomics and ecological sustainability

1131 Socioeconomic Sustainability As one of the most important economicdrivers to secure and improve the living standards of people in the world energysupply security is of crucial value for current and future generations Fossil fuelsrun out sooner or later as can be seen in Figure 12 they are not renewable on anacceptable time scale

This figure depicts the so-called RP ratios for different sources The RP ratio is theratio of the current proven reserves to production level The unit is years and it is ameasure of the expected time a certain fuel source is expected to be available

On a global scale it appears that oil and natural gas reserves will be availablemdashgiven the figures of 2012mdashfor an expected approximately 55 years and coal substan-tially longer (gt100 years) Of course new contributions to the reserves may be

0

50

100

150

200

250

1980 1985 1990 1995 2000 2005 2010 2015

RP

(yea

rs)

Oil

Coal

Natural gas

FIGURE 12 Overview of world (top) and regional (bottom) reserves-to-production (RP)ratios for oil natural gas and coal respectively (end 2012 status) Figures are based on datafrom BP (2013)

5ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

North America

S amp Cent America

Europe amp Eurasia

Middle East

Africa

Asia Pacific

0 20 40 60

RP (years)

80 100 120 140

North America

S amp Cent America

Europe amp Eurasia

Middle East

Africa

Asia Pacific

0

RP (years)

North America

S amp Cent America

Europe amp Eurasia

Middle East amp Africa

Asia Pacific

0 50 100 150 200 250 300RP (years)

50 100 150 200

FIGURE 12 (Continued )

6 INTRODUCTION

discovered in the (near) future but that does not change the inherently limited supplynature of the fossil fuel sources Regionally there are also significant differenceswhich is important in the context of energy policy developments on the differentcontinents

For the price developments of the fossil fuels not only their forecasted availabilityis of importance but also the market development in a landscape highly determined bypolitics Already well before the last resources of a fuel will have been depleted themarket will be severely stressed For the economies in the world fuel cost develop-ment is therefore also a primary point of concern From past developments particu-larly regarding oil it has been shown that substantial fuel price fluctuations (volatility)occur which has an impact on the global economy (eg food prices) that is difficult topredict Supply and demand will determine the price evolution for each fuel sourcebut the development of the market structure is also essential there is a large differencebetween a free market and an oligopoly or monopoly situation In this respect diver-sification of fuel sources with associated differentiation in suppliers is advantageousas it makes societies less prone to price manipulation by eg cartel formation andsudden disruptions of supply (Johansson et al 1993)

Self-sufficiency concerning energy supply is often mentioned as target of countriesfor (longer-term) sustainable economic development However not all countries haveaccess to resources within their territories that are sufficient for such a target othercountries on the other hand have a structural surplus Relief of trade barriers canhelp mitigate this structural discrepancy Also in the context of economic sustaina-bility a good trade balance should be maintained in relation to the energy supplywithin nations

Regarding social sustainability in the context of energy supply reduction of pov-erty should be mentioned first a good supply structure of energy carriers is one of thebasic requirements for such a development next to access to clean drinking water andgood soil for agricultural activity Associated herewith expectedly substantial healthimprovement should result from a good energy supply infrastructure Job creation andmaintenance is another aspect of social sustainability and certain energy supply formscan contribute significantly to this Also maintaining (or improving) societiesrsquo socialcohesion is an aspect that can be impacted by the energy supply structure

1132 Ecological Sustainability The energy supply structure should notcompromise the sound development of our environment both from a local and globalperspective One of the major issues in this respect is global warming which is for themain part attributed to the release of greenhouse gases (GHG) from fossil fuel com-bustion Other issues are related to local emissions of acid rain precursors and partic-ulate matter (PM)

Climate Change the Greenhouse Effect and Greenhouse Gas EmissionReduction The greenhouse effect occurs naturally to a large extent Without thiseffect the Earthrsquos average global temperature would reach only a low minus18C ratherthan the current approximate +15C Water vapor is the largest contributor to thiseffect with a complex role for clouds but also CO2 in the atmosphere plays a

7ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

significant role More than a century ago Arrhenius (1896) already identified thisrole in the Earthrsquos temperature control Ice core studies reveal that on millennial timescales changes in CO2 content recorded are highly correlated with changes in tem-perature although some temperature changes have occurred without a significantCO2 concentration change but the opposite does not appear to have happened(Falkowski et al 2000) Less pronounced roles are played by CH4 N2O (nitrousoxide) and several types of chlorofluorocarbons (CFCs) and SF6 It is the CO2CH4 N2O and CFC concentrations in the atmosphere upon which manrsquos industrial

0

1

Rad

iati

ve

forc

ing (

Wm

2)

350

(a)

300

Car

bon d

ioxid

e (p

pm

)

250

300

350

400

1800 1900

Year

2000

(b)

1500

2000

1000

Met

han

e (p

pb)

500

0

02

04

Rad

iati

ve

forc

ing (

Wm

2)

1000

500

1500

2000

1900

Year

20001800

FIGURE 13 Atmospheric concentrations of CO2 CH4 and N2O over the last 10000 years(large panels) and since 1750 (inset panels) Measurements are shown from ice cores (symbolswith different grey shades for different studies) and atmospheric samples (light grey lines insteep curve part red lines in the original publication) The corresponding radiative forcings(net solar energy flux to the earth) relative to 1750 are shown on the right-hand axes of the largepanels (SourceReproducedwithpermission fromIPCC(2007) figure23 figureSPM1copyIPCC)

8 INTRODUCTION

and household activities have a measurable impact Scientists largely agree on thepoint that in the last few centuries the activities of humans have directly or indirectlycaused the concentrations of the major GHG to increase This is exemplified byFigure 13 The atmospheric CO2 concentration varies to some extent from placeto place and from season to season It has been shown that concentrations are some-what higher in the northern hemisphere than in the southern hemisphere as most of theanthropogenic sources of CO2 are located north of the equator The difference in landsurface covered with forests being more concentrated north of the equator causeslarger seasonal fluctuations due to comparatively shorter growth periods than in thegenerally milder southern hemisphere locations that are under the influence of largeroceanic surfaces

Oscillations of atmospheric CO2 concentrations between about 180 and 280 ppmv

have occurred in the past approximately 480000 years in cycles of 100000 yearsbut it appears now we have abandoned this cycling behavior in a remarkably shorttime frame

Studies at the NASA Goddard Institute for Space Studies in New York (UnitedStates) have shown that over the past few decades the combined warming effectof non-CO2 GHG should have been comparable to that of CO2 alone However whileeach of the GHGmentioned earlier acts to warm the surface of the Earth the long-termclimatic effects of the other GHG differ from those of CO2 Methane eg has anatmospheric lifetime of only about 12 years By comparison newly added CO2 willremain for a time span of tens to thousands of years As a result about 65 of thecarbon dioxide that human activities have generated since the start of the IndustrialRevolution is in the air we breathe today A historical record of the amount ofCO2 in the atmosphere can be found in bubbles of air in arctic ice layers dating backas far as 600000 years The depth of such a layer is a measure of its time of formation

(c)

10000 5000

Time (before 2005)

0

0

01

Rad

iati

ve

forc

ing (

Wm

2)

300

270

Nit

rous

oxid

e (p

pb)

270

240

300

330

1800 1900

Year

2000

FIGURE 13 (Continued )

9ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

Another difference is that the principal anthropogenic sources of methane-bacterialfermentation in rice paddies and in the intestines of cattle are related to food produc-tion and hence are roughly proportional to the number of people on the planetBecause CH4 has such a short atmospheric lifetime the amount that is in the air isa good indicator of how much is being added with time Should the global populationdouble over the next half century the concentration of CH4 could also double but it isnot likely to rise by much more than that This would add at most a few tenths of adegree to the mean temperature of the Earth Future CO2 increases could in contrastwarm the climate by 10C or more

Nitrous oxide (N2O) and CFCs are in some ways more like CO2 in that oncereleased they remain in the atmosphere for a century or more The production ofN2O however is only indirectly dependent on human activities Its principal sourceis a natural one the bacterial removal of nitrogen from soils and although the worldpopulation swells in coming years the amount in the air should increase only slowly

The outlook for many CFCs is even more promising Today the most abundant ofthese man-made compounds freon-11 and freon-12 are being phased out of produc-tion altogether by international agreements because of their damaging effects on strat-ospheric ozone Indeed the concentration of one of these gases freon-11 peaked in1994 and is now in a slow decline that should continue for the next century or so Thefreon-12 concentration has not yet leveled off but is expected to do so within the nextfew years In terms of climatic effects the main threat from CFCs comes from otherlong-lived compounds that may be used to replace the ones that have been phased outand that could also act as GHG Since these possibly harmful replacement gases are asyet present in only small amounts and since as noted earlier projected increases inCH4 and N2O are so much less severe we shall for the rest of this discussion focussolely on the most important anthropogenic GHG CO2

Some experts have estimated that the Earthrsquos average global temperature has alreadyincreased by more than 05C since the mid-1900s due to this human-enhanced green-house effect also impacts on sea level (rising) and snow coverage (tending to decrease)have been investigated the results of which are summarized in Figure 14

Like most other planets and planetoids in the universe the Earth contains a greatdeal of carbon which is slowly and continually transported from the mantle to thecrust and back again in the course of volcanic eruption and subduction phenomenaThe portion that finds itself near the surface is continually exchanged and recycledamong plants animals soil air and oceans In some of these temporary stocks car-bon is more securely held while in others it more readily combines with oxygen in theair to form CO2 In order to predict how atmospheric CO2 levels and climate maychange in the future it is important to understand where carbon is stored and whatits dynamic cycling behavior looks like The carbon reservoirs that are most relevantto global warming are listed in Table 11 with the total amount of carbon that theycontained in 2000

The atmosphere contains approximately 720 Gt C in the form of CO2 currentmeasured atmospheric CO2 concentrations are nearly 400 ppmv The rate of changein this carbon stock not only depends on human activities but also on biogeochemicaland climatological processes and their interactions with the global carbon cycle

10 INTRODUCTION

Jan Leen Kloosterman (Director of Education Sustainable Energy Technology SET)for the financial support from the SET program for editorial assistance We would alsolike to thank the people at Wiley for the smooth cooperation during the preparation ofthe manuscript Finally we would like to thank the ones close to usmdashKlarine (WdJ)and Ceciel Fenne and Chris (JRvO)mdashfor their understanding and support during allthe evenings and weekends that the writing and editing took

xvi ACKNOWLEDGMENTS

LIST OF CONTRIBUTORS

PV Aravind Drir Department of Process and Energy Energy TechnologySection Faculty of Mechanical Maritime and Materials Engineering DelftUniversity of Technology Delft the Netherlands

Isabel WCE Arends Profdr Department of Biotechnology Biocatalysis GroupFaculty of Applied Sciences Delft University of Technology Delft theNetherlands

Rob JM Bastiaans Drir Department of Mechanical Engineering CombustionTechnology Section Eindhoven University of Technology Eindhoven theNetherlands

Maria C Cuellar Dr Department of Biotechnology BioProcess EngineeringGroup Faculty of Applied Sciences Delft University of Technology Delft theNetherlands

Martina Fantini Drir Department of Process and Energy Energy TechnologySection Faculty of Mechanical Maritime and Materials Engineering DelftUniversity of Technology Delft the Netherlands

Johan Grievink Prof ir Department of Chemical Engineering Product amp ProcessEngineering Group Faculty of Applied Sciences Delft University of TechnologyDelft the Netherlands

ArnoHH Janssen Ir ECN Biomass amp Energy Efficiency Petten the Netherlands

Wiebren de Jong Drir Department of Process and Energy Energy TechnologySection Faculty of Mechanical Maritime and Materials Engineering DelftUniversity of Technology Delft the Netherlands

xvii

Yash Joshi Ir Department of Process and Energy Energy Technology SectionFaculty of Mechanical Maritime and Materials Engineering Delft University ofTechnology Delft the Netherlands

Sascha RA Kersten Profdrir Sustainable Process Technology Group Facultyof Science and Technology University of Twente Enschede the Netherlands

Jaap HA Kiel Profdrir ECN Biomass amp Energy Efficiency Petten andDepartment of Process and Energy Energy Technology Section Faculty ofMechanical Maritime andMaterials Engineering Delft University of TechnologyDelft the Netherlands

Robbert Kleerebezem Drir Department of Biotechnology EnvironmentalBiotechnology Group Faculty of Applied Sciences Delft University of TechnologyDelft the Netherlands

Ming Liu Drir Department of Process and Energy Energy Technology SectionFaculty of Mechanical Maritime and Materials Engineering Delft University ofTechnology Delft the Netherlands

Lilian de Martiacuten Dr Department of Chemical Engineering Product amp ProcessEngineering Group Faculty of Applied Sciences Delft University of TechnologyDelft the Netherlands

Jeroen A van Oijen Drir Department of Mechanical Engineering CombustionTechnology Section Eindhoven University of Technology Eindhoven theNetherlands

J Ruud van Ommen Drir Department of Chemical Engineering Product ampProcess Engineering Group Faculty of Applied Sciences Delft University ofTechnology Delft the Netherlands

Stijn RG Oudenhoven Ir Sustainable Process Technology Group Faculty ofScience and Technology University of Twente Enschede the Netherlands

Dirk JEM Roekaerts Profdr Department of Process and Energy FluidMechanics Section Faculty of Mechanical Maritime and Materials EngineeringDelft University of Technology Delft the Netherlands

Adrie JJ Straathof Drir Department of Biotechnology BioProcess EngineeringGroup Faculty of Applied Sciences Delft University of Technology Delft theNetherlands

Pieter LJ Swinkels Ir Faculty of Applied Sciences Delft Product amp ProcessDesign Institute Delft University of Technology Delft the Netherlands

xviii LIST OF CONTRIBUTORS

PART I

SOCIAL CONTEXT AND STRUCTURALBASIS OF BIOMASS AS A RENEWABLEENERGY SOURCES

1INTRODUCTION SOCIOECONOMICASPECTS OF BIOMASS CONVERSION

WIEBREN DE JONG1 AND J RUUD VAN OMMEN2

1Department of Process and Energy Energy Technology Section Faculty of MechanicalMaritime and Materials Engineering Delft University of Technology Delft the Netherlands2Department of Chemical Engineering Product amp Process Engineering Group Faculty ofApplied Sciences Delft University of Technology Delft the Netherlands

ACRONYMS

CDM clean development mechanismCFCs chlorofluorocarbonsdLUC direct land use changeGDP gross domestic productGHG greenhouse gasiLUC indirect land use changeJI joint implementationLCA life cycle assessmentLUC land use changeRP ratio reserves-to-production ratio [y]TOE tonnes of oil equivalent(s) (= 4187 GJ)UNFCCC United Nations Framework Convention on Climate Change

Biomass as a Sustainable Energy Source for the Future Fundamentals of Conversion ProcessesFirst Edition Edited by Wiebren de Jong and J Ruud van Ommencopy 2015 American Institute of Chemical Engineers Inc Published 2015 by John Wiley amp Sons Inc

3

11 ENERGY SUPPLY ECONOMIC AND ENVIRONMENTALCONSIDERATIONS

111 Introduction The Importance of Energy Supply

In the past two centuries since the Industrial Revolution in the 1700s that was initiatedby the invention of the steam turbine the world has undergone a drastic change due tothe steeply increased contribution of fossil fuels (coal oil and natural gas) to modernsocietiesrsquo energy supply (McKay 2009) Though the Chinese society already usedcoal for energy supply in approximately 1000 BC and the Romans prior to AD 400(World-Coal-Institute 2005) the first written references indicating its use are fromabout the thirteenth century and beyond (Hubbert 1949) These hydrocarbon fuelsso far have been considered essential as they are comparatively cheap and convenientenergy carriers used for heating cooking lighting and mechanical as well as electricpower production and have been widely used as transportation fuels and feedstocksfor the manufacture of bulk and fine chemicals as well as other materials with a widerange of applications Rapid global population growth expansion of economies andhigher standards have caused an enormous increase in worldwide energy consump-tion which was partly made possible by the supply of cheap fossil fuels

112 Development of Global Energy Demand

Figure 11 shows a scenario toward the year 2030 presented by the oil company BPconcerning population growth in relation to developments in total primary energyutilization and gross domestic product (GDP) The figure shows that global energy

Billion

Rest of

the world

India

China

9

8

7

6

5

4

3

2

1

0

Population

Billion toe

18

15

12

9

6

3

0

Energy

Trillion $2010 PPP

180

150

120

90

60

30

01970 1990 2010 2030 1970 1990 2010 2030 1970 1990 2010 2030

GDP

FIGURE 11 Prospected global growth rates in population energy demand and GDP 1 toe =41868104 MJ (Source Adapted from BP see tinyurlcom7hlmqxn)

4 INTRODUCTION

demand will rise substantially from the current level with an increasing share fromChina and India This rise of the primary energy demand is projected to be larger thanthe population growth and this will cause a stress on the limited global resources Theprojected GDP even increases stronger so it is expected that average living standardsincrease which will result in additional strain on the available resources

113 Sustainability of Energy Supply

One of the major questions in the world arising from the general picture sketched inSection 112 is how mankind can ensure a global sustainable development for the(near) future In this context sustainability of our energy supply is of paramountimportance The key issues are discussed in the following text both from a pointof view of global socioeconomics and ecological sustainability

1131 Socioeconomic Sustainability As one of the most important economicdrivers to secure and improve the living standards of people in the world energysupply security is of crucial value for current and future generations Fossil fuelsrun out sooner or later as can be seen in Figure 12 they are not renewable on anacceptable time scale

