Cogeneration July August 2013

Cw w w. c o s p p . c o m

OnSite Power Production

WORLD ALLIANCE FOR DECENTRALIZED ENERGY

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SUPERCRITICAL CO2 REFINES COGENERATION n ENHANCING SCADA FOR COGENERATION n EFFICIENCY BREAKTHROUGH IN SOLAR THERMAL CELLS n REFURBISHMENT DRIVES GROWTH IN RUSSIA n AWARD-WINNING CHP IN THE UKS n MEXICAN INDUSTRY TAPS COGEN POTENTIAL n THE MAN DRIVING DOUBLE-DIGIT GROWTH AT MWM

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London 2012 Games leave CCHP legacy

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PAKISTAN ONCE AGAIN TURNS TO BIOGASSE COGEN n SELF GENERATION TAKES HOLD IN UK n YOUR HRSG AND ADRESSING THE FAC CORROSION ISSUE

n FLANDERS 20-YEAR LOVE AFFAIR WITH COGENERATION n OPTIMIZATION AT AN INDUSTRIAL CHP FACILITY IN PORTUGAL n GUIDE TO POWER-GEN BRASIL

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Biomass CHP: A how-to guide to optimize operations

DIRECTORY ISSUE 2013

1307cospp_C1 1 7/18/13 4:37 PM

METKA is a leading EPC (Engineering-Procurement-Construction) contractor for large-scale energy production projects,

well-known for its ability to reliably deliver complex projects throughout Europe, the Middle East and Africa.

The company has strong expertise in gas turbine based power plants, with a broad range of experience in state-of-the-art

combined cycle and co-generation projects. In the co-generation sector, METKA delivers solutions which are optimized to

meet specifc project needs, whether for a new district heating plant or the upgrading of a large industrial facility.

With over 50 years of experience, and the resources to execute complex co-generation projects, METKA is a reliable partner

for utilities, industrial customers and local communities.

Experience in large scale cogeneration power plants

METKA has successfully completed a major co-generation project for Aluminium of Greece, the largest of its kind in Europe. The

334 MW Combined Heat and Power (CHP) Plant is located at the site of the most important vertically integrated alumina and

aluminium production complex in the region.

The CHP Plant operates with natural gas, and produces steam for the alumina production process, as well as electricity which

is exported to the national grid with signifcant improvement to the overall environmental performance of the production

complex.

Fundamental design requirements included:

High reliability of the steam supply to the alumina process. This is critical since interruption of the steam supply can lead

to severe damage and extended shutdowns of the plant.

Operational fexibility. The CHP plant is designed to meet the electricity and steam demands of the production complex

under a wide range of operational modes.

Steam quality. The requirement is for the cogeneration plant to deliver superheated HP and MP steam at precisely

defned pressure and temperature.

Operational independence. The CHP plant will produce enough electrical power to fulfll the needs of the production

complex so that can work independently of the national grid if necessary

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Cogeneration & OnSite Power Production | July - August 2013 www.cospp.com2

Contents Volume 14 Number 4July-August 2013

12

12 Promoting biogasse cogen in Pakistan Pakistan would gain much if it greatly scaled up its cogeneration fred by biogasse, the sugar mill by-product. But is its new plan to do so more promising than previous

failed initiatives?

By Rahimullah Yusufzai and Robert Stokes

20 Biomass-fred CHP plant optimization Flue gas condensing and combustion air humidifcation can beneft the operations of a cogeneration/ CHP plant. Using a wood-burning facility in Sweden as an example, these

processes are shown to help optimize operations over a yearly cycle.

By Daniel Jedfelt, Risto Etelaho and Tarja Korhonen

26 Growing popularity of self-generation in the UK ENER-G reports an acceleration in the uptake of its pay-as-you-save discount energy purchase scheme in the UK, and more businesses are warming to the idea of green power

self-generation.

By Richard Baillie

39 CHP in Belgiums Flanders Over a period of 20 years, CHP in Flanders has evolved from a marginal technology, primarily serving the process industry, to an important contributor to the Flemish energy

system. How the sector developed over that time-frame is explored, and what the future

may hold is pondered.

By Erwin Cornelis and Kaat Jespers

46 Water/steam chemistry: HRSG protection A core part of many modern cogeneration/CHP units is the heat recovery steam generator (HRSG). However, there is concern that the industry is ignoring fow-accelerated corrosion in

HRSGs, which are particularly susceptible, and is doing so at its peril.

