Fuels from Microalgae - NREL .element of the Biofuels Program, ... Microalgae, which have been called

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  • SIRI/SP-320-3396DE88001192

    FUELSM FROM EICROALGA

    June 1989

    A Product of the Solar Technical Information ProgramProduced by the Development and Communications Office

    Solar Energy Research Institute1617 Cole Boulevard

    Golden, Colorado 80401-3393

    Operated by Midwest Research Institute for theU.S. Department of Energy

    S-~I ~-=~_ III III- ~~~

  • NOTICE

    This report was prepared as an account of work sponsored by an agency of the United States government. Neither the United States government nor anyagency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, com-pleteness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights"Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily con-stitute or imply its endorsement, recommendation, or favoring by the United States government or any agency thereof. The views and opinions of authorsexpressed herein do not necessarily state or reflect those of the United States government or any agency thereof.

    Printed in the United States of AmericaAvailable from:

    National Technical Information ServiceU.S. Department of Commerce

    5285 Port Royal RoadSpringfield, VA 22161

    Price: Microfiche A01Printed Copy A03

    Codes are used for pricing all publications. The code is determined by the number of pages in the publication. Information pertaining to the pricing codescan be found in the current issue of the following publications which are generally available in most libraries: Energy Research Abstracts (ERA); Govern-ment Reports Announcements and Index (GRA and I); Scientific and Technical Abstract Reports (STAR); and publication NTIS-PR-360 available from NTIS 4at the above address.

  • PREFACE

    Many species of aquatic plants can provide a sour.ce of renewable energy. Somespecies of microalgae, in particular, produce lipids--oils that can be extracted and con-verted to a diesel fuel substitute or to gasoline. Since 1979 the Aquatic Species Programelement of the Biofuels Program, sponsored by the U.S. Department of Energy's (DOE)Biofuels and Municipal Waste Technology Division and managed by the Solar EnergyResearch Institute (SERI), has supported fundamental and applied research to develop thetechnology for using this renewable energy resource.

    This document, produced by the Solar Technical Information Program, provides anoverview of the DOE/SERI Aquatic Species Program element. Chapter I is an introduc-tion to the program and to microalgae. Chapter 2 is an overview of the general princi-ples involved in making fuels from microalgae. It also outlines the technical challengesto producing economic, high-energy transportation fuels. Chapter 3 provides an overviewof the Algal Production and Economic Model (APEM). This model was developed byresearchers within the program to identify aspects of the process critical to performancewith the greatest potential to reduce costs. The analysis using this model has helpeddirect research sponsored by the program. Finally, Chapter 4 provides an overview ofthe Aquatic Species Program and describes current research.

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  • SUMMARY

    Liquid fuels playa vital part in the economy of the United States--primarily fortransportation. In fact, liquid fuels, such as gasoline and diesel fuel, made up 4296 of theenergy consumed in 1988. About a third of these fuels is derived from imported petro-leum, contributing more than $40 billion to the trade deficit. This portion is expected toincrease as domestic petroleum production continues to decline. It is clearly in our bestinterest to develop alternative domestic energy resources to reduce our dependence onforeign oil.

    Biomass--plants such as grasses, trees, and aquatic algae--is such an alternative.Aquatic algae, in particular, show promise and form the basis of research supported bythe U.S. Department of Energy (DOE). The Aquatic Species Program element, managedby the Solar Energy Research Institute (SERI), was created in 1979 to evaluate the poten-tial of aquatic plants as a renewable energy source. Since 1982, research has investigatedmicroalgae that produce lipids, oils that can be converted to a diesel fuel substitute or togasoline. Research sponsored by the program has produced exciting results. Withcontinued research and development, this technology could make a significantcontribution to our fuel requirements in the next century.