This figure depicts the so-called RP ratios for different sources The RP ratio is theratio of the current proven reserves to production level The unit is years and it is ameasure of the expected time a certain fuel source is expected to be available

On a global scale it appears that oil and natural gas reserves will be availablemdashgiven the figures of 2012mdashfor an expected approximately 55 years and coal substan-tially longer (gt100 years) Of course new contributions to the reserves may be

0

50

100

150

200

250

1980 1985 1990 1995 2000 2005 2010 2015

RP

(yea

rs)

Oil

Coal

Natural gas

FIGURE 12 Overview of world (top) and regional (bottom) reserves-to-production (RP)ratios for oil natural gas and coal respectively (end 2012 status) Figures are based on datafrom BP (2013)

5ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

North America

S amp Cent America

Europe amp Eurasia

Middle East

Africa

Asia Pacific

0 20 40 60

RP (years)

80 100 120 140

North America

S amp Cent America

Europe amp Eurasia

Middle East

Africa

Asia Pacific

0

RP (years)

North America

S amp Cent America

Europe amp Eurasia

Middle East amp Africa

Asia Pacific

0 50 100 150 200 250 300RP (years)

50 100 150 200

FIGURE 12 (Continued )

6 INTRODUCTION

discovered in the (near) future but that does not change the inherently limited supplynature of the fossil fuel sources Regionally there are also significant differenceswhich is important in the context of energy policy developments on the differentcontinents

For the price developments of the fossil fuels not only their forecasted availabilityis of importance but also the market development in a landscape highly determined bypolitics Already well before the last resources of a fuel will have been depleted themarket will be severely stressed For the economies in the world fuel cost develop-ment is therefore also a primary point of concern From past developments particu-larly regarding oil it has been shown that substantial fuel price fluctuations (volatility)occur which has an impact on the global economy (eg food prices) that is difficult topredict Supply and demand will determine the price evolution for each fuel sourcebut the development of the market structure is also essential there is a large differencebetween a free market and an oligopoly or monopoly situation In this respect diver-sification of fuel sources with associated differentiation in suppliers is advantageousas it makes societies less prone to price manipulation by eg cartel formation andsudden disruptions of supply (Johansson et al 1993)

Self-sufficiency concerning energy supply is often mentioned as target of countriesfor (longer-term) sustainable economic development However not all countries haveaccess to resources within their territories that are sufficient for such a target othercountries on the other hand have a structural surplus Relief of trade barriers canhelp mitigate this structural discrepancy Also in the context of economic sustaina-bility a good trade balance should be maintained in relation to the energy supplywithin nations

Regarding social sustainability in the context of energy supply reduction of pov-erty should be mentioned first a good supply structure of energy carriers is one of thebasic requirements for such a development next to access to clean drinking water andgood soil for agricultural activity Associated herewith expectedly substantial healthimprovement should result from a good energy supply infrastructure Job creation andmaintenance is another aspect of social sustainability and certain energy supply formscan contribute significantly to this Also maintaining (or improving) societiesrsquo socialcohesion is an aspect that can be impacted by the energy supply structure

1132 Ecological Sustainability The energy supply structure should notcompromise the sound development of our environment both from a local and globalperspective One of the major issues in this respect is global warming which is for themain part attributed to the release of greenhouse gases (GHG) from fossil fuel com-bustion Other issues are related to local emissions of acid rain precursors and partic-ulate matter (PM)

Climate Change the Greenhouse Effect and Greenhouse Gas EmissionReduction The greenhouse effect occurs naturally to a large extent Without thiseffect the Earthrsquos average global temperature would reach only a low minus18C ratherthan the current approximate +15C Water vapor is the largest contributor to thiseffect with a complex role for clouds but also CO2 in the atmosphere plays a

7ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

significant role More than a century ago Arrhenius (1896) already identified thisrole in the Earthrsquos temperature control Ice core studies reveal that on millennial timescales changes in CO2 content recorded are highly correlated with changes in tem-perature although some temperature changes have occurred without a significantCO2 concentration change but the opposite does not appear to have happened(Falkowski et al 2000) Less pronounced roles are played by CH4 N2O (nitrousoxide) and several types of chlorofluorocarbons (CFCs) and SF6 It is the CO2CH4 N2O and CFC concentrations in the atmosphere upon which manrsquos industrial

0

1

Rad

iati

ve

forc

ing (

Wm

2)

350

(a)

300

Car

bon d

ioxid

e (p

pm

)

250

300

350

400

1800 1900

Year

2000

(b)

1500

2000

1000

Met

han

e (p

pb)

500

0

02

04

Rad

iati

ve

forc

ing (

Wm

2)

1000

500

1500

2000

1900

Year

20001800

FIGURE 13 Atmospheric concentrations of CO2 CH4 and N2O over the last 10000 years(large panels) and since 1750 (inset panels) Measurements are shown from ice cores (symbolswith different grey shades for different studies) and atmospheric samples (light grey lines insteep curve part red lines in the original publication) The corresponding radiative forcings(net solar energy flux to the earth) relative to 1750 are shown on the right-hand axes of the largepanels (SourceReproducedwithpermission fromIPCC(2007) figure23 figureSPM1copyIPCC)

8 INTRODUCTION

and household activities have a measurable impact Scientists largely agree on thepoint that in the last few centuries the activities of humans have directly or indirectlycaused the concentrations of the major GHG to increase This is exemplified byFigure 13 The atmospheric CO2 concentration varies to some extent from placeto place and from season to season It has been shown that concentrations are some-what higher in the northern hemisphere than in the southern hemisphere as most of theanthropogenic sources of CO2 are located north of the equator The difference in landsurface covered with forests being more concentrated north of the equator causeslarger seasonal fluctuations due to comparatively shorter growth periods than in thegenerally milder southern hemisphere locations that are under the influence of largeroceanic surfaces

Oscillations of atmospheric CO2 concentrations between about 180 and 280 ppmv

have occurred in the past approximately 480000 years in cycles of 100000 yearsbut it appears now we have abandoned this cycling behavior in a remarkably shorttime frame

Studies at the NASA Goddard Institute for Space Studies in New York (UnitedStates) have shown that over the past few decades the combined warming effectof non-CO2 GHG should have been comparable to that of CO2 alone However whileeach of the GHGmentioned earlier acts to warm the surface of the Earth the long-termclimatic effects of the other GHG differ from those of CO2 Methane eg has anatmospheric lifetime of only about 12 years By comparison newly added CO2 willremain for a time span of tens to thousands of years As a result about 65 of thecarbon dioxide that human activities have generated since the start of the IndustrialRevolution is in the air we breathe today A historical record of the amount ofCO2 in the atmosphere can be found in bubbles of air in arctic ice layers dating backas far as 600000 years The depth of such a layer is a measure of its time of formation

(c)

10000 5000

Time (before 2005)

0

0

01

Rad

iati

ve

forc

ing (

Wm

2)

300

270

Nit

rous

oxid

e (p

pb)

270

240

300

330

1800 1900

Year

2000

FIGURE 13 (Continued )

9ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

Another difference is that the principal anthropogenic sources of methane-bacterialfermentation in rice paddies and in the intestines of cattle are related to food produc-tion and hence are roughly proportional to the number of people on the planetBecause CH4 has such a short atmospheric lifetime the amount that is in the air isa good indicator of how much is being added with time Should the global populationdouble over the next half century the concentration of CH4 could also double but it isnot likely to rise by much more than that This would add at most a few tenths of adegree to the mean temperature of the Earth Future CO2 increases could in contrastwarm the climate by 10C or more

Nitrous oxide (N2O) and CFCs are in some ways more like CO2 in that oncereleased they remain in the atmosphere for a century or more The production ofN2O however is only indirectly dependent on human activities Its principal sourceis a natural one the bacterial removal of nitrogen from soils and although the worldpopulation swells in coming years the amount in the air should increase only slowly

The outlook for many CFCs is even more promising Today the most abundant ofthese man-made compounds freon-11 and freon-12 are being phased out of produc-tion altogether by international agreements because of their damaging effects on strat-ospheric ozone Indeed the concentration of one of these gases freon-11 peaked in1994 and is now in a slow decline that should continue for the next century or so Thefreon-12 concentration has not yet leveled off but is expected to do so within the nextfew years In terms of climatic effects the main threat from CFCs comes from otherlong-lived compounds that may be used to replace the ones that have been phased outand that could also act as GHG Since these possibly harmful replacement gases are asyet present in only small amounts and since as noted earlier projected increases inCH4 and N2O are so much less severe we shall for the rest of this discussion focussolely on the most important anthropogenic GHG CO2

Some experts have estimated that the Earthrsquos average global temperature has alreadyincreased by more than 05C since the mid-1900s due to this human-enhanced green-house effect also impacts on sea level (rising) and snow coverage (tending to decrease)have been investigated the results of which are summarized in Figure 14

Like most other planets and planetoids in the universe the Earth contains a greatdeal of carbon which is slowly and continually transported from the mantle to thecrust and back again in the course of volcanic eruption and subduction phenomenaThe portion that finds itself near the surface is continually exchanged and recycledamong plants animals soil air and oceans In some of these temporary stocks car-bon is more securely held while in others it more readily combines with oxygen in theair to form CO2 In order to predict how atmospheric CO2 levels and climate maychange in the future it is important to understand where carbon is stored and whatits dynamic cycling behavior looks like The carbon reservoirs that are most relevantto global warming are listed in Table 11 with the total amount of carbon that theycontained in 2000

The atmosphere contains approximately 720 Gt C in the form of CO2 currentmeasured atmospheric CO2 concentrations are nearly 400 ppmv The rate of changein this carbon stock not only depends on human activities but also on biogeochemicaland climatological processes and their interactions with the global carbon cycle

10 INTRODUCTION

LIST OF CONTRIBUTORS

PV Aravind Drir Department of Process and Energy Energy TechnologySection Faculty of Mechanical Maritime and Materials Engineering DelftUniversity of Technology Delft the Netherlands

Isabel WCE Arends Profdr Department of Biotechnology Biocatalysis GroupFaculty of Applied Sciences Delft University of Technology Delft theNetherlands

Rob JM Bastiaans Drir Department of Mechanical Engineering CombustionTechnology Section Eindhoven University of Technology Eindhoven theNetherlands

Maria C Cuellar Dr Department of Biotechnology BioProcess EngineeringGroup Faculty of Applied Sciences Delft University of Technology Delft theNetherlands

Martina Fantini Drir Department of Process and Energy Energy TechnologySection Faculty of Mechanical Maritime and Materials Engineering DelftUniversity of Technology Delft the Netherlands

Johan Grievink Prof ir Department of Chemical Engineering Product amp ProcessEngineering Group Faculty of Applied Sciences Delft University of TechnologyDelft the Netherlands

ArnoHH Janssen Ir ECN Biomass amp Energy Efficiency Petten the Netherlands

Wiebren de Jong Drir Department of Process and Energy Energy TechnologySection Faculty of Mechanical Maritime and Materials Engineering DelftUniversity of Technology Delft the Netherlands

xvii

Yash Joshi Ir Department of Process and Energy Energy Technology SectionFaculty of Mechanical Maritime and Materials Engineering Delft University ofTechnology Delft the Netherlands

Sascha RA Kersten Profdrir Sustainable Process Technology Group Facultyof Science and Technology University of Twente Enschede the Netherlands

Jaap HA Kiel Profdrir ECN Biomass amp Energy Efficiency Petten andDepartment of Process and Energy Energy Technology Section Faculty ofMechanical Maritime andMaterials Engineering Delft University of TechnologyDelft the Netherlands

Robbert Kleerebezem Drir Department of Biotechnology EnvironmentalBiotechnology Group Faculty of Applied Sciences Delft University of TechnologyDelft the Netherlands

Ming Liu Drir Department of Process and Energy Energy Technology SectionFaculty of Mechanical Maritime and Materials Engineering Delft University ofTechnology Delft the Netherlands

Lilian de Martiacuten Dr Department of Chemical Engineering Product amp ProcessEngineering Group Faculty of Applied Sciences Delft University of TechnologyDelft the Netherlands

Jeroen A van Oijen Drir Department of Mechanical Engineering CombustionTechnology Section Eindhoven University of Technology Eindhoven theNetherlands

J Ruud van Ommen Drir Department of Chemical Engineering Product ampProcess Engineering Group Faculty of Applied Sciences Delft University ofTechnology Delft the Netherlands

Stijn RG Oudenhoven Ir Sustainable Process Technology Group Faculty ofScience and Technology University of Twente Enschede the Netherlands

Dirk JEM Roekaerts Profdr Department of Process and Energy FluidMechanics Section Faculty of Mechanical Maritime and Materials EngineeringDelft University of Technology Delft the Netherlands

Adrie JJ Straathof Drir Department of Biotechnology BioProcess EngineeringGroup Faculty of Applied Sciences Delft University of Technology Delft theNetherlands

Pieter LJ Swinkels Ir Faculty of Applied Sciences Delft Product amp ProcessDesign Institute Delft University of Technology Delft the Netherlands

xviii LIST OF CONTRIBUTORS

PART I

SOCIAL CONTEXT AND STRUCTURALBASIS OF BIOMASS AS A RENEWABLEENERGY SOURCES

1INTRODUCTION SOCIOECONOMICASPECTS OF BIOMASS CONVERSION

WIEBREN DE JONG1 AND J RUUD VAN OMMEN2

1Department of Process and Energy Energy Technology Section Faculty of MechanicalMaritime and Materials Engineering Delft University of Technology Delft the Netherlands2Department of Chemical Engineering Product amp Process Engineering Group Faculty ofApplied Sciences Delft University of Technology Delft the Netherlands

ACRONYMS

CDM clean development mechanismCFCs chlorofluorocarbonsdLUC direct land use changeGDP gross domestic productGHG greenhouse gasiLUC indirect land use changeJI joint implementationLCA life cycle assessmentLUC land use changeRP ratio reserves-to-production ratio [y]TOE tonnes of oil equivalent(s) (= 4187 GJ)UNFCCC United Nations Framework Convention on Climate Change

Biomass as a Sustainable Energy Source for the Future Fundamentals of Conversion ProcessesFirst Edition Edited by Wiebren de Jong and J Ruud van Ommencopy 2015 American Institute of Chemical Engineers Inc Published 2015 by John Wiley amp Sons Inc

3

11 ENERGY SUPPLY ECONOMIC AND ENVIRONMENTALCONSIDERATIONS

111 Introduction The Importance of Energy Supply

In the past two centuries since the Industrial Revolution in the 1700s that was initiatedby the invention of the steam turbine the world has undergone a drastic change due tothe steeply increased contribution of fossil fuels (coal oil and natural gas) to modernsocietiesrsquo energy supply (McKay 2009) Though the Chinese society already usedcoal for energy supply in approximately 1000 BC and the Romans prior to AD 400(World-Coal-Institute 2005) the first written references indicating its use are fromabout the thirteenth century and beyond (Hubbert 1949) These hydrocarbon fuelsso far have been considered essential as they are comparatively cheap and convenientenergy carriers used for heating cooking lighting and mechanical as well as electricpower production and have been widely used as transportation fuels and feedstocksfor the manufacture of bulk and fine chemicals as well as other materials with a widerange of applications Rapid global population growth expansion of economies andhigher standards have caused an enormous increase in worldwide energy consump-tion which was partly made possible by the supply of cheap fossil fuels

112 Development of Global Energy Demand

Figure 11 shows a scenario toward the year 2030 presented by the oil company BPconcerning population growth in relation to developments in total primary energyutilization and gross domestic product (GDP) The figure shows that global energy

Billion

Rest of

the world

India

China

9

8

7

6

5

4

3

2

1

0

Population

Billion toe

18

15

12

9

6

3

0

Energy

Trillion $2010 PPP

180

150

120

90

60

30

01970 1990 2010 2030 1970 1990 2010 2030 1970 1990 2010 2030

GDP

FIGURE 11 Prospected global growth rates in population energy demand and GDP 1 toe =41868104 MJ (Source Adapted from BP see tinyurlcom7hlmqxn)

4 INTRODUCTION

demand will rise substantially from the current level with an increasing share fromChina and India This rise of the primary energy demand is projected to be larger thanthe population growth and this will cause a stress on the limited global resources Theprojected GDP even increases stronger so it is expected that average living standardsincrease which will result in additional strain on the available resources

113 Sustainability of Energy Supply

One of the major questions in the world arising from the general picture sketched inSection 112 is how mankind can ensure a global sustainable development for the(near) future In this context sustainability of our energy supply is of paramountimportance The key issues are discussed in the following text both from a pointof view of global socioeconomics and ecological sustainability

1131 Socioeconomic Sustainability As one of the most important economicdrivers to secure and improve the living standards of people in the world energysupply security is of crucial value for current and future generations Fossil fuelsrun out sooner or later as can be seen in Figure 12 they are not renewable on anacceptable time scale

This figure depicts the so-called RP ratios for different sources The RP ratio is theratio of the current proven reserves to production level The unit is years and it is ameasure of the expected time a certain fuel source is expected to be available

On a global scale it appears that oil and natural gas reserves will be availablemdashgiven the figures of 2012mdashfor an expected approximately 55 years and coal substan-tially longer (gt100 years) Of course new contributions to the reserves may be

0

50

100

150

200

250

1980 1985 1990 1995 2000 2005 2010 2015

RP

(yea

rs)