By Brad Beucker

FeaturesCw w w. c o s p p . c o m



In Association With

July - August 2013

PAKISTAN ONCE AGAIN TURNS TO BIOGASSE COGEN n SELF GENERATION TAKES HOLD IN UK n YOUR HRSG AND ADRESSING THE FAC CORROSION ISSUE

n FLANDERS 20-YEAR LOVE AFFAIR WITH COGENERATION n OPTIMIZATION AT AN INDUSTRIAL CHP FACILITY IN PORTUGAL n GUIDE TO POWER-GEN BRASIL

Biomass CHP: A how-to guide to optimize operations

DIRECTORY ISSUE 2013

Cover photograph: The Moskogen biomass-fred CHP plant provides

90% of the district heating consumption in the city of Swedish

city of Kalmar. See the feature article staring on p.20. PHOTO: KALMAR ENERGI

1307cospp_2 2 7/18/13 4:40 PM

www.cospp.com

ISSN 14690349

Chairman: Frank T. Lauinger

President/CEO: Robert F. Biolchini

Chief Financial Offcer: Mark C. Wilmoth

Group Publisher: Glenn Ensor

Chief Editor: Dr. Heather Johnstone

Managing Editor: Dr. Jacob Klimstra

Production Editor: Mukund Pandit

Consulting Editor: David Sweet

Contributing Editor Steve Hodgson

Design: Keith Hackett

Production Coordinator: Kimberlee Smith

Sales Manager: Natasha Cole

Advertising:

Natasha Cole on +1 713 621 9720

or [email protected]

Editorial/News contact:

Diarmaid Williams,

e-mail: [email protected]

Published by PennWell International Ltd,

The Water Tower,

Gunpowder Mill, Powdermill Lane,

Waltham Abbey, Essex EN9 1BN, UK

Tel: +44 1992 656 600

Fax: +44 1992 656 700

e-mail: [email protected]

Web: www.cospp.com

Published in association with the World Alliance for Decentralized Energy (WADE)

2013 PennWell International Publications Ltd. All rights reserved. No part of this publication may be reproduced in any form or by any means, whether electronic, mechanical or otherwise including photocopying, recording or any information storage or retrieval system without the prior written consent of the Publishers. While every attempt is made to ensure the accuracy of the information contained in this magazine, neither the Publishers, Editors nor the authors accept any liability for errors or omissions. Opinions expressed in this publication are not necessarily those of the Publishers or Editor.

Subscriptions: Copies of the magazine are circulated free to qualifed professionals who complete one of the printed circulation forms included in the magazine. Extra copies of these forms may be obtained from the publishers. The magazine may also be obtained on subscription; the price for one year (six issues) is US$133 in Europe, US$153 elsewhere, including air mail postage. Digital copies are available at US$60. To start a subscription call Omeda Communications at +1 847 559 7330. Cogeneration and On-Site Power Production is published six times a year by Pennwell Corp., The Water Tower, Gunpowder Mill, Powdermill Lane, Waltham Abbey, Essex EN9 1BN, UK, and distributed in the USA by SPP at 75 Aberdeen Road, Emigsville, PA 17318-0437. Periodicals postage paid at Emigsville, PA. POSTMASTER: send address changes to Cogeneration and On-Site Power Production, c/o P.O. Box 437, Emigsville, PA 17318.

Reprints: If you would like to have a recent article reprinted for a conference or for use as marketing tool, please contact Rhonda Brown. Email: [email protected]. Tel +1 866 879 9144, extn 194 or direct line +1 219-878-6094.

Printed in the UK by Williams Press Ltd on elemental chlorine-free paper from sustainable forests.

Member, BPA Worldwide

www.cospp.com

39 20

28

Project Profle

28 Optimization of industrial CHP in Portugal

The operators of a CHP plant at

a large petrochemcial facility in

Portugal were struggling to run the

plant in the most economic way

because of the requirement for

high operational fexibility, liquidity

of the cost and constantly varying

site demands. We fnd out how

this issue has been successfully

resolved.

By Joo Coelho and Pascal Stijns

6 Editor Letter

8 Insight

10 WADE Comment

54 WADE pages

91 Diary

92 Advertisers index

Regulars

An international directory of the key

companies in the felds of cogeneration and

on-site power generation.