    Microalgae, which have been called the most productive biochemical factories inthe world, grow very fast, doubling their weight three to five times a day. Species havebeen found that grow rapidly, produce large quantities of oils, tolerate wide variations intemperature, and can live in saline water. Because of climate and cost considerations,these characteristics make microalgae well-suited for. initial deployment in the south-western United States. The algae would be grown in saline water in large outdoor ponds,making use of the area's high solar radiation and open flat land with few competing uses(Le., low land costs). Large resources of underground saline water are also available inthe region at low cost.

    Beside water and sunlight, microalgae need large additions of carbon dioxide togrow and produce lipids in the quantities required for economical liquid fuel production.This requirement provides another advantage to the technology--reducing the atmos-pheric gases that contribute to global warming. A microalgal facility could be sited nextto a power plant or industry that burns fossil fuels and could recycle part of the carbondioxide from flue gases into liquid fuels. This would decrease the amount of carbondioxide released into the atmosphere.

    The program element supports research at SERI, at universities, at governmentlaboratories, and in industry. Current research is concentrated in six areas:

    Genetic engineering of microalgae for lipid production at high growth rates Identification of "trigger points" in biochemical pathways to turn lipid production on'

    and off Development of inexpensive, large-scale, outdoor culture technologies to grow

    microalgae Evaluation of resource requirements and environmental impacts of microalgae facili-

    ties in the desert Southwest Development of technologies for converting microalgal lipids into high-value liquid

    transportation fuels, particularly diesel fuel Transfer of the technology to the private sector for continued development by involv-

    ing industry at the earliest possible time.

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  • Results of these activities are expected to lead to a technically and economicallyfeasible process in the early part of the next century. Research has already reduced theprojected price of diesel derived from microalgae from $18 per gallon in 1983 to lessthan $7 per gallon today. This is an impressive start. By 2010 we should have the tech-nology that will allow us to produce competitively priced fuel from microalgae.

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  • CONTENTS

    Page

    Chapter 1: Introduction to the Aquatic Species Program .Introduction to Microalgae .Microalgae as a Source of Energy .The Aquatic Species Program

    Optimizing the Organism Optimizing the Fuel Conversion Process Optimizing the System Design .

    1135566

    . . 0

    . ..........................

    101010101112131414141516161717

    .....................................................................................................................

    Chapter 2: Principles of Microalgal Fuels Technology Mass Culturing of Microalgae " " "

    Light ........................WaterCarbon Dioxide . "Nutrients Growth ConditionsAlgal Species Selection

    Culture Production SystemsEngineering and Construction " ""." "Harvesting "

    Fuels from Microalgae Characteristics of Conventional Fuels Characteristics of Microalgal Biomass Fuel Conversion Processes

    191920222223232424

    32

    2627272828303031

    35

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    APEM Parameter Values ..

    ...........................................................

    Carbon Dioxide Demand Algal Productivity and Products Algal Harvesting Alternative Fuel Products .

    Chapter 3: Economics of Microalgal Fuels Algal Production and Economic Model Running the Algal Production and Economic Model Analysis Results

    Water Demand ..

    Appendix:

    Chapter 4: Aquatic Species Program Research Microalgal Growth and Lipid Production

    Species Characterization .Biochemistry of Lipid Accumulation Genetic Engineering "Engineering Design Harvesting and Conversion Technology

    Future Research ...

    References

    Availability of Algal Production and Economic Model 37

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  • CHAPTER 1INTRODUCTION TO THE AQUATIC SPECIES PROGRAM

    The Arab oil embargo of the early 1970s encouraged many nations to look for newsources of energy for heating, electricity, and transportation. One potential source,biomass,* is an attractive option because it is renewable and can provide all the forms ofenergy we need. Unlike finite deposits of coal, oil, and natural gas, biomass can beproduced almost anywhere and under a wide range of environmental conditions. The firstbiomass sources considered for energy production were wood and agricultural productslike corn. But other sources of biomass also have potential for energy production, andresearch has been initiated to develop these alternatives.

    Considered among the