Oil

Coal

Natural gas

FIGURE 12 Overview of world (top) and regional (bottom) reserves-to-production (RP)ratios for oil natural gas and coal respectively (end 2012 status) Figures are based on datafrom BP (2013)

5ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

North America

S amp Cent America

Europe amp Eurasia

Middle East

Africa

Asia Pacific

0 20 40 60

RP (years)

80 100 120 140

North America

S amp Cent America

Europe amp Eurasia

Middle East

Africa

Asia Pacific

0

RP (years)

North America

S amp Cent America

Europe amp Eurasia

Middle East amp Africa

Asia Pacific

0 50 100 150 200 250 300RP (years)

50 100 150 200

FIGURE 12 (Continued )

6 INTRODUCTION

discovered in the (near) future but that does not change the inherently limited supplynature of the fossil fuel sources Regionally there are also significant differenceswhich is important in the context of energy policy developments on the differentcontinents

For the price developments of the fossil fuels not only their forecasted availabilityis of importance but also the market development in a landscape highly determined bypolitics Already well before the last resources of a fuel will have been depleted themarket will be severely stressed For the economies in the world fuel cost develop-ment is therefore also a primary point of concern From past developments particu-larly regarding oil it has been shown that substantial fuel price fluctuations (volatility)occur which has an impact on the global economy (eg food prices) that is difficult topredict Supply and demand will determine the price evolution for each fuel sourcebut the development of the market structure is also essential there is a large differencebetween a free market and an oligopoly or monopoly situation In this respect diver-sification of fuel sources with associated differentiation in suppliers is advantageousas it makes societies less prone to price manipulation by eg cartel formation andsudden disruptions of supply (Johansson et al 1993)

Self-sufficiency concerning energy supply is often mentioned as target of countriesfor (longer-term) sustainable economic development However not all countries haveaccess to resources within their territories that are sufficient for such a target othercountries on the other hand have a structural surplus Relief of trade barriers canhelp mitigate this structural discrepancy Also in the context of economic sustaina-bility a good trade balance should be maintained in relation to the energy supplywithin nations

Regarding social sustainability in the context of energy supply reduction of pov-erty should be mentioned first a good supply structure of energy carriers is one of thebasic requirements for such a development next to access to clean drinking water andgood soil for agricultural activity Associated herewith expectedly substantial healthimprovement should result from a good energy supply infrastructure Job creation andmaintenance is another aspect of social sustainability and certain energy supply formscan contribute significantly to this Also maintaining (or improving) societiesrsquo socialcohesion is an aspect that can be impacted by the energy supply structure

1132 Ecological Sustainability The energy supply structure should notcompromise the sound development of our environment both from a local and globalperspective One of the major issues in this respect is global warming which is for themain part attributed to the release of greenhouse gases (GHG) from fossil fuel com-bustion Other issues are related to local emissions of acid rain precursors and partic-ulate matter (PM)

Climate Change the Greenhouse Effect and Greenhouse Gas EmissionReduction The greenhouse effect occurs naturally to a large extent Without thiseffect the Earthrsquos average global temperature would reach only a low minus18C ratherthan the current approximate +15C Water vapor is the largest contributor to thiseffect with a complex role for clouds but also CO2 in the atmosphere plays a

7ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

significant role More than a century ago Arrhenius (1896) already identified thisrole in the Earthrsquos temperature control Ice core studies reveal that on millennial timescales changes in CO2 content recorded are highly correlated with changes in tem-perature although some temperature changes have occurred without a significantCO2 concentration change but the opposite does not appear to have happened(Falkowski et al 2000) Less pronounced roles are played by CH4 N2O (nitrousoxide) and several types of chlorofluorocarbons (CFCs) and SF6 It is the CO2CH4 N2O and CFC concentrations in the atmosphere upon which manrsquos industrial

0

1

Rad

iati

ve

forc

ing (

Wm

2)

350

(a)

300

Car

bon d

ioxid

e (p

pm

)

250

300

350

400

1800 1900

Year

2000

(b)

1500

2000

1000

Met

han

e (p

pb)

500

0

02

04

Rad

iati

ve

forc

ing (

Wm

2)

1000

500

1500

2000

1900

Year

20001800

FIGURE 13 Atmospheric concentrations of CO2 CH4 and N2O over the last 10000 years(large panels) and since 1750 (inset panels) Measurements are shown from ice cores (symbolswith different grey shades for different studies) and atmospheric samples (light grey lines insteep curve part red lines in the original publication) The corresponding radiative forcings(net solar energy flux to the earth) relative to 1750 are shown on the right-hand axes of the largepanels (SourceReproducedwithpermission fromIPCC(2007) figure23 figureSPM1copyIPCC)

8 INTRODUCTION

and household activities have a measurable impact Scientists largely agree on thepoint that in the last few centuries the activities of humans have directly or indirectlycaused the concentrations of the major GHG to increase This is exemplified byFigure 13 The atmospheric CO2 concentration varies to some extent from placeto place and from season to season It has been shown that concentrations are some-what higher in the northern hemisphere than in the southern hemisphere as most of theanthropogenic sources of CO2 are located north of the equator The difference in landsurface covered with forests being more concentrated north of the equator causeslarger seasonal fluctuations due to comparatively shorter growth periods than in thegenerally milder southern hemisphere locations that are under the influence of largeroceanic surfaces

Oscillations of atmospheric CO2 concentrations between about 180 and 280 ppmv

have occurred in the past approximately 480000 years in cycles of 100000 yearsbut it appears now we have abandoned this cycling behavior in a remarkably shorttime frame

Studies at the NASA Goddard Institute for Space Studies in New York (UnitedStates) have shown that over the past few decades the combined warming effectof non-CO2 GHG should have been comparable to that of CO2 alone However whileeach of the GHGmentioned earlier acts to warm the surface of the Earth the long-termclimatic effects of the other GHG differ from those of CO2 Methane eg has anatmospheric lifetime of only about 12 years By comparison newly added CO2 willremain for a time span of tens to thousands of years As a result about 65 of thecarbon dioxide that human activities have generated since the start of the IndustrialRevolution is in the air we breathe today A historical record of the amount ofCO2 in the atmosphere can be found in bubbles of air in arctic ice layers dating backas far as 600000 years The depth of such a layer is a measure of its time of formation

(c)

10000 5000

Time (before 2005)

0

0

01

Rad

iati

ve

forc

ing (

Wm

2)

300

270

Nit

rous

oxid

e (p

pb)

270

240

300

330

1800 1900

Year

2000

FIGURE 13 (Continued )

9ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

Another difference is that the principal anthropogenic sources of methane-bacterialfermentation in rice paddies and in the intestines of cattle are related to food produc-tion and hence are roughly proportional to the number of people on the planetBecause CH4 has such a short atmospheric lifetime the amount that is in the air isa good indicator of how much is being added with time Should the global populationdouble over the next half century the concentration of CH4 could also double but it isnot likely to rise by much more than that This would add at most a few tenths of adegree to the mean temperature of the Earth Future CO2 increases could in contrastwarm the climate by 10C or more

Nitrous oxide (N2O) and CFCs are in some ways more like CO2 in that oncereleased they remain in the atmosphere for a century or more The production ofN2O however is only indirectly dependent on human activities Its principal sourceis a natural one the bacterial removal of nitrogen from soils and although the worldpopulation swells in coming years the amount in the air should increase only slowly

The outlook for many CFCs is even more promising Today the most abundant ofthese man-made compounds freon-11 and freon-12 are being phased out of produc-tion altogether by international agreements because of their damaging effects on strat-ospheric ozone Indeed the concentration of one of these gases freon-11 peaked in1994 and is now in a slow decline that should continue for the next century or so Thefreon-12 concentration has not yet leveled off but is expected to do so within the nextfew years In terms of climatic effects the main threat from CFCs comes from otherlong-lived compounds that may be used to replace the ones that have been phased outand that could also act as GHG Since these possibly harmful replacement gases are asyet present in only small amounts and since as noted earlier projected increases inCH4 and N2O are so much less severe we shall for the rest of this discussion focussolely on the most important anthropogenic GHG CO2

Some experts have estimated that the Earthrsquos average global temperature has alreadyincreased by more than 05C since the mid-1900s due to this human-enhanced green-house effect also impacts on sea level (rising) and snow coverage (tending to decrease)have been investigated the results of which are summarized in Figure 14

Like most other planets and planetoids in the universe the Earth contains a greatdeal of carbon which is slowly and continually transported from the mantle to thecrust and back again in the course of volcanic eruption and subduction phenomenaThe portion that finds itself near the surface is continually exchanged and recycledamong plants animals soil air and oceans In some of these temporary stocks car-bon is more securely held while in others it more readily combines with oxygen in theair to form CO2 In order to predict how atmospheric CO2 levels and climate maychange in the future it is important to understand where carbon is stored and whatits dynamic cycling behavior looks like The carbon reservoirs that are most relevantto global warming are listed in Table 11 with the total amount of carbon that theycontained in 2000

The atmosphere contains approximately 720 Gt C in the form of CO2 currentmeasured atmospheric CO2 concentrations are nearly 400 ppmv The rate of changein this carbon stock not only depends on human activities but also on biogeochemicaland climatological processes and their interactions with the global carbon cycle

10 INTRODUCTION

Yash Joshi Ir Department of Process and Energy Energy Technology SectionFaculty of Mechanical Maritime and Materials Engineering Delft University ofTechnology Delft the Netherlands

Sascha RA Kersten Profdrir Sustainable Process Technology Group Facultyof Science and Technology University of Twente Enschede the Netherlands

Jaap HA Kiel Profdrir ECN Biomass amp Energy Efficiency Petten andDepartment of Process and Energy Energy Technology Section Faculty ofMechanical Maritime andMaterials Engineering Delft University of TechnologyDelft the Netherlands

Robbert Kleerebezem Drir Department of Biotechnology EnvironmentalBiotechnology Group Faculty of Applied Sciences Delft University of TechnologyDelft the Netherlands

Ming Liu Drir Department of Process and Energy Energy Technology SectionFaculty of Mechanical Maritime and Materials Engineering Delft University ofTechnology Delft the Netherlands

Lilian de Martiacuten Dr Department of Chemical Engineering Product amp ProcessEngineering Group Faculty of Applied Sciences Delft University of TechnologyDelft the Netherlands

Jeroen A van Oijen Drir Department of Mechanical Engineering CombustionTechnology Section Eindhoven University of Technology Eindhoven theNetherlands

J Ruud van Ommen Drir Department of Chemical Engineering Product ampProcess Engineering Group Faculty of Applied Sciences Delft University ofTechnology Delft the Netherlands

Stijn RG Oudenhoven Ir Sustainable Process Technology Group Faculty ofScience and Technology University of Twente Enschede the Netherlands

Dirk JEM Roekaerts Profdr Department of Process and Energy FluidMechanics Section Faculty of Mechanical Maritime and Materials EngineeringDelft University of Technology Delft the Netherlands

Adrie JJ Straathof Drir Department of Biotechnology BioProcess EngineeringGroup Faculty of Applied Sciences Delft University of Technology Delft theNetherlands

Pieter LJ Swinkels Ir Faculty of Applied Sciences Delft Product amp ProcessDesign Institute Delft University of Technology Delft the Netherlands

xviii LIST OF CONTRIBUTORS

PART I

SOCIAL CONTEXT AND STRUCTURALBASIS OF BIOMASS AS A RENEWABLEENERGY SOURCES

1INTRODUCTION SOCIOECONOMICASPECTS OF BIOMASS CONVERSION

WIEBREN DE JONG1 AND J RUUD VAN OMMEN2

1Department of Process and Energy Energy Technology Section Faculty of MechanicalMaritime and Materials Engineering Delft University of Technology Delft the Netherlands2Department of Chemical Engineering Product amp Process Engineering Group Faculty ofApplied Sciences Delft University of Technology Delft the Netherlands

ACRONYMS

CDM clean development mechanismCFCs chlorofluorocarbonsdLUC direct land use changeGDP gross domestic productGHG greenhouse gasiLUC indirect land use changeJI joint implementationLCA life cycle assessmentLUC land use changeRP ratio reserves-to-production ratio [y]TOE tonnes of oil equivalent(s) (= 4187 GJ)UNFCCC United Nations Framework Convention on Climate Change

Biomass as a Sustainable Energy Source for the Future Fundamentals of Conversion ProcessesFirst Edition Edited by Wiebren de Jong and J Ruud van Ommencopy 2015 American Institute of Chemical Engineers Inc Published 2015 by John Wiley amp Sons Inc

3

11 ENERGY SUPPLY ECONOMIC AND ENVIRONMENTALCONSIDERATIONS

111 Introduction The Importance of Energy Supply

In the past two centuries since the Industrial Revolution in the 1700s that was initiatedby the invention of the steam turbine the world has undergone a drastic change due tothe steeply increased contribution of fossil fuels (coal oil and natural gas) to modernsocietiesrsquo energy supply (McKay 2009) Though the Chinese society already usedcoal for energy supply in approximately 1000 BC and the Romans prior to AD 400(World-Coal-Institute 2005) the first written references indicating its use are fromabout the thirteenth century and beyond (Hubbert 1949) These hydrocarbon fuelsso far have been considered essential as they are comparatively cheap and convenientenergy carriers used for heating cooking lighting and mechanical as well as electricpower production and have been widely used as transportation fuels and feedstocksfor the manufacture of bulk and fine chemicals as well as other materials with a widerange of applications Rapid global population growth expansion of economies andhigher standards have caused an enormous increase in worldwide energy consump-tion which was partly made possible by the supply of cheap fossil fuels

112 Development of Global Energy Demand

Figure 11 shows a scenario toward the year 2030 presented by the oil company BPconcerning population growth in relation to developments in total primary energyutilization and gross domestic product (GDP) The figure shows that global energy

Billion

Rest of

the world

India

China

9

8

7

6

5

4

3

2

1

0

Population

Billion toe

18

15

12

9

6

3

0

Energy

Trillion $2010 PPP

180

150

120

90

60

30

01970 1990 2010 2030 1970 1990 2010 2030 1970 1990 2010 2030

GDP

FIGURE 11 Prospected global growth rates in population energy demand and GDP 1 toe =41868104 MJ (Source Adapted from BP see tinyurlcom7hlmqxn)

4 INTRODUCTION

demand will rise substantially from the current level with an increasing share fromChina and India This rise of the primary energy demand is projected to be larger thanthe population growth and this will cause a stress on the limited global resources Theprojected GDP even increases stronger so it is expected that average living standardsincrease which will result in additional strain on the available resources

113 Sustainability of Energy Supply

One of the major questions in the world arising from the general picture sketched inSection 112 is how mankind can ensure a global sustainable development for the(near) future In this context sustainability of our energy supply is of paramountimportance The key issues are discussed in the following text both from a pointof view of global socioeconomics and ecological sustainability

1131 Socioeconomic Sustainability As one of the most important economicdrivers to secure and improve the living standards of people in the world energysupply security is of crucial value for current and future generations Fossil fuelsrun out sooner or later as can be seen in Figure 12 they are not renewable on anacceptable time scale

This figure depicts the so-called RP ratios for different sources The RP ratio is theratio of the current proven reserves to production level The unit is years and it is ameasure of the expected time a certain fuel source is expected to be available

On a global scale it appears that oil and natural gas reserves will be availablemdashgiven the figures of 2012mdashfor an expected approximately 55 years and coal substan-tially longer (gt100 years) Of course new contributions to the reserves may be

0

50

100

150

200

250

1980 1985 1990 1995 2000 2005 2010 2015

RP

(yea

rs)

Oil

Coal

Natural gas

FIGURE 12 Overview of world (top) and regional (bottom) reserves-to-production (RP)ratios for oil natural gas and coal respectively (end 2012 status) Figures are based on datafrom BP (2013)

5ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

North America

S amp Cent America

Europe amp Eurasia

Middle East

Africa

Asia Pacific

0 20 40 60

RP (years)

80 100 120 140

North America

S amp Cent America

Europe amp Eurasia

Middle East

Africa

Asia Pacific

0

RP (years)

North America

S amp Cent America

Europe amp Eurasia

Middle East amp Africa

Asia Pacific

0 50 100 150 200 250 300RP (years)

50 100 150 200

FIGURE 12 (Continued )

6 INTRODUCTION

discovered in the (near) future but that does not change the inherently limited supplynature of the fossil fuel sources Regionally there are also significant differenceswhich is important in the context of energy policy developments on the differentcontinents

For the price developments of the fossil fuels not only their forecasted availabilityis of importance but also the market development in a landscape highly determined bypolitics Already well before the last resources of a fuel will have been depleted themarket will be severely stressed For the economies in the world fuel cost develop-ment is therefore also a primary point of concern From past developments particu-larly regarding oil it has been shown that substantial fuel price fluctuations (volatility)occur which has an impact on the global economy (eg food prices) that is difficult topredict Supply and demand will determine the price evolution for each fuel sourcebut the development of the market structure is also essential there is a large differencebetween a free market and an oligopoly or monopoly situation In this respect diver-sification of fuel sources with associated differentiation in suppliers is advantageousas it makes societies less prone to price manipulation by eg cartel formation andsudden disruptions of supply (Johansson et al 1993)

Self-sufficiency concerning energy supply is often mentioned as target of countriesfor (longer-term) sustainable economic development However not all countries haveaccess to resources within their territories that are sufficient for such a target othercountries on the other hand have a structural surplus Relief of trade barriers canhelp mitigate this structural discrepancy Also in the context of economic sustaina-bility a good trade balance should be maintained in relation to the energy supplywithin nations

Regarding social sustainability in the context of energy supply reduction of pov-erty should be mentioned first a good supply structure of energy carriers is one of thebasic requirements for such a development next to access to clean drinking water andgood soil for agricultural activity Associated herewith expectedly substantial healthimprovement should result from a good energy supply infrastructure Job creation andmaintenance is another aspect of social sustainability and certain energy supply formscan contribute significantly to this Also maintaining (or improving) societiesrsquo socialcohesion is an aspect that can be impacted by the energy supply structure

1132 Ecological Sustainability The energy supply structure should notcompromise the sound development of our environment both from a local and globalperspective One of the major issues in this respect is global warming which is for themain part attributed to the release of greenhouse gases (GHG) from fossil fuel com-bustion Other issues are related to local emissions of acid rain precursors and partic-ulate matter (PM)

Climate Change the Greenhouse Effect and Greenhouse Gas EmissionReduction The greenhouse effect occurs naturally to a large extent Without thiseffect the Earthrsquos average global temperature would reach only a low minus18C ratherthan the current approximate +15C Water vapor is the largest contributor to thiseffect with a complex role for clouds but also CO2 in the atmosphere plays a

7ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

significant role More than a century ago Arrhenius (1896) already identified thisrole in the Earthrsquos temperature control Ice core studies reveal that on millennial timescales changes in CO2 content recorded are highly correlated with changes in tem-perature although some temperature changes have occurred without a significantCO2 concentration change but the opposite does not appear to have happened(Falkowski et al 2000) Less pronounced roles are played by CH4 N2O (nitrousoxide) and several types of chlorofluorocarbons (CFCs) and SF6 It is the CO2CH4 N2O and CFC concentrations in the atmosphere upon which manrsquos industrial

0

1

Rad

iati

ve

forc

ing (

Wm

2)

350

(a)

300

Car

bon d

ioxid

e (p

pm

)

250

300

350

400

1800 1900

Year

2000

(b)

1500

2000

1000

Met

han

e (p

pb)

500

0

02

04

Rad

iati

ve

forc

ing (

Wm

2)

1000

500

1500

2000

1900

Year

20001800

FIGURE 13 Atmospheric concentrations of CO2 CH4 and N2O over the last 10000 years(large panels) and since 1750 (inset panels) Measurements are shown from ice cores (symbolswith different grey shades for different studies) and atmospheric samples (light grey lines insteep curve part red lines in the original publication) The corresponding radiative forcings(net solar energy flux to the earth) relative to 1750 are shown on the right-hand axes of the largepanels (SourceReproducedwithpermission fromIPCC(2007) figure23 figureSPM1copyIPCC)

8 INTRODUCTION

and household activities have a measurable impact Scientists largely agree on thepoint that in the last few centuries the activities of humans have directly or indirectlycaused the concentrations of the major GHG to increase This is exemplified byFigure 13 The atmospheric CO2 concentration varies to some extent from placeto place and from season to season It has been shown that concentrations are some-what higher in the northern hemisphere than in the southern hemisphere as most of theanthropogenic sources of CO2 are located north of the equator The difference in landsurface covered with forests being more concentrated north of the equator causeslarger seasonal fluctuations due to comparatively shorter growth periods than in thegenerally milder southern hemisphere locations that are under the influence of largeroceanic surfaces

Oscillations of atmospheric CO2 concentrations between about 180 and 280 ppmv

have occurred in the past approximately 480000 years in cycles of 100000 yearsbut it appears now we have abandoned this cycling behavior in a remarkably shorttime frame

Studies at the NASA Goddard Institute for Space Studies in New York (UnitedStates) have shown that over the past few decades the combined warming effectof non-CO2 GHG should have been comparable to that of CO2 alone However whileeach of the GHGmentioned earlier acts to warm the surface of the Earth the long-termclimatic effects of the other GHG differ from those of CO2 Methane eg has anatmospheric lifetime of only about 12 years By comparison newly added CO2 willremain for a time span of tens to thousands of years As a result about 65 of thecarbon dioxide that human activities have generated since the start of the IndustrialRevolution is in the air we breathe today A historical record of the amount ofCO2 in the atmosphere can be found in bubbles of air in arctic ice layers dating backas far as 600000 years The depth of such a layer is a measure of its time of formation

(c)

10000 5000

Time (before 2005)

0

0

01

Rad

iati

ve

forc

ing (

Wm

2)

300

270

Nit

rous

oxid

e (p

pb)

270

240

300

330

1800 1900

Year

2000

FIGURE 13 (Continued )

9ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

Another difference is that the principal anthropogenic sources of methane-bacterialfermentation in rice paddies and in the intestines of cattle are related to food produc-tion and hence are roughly proportional to the number of people on the planetBecause CH4 has such a short atmospheric lifetime the amount that is in the air isa good indicator of how much is being added with time Should the global populationdouble over the next half century the concentration of CH4 could also double but it isnot likely to rise by much more than that This would add at most a few tenths of adegree to the mean temperature of the Earth Future CO2 increases could in contrastwarm the climate by 10C or more

Nitrous oxide (N2O) and CFCs are in some ways more like CO2 in that oncereleased they remain in the atmosphere for a century or more The production ofN2O however is only indirectly dependent on human activities Its principal sourceis a natural one the bacterial removal of nitrogen from soils and although the worldpopulation swells in coming years the amount in the air should increase only slowly

The outlook for many CFCs is even more promising Today the most abundant ofthese man-made compounds freon-11 and freon-12 are being phased out of produc-tion altogether by international agreements because of their damaging effects on strat-ospheric ozone Indeed the concentration of one of these gases freon-11 peaked in1994 and is now in a slow decline that should continue for the next century or so Thefreon-12 concentration has not yet leveled off but is expected to do so within the nextfew years In terms of climatic effects the main threat from CFCs comes from otherlong-lived compounds that may be used to replace the ones that have been phased outand that could also act as GHG Since these possibly harmful replacement gases are asyet present in only small amounts and since as noted earlier projected increases inCH4 and N2O are so much less severe we shall for the rest of this discussion focussolely on the most important anthropogenic GHG CO2

Some experts have estimated that the Earthrsquos average global temperature has alreadyincreased by more than 05C since the mid-1900s due to this human-enhanced green-house effect also impacts on sea level (rising) and snow coverage (tending to decrease)have been investigated the results of which are summarized in Figure 14

Like most other planets and planetoids in the universe the Earth contains a greatdeal of carbon which is slowly and continually transported from the mantle to thecrust and back again in the course of volcanic eruption and subduction phenomenaThe portion that finds itself near the surface is continually exchanged and recycledamong plants animals soil air and oceans In some of these temporary stocks car-bon is more securely held while in others it more readily combines with oxygen in theair to form CO2 In order to predict how atmospheric CO2 levels and climate maychange in the future it is important to understand where carbon is stored and whatits dynamic cycling behavior looks like The carbon reservoirs that are most relevantto global warming are listed in Table 11 with the total amount of carbon that theycontained in 2000

The atmosphere contains approximately 720 Gt C in the form of CO2 currentmeasured atmospheric CO2 concentrations are nearly 400 ppmv The rate of changein this carbon stock not only depends on human activities but also on biogeochemicaland climatological processes and their interactions with the global carbon cycle

10 INTRODUCTION

PART I

SOCIAL CONTEXT AND STRUCTURALBASIS OF BIOMASS AS A RENEWABLEENERGY SOURCES

1INTRODUCTION SOCIOECONOMICASPECTS OF BIOMASS CONVERSION

WIEBREN DE JONG1 AND J RUUD VAN OMMEN2

1Department of Process and Energy Energy Technology Section Faculty of MechanicalMaritime and Materials Engineering Delft University of Technology Delft the Netherlands2Department of Chemical Engineering Product amp Process Engineering Group Faculty ofApplied Sciences Delft University of Technology Delft the Netherlands

ACRONYMS

CDM clean development mechanismCFCs chlorofluorocarbonsdLUC direct land use changeGDP gross domestic productGHG greenhouse gasiLUC indirect land use changeJI joint implementationLCA life cycle assessmentLUC land use changeRP ratio reserves-to-production ratio [y]TOE tonnes of oil equivalent(s) (= 4187 GJ)UNFCCC United Nations Framework Convention on Climate Change

Biomass as a Sustainable Energy Source for the Future Fundamentals of Conversion ProcessesFirst Edition Edited by Wiebren de Jong and J Ruud van Ommencopy 2015 American Institute of Chemical Engineers Inc Published 2015 by John Wiley amp Sons Inc

3

11 ENERGY SUPPLY ECONOMIC AND ENVIRONMENTALCONSIDERATIONS

111 Introduction The Importance of Energy Supply

In the past two centuries since the Industrial Revolution in the 1700s that was initiatedby the invention of the steam turbine the world has undergone a drastic change due tothe steeply increased contribution of fossil fuels (coal oil and natural gas) to modernsocietiesrsquo energy supply (McKay 2009) Though the Chinese society already usedcoal for energy supply in approximately 1000 BC and the Romans prior to AD 400(World-Coal-Institute 2005) the first written references indicating its use are fromabout the thirteenth century and beyond (Hubbert 1949) These hydrocarbon fuelsso far have been considered essential as they are comparatively cheap and convenientenergy carriers used for heating cooking lighting and mechanical as well as electricpower production and have been widely used as transportation fuels and feedstocksfor the manufacture of bulk and fine chemicals as well as other materials with a widerange of applications Rapid global population growth expansion of economies andhigher standards have caused an enormous increase in worldwide energy consump-tion which was partly made possible by the supply of cheap fossil fuels

112 Development of Global Energy Demand

Figure 11 shows a scenario toward the year 2030 presented by the oil company BPconcerning population growth in relation to developments in total primary energyutilization and gross domestic product (GDP) The figure shows that global energy

Billion

Rest of

the world

India

China

9

8

7

6

5

4

3

2

1

0

Population

Billion toe

18

15

12

9

6

3

0

Energy

Trillion $2010 PPP

180

150

120

90

60

30

01970 1990 2010 2030 1970 1990 2010 2030 1970 1990 2010 2030

GDP

FIGURE 11 Prospected global growth rates in population energy demand and GDP 1 toe =41868104 MJ (Source Adapted from BP see tinyurlcom7hlmqxn)

4 INTRODUCTION

demand will rise substantially from the current level with an increasing share fromChina and India This rise of the primary energy demand is projected to be larger thanthe population growth and this will cause a stress on the limited global resources Theprojected GDP even increases stronger so it is expected that average living standardsincrease which will result in additional strain on the available resources

113 Sustainability of Energy Supply

One of the major questions in the world arising from the general picture sketched inSection 112 is how mankind can ensure a global sustainable development for the(near) future In this context sustainability of our energy supply is of paramountimportance The key issues are discussed in the following text both from a pointof view of global socioeconomics and ecological sustainability

1131 Socioeconomic Sustainability As one of the most important economicdrivers to secure and improve the living standards of people in the world energysupply security is of crucial value for current and future generations Fossil fuelsrun out sooner or later as can be seen in Figure 12 they are not renewable on anacceptable time scale

This figure depicts the so-called RP ratios for different sources The RP ratio is theratio of the current proven reserves to production level The unit is years and it is ameasure of the expected time a certain fuel source is expected to be available

On a global scale it appears that oil and natural gas reserves will be availablemdashgiven the figures of 2012mdashfor an expected approximately 55 years and coal substan-tially longer (gt100 years) Of course new contributions to the reserves may be

0

50

100

150

200

250

1980 1985 1990 1995 2000 2005 2010 2015

RP

(yea

rs)

Oil

Coal

Natural gas

FIGURE 12 Overview of world (top) and regional (bottom) reserves-to-production (RP)ratios for oil natural gas and coal respectively (end 2012 status) Figures are based on datafrom BP (2013)

5ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

North America

S amp Cent America

Europe amp Eurasia

Middle East

Africa

Asia Pacific

0 20 40 60

RP (years)

80 100 120 140

North America

S amp Cent America

Europe amp Eurasia

Middle East

Africa

Asia Pacific

0

RP (years)

North America

S amp Cent America

Europe amp Eurasia

Middle East amp Africa

Asia Pacific

0 50 100 150 200 250 300RP (years)

50 100 150 200

FIGURE 12 (Continued )

6 INTRODUCTION

discovered in the (near) future but that does not change the inherently limited supplynature of the fossil fuel sources Regionally there are also significant differenceswhich is important in the context of energy policy developments on the differentcontinents

For the price developments of the fossil fuels not only their forecasted availabilityis of importance but also the market development in a landscape highly determined bypolitics Already well before the last resources of a fuel will have been depleted themarket will be severely stressed For the economies in the world fuel cost develop-ment is therefore also a primary point of concern From past developments particu-larly regarding oil it has been shown that substantial fuel price fluctuations (volatility)occur which has an impact on the global economy (eg food prices) that is difficult topredict Supply and demand will determine the price evolution for each fuel sourcebut the development of the market structure is also essential there is a large differencebetween a free market and an oligopoly or monopoly situation In this respect diver-sification of fuel sources with associated differentiation in suppliers is advantageousas it makes societies less prone to price manipulation by eg cartel formation andsudden disruptions of supply (Johansson et al 1993)

Self-sufficiency concerning energy supply is often mentioned as target of countriesfor (longer-term) sustainable economic development However not all countries haveaccess to resources within their territories that are sufficient for such a target othercountries on the other hand have a structural surplus Relief of trade barriers canhelp mitigate this structural discrepancy Also in the context of economic sustaina-bility a good trade balance should be maintained in relation to the energy supplywithin nations

Regarding social sustainability in the context of energy supply reduction of pov-erty should be mentioned first a good supply structure of energy carriers is one of thebasic requirements for such a development next to access to clean drinking water andgood soil for agricultural activity Associated herewith expectedly substantial healthimprovement should result from a good energy supply infrastructure Job creation andmaintenance is another aspect of social sustainability and certain energy supply formscan contribute significantly to this Also maintaining (or improving) societiesrsquo socialcohesion is an aspect that can be impacted by the energy supply structure

1132 Ecological Sustainability The energy supply structure should notcompromise the sound development of our environment both from a local and globalperspective One of the major issues in this respect is global warming which is for themain part attributed to the release of greenhouse gases (GHG) from fossil fuel com-bustion Other issues are related to local emissions of acid rain precursors and partic-ulate matter (PM)

Climate Change the Greenhouse Effect and Greenhouse Gas EmissionReduction The greenhouse effect occurs naturally to a large extent Without thiseffect the Earthrsquos average global temperature would reach only a low minus18C ratherthan the current approximate +15C Water vapor is the largest contributor to thiseffect with a complex role for clouds but also CO2 in the atmosphere plays a

7ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

significant role More than a century ago Arrhenius (1896) already identified thisrole in the Earthrsquos temperature control Ice core studies reveal that on millennial timescales changes in CO2 content recorded are highly correlated with changes in tem-perature although some temperature changes have occurred without a significantCO2 concentration change but the opposite does not appear to have happened(Falkowski et al 2000) Less pronounced roles are played by CH4 N2O (nitrousoxide) and several types of chlorofluorocarbons (CFCs) and SF6 It is the CO2CH4 N2O and CFC concentrations in the atmosphere upon which manrsquos industrial

0

1

Rad

iati

ve

forc

ing (

Wm

2)

350

(a)

300

Car

bon d

ioxid

e (p

pm

)

250

300

350

400

1800 1900

Year

2000

(b)

1500

2000

1000

Met

han

e (p

pb)

500

0

02

04

Rad

iati

ve

forc

ing (

Wm

2)

1000

500

1500

2000

1900

Year

20001800

FIGURE 13 Atmospheric concentrations of CO2 CH4 and N2O over the last 10000 years(large panels) and since 1750 (inset panels) Measurements are shown from ice cores (symbolswith different grey shades for different studies) and atmospheric samples (light grey lines insteep curve part red lines in the original publication) The corresponding radiative forcings(net solar energy flux to the earth) relative to 1750 are shown on the right-hand axes of the largepanels (SourceReproducedwithpermission fromIPCC(2007) figure23 figureSPM1copyIPCC)

8 INTRODUCTION

and household activities have a measurable impact Scientists largely agree on thepoint that in the last few centuries the activities of humans have directly or indirectlycaused the concentrations of the major GHG to increase This is exemplified byFigure 13 The atmospheric CO2 concentration varies to some extent from placeto place and from season to season It has been shown that concentrations are some-what higher in the northern hemisphere than in the southern hemisphere as most of theanthropogenic sources of CO2 are located north of the equator The difference in landsurface covered with forests being more concentrated north of the equator causeslarger seasonal fluctuations due to comparatively shorter growth periods than in thegenerally milder southern hemisphere locations that are under the influence of largeroceanic surfaces

Oscillations of atmospheric CO2 concentrations between about 180 and 280 ppmv

have occurred in the past approximately 480000 years in cycles of 100000 yearsbut it appears now we have abandoned this cycling behavior in a remarkably shorttime frame

Studies at the NASA Goddard Institute for Space Studies in New York (UnitedStates) have shown that over the past few decades the combined warming effectof non-CO2 GHG should have been comparable to that of CO2 alone However whileeach of the GHGmentioned earlier acts to warm the surface of the Earth the long-termclimatic effects of the other GHG differ from those of CO2 Methane eg has anatmospheric lifetime of only about 12 years By comparison newly added CO2 willremain for a time span of tens to thousands of years As a result about 65 of thecarbon dioxide that human activities have generated since the start of the IndustrialRevolution is in the air we breathe today A historical record of the amount ofCO2 in the atmosphere can be found in bubbles of air in arctic ice layers dating backas far as 600000 years The depth of such a layer is a measure of its time of formation

(c)

10000 5000

Time (before 2005)

0

0

01

Rad

iati

ve

forc

ing (

Wm

2)

300

270

Nit

rous

oxid

e (p

pb)

270

240

300

330

1800 1900

Year

2000

FIGURE 13 (Continued )

9ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

Another difference is that the principal anthropogenic sources of methane-bacterialfermentation in rice paddies and in the intestines of cattle are related to food produc-tion and hence are roughly proportional to the number of people on the planetBecause CH4 has such a short atmospheric lifetime the amount that is in the air isa good indicator of how much is being added with time Should the global populationdouble over the next half century the concentration of CH4 could also double but it isnot likely to rise by much more than that This would add at most a few tenths of adegree to the mean temperature of the Earth Future CO2 increases could in contrastwarm the climate by 10C or more

Nitrous oxide (N2O) and CFCs are in some ways more like CO2 in that oncereleased they remain in the atmosphere for a century or more The production ofN2O however is only indirectly dependent on human activities Its principal sourceis a natural one the bacterial removal of nitrogen from soils and although the worldpopulation swells in coming years the amount in the air should increase only slowly

The outlook for many CFCs is even more promising Today the most abundant ofthese man-made compounds freon-11 and freon-12 are being phased out of produc-tion altogether by international agreements because of their damaging effects on strat-ospheric ozone Indeed the concentration of one of these gases freon-11 peaked in1994 and is now in a slow decline that should continue for the next century or so Thefreon-12 concentration has not yet leveled off but is expected to do so within the nextfew years In terms of climatic effects the main threat from CFCs comes from otherlong-lived compounds that may be used to replace the ones that have been phased outand that could also act as GHG Since these possibly harmful replacement gases are asyet present in only small amounts and since as noted earlier projected increases inCH4 and N2O are so much less severe we shall for the rest of this discussion focussolely on the most important anthropogenic GHG CO2

Some experts have estimated that the Earthrsquos average global temperature has alreadyincreased by more than 05C since the mid-1900s due to this human-enhanced green-house effect also impacts on sea level (rising) and snow coverage (tending to decrease)have been investigated the results of which are summarized in Figure 14

Like most other planets and planetoids in the universe the Earth contains a greatdeal of carbon which is slowly and continually transported from the mantle to thecrust and back again in the course of volcanic eruption and subduction phenomenaThe portion that finds itself near the surface is continually exchanged and recycledamong plants animals soil air and oceans In some of these temporary stocks car-bon is more securely held while in others it more readily combines with oxygen in theair to form CO2 In order to predict how atmospheric CO2 levels and climate maychange in the future it is important to understand where carbon is stored and whatits dynamic cycling behavior looks like The carbon reservoirs that are most relevantto global warming are listed in Table 11 with the total amount of carbon that theycontained in 2000

The atmosphere contains approximately 720 Gt C in the form of CO2 currentmeasured atmospheric CO2 concentrations are nearly 400 ppmv The rate of changein this carbon stock not only depends on human activities but also on biogeochemicaland climatological processes and their interactions with the global carbon cycle

10 INTRODUCTION

1INTRODUCTION SOCIOECONOMICASPECTS OF BIOMASS CONVERSION

WIEBREN DE JONG1 AND J RUUD VAN OMMEN2

1Department of Process and Energy Energy Technology Section Faculty of MechanicalMaritime and Materials Engineering Delft University of Technology Delft the Netherlands2Department of Chemical Engineering Product amp Process Engineering Group Faculty ofApplied Sciences Delft University of Technology Delft the Netherlands

ACRONYMS

CDM clean development mechanismCFCs chlorofluorocarbonsdLUC direct land use changeGDP gross domestic productGHG greenhouse gasiLUC indirect land use changeJI joint implementationLCA life cycle assessmentLUC land use changeRP ratio reserves-to-production ratio [y]TOE tonnes of oil equivalent(s) (= 4187 GJ)UNFCCC United Nations Framework Convention on Climate Change

Biomass as a Sustainable Energy Source for the Future Fundamentals of Conversion ProcessesFirst Edition Edited by Wiebren de Jong and J Ruud van Ommencopy 2015 American Institute of Chemical Engineers Inc Published 2015 by John Wiley amp Sons Inc

3

11 ENERGY SUPPLY ECONOMIC AND ENVIRONMENTALCONSIDERATIONS

111 Introduction The Importance of Energy Supply

In the past two centuries since the Industrial Revolution in the 1700s that was initiatedby the invention of the steam turbine the world has undergone a drastic change due tothe steeply increased contribution of fossil fuels (coal oil and natural gas) to modernsocietiesrsquo energy supply (McKay 2009) Though the Chinese society already usedcoal for energy supply in approximately 1000 BC and the Romans prior to AD 400(World-Coal-Institute 2005) the first written references indicating its use are fromabout the thirteenth century and beyond (Hubbert 1949) These hydrocarbon fuelsso far have been considered essential as they are comparatively cheap and convenientenergy carriers used for heating cooking lighting and mechanical as well as electricpower production and have been widely used as transportation fuels and feedstocksfor the manufacture of bulk and fine chemicals as well as other materials with a widerange of applications Rapid global population growth expansion of economies andhigher standards have caused an enormous increase in worldwide energy consump-tion which was partly made possible by the supply of cheap fossil fuels

112 Development of Global Energy Demand

Figure 11 shows a scenario toward the year 2030 presented by the oil company BPconcerning population growth in relation to developments in total primary energyutilization and gross domestic product (GDP) The figure shows that global energy

Billion

Rest of

the world

India

China

9

8

7

6

5

4

3

2

1

0

Population

Billion toe

18

15

12

9

6

3

0

Energy

Trillion $2010 PPP

180

150

120

90

60

30

01970 1990 2010 2030 1970 1990 2010 2030 1970 1990 2010 2030

GDP

FIGURE 11 Prospected global growth rates in population energy demand and GDP 1 toe =41868104 MJ (Source Adapted from BP see tinyurlcom7hlmqxn)

4 INTRODUCTION

demand will rise substantially from the current level with an increasing share fromChina and India This rise of the primary energy demand is projected to be larger thanthe population growth and this will cause a stress on the limited global resources Theprojected GDP even increases stronger so it is expected that average living standardsincrease which will result in additional strain on the available resources

113 Sustainability of Energy Supply

One of the major questions in the world arising from the general picture sketched inSection 112 is how mankind can ensure a global sustainable development for the(near) future In this context sustainability of our energy supply is of paramountimportance The key issues are discussed in the following text both from a pointof view of global socioeconomics and ecological sustainability

1131 Socioeconomic Sustainability As one of the most important economicdrivers to secure and improve the living standards of people in the world energysupply security is of crucial value for current and future generations Fossil fuelsrun out sooner or later as can be seen in Figure 12 they are not renewable on anacceptable time scale

This figure depicts the so-called RP ratios for different sources The RP ratio is theratio of the current proven reserves to production level The unit is years and it is ameasure of the expected time a certain fuel source is expected to be available

On a global scale it appears that oil and natural gas reserves will be availablemdashgiven the figures of 2012mdashfor an expected approximately 55 years and coal substan-tially longer (gt100 years) Of course new contributions to the reserves may be

0

50

100

150

200

250

1980 1985 1990 1995 2000 2005 2010 2015

RP

(yea

rs)

Oil

Coal

Natural gas

FIGURE 12 Overview of world (top) and regional (bottom) reserves-to-production (RP)ratios for oil natural gas and coal respectively (end 2012 status) Figures are based on datafrom BP (2013)

5ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

North America

S amp Cent America

Europe amp Eurasia

Middle East

Africa

Asia Pacific

0 20 40 60

RP (years)

80 100 120 140

North America

S amp Cent America

Europe amp Eurasia

Middle East

Africa

Asia Pacific

0

RP (years)

North America

S amp Cent America

Europe amp Eurasia

Middle East amp Africa

Asia Pacific

0 50 100 150 200 250 300RP (years)

50 100 150 200

FIGURE 12 (Continued )

6 INTRODUCTION

discovered in the (near) future but that does not change the inherently limited supplynature of the fossil fuel sources Regionally there are also significant differenceswhich is important in the context of energy policy developments on the differentcontinents

For the price developments of the fossil fuels not only their forecasted availabilityis of importance but also the market development in a landscape highly determined bypolitics Already well before the last resources of a fuel will have been depleted themarket will be severely stressed For the economies in the world fuel cost develop-ment is therefore also a primary point of concern From past developments particu-larly regarding oil it has been shown that substantial fuel price fluctuations (volatility)occur which has an impact on the global economy (eg food prices) that is difficult topredict Supply and demand will determine the price evolution for each fuel sourcebut the development of the market structure is also essential there is a large differencebetween a free market and an oligopoly or monopoly situation In this respect diver-sification of fuel sources with associated differentiation in suppliers is advantageousas it makes societies less prone to price manipulation by eg cartel formation andsudden disruptions of supply (Johansson et al 1993)

Self-sufficiency concerning energy supply is often mentioned as target of countriesfor (longer-term) sustainable economic development However not all countries haveaccess to resources within their territories that are sufficient for such a target othercountries on the other hand have a structural surplus Relief of trade barriers canhelp mitigate this structural discrepancy Also in the context of economic sustaina-bility a good trade balance should be maintained in relation to the energy supplywithin nations

Regarding social sustainability in the context of energy supply reduction of pov-erty should be mentioned first a good supply structure of energy carriers is one of thebasic requirements for such a development next to access to clean drinking water andgood soil for agricultural activity Associated herewith expectedly substantial healthimprovement should result from a good energy supply infrastructure Job creation andmaintenance is another aspect of social sustainability and certain energy supply formscan contribute significantly to this Also maintaining (or improving) societiesrsquo socialcohesion is an aspect that can be impacted by the energy supply structure

1132 Ecological Sustainability The energy supply structure should notcompromise the sound development of our environment both from a local and globalperspective One of the major issues in this respect is global warming which is for themain part attributed to the release of greenhouse gases (GHG) from fossil fuel com-bustion Other issues are related to local emissions of acid rain precursors and partic-ulate matter (PM)

Climate Change the Greenhouse Effect and Greenhouse Gas EmissionReduction The greenhouse effect occurs naturally to a large extent Without thiseffect the Earthrsquos average global temperature would reach only a low minus18C ratherthan the current approximate +15C Water vapor is the largest contributor to thiseffect with a complex role for clouds but also CO2 in the atmosphere plays a

7ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

significant role More than a century ago Arrhenius (1896) already identified thisrole in the Earthrsquos temperature control Ice core studies reveal that on millennial timescales changes in CO2 content recorded are highly correlated with changes in tem-perature although some temperature changes have occurred without a significantCO2 concentration change but the opposite does not appear to have happened(Falkowski et al 2000) Less pronounced roles are played by CH4 N2O (nitrousoxide) and several types of chlorofluorocarbons (CFCs) and SF6 It is the CO2CH4 N2O and CFC concentrations in the atmosphere upon which manrsquos industrial

0

1

Rad

iati

ve

forc

ing (

Wm

2)

350

(a)

300

Car

bon d

ioxid

e (p

pm

)

250

300

350

400

1800 1900

Year

2000

(b)

1500

2000

1000

Met

han

e (p

pb)

500

0

02

04

Rad

iati

ve

forc

ing (

Wm

2)

1000

500

1500

2000

1900

Year

20001800

FIGURE 13 Atmospheric concentrations of CO2 CH4 and N2O over the last 10000 years(large panels) and since 1750 (inset panels) Measurements are shown from ice cores (symbolswith different grey shades for different studies) and atmospheric samples (light grey lines insteep curve part red lines in the original publication) The corresponding radiative forcings(net solar energy flux to the earth) relative to 1750 are shown on the right-hand axes of the largepanels (SourceReproducedwithpermission fromIPCC(2007) figure23 figureSPM1copyIPCC)

8 INTRODUCTION

and household activities have a measurable impact Scientists largely agree on thepoint that in the last few centuries the activities of humans have directly or indirectlycaused the concentrations of the major GHG to increase This is exemplified byFigure 13 The atmospheric CO2 concentration varies to some extent from placeto place and from season to season It has been shown that concentrations are some-what higher in the northern hemisphere than in the southern hemisphere as most of theanthropogenic sources of CO2 are located north of the equator The difference in landsurface covered with forests being more concentrated north of the equator causeslarger seasonal fluctuations due to comparatively shorter growth periods than in thegenerally milder southern hemisphere locations that are under the influence of largeroceanic surfaces

Oscillations of atmospheric CO2 concentrations between about 180 and 280 ppmv

have occurred in the past approximately 480000 years in cycles of 100000 yearsbut it appears now we have abandoned this cycling behavior in a remarkably shorttime frame

Studies at the NASA Goddard Institute for Space Studies in New York (UnitedStates) have shown that over the past few decades the combined warming effectof non-CO2 GHG should have been comparable to that of CO2 alone However whileeach of the GHGmentioned earlier acts to warm the surface of the Earth the long-termclimatic effects of the other GHG differ from those of CO2 Methane eg has anatmospheric lifetime of only about 12 years By comparison newly added CO2 willremain for a time span of tens to thousands of years As a result about 65 of thecarbon dioxide that human activities have generated since the start of the IndustrialRevolution is in the air we breathe today A historical record of the amount ofCO2 in the atmosphere can be found in bubbles of air in arctic ice layers dating backas far as 600000 years The depth of such a layer is a measure of its time of formation

(c)

10000 5000

Time (before 2005)

0

0

01

Rad

iati

ve

forc

ing (

Wm

2)

300

270

Nit

rous

oxid

e (p

pb)

270

240

300

330

1800 1900

Year

2000

FIGURE 13 (Continued )

9ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

Another difference is that the principal anthropogenic sources of methane-bacterialfermentation in rice paddies and in the intestines of cattle are related to food produc-tion and hence are roughly proportional to the number of people on the planetBecause CH4 has such a short atmospheric lifetime the amount that is in the air isa good indicator of how much is being added with time Should the global populationdouble over the next half century the concentration of CH4 could also double but it isnot likely to rise by much more than that This would add at most a few tenths of adegree to the mean temperature of the Earth Future CO2 increases could in contrastwarm the climate by 10C or more

Nitrous oxide (N2O) and CFCs are in some ways more like CO2 in that oncereleased they remain in the atmosphere for a century or more The production ofN2O however is only indirectly dependent on human activities Its principal sourceis a natural one the bacterial removal of nitrogen from soils and although the worldpopulation swells in coming years the amount in the air should increase only slowly

The outlook for many CFCs is even more promising Today the most abundant ofthese man-made compounds freon-11 and freon-12 are being phased out of produc-tion altogether by international agreements because of their damaging effects on strat-ospheric ozone Indeed the concentration of one of these gases freon-11 peaked in1994 and is now in a slow decline that should continue for the next century or so Thefreon-12 concentration has not yet leveled off but is expected to do so within the nextfew years In terms of climatic effects the main threat from CFCs comes from otherlong-lived compounds that may be used to replace the ones that have been phased outand that could also act as GHG Since these possibly harmful replacement gases are asyet present in only small amounts and since as noted earlier projected increases inCH4 and N2O are so much less severe we shall for the rest of this discussion focussolely on the most important anthropogenic GHG CO2

Some experts have estimated that the Earthrsquos average global temperature has alreadyincreased by more than 05C since the mid-1900s due to this human-enhanced green-house effect also impacts on sea level (rising) and snow coverage (tending to decrease)have been investigated the results of which are summarized in Figure 14

Like most other planets and planetoids in the universe the Earth contains a greatdeal of carbon which is slowly and continually transported from the mantle to thecrust and back again in the course of volcanic eruption and subduction phenomenaThe portion that finds itself near the surface is continually exchanged and recycledamong plants animals soil air and oceans In some of these temporary stocks car-bon is more securely held while in others it more readily combines with oxygen in theair to form CO2 In order to predict how atmospheric CO2 levels and climate maychange in the future it is important to understand where carbon is stored and whatits dynamic cycling behavior looks like The carbon reservoirs that are most relevantto global warming are listed in Table 11 with the total amount of carbon that theycontained in 2000

The atmosphere contains approximately 720 Gt C in the form of CO2 currentmeasured atmospheric CO2 concentrations are nearly 400 ppmv The rate of changein this carbon stock not only depends on human activities but also on biogeochemicaland climatological processes and their interactions with the global carbon cycle

10 INTRODUCTION

11 ENERGY SUPPLY ECONOMIC AND ENVIRONMENTALCONSIDERATIONS

111 Introduction The Importance of Energy Supply

In the past two centuries since the Industrial Revolution in the 1700s that was initiatedby the invention of the steam turbine the world has undergone a drastic change due tothe steeply increased contribution of fossil fuels (coal oil and natural gas) to modernsocietiesrsquo energy supply (McKay 2009) Though the Chinese society already usedcoal for energy supply in approximately 1000 BC and the Romans prior to AD 400(World-Coal-Institute 2005) the first written references indicating its use are fromabout the thirteenth century and beyond (Hubbert 1949) These hydrocarbon fuelsso far have been considered essential as they are comparatively cheap and convenientenergy carriers used for heating cooking lighting and mechanical as well as electricpower production and have been widely used as transportation fuels and feedstocksfor the manufacture of bulk and fine chemicals as well as other materials with a widerange of applications Rapid global population growth expansion of economies andhigher standards have caused an enormous increase in worldwide energy consump-tion which was partly made possible by the supply of cheap fossil fuels

112 Development of Global Energy Demand

Figure 11 shows a scenario toward the year 2030 presented by the oil company BPconcerning population growth in relation to developments in total primary energyutilization and gross domestic product (GDP) The figure shows that global energy

Billion

Rest of

the world

India

China

9

8

7

6

5

4

3

2

1

0

Population

Billion toe

18

15

12

9

6

3

0

Energy

Trillion $2010 PPP

180

150

120

90

60

30

01970 1990 2010 2030 1970 1990 2010 2030 1970 1990 2010 2030

GDP

FIGURE 11 Prospected global growth rates in population energy demand and GDP 1 toe =41868104 MJ (Source Adapted from BP see tinyurlcom7hlmqxn)

4 INTRODUCTION

demand will rise substantially from the current level with an increasing share fromChina and India This rise of the primary energy demand is projected to be larger thanthe population growth and this will cause a stress on the limited global resources Theprojected GDP even increases stronger so it is expected that average living standardsincrease which will result in additional strain on the available resources

113 Sustainability of Energy Supply

One of the major questions in the world arising from the general picture sketched inSection 112 is how mankind can ensure a global sustainable development for the(near) future In this context sustainability of our energy supply is of paramountimportance The key issues are discussed in the following text both from a pointof view of global socioeconomics and ecological sustainability

1131 Socioeconomic Sustainability As one of the most important economicdrivers to secure and improve the living standards of people in the world energysupply security is of crucial value for current and future generations Fossil fuelsrun out sooner or later as can be seen in Figure 12 they are not renewable on anacceptable time scale

This figure depicts the so-called RP ratios for different sources The RP ratio is theratio of the current proven reserves to production level The unit is years and it is ameasure of the expected time a certain fuel source is expected to be available

On a global scale it appears that oil and natural gas reserves will be availablemdashgiven the figures of 2012mdashfor an expected approximately 55 years and coal substan-tially longer (gt100 years) Of course new contributions to the reserves may be

0

50

100

150

200

250

1980 1985 1990 1995 2000 2005 2010 2015

RP

(yea

rs)

Oil

Coal

Natural gas

FIGURE 12 Overview of world (top) and regional (bottom) reserves-to-production (RP)ratios for oil natural gas and coal respectively (end 2012 status) Figures are based on datafrom BP (2013)

5ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

North America

S amp Cent America

Europe amp Eurasia

Middle East

Africa

Asia Pacific

0 20 40 60

RP (years)

80 100 120 140

North America

S amp Cent America

Europe amp Eurasia

Middle East

Africa

Asia Pacific

0

RP (years)

North America

S amp Cent America

Europe amp Eurasia

Middle East amp Africa

Asia Pacific

0 50 100 150 200 250 300RP (years)

50 100 150 200

FIGURE 12 (Continued )

6 INTRODUCTION

discovered in the (near) future but that does not change the inherently limited supplynature of the fossil fuel sources Regionally there are also significant differenceswhich is important in the context of energy policy developments on the differentcontinents

For the price developments of the fossil fuels not only their forecasted availabilityis of importance but also the market development in a landscape highly determined bypolitics Already well before the last resources of a fuel will have been depleted themarket will be severely stressed For the economies in the world fuel cost develop-ment is therefore also a primary point of concern From past developments particu-larly regarding oil it has been shown that substantial fuel price fluctuations (volatility)occur which has an impact on the global economy (eg food prices) that is difficult topredict Supply and demand will determine the price evolution for each fuel sourcebut the development of the market structure is also essential there is a large differencebetween a free market and an oligopoly or monopoly situation In this respect diver-sification of fuel sources with associated differentiation in suppliers is advantageousas it makes societies less prone to price manipulation by eg cartel formation andsudden disruptions of supply (Johansson et al 1993)

Self-sufficiency concerning energy supply is often mentioned as target of countriesfor (longer-term) sustainable economic development However not all countries haveaccess to resources within their territories that are sufficient for such a target othercountries on the other hand have a structural surplus Relief of trade barriers canhelp mitigate this structural discrepancy Also in the context of economic sustaina-bility a good trade balance should be maintained in relation to the energy supplywithin nations

Regarding social sustainability in the context of energy supply reduction of pov-erty should be mentioned first a good supply structure of energy carriers is one of thebasic requirements for such a development next to access to clean drinking water andgood soil for agricultural activity Associated herewith expectedly substantial healthimprovement should result from a good energy supply infrastructure Job creation andmaintenance is another aspect of social sustainability and certain energy supply formscan contribute significantly to this Also maintaining (or improving) societiesrsquo socialcohesion is an aspect that can be impacted by the energy supply structure

1132 Ecological Sustainability The energy supply structure should notcompromise the sound development of our environment both from a local and globalperspective One of the major issues in this respect is global warming which is for themain part attributed to the release of greenhouse gases (GHG) from fossil fuel com-bustion Other issues are related to local emissions of acid rain precursors and partic-ulate matter (PM)

Climate Change the Greenhouse Effect and Greenhouse Gas EmissionReduction The greenhouse effect occurs naturally to a large extent Without thiseffect the Earthrsquos average global temperature would reach only a low minus18C ratherthan the current approximate +15C Water vapor is the largest contributor to thiseffect with a complex role for clouds but also CO2 in the atmosphere plays a

7ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

significant role More than a century ago Arrhenius (1896) already identified thisrole in the Earthrsquos temperature control Ice core studies reveal that on millennial timescales changes in CO2 content recorded are highly correlated with changes in tem-perature although some temperature changes have occurred without a significantCO2 concentration change but the opposite does not appear to have happened(Falkowski et al 2000) Less pronounced roles are played by CH4 N2O (nitrousoxide) and several types of chlorofluorocarbons (CFCs) and SF6 It is the CO2CH4 N2O and CFC concentrations in the atmosphere upon which manrsquos industrial

0

1

Rad

iati

ve

forc

ing (

Wm

2)

350

(a)

300

Car

bon d

ioxid

e (p

pm

)

250

300

350

400

1800 1900

Year

2000

(b)

1500

2000

1000

Met

han

e (p

pb)

500

0

02

04

Rad

iati

ve

forc

ing (

Wm

2)

1000

500

1500

2000

1900

Year

20001800

FIGURE 13 Atmospheric concentrations of CO2 CH4 and N2O over the last 10000 years(large panels) and since 1750 (inset panels) Measurements are shown from ice cores (symbolswith different grey shades for different studies) and atmospheric samples (light grey lines insteep curve part red lines in the original publication) The corresponding radiative forcings(net solar energy flux to the earth) relative to 1750 are shown on the right-hand axes of the largepanels (SourceReproducedwithpermission fromIPCC(2007) figure23 figureSPM1copyIPCC)

8 INTRODUCTION

and household activities have a measurable impact Scientists largely agree on thepoint that in the last few centuries the activities of humans have directly or indirectlycaused the concentrations of the major GHG to increase This is exemplified byFigure 13 The atmospheric CO2 concentration varies to some extent from placeto place and from season to season It has been shown that concentrations are some-what higher in the northern hemisphere than in the southern hemisphere as most of theanthropogenic sources of CO2 are located north of the equator The difference in landsurface covered with forests being more concentrated north of the equator causeslarger seasonal fluctuations due to comparatively shorter growth periods than in thegenerally milder southern hemisphere locations that are under the influence of largeroceanic surfaces

Oscillations of atmospheric CO2 concentrations between about 180 and 280 ppmv

have occurred in the past approximately 480000 years in cycles of 100000 yearsbut it appears now we have abandoned this cycling behavior in a remarkably shorttime frame

Studies at the NASA Goddard Institute for Space Studies in New York (UnitedStates) have shown that over the past few decades the combined warming effectof non-CO2 GHG should have been comparable to that of CO2 alone However whileeach of the GHGmentioned earlier acts to warm the surface of the Earth the long-termclimatic effects of the other GHG differ from those of CO2 Methane eg has anatmospheric lifetime of only about 12 years By comparison newly added CO2 willremain for a time span of tens to thousands of years As a result about 65 of thecarbon dioxide that human activities have generated since the start of the IndustrialRevolution is in the air we breathe today A historical record of the amount ofCO2 in the atmosphere can be found in bubbles of air in arctic ice layers dating backas far as 600000 years The depth of such a layer is a measure of its time of formation

(c)

10000 5000

Time (before 2005)

0

0

01

Rad

iati

ve

forc

ing (

Wm

2)

300

270

Nit

rous

oxid

e (p

pb)

270

240

300

330

1800 1900

Year

2000

FIGURE 13 (Continued )

9ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

Another difference is that the principal anthropogenic sources of methane-bacterialfermentation in rice paddies and in the intestines of cattle are related to food produc-tion and hence are roughly proportional to the number of people on the planetBecause CH4 has such a short atmospheric lifetime the amount that is in the air isa good indicator of how much is being added with time Should the global populationdouble over the next half century the concentration of CH4 could also double but it isnot likely to rise by much more than that This would add at most a few tenths of adegree to the mean temperature of the Earth Future CO2 increases could in contrastwarm the climate by 10C or more

Nitrous oxide (N2O) and CFCs are in some ways more like CO2 in that oncereleased they remain in the atmosphere for a century or more The production ofN2O however is only indirectly dependent on human activities Its principal sourceis a natural one the bacterial removal of nitrogen from soils and although the worldpopulation swells in coming years the amount in the air should increase only slowly

The outlook for many CFCs is even more promising Today the most abundant ofthese man-made compounds freon-11 and freon-12 are being phased out of produc-tion altogether by international agreements because of their damaging effects on strat-ospheric ozone Indeed the concentration of one of these gases freon-11 peaked in1994 and is now in a slow decline that should continue for the next century or so Thefreon-12 concentration has not yet leveled off but is expected to do so within the nextfew years In terms of climatic effects the main threat from CFCs comes from otherlong-lived compounds that may be used to replace the ones that have been phased outand that could also act as GHG Since these possibly harmful replacement gases are asyet present in only small amounts and since as noted earlier projected increases inCH4 and N2O are so much less severe we shall for the rest of this discussion focussolely on the most important anthropogenic GHG CO2

Some experts have estimated that the Earthrsquos average global temperature has alreadyincreased by more than 05C since the mid-1900s due to this human-enhanced green-house effect also impacts on sea level (rising) and snow coverage (tending to decrease)have been investigated the results of which are summarized in Figure 14

Like most other planets and planetoids in the universe the Earth contains a greatdeal of carbon which is slowly and continually transported from the mantle to thecrust and back again in the course of volcanic eruption and subduction phenomenaThe portion that finds itself near the surface is continually exchanged and recycledamong plants animals soil air and oceans In some of these temporary stocks car-bon is more securely held while in others it more readily combines with oxygen in theair to form CO2 In order to predict how atmospheric CO2 levels and climate maychange in the future it is important to understand where carbon is stored and whatits dynamic cycling behavior looks like The carbon reservoirs that are most relevantto global warming are listed in Table 11 with the total amount of carbon that theycontained in 2000

The atmosphere contains approximately 720 Gt C in the form of CO2 currentmeasured atmospheric CO2 concentrations are nearly 400 ppmv The rate of changein this carbon stock not only depends on human activities but also on biogeochemicaland climatological processes and their interactions with the global carbon cycle

10 INTRODUCTION

demand will rise substantially from the current level with an increasing share fromChina and India This rise of the primary energy demand is projected to be larger thanthe population growth and this will cause a stress on the limited global resources Theprojected GDP even increases stronger so it is expected that average living standardsincrease which will result in additional strain on the available resources

113 Sustainability of Energy Supply

One of the major questions in the world arising from the general picture sketched inSection 112 is how mankind can ensure a global sustainable development for the(near) future In this context sustainability of our energy supply is of paramountimportance The key issues are discussed in the following text both from a pointof view of global socioeconomics and ecological sustainability

1131 Socioeconomic Sustainability As one of the most important economicdrivers to secure and improve the living standards of people in the world energysupply security is of crucial value for current and future generations Fossil fuelsrun out sooner or later as can be seen in Figure 12 they are not renewable on anacceptable time scale

This figure depicts the so-called RP ratios for different sources The RP ratio is theratio of the current proven reserves to production level The unit is years and it is ameasure of the expected time a certain fuel source is expected to be available

On a global scale it appears that oil and natural gas reserves will be availablemdashgiven the figures of 2012mdashfor an expected approximately 55 years and coal substan-tially longer (gt100 years) Of course new contributions to the reserves may be

0

50

100

150

200

250

1980 1985 1990 1995 2000 2005 2010 2015

RP

(yea

rs)

Oil

Coal

Natural gas

FIGURE 12 Overview of world (top) and regional (bottom) reserves-to-production (RP)ratios for oil natural gas and coal respectively (end 2012 status) Figures are based on datafrom BP (2013)

5ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

North America

S amp Cent America

Europe amp Eurasia

Middle East

Africa

Asia Pacific

0 20 40 60

RP (years)

80 100 120 140

North America

S amp Cent America

Europe amp Eurasia

Middle East

Africa

Asia Pacific

0

RP (years)

North America

S amp Cent America

Europe amp Eurasia

Middle East amp Africa

Asia Pacific

0 50 100 150 200 250 300RP (years)

50 100 150 200

FIGURE 12 (Continued )

6 INTRODUCTION

discovered in the (near) future but that does not change the inherently limited supplynature of the fossil fuel sources Regionally there are also significant differenceswhich is important in the context of energy policy developments on the differentcontinents

For the price developments of the fossil fuels not only their forecasted availabilityis of importance but also the market development in a landscape highly determined bypolitics Already well before the last resources of a fuel will have been depleted themarket will be severely stressed For the economies in the world fuel cost develop-ment is therefore also a primary point of concern From past developments particu-larly regarding oil it has been shown that substantial fuel price fluctuations (volatility)occur which has an impact on the global economy (eg food prices) that is difficult topredict Supply and demand will determine the price evolution for each fuel sourcebut the development of the market structure is also essential there is a large differencebetween a free market and an oligopoly or monopoly situation In this respect diver-sification of fuel sources with associated differentiation in suppliers is advantageousas it makes societies less prone to price manipulation by eg cartel formation andsudden disruptions of supply (Johansson et al 1993)

Self-sufficiency concerning energy supply is often mentioned as target of countriesfor (longer-term) sustainable economic development However not all countries haveaccess to resources within their territories that are sufficient for such a target othercountries on the other hand have a structural surplus Relief of trade barriers canhelp mitigate this structural discrepancy Also in the context of economic sustaina-bility a good trade balance should be maintained in relation to the energy supplywithin nations

Regarding social sustainability in the context of energy supply reduction of pov-erty should be mentioned first a good supply structure of energy carriers is one of thebasic requirements for such a development next to access to clean drinking water andgood soil for agricultural activity Associated herewith expectedly substantial healthimprovement should result from a good energy supply infrastructure Job creation andmaintenance is another aspect of social sustainability and certain energy supply formscan contribute significantly to this Also maintaining (or improving) societiesrsquo socialcohesion is an aspect that can be impacted by the energy supply structure

1132 Ecological Sustainability The energy supply structure should notcompromise the sound development of our environment both from a local and globalperspective One of the major issues in this respect is global warming which is for themain part attributed to the release of greenhouse gases (GHG) from fossil fuel com-bustion Other issues are related to local emissions of acid rain precursors and partic-ulate matter (PM)

Climate Change the Greenhouse Effect and Greenhouse Gas EmissionReduction The greenhouse effect occurs naturally to a large extent Without thiseffect the Earthrsquos average global temperature would reach only a low minus18C ratherthan the current approximate +15C Water vapor is the largest contributor to thiseffect with a complex role for clouds but also CO2 in the atmosphere plays a

7ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

significant role More than a century ago Arrhenius (1896) already identified thisrole in the Earthrsquos temperature control Ice core studies reveal that on millennial timescales changes in CO2 content recorded are highly correlated with changes in tem-perature although some temperature changes have occurred without a significantCO2 concentration change but the opposite does not appear to have happened(Falkowski et al 2000) Less pronounced roles are played by CH4 N2O (nitrousoxide) and several types of chlorofluorocarbons (CFCs) and SF6 It is the CO2CH4 N2O and CFC concentrations in the atmosphere upon which manrsquos industrial

0

1

Rad

iati

ve

forc

ing (

Wm

2)

350

(a)

300

Car

bon d

ioxid

e (p

pm

)

250

300

350

400

1800 1900

Year

2000

(b)

1500

2000

1000

Met

han

e (p

pb)

500

0

02

04

Rad

iati

ve

forc

ing (

Wm

2)

1000

500

1500

2000

1900

Year

20001800

FIGURE 13 Atmospheric concentrations of CO2 CH4 and N2O over the last 10000 years(large panels) and since 1750 (inset panels) Measurements are shown from ice cores (symbolswith different grey shades for different studies) and atmospheric samples (light grey lines insteep curve part red lines in the original publication) The corresponding radiative forcings(net solar energy flux to the earth) relative to 1750 are shown on the right-hand axes of the largepanels (SourceReproducedwithpermission fromIPCC(2007) figure23 figureSPM1copyIPCC)

8 INTRODUCTION

and household activities have a measurable impact Scientists largely agree on thepoint that in the last few centuries the activities of humans have directly or indirectlycaused the concentrations of the major GHG to increase This is exemplified byFigure 13 The atmospheric CO2 concentration varies to some extent from placeto place and from season to season It has been shown that concentrations are some-what higher in the northern hemisphere than in the southern hemisphere as most of theanthropogenic sources of CO2 are located north of the equator The difference in landsurface covered with forests being more concentrated north of the equator causeslarger seasonal fluctuations due to comparatively shorter growth periods than in thegenerally milder southern hemisphere locations that are under the influence of largeroceanic surfaces

Oscillations of atmospheric CO2 concentrations between about 180 and 280 ppmv

have occurred in the past approximately 480000 years in cycles of 100000 yearsbut it appears now we have abandoned this cycling behavior in a remarkably shorttime frame

Studies at the NASA Goddard Institute for Space Studies in New York (UnitedStates) have shown that over the past few decades the combined warming effectof non-CO2 GHG should have been comparable to that of CO2 alone However whileeach of the GHGmentioned earlier acts to warm the surface of the Earth the long-termclimatic effects of the other GHG differ from those of CO2 Methane eg has anatmospheric lifetime of only about 12 years By comparison newly added CO2 willremain for a time span of tens to thousands of years As a result about 65 of thecarbon dioxide that human activities have generated since the start of the IndustrialRevolution is in the air we breathe today A historical record of the amount ofCO2 in the atmosphere can be found in bubbles of air in arctic ice layers dating backas far as 600000 years The depth of such a layer is a measure of its time of formation

(c)

10000 5000

Time (before 2005)

0

0

01

Rad

iati

ve

forc

ing (

Wm

2)

300

270

Nit

rous

oxid

e (p

pb)

270

240

300

330

1800 1900

Year

2000

FIGURE 13 (Continued )

9ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

Another difference is that the principal anthropogenic sources of methane-bacterialfermentation in rice paddies and in the intestines of cattle are related to food produc-tion and hence are roughly proportional to the number of people on the planetBecause CH4 has such a short atmospheric lifetime the amount that is in the air isa good indicator of how much is being added with time Should the global populationdouble over the next half century the concentration of CH4 could also double but it isnot likely to rise by much more than that This would add at most a few tenths of adegree to the mean temperature of the Earth Future CO2 increases could in contrastwarm the climate by 10C or more

Nitrous oxide (N2O) and CFCs are in some ways more like CO2 in that oncereleased they remain in the atmosphere for a century or more The production ofN2O however is only indirectly dependent on human activities Its principal sourceis a natural one the bacterial removal of nitrogen from soils and although the worldpopulation swells in coming years the amount in the air should increase only slowly

The outlook for many CFCs is even more promising Today the most abundant ofthese man-made compounds freon-11 and freon-12 are being phased out of produc-tion altogether by international agreements because of their damaging effects on strat-ospheric ozone Indeed the concentration of one of these gases freon-11 peaked in1994 and is now in a slow decline that should continue for the next century or so Thefreon-12 concentration has not yet leveled off but is expected to do so within the nextfew years In terms of climatic effects the main threat from CFCs comes from otherlong-lived compounds that may be used to replace the ones that have been phased outand that could also act as GHG Since these possibly harmful replacement gases are asyet present in only small amounts and since as noted earlier projected increases inCH4 and N2O are so much less severe we shall for the rest of this discussion focussolely on the most important anthropogenic GHG CO2

Some experts have estimated that the Earthrsquos average global temperature has alreadyincreased by more than 05C since the mid-1900s due to this human-enhanced green-house effect also impacts on sea level (rising) and snow coverage (tending to decrease)have been investigated the results of which are summarized in Figure 14

Like most other planets and planetoids in the universe the Earth contains a greatdeal of carbon which is slowly and continually transported from the mantle to thecrust and back again in the course of volcanic eruption and subduction phenomenaThe portion that finds itself near the surface is continually exchanged and recycledamong plants animals soil air and oceans In some of these temporary stocks car-bon is more securely held while in others it more readily combines with oxygen in theair to form CO2 In order to predict how atmospheric CO2 levels and climate maychange in the future it is important to understand where carbon is stored and whatits dynamic cycling behavior looks like The carbon reservoirs that are most relevantto global warming are listed in Table 11 with the total amount of carbon that theycontained in 2000

The atmosphere contains approximately 720 Gt C in the form of CO2 currentmeasured atmospheric CO2 concentrations are nearly 400 ppmv The rate of changein this carbon stock not only depends on human activities but also on biogeochemicaland climatological processes and their interactions with the global carbon cycle

10 INTRODUCTION

North America

S amp Cent America

Europe amp Eurasia

Middle East

Africa

Asia Pacific

0 20 40 60

RP (years)

80 100 120 140

North America

S amp Cent America

Europe amp Eurasia

Middle East

Africa

Asia Pacific

0

RP (years)

North America

S amp Cent America

Europe amp Eurasia

Middle East amp Africa

Asia Pacific

0 50 100 150 200 250 300RP (years)

50 100 150 200

FIGURE 12 (Continued )

6 INTRODUCTION

discovered in the (near) future but that does not change the inherently limited supplynature of the fossil fuel sources Regionally there are also significant differenceswhich is important in the context of energy policy developments on the differentcontinents

For the price developments of the fossil fuels not only their forecasted availabilityis of importance but also the market development in a landscape highly determined bypolitics Already well before the last resources of a fuel will have been depleted themarket will be severely stressed For the economies in the world fuel cost develop-ment is therefore also a primary point of concern From past developments particu-larly regarding oil it has been shown that substantial fuel price fluctuations (volatility)occur which has an impact on the global economy (eg food prices) that is difficult topredict Supply and demand will determine the price evolution for each fuel sourcebut the development of the market structure is also essential there is a large differencebetween a free market and an oligopoly or monopoly situation In this respect diver-sification of fuel sources with associated differentiation in suppliers is advantageousas it makes societies less prone to price manipulation by eg cartel formation andsudden disruptions of supply (Johansson et al 1993)

Self-sufficiency concerning energy supply is often mentioned as target of countriesfor (longer-term) sustainable economic development However not all countries haveaccess to resources within their territories that are sufficient for such a target othercountries on the other hand have a structural surplus Relief of trade barriers canhelp mitigate this structural discrepancy Also in the context of economic sustaina-bility a good trade balance should be maintained in relation to the energy supplywithin nations

Regarding social sustainability in the context of energy supply reduction of pov-erty should be mentioned first a good supply structure of energy carriers is one of thebasic requirements for such a development next to access to clean drinking water andgood soil for agricultural activity Associated herewith expectedly substantial healthimprovement should result from a good energy supply infrastructure Job creation andmaintenance is another aspect of social sustainability and certain energy supply formscan contribute significantly to this Also maintaining (or improving) societiesrsquo socialcohesion is an aspect that can be impacted by the energy supply structure

1132 Ecological Sustainability The energy supply structure should notcompromise the sound development of our environment both from a local and globalperspective One of the major issues in this respect is global warming which is for themain part attributed to the release of greenhouse gases (GHG) from fossil fuel com-bustion Other issues are related to local emissions of acid rain precursors and partic-ulate matter (PM)

Climate Change the Greenhouse Effect and Greenhouse Gas EmissionReduction The greenhouse effect occurs naturally to a large extent Without thiseffect the Earthrsquos average global temperature would reach only a low minus18C ratherthan the current approximate +15C Water vapor is the largest contributor to thiseffect with a complex role for clouds but also CO2 in the atmosphere plays a

7ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

significant role More than a century ago Arrhenius (1896) already identified thisrole in the Earthrsquos temperature control Ice core studies reveal that on millennial timescales changes in CO2 content recorded are highly correlated with changes in tem-perature although some temperature changes have occurred without a significantCO2 concentration change but the opposite does not appear to have happened(Falkowski et al 2000) Less pronounced roles are played by CH4 N2O (nitrousoxide) and several types of chlorofluorocarbons (CFCs) and SF6 It is the CO2CH4 N2O and CFC concentrations in the atmosphere upon which manrsquos industrial

0

1

Rad

iati

ve

forc

ing (

Wm

2)

350

(a)

300

Car

bon d

ioxid

e (p

pm

)

250

300

350

400

1800 1900

Year

2000

(b)

1500

2000

1000

Met

han

e (p

pb)

500

0

02

04

Rad

iati

ve

forc

ing (

Wm

2)

1000

500

1500

2000

1900

Year

20001800

FIGURE 13 Atmospheric concentrations of CO2 CH4 and N2O over the last 10000 years(large panels) and since 1750 (inset panels) Measurements are shown from ice cores (symbolswith different grey shades for different studies) and atmospheric samples (light grey lines insteep curve part red lines in the original publication) The corresponding radiative forcings(net solar energy flux to the earth) relative to 1750 are shown on the right-hand axes of the largepanels (SourceReproducedwithpermission fromIPCC(2007) figure23 figureSPM1copyIPCC)

8 INTRODUCTION

and household activities have a measurable impact Scientists largely agree on thepoint that in the last few centuries the activities of humans have directly or indirectlycaused the concentrations of the major GHG to increase This is exemplified byFigure 13 The atmospheric CO2 concentration varies to some extent from placeto place and from season to season It has been shown that concentrations are some-what higher in the northern hemisphere than in the southern hemisphere as most of theanthropogenic sources of CO2 are located north of the equator The difference in landsurface covered with forests being more concentrated north of the equator causeslarger seasonal fluctuations due to comparatively shorter growth periods than in thegenerally milder southern hemisphere locations that are under the influence of largeroceanic surfaces

Oscillations of atmospheric CO2 concentrations between about 180 and 280 ppmv

have occurred in the past approximately 480000 years in cycles of 100000 yearsbut it appears now we have abandoned this cycling behavior in a remarkably shorttime frame

Studies at the NASA Goddard Institute for Space Studies in New York (UnitedStates) have shown that over the past few decades the combined warming effectof non-CO2 GHG should have been comparable to that of CO2 alone However whileeach of the GHGmentioned earlier acts to warm the surface of the Earth the long-termclimatic effects of the other GHG differ from those of CO2 Methane eg has anatmospheric lifetime of only about 12 years By comparison newly added CO2 willremain for a time span of tens to thousands of years As a result about 65 of thecarbon dioxide that human activities have generated since the start of the IndustrialRevolution is in the air we breathe today A historical record of the amount ofCO2 in the atmosphere can be found in bubbles of air in arctic ice layers dating backas far as 600000 years The depth of such a layer is a measure of its time of formation

(c)

10000 5000

Time (before 2005)

0

0

01

Rad

iati

ve

forc

ing (

Wm

2)

300

270

Nit

rous

oxid

e (p

pb)

270

240

300

330

1800 1900

Year

2000

FIGURE 13 (Continued )

9ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

Another difference is that the principal anthropogenic sources of methane-bacterialfermentation in rice paddies and in the intestines of cattle are related to food produc-tion and hence are roughly proportional to the number of people on the planetBecause CH4 has such a short atmospheric lifetime the amount that is in the air isa good indicator of how much is being added with time Should the global populationdouble over the next half century the concentration of CH4 could also double but it isnot likely to rise by much more than that This would add at most a few tenths of adegree to the mean temperature of the Earth Future CO2 increases could in contrastwarm the climate by 10C or more

Nitrous oxide (N2O) and CFCs are in some ways more like CO2 in that oncereleased they remain in the atmosphere for a century or more The production ofN2O however is only indirectly dependent on human activities Its principal sourceis a natural one the bacterial removal of nitrogen from soils and although the worldpopulation swells in coming years the amount in the air should increase only slowly

The outlook for many CFCs is even more promising Today the most abundant ofthese man-made compounds freon-11 and freon-12 are being phased out of produc-tion altogether by international agreements because of their damaging effects on strat-ospheric ozone Indeed the concentration of one of these gases freon-11 peaked in1994 and is now in a slow decline that should continue for the next century or so Thefreon-12 concentration has not yet leveled off but is expected to do so within the nextfew years In terms of climatic effects the main threat from CFCs comes from otherlong-lived compounds that may be used to replace the ones that have been phased outand that could also act as GHG Since these possibly harmful replacement gases are asyet present in only small amounts and since as noted earlier projected increases inCH4 and N2O are so much less severe we shall for the rest of this discussion focussolely on the most important anthropogenic GHG CO2

Some experts have estimated that the Earthrsquos average global temperature has alreadyincreased by more than 05C since the mid-1900s due to this human-enhanced green-house effect also impacts on sea level (rising) and snow coverage (tending to decrease)have been investigated the results of which are summarized in Figure 14

Like most other planets and planetoids in the universe the Earth contains a greatdeal of carbon which is slowly and continually transported from the mantle to thecrust and back again in the course of volcanic eruption and subduction phenomenaThe portion that finds itself near the surface is continually exchanged and recycledamong plants animals soil air and oceans In some of these temporary stocks car-bon is more securely held while in others it more readily combines with oxygen in theair to form CO2 In order to predict how atmospheric CO2 levels and climate maychange in the future it is important to understand where carbon is stored and whatits dynamic cycling behavior looks like The carbon reservoirs that are most relevantto global warming are listed in Table 11 with the total amount of carbon that theycontained in 2000

The atmosphere contains approximately 720 Gt C in the form of CO2 currentmeasured atmospheric CO2 concentrations are nearly 400 ppmv The rate of changein this carbon stock not only depends on human activities but also on biogeochemicaland climatological processes and their interactions with the global carbon cycle

10 INTRODUCTION

discovered in the (near) future but that does not change the inherently limited supplynature of the fossil fuel sources Regionally there are also significant differenceswhich is important in the context of energy policy developments on the differentcontinents

For the price developments of the fossil fuels not only their forecasted availabilityis of importance but also the market development in a landscape highly determined bypolitics Already well before the last resources of a fuel will have been depleted themarket will be severely stressed For the economies in the world fuel cost develop-ment is therefore also a primary point of concern From past developments particu-larly regarding oil it has been shown that substantial fuel price fluctuations (volatility)occur which has an impact on the global economy (eg food prices) that is difficult topredict Supply and demand will determine the price evolution for each fuel sourcebut the development of the market structure is also essential there is a large differencebetween a free market and an oligopoly or monopoly situation In this respect diver-sification of fuel sources with associated differentiation in suppliers is advantageousas it makes societies less prone to price manipulation by eg cartel formation andsudden disruptions of supply (Johansson et al 1993)

Self-sufficiency concerning energy supply is often mentioned as target of countriesfor (longer-term) sustainable economic development However not all countries haveaccess to resources within their territories that are sufficient for such a target othercountries on the other hand have a structural surplus Relief of trade barriers canhelp mitigate this structural discrepancy Also in the context of economic sustaina-bility a good trade balance should be maintained in relation to the energy supplywithin nations

Regarding social sustainability in the context of energy supply reduction of pov-erty should be mentioned first a good supply structure of energy carriers is one of thebasic requirements for such a development next to access to clean drinking water andgood soil for agricultural activity Associated herewith expectedly substantial healthimprovement should result from a good energy supply infrastructure Job creation andmaintenance is another aspect of social sustainability and certain energy supply formscan contribute significantly to this Also maintaining (or improving) societiesrsquo socialcohesion is an aspect that can be impacted by the energy supply structure

1132 Ecological Sustainability The energy supply structure should notcompromise the sound development of our environment both from a local and globalperspective One of the major issues in this respect is global warming which is for themain part attributed to the release of greenhouse gases (GHG) from fossil fuel com-bustion Other issues are related to local emissions of acid rain precursors and partic-ulate matter (PM)

Climate Change the Greenhouse Effect and Greenhouse Gas EmissionReduction The greenhouse effect occurs naturally to a large extent Without thiseffect the Earthrsquos average global temperature would reach only a low minus18C ratherthan the current approximate +15C Water vapor is the largest contributor to thiseffect with a complex role for clouds but also CO2 in the atmosphere plays a

7ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

significant role More than a century ago Arrhenius (1896) already identified thisrole in the Earthrsquos temperature control Ice core studies reveal that on millennial timescales changes in CO2 content recorded are highly correlated with changes in tem-perature although some temperature changes have occurred without a significantCO2 concentration change but the opposite does not appear to have happened(Falkowski et al 2000) Less pronounced roles are played by CH4 N2O (nitrousoxide) and several types of chlorofluorocarbons (CFCs) and SF6 It is the CO2CH4 N2O and CFC concentrations in the atmosphere upon which manrsquos industrial

0

1

Rad

iati

ve

forc

ing (

Wm

2)

350

(a)

300

Car

bon d

ioxid

e (p

pm

)

250

300

350

400

1800 1900

Year

2000

(b)

1500

2000

1000

Met

han

e (p

pb)

500

0

02

04

Rad

iati

ve

forc

ing (

Wm

2)

1000

500

1500

2000

1900

Year

20001800

FIGURE 13 Atmospheric concentrations of CO2 CH4 and N2O over the last 10000 years(large panels) and since 1750 (inset panels) Measurements are shown from ice cores (symbolswith different grey shades for different studies) and atmospheric samples (light grey lines insteep curve part red lines in the original publication) The corresponding radiative forcings(net solar energy flux to the earth) relative to 1750 are shown on the right-hand axes of the largepanels (SourceReproducedwithpermission fromIPCC(2007) figure23 figureSPM1copyIPCC)

8 INTRODUCTION

and household activities have a measurable impact Scientists largely agree on thepoint that in the last few centuries the activities of humans have directly or indirectlycaused the concentrations of the major GHG to increase This is exemplified byFigure 13 The atmospheric CO2 concentration varies to some extent from placeto place and from season to season It has been shown that concentrations are some-what higher in the northern hemisphere than in the southern hemisphere as most of theanthropogenic sources of CO2 are located north of the equator The difference in landsurface covered with forests being more concentrated north of the equator causeslarger seasonal fluctuations due to comparatively shorter growth periods than in thegenerally milder southern hemisphere locations that are under the influence of largeroceanic surfaces

Oscillations of atmospheric CO2 concentrations between about 180 and 280 ppmv

have occurred in the past approximately 480000 years in cycles of 100000 yearsbut it appears now we have abandoned this cycling behavior in a remarkably shorttime frame

Studies at the NASA Goddard Institute for Space Studies in New York (UnitedStates) have shown that over the past few decades the combined warming effectof non-CO2 GHG should have been comparable to that of CO2 alone However whileeach of the GHGmentioned earlier acts to warm the surface of the Earth the long-termclimatic effects of the other GHG differ from those of CO2 Methane eg has anatmospheric lifetime of only about 12 years By comparison newly added CO2 willremain for a time span of tens to thousands of years As a result about 65 of thecarbon dioxide that human activities have generated since the start of the IndustrialRevolution is in the air we breathe today A historical record of the amount ofCO2 in the atmosphere can be found in bubbles of air in arctic ice layers dating backas far as 600000 years The depth of such a layer is a measure of its time of formation

(c)

10000 5000

Time (before 2005)

0

0

01

Rad

iati

ve

forc

ing (

Wm

2)

300

270

Nit

rous

oxid

e (p

pb)

270

240

300

330

1800 1900

Year

2000

FIGURE 13 (Continued )

9ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

Another difference is that the principal anthropogenic sources of methane-bacterialfermentation in rice paddies and in the intestines of cattle are related to food produc-tion and hence are roughly proportional to the number of people on the planetBecause CH4 has such a short atmospheric lifetime the amount that is in the air isa good indicator of how much is being added with time Should the global populationdouble over the next half century the concentration of CH4 could also double but it isnot likely to rise by much more than that This would add at most a few tenths of adegree to the mean temperature of the Earth Future CO2 increases could in contrastwarm the climate by 10C or more

Nitrous oxide (N2O) and CFCs are in some ways more like CO2 in that oncereleased they remain in the atmosphere for a century or more The production ofN2O however is only indirectly dependent on human activities Its principal sourceis a natural one the bacterial removal of nitrogen from soils and although the worldpopulation swells in coming years the amount in the air should increase only slowly

The outlook for many CFCs is even more promising Today the most abundant ofthese man-made compounds freon-11 and freon-12 are being phased out of produc-tion altogether by international agreements because of their damaging effects on strat-ospheric ozone Indeed the concentration of one of these gases freon-11 peaked in1994 and is now in a slow decline that should continue for the next century or so Thefreon-12 concentration has not yet leveled off but is expected to do so within the nextfew years In terms of climatic effects the main threat from CFCs comes from otherlong-lived compounds that may be used to replace the ones that have been phased outand that could also act as GHG Since these possibly harmful replacement gases are asyet present in only small amounts and since as noted earlier projected increases inCH4 and N2O are so much less severe we shall for the rest of this discussion focussolely on the most important anthropogenic GHG CO2

Some experts have estimated that the Earthrsquos average global temperature has alreadyincreased by more than 05C since the mid-1900s due to this human-enhanced green-house effect also impacts on sea level (rising) and snow coverage (tending to decrease)have been investigated the results of which are summarized in Figure 14

Like most other planets and planetoids in the universe the Earth contains a greatdeal of carbon which is slowly and continually transported from the mantle to thecrust and back again in the course of volcanic eruption and subduction phenomenaThe portion that finds itself near the surface is continually exchanged and recycledamong plants animals soil air and oceans In some of these temporary stocks car-bon is more securely held while in others it more readily combines with oxygen in theair to form CO2 In order to predict how atmospheric CO2 levels and climate maychange in the future it is important to understand where carbon is stored and whatits dynamic cycling behavior looks like The carbon reservoirs that are most relevantto global warming are listed in Table 11 with the total amount of carbon that theycontained in 2000

The atmosphere contains approximately 720 Gt C in the form of CO2 currentmeasured atmospheric CO2 concentrations are nearly 400 ppmv The rate of changein this carbon stock not only depends on human activities but also on biogeochemicaland climatological processes and their interactions with the global carbon cycle

10 INTRODUCTION

significant role More than a century ago Arrhenius (1896) already identified thisrole in the Earthrsquos temperature control Ice core studies reveal that on millennial timescales changes in CO2 content recorded are highly correlated with changes in tem-perature although some temperature changes have occurred without a significantCO2 concentration change but the opposite does not appear to have happened(Falkowski et al 2000) Less pronounced roles are played by CH4 N2O (nitrousoxide) and several types of chlorofluorocarbons (CFCs) and SF6 It is the CO2CH4 N2O and CFC concentrations in the atmosphere upon which manrsquos industrial

0

1

Rad

iati

ve

forc

ing (

Wm

2)

350

(a)

300

Car

bon d

ioxid

e (p

pm

)

250

300

350

400

1800 1900

Year

2000

(b)

1500

2000

1000

Met

han

e (p

pb)

500

0

02

04

Rad

iati

ve

forc

ing (

Wm

2)

1000

500

1500

2000

1900

Year

20001800

FIGURE 13 Atmospheric concentrations of CO2 CH4 and N2O over the last 10000 years(large panels) and since 1750 (inset panels) Measurements are shown from ice cores (symbolswith different grey shades for different studies) and atmospheric samples (light grey lines insteep curve part red lines in the original publication) The corresponding radiative forcings(net solar energy flux to the earth) relative to 1750 are shown on the right-hand axes of the largepanels (SourceReproducedwithpermission fromIPCC(2007) figure23 figureSPM1copyIPCC)

8 INTRODUCTION

and household activities have a measurable impact Scientists largely agree on thepoint that in the last few centuries the activities of humans have directly or indirectlycaused the concentrations of the major GHG to increase This is exemplified byFigure 13 The atmospheric CO2 concentration varies to some extent from placeto place and from season to season It has been shown that concentrations are some-what higher in the northern hemisphere than in the southern hemisphere as most of theanthropogenic sources of CO2 are located north of the equator The difference in landsurface covered with forests being more concentrated north of the equator causeslarger seasonal fluctuations due to comparatively shorter growth periods than in thegenerally milder southern hemisphere locations that are under the influence of largeroceanic surfaces

Oscillations of atmospheric CO2 concentrations between about 180 and 280 ppmv

have occurred in the past approximately 480000 years in cycles of 100000 yearsbut it appears now we have abandoned this cycling behavior in a remarkably shorttime frame

Studies at the NASA Goddard Institute for Space Studies in New York (UnitedStates) have shown that over the past few decades the combined warming effectof non-CO2 GHG should have been comparable to that of CO2 alone However whileeach of the GHGmentioned earlier acts to warm the surface of the Earth the long-termclimatic effects of the other GHG differ from those of CO2 Methane eg has anatmospheric lifetime of only about 12 years By comparison newly added CO2 willremain for a time span of tens to thousands of years As a result about 65 of thecarbon dioxide that human activities have generated since the start of the IndustrialRevolution is in the air we breathe today A historical record of the amount ofCO2 in the atmosphere can be found in bubbles of air in arctic ice layers dating backas far as 600000 years The depth of such a layer is a measure of its time of formation

(c)

10000 5000

Time (before 2005)

0

0

01

Rad

iati

ve

forc

ing (

Wm

2)

300

270

Nit

rous

oxid

e (p

pb)

270

240

300

330

1800 1900

Year

2000

FIGURE 13 (Continued )

9ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

Another difference is that the principal anthropogenic sources of methane-bacterialfermentation in rice paddies and in the intestines of cattle are related to food produc-tion and hence are roughly proportional to the number of people on the planetBecause CH4 has such a short atmospheric lifetime the amount that is in the air isa good indicator of how much is being added with time Should the global populationdouble over the next half century the concentration of CH4 could also double but it isnot likely to rise by much more than that This would add at most a few tenths of adegree to the mean temperature of the Earth Future CO2 increases could in contrastwarm the climate by 10C or more

Nitrous oxide (N2O) and CFCs are in some ways more like CO2 in that oncereleased they remain in the atmosphere for a century or more The production ofN2O however is only indirectly dependent on human activities Its principal sourceis a natural one the bacterial removal of nitrogen from soils and although the worldpopulation swells in coming years the amount in the air should increase only slowly

The outlook for many CFCs is even more promising Today the most abundant ofthese man-made compounds freon-11 and freon-12 are being phased out of produc-tion altogether by international agreements because of their damaging effects on strat-ospheric ozone Indeed the concentration of one of these gases freon-11 peaked in1994 and is now in a slow decline that should continue for the next century or so Thefreon-12 concentration has not yet leveled off but is expected to do so within the nextfew years In terms of climatic effects the main threat from CFCs comes from otherlong-lived compounds that may be used to replace the ones that have been phased outand that could also act as GHG Since these possibly harmful replacement gases are asyet present in only small amounts and since as noted earlier projected increases inCH4 and N2O are so much less severe we shall for the rest of this discussion focussolely on the most important anthropogenic GHG CO2

Some experts have estimated that the Earthrsquos average global temperature has alreadyincreased by more than 05C since the mid-1900s due to this human-enhanced green-house effect also impacts on sea level (rising) and snow coverage (tending to decrease)have been investigated the results of which are summarized in Figure 14

Like most other planets and planetoids in the universe the Earth contains a greatdeal of carbon which is slowly and continually transported from the mantle to thecrust and back again in the course of volcanic eruption and subduction phenomenaThe portion that finds itself near the surface is continually exchanged and recycledamong plants animals soil air and oceans In some of these temporary stocks car-bon is more securely held while in others it more readily combines with oxygen in theair to form CO2 In order to predict how atmospheric CO2 levels and climate maychange in the future it is important to understand where carbon is stored and whatits dynamic cycling behavior looks like The carbon reservoirs that are most relevantto global warming are listed in Table 11 with the total amount of carbon that theycontained in 2000

The atmosphere contains approximately 720 Gt C in the form of CO2 currentmeasured atmospheric CO2 concentrations are nearly 400 ppmv The rate of changein this carbon stock not only depends on human activities but also on biogeochemicaland climatological processes and their interactions with the global carbon cycle

10 INTRODUCTION

and household activities have a measurable impact Scientists largely agree on thepoint that in the last few centuries the activities of humans have directly or indirectlycaused the concentrations of the major GHG to increase This is exemplified byFigure 13 The atmospheric CO2 concentration varies to some extent from placeto place and from season to season It has been shown that concentrations are some-what higher in the northern hemisphere than in the southern hemisphere as most of theanthropogenic sources of CO2 are located north of the equator The difference in landsurface covered with forests being more concentrated north of the equator causeslarger seasonal fluctuations due to comparatively shorter growth periods than in thegenerally milder southern hemisphere locations that are under the influence of largeroceanic surfaces

Oscillations of atmospheric CO2 concentrations between about 180 and 280 ppmv

have occurred in the past approximately 480000 years in cycles of 100000 yearsbut it appears now we have abandoned this cycling behavior in a remarkably shorttime frame

Studies at the NASA Goddard Institute for Space Studies in New York (UnitedStates) have shown that over the past few decades the combined warming effectof non-CO2 GHG should have been comparable to that of CO2 alone However whileeach of the GHGmentioned earlier acts to warm the surface of the Earth the long-termclimatic effects of the other GHG differ from those of CO2 Methane eg has anatmospheric lifetime of only about 12 years By comparison newly added CO2 willremain for a time span of tens to thousands of years As a result about 65 of thecarbon dioxide that human activities have generated since the start of the IndustrialRevolution is in the air we breathe today A historical record of the amount ofCO2 in the atmosphere can be found in bubbles of air in arctic ice layers dating backas far as 600000 years The depth of such a layer is a measure of its time of formation

(c)

10000 5000

Time (before 2005)

0

0

01

Rad

iati

ve

forc

ing (

Wm

2)

300

270

Nit

rous

oxid

e (p

pb)

270

240

300

330

1800 1900

Year

2000

FIGURE 13 (Continued )

9ENERGY SUPPLY ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS

Another difference is that the principal anthropogenic sources of methane-bacterialfermentation in rice paddies and in the intestines of cattle are related to food produc-tion and hence are roughly proportional to the number of people on the planetBecause CH4 has such a short atmospheric lifetime the amount that is in the air isa good indicator of how much is being added with time Should the global populationdouble over the next half century the concentration of CH4 could also double but it isnot likely to rise by much more than that This would add at most a few tenths of adegree to the mean temperature of the Earth Future CO2 increases could in contrastwarm the climate by 10C or more

Nitrous oxide (N2O) and CFCs are in some ways more like CO2 in that oncereleased they remain in the atmosphere for a century or more The production ofN2O however is only indirectly dependent on human activities Its principal sourceis a natural one the bacterial removal of nitrogen from soils and although the worldpopulation swells in coming years the amount in the air should increase only slowly

The outlook for many CFCs is even more promising Today the most abundant ofthese man-made compounds freon-11 and freon-12 are being phased out of produc-tion altogether by international agreements because of their damaging effects on strat-ospheric ozone Indeed the concentration of one of these gases freon-11 peaked in1994 and is now in a slow decline that should continue for the next century or so Thefreon-12 concentration has not yet leveled off but is expected to do so within the nextfew years In terms of climatic effects the main threat from CFCs comes from otherlong-lived compounds that may be used to replace the ones that have been phased outand that could also act as GHG Since these possibly harmful replacement gases are asyet present in only small amounts and since as noted earlier projected increases inCH4 and N2O are so much less severe we shall for the rest of this discussion focussolely on the most important anthropogenic GHG CO2

Some experts have estimated that the Earthrsquos average global temperature has alreadyincreased by more than 05C since the mid-1900s due to this human-enhanced green-house effect also impacts on sea level (rising) and snow coverage (tending to decrease)have been investigated the results of which are summarized in Figure 14

Like most other planets and planetoids in the universe the Earth contains a greatdeal of carbon which is slowly and continually transported from the mantle to thecrust and back again in the course of volcanic eruption and subduction phenomenaThe portion that finds itself near the surface is continually exchanged and recycledamong plants animals soil air and oceans In some of these temporary stocks car-bon is more securely held while in others it more readily combines with oxygen in theair to form CO2 In order to predict how atmospheric CO2 levels and climate maychange in the future it is important to understand where carbon is stored and whatits dynamic cycling behavior looks like The carbon reservoirs that are most relevantto global warming are listed in Table 11 with the total amount of carbon that theycontained in 2000

The atmosphere contains approximately 720 Gt C in the form of CO2 currentmeasured atmospheric CO2 concentrations are nearly 400 ppmv The rate of changein this carbon stock not only depends on human activities but also on biogeochemicaland climatological processes and their interactions with the global carbon cycle

10 INTRODUCTION

Another difference is that the principal anthropogenic sources of methane-bacterialfermentation in rice paddies and in the intestines of cattle are related to food produc-tion and hence are roughly proportional to the number of people on the planetBecause CH4 has such a short atmospheric lifetime the amount that is in the air isa good indicator of how much is being added with time Should the global populationdouble over the next half century the concentration of CH4 could also double but it isnot likely to rise by much more than that This would add at most a few tenths of adegree to the mean temperature of the Earth Future CO2 increases could in contrastwarm the climate by 10C or more

Nitrous oxide (N2O) and CFCs are in some ways more like CO2 in that oncereleased they remain in the atmosphere for a century or more The production ofN2O however is only indirectly dependent on human activities Its principal sourceis a natural one the bacterial removal of nitrogen from soils and although the worldpopulation swells in coming years the amount in the air should increase only slowly

The outlook for many CFCs is even more promising Today the most abundant ofthese man-made compounds freon-11 and freon-12 are being phased out of produc-tion altogether by international agreements because of their damaging effects on strat-ospheric ozone Indeed the concentration of one of these gases freon-11 peaked in1994 and is now in a slow decline that should continue for the next century or so Thefreon-12 concentration has not yet leveled off but is expected to do so within the nextfew years In terms of climatic effects the main threat from CFCs comes from otherlong-lived compounds that may be used to replace the ones that have been phased outand that could also act as GHG Since these possibly harmful replacement gases are asyet present in only small amounts and since as noted earlier projected increases inCH4 and N2O are so much less severe we shall for the rest of this discussion focussolely on the most important anthropogenic GHG CO2

Some experts have estimated that the Earthrsquos average global temperature has alreadyincreased by more than 05C since the mid-1900s due to this human-enhanced green-house effect also impacts on sea level (rising) and snow coverage (tending to decrease)have been investigated the results of which are summarized in Figure 14

Like most other planets and planetoids in the universe the Earth contains a greatdeal of carbon which is slowly and continually transported from the mantle to thecrust and back again in the course of volcanic eruption and subduction phenomenaThe portion that finds itself near the surface is continually exchanged and recycledamong plants animals soil air and oceans In some of these temporary stocks car-bon is more securely held while in others it more readily combines with oxygen in theair to form CO2 In order to predict how atmospheric CO2 levels and climate maychange in the future it is important to understand where carbon is stored and whatits dynamic cycling behavior looks like The carbon reservoirs that are most relevantto global warming are listed in Table 11 with the total amount of carbon that theycontained in 2000

The atmosphere contains approximately 720 Gt C in the form of CO2 currentmeasured atmospheric CO2 concentrations are nearly 400 ppmv The rate of changein this carbon stock not only depends on human activities but also on biogeochemicaland climatological processes and their interactions with the global carbon cycle

10 INTRODUCTION