58 Directory index

59 Product & services listing

69 A-Z company listing

Directory

1307cospp_3 3 7/18/13 4:41 PM

1307cospp_4 4 7/18/13 4:41 PM


1307cospp_5 5 7/18/13 4:41 PM

Editors Letter


The heat is on

This editors letter is not about a

famous 1980s song but about new

opportunities for cogen/CHP and

on-site power production. This June,

Maria van der Hoeven, executive director of

the International Energy Agency (IEA), cited

its recent report by stating that in fve years

time, 25% of the worlds electricity supply will

come from renewable sources. This will be

predominantly the result of a steady growth

in the installed capacity of wind turbines and

photovoltaic panels. Generators based on

biomass and biogas are also expected to

contribute to the increase.

Reducing the use of fossil fuels and the

associated emissions is the main reason that

renewable energy is now globally promoted.

Government-introduced incentive schemes

compensate investors in renewable energy

sources in case of negative fnancial yields. As

a result, some countries have so many wind

turbines and solar panels that the traditional

electricity generators are at times almost

completely excluded from the grid. Examples

are found in Germany and Denmark.

Nevertheless, the intermittency of

renewables ensure that fuel-based power

plants still have to fll the gaps when the sun

sets, the wind subsides or demand changes.

Traditional power plants running on coal,

for example, lack the necessary fexibility

for this. Moreover, if only 1 GW of power from

dispatchable power plants remains on line

for a total demand of 10 GW, a substantial

number of generating units should deliver

this 1 GW. Having just two larger units of each

500 MW in parallel providing this 1 GW could

result in insuffcient reliability. Distributed

generators, in contrast, have the right capacity

and the right properties to provide fast ramping

up and down of their output to enable the

application of renewable electricity sources.

Policy makers often focus on making

electricity production sustainable. Yet,

there is a substantial demand for heat in

the world, not only for space heating but

also for sanitary water and for industries.

Cogeneration systems have proven to

provide electricity and heat at very high fuel

effciency, sometimes exceeding 90%.

If the demand patterns of power and

heat do not fully coincide, heat storage

offers a solution. Storing heat in water tanks is

relatively cheap. The nice thing now is that in

times of surplus electricity from renewables,

and consequently low electricity prices,

heating coils can easily be used to heat

the water in such storage tanks. The extra

investment costs are almost negligible. This

can be seen as an integrated solution to

make district heating systems and stand-

alone cogeneration units even greener.

Distributed electricity generation can

also help to stabilize voltage by injecting

reactive power into the grid. Reactive power

needs are best solved locally to avoid high

transmission losses.

Ultimately, the prediction by the IEA

about a gradual increase in the fraction of

renewable electricity sources is a positive

message for cogeneration and on-site

power production. The utilisation factor of

such generators might decrease somewhat

compared with that in the past, but a

reduction in global fuel consumption has

always been the intention.

Nevertheless, distributed generation

and cogeneration based on units of a

moderate power capacity each will be

an indispensable link in any future power

supply systems.

Jacob Klimstra

Managing Editor

P.S. Dont forget to visit www.cospp.com to

see regular news updates, the current issue

of the magazine in full, and an archive of

articles from previous issues. Its the same

website address to sign-up for our fortnightly

e-newsletter too.

Dr. Jacob Klimstra

1307cospp_6 6 7/18/13 4:41 PM

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Insight

Sydney aims for major trigeneration plan

Imagine a major global city planning

to cut its (mainly coal-fred) carbon

emissions by 70% by 2030, through

the development of a co-ordinated,

decentralized network of gas and

refuse-fuelled trigeneration schemes.

That city is Sydney, Australia, which

has just adopted a Trigeneration

Master Plan to add fesh to the bones

of its 2008 Sustainable Sydney 2030

the Vision report.

The original vision set out a path for

reaching the carbon reduction target

through the use of a wide range

of measures improving energy

effciency, encouraging people to

cycle and walk, utilizing waste as a

resource, converting non-recyclable

waste to energy, recycling water,

renewable energy and crucially

a decentralized energy network,

powered by a series of trigeneration

schemes.

Central to Sydneys vision are what

it calls green transformers the

co-location of trigeneration plants

with waste collection/treatment and

recycled water treatment plants to

make low-carbon precincts. These

transformers expected to deliver the

greatest reduction in greenhouse gas

emissions.

So far, so ambitious. The city aims

to replace electricity supplied to city

buildings from remote, coal-fred,

electricity-only power stations; with

power from local, smaller-scale, gas

engine-based trigeneration plants

that will also feed hot and, using

absorption chilling equipment,

chilled water around local thermal

energy networks. Buildings in Sydney

need cooling as well as heating

hence trigeneration as opposed

to cogeneration. Aside from system

effciency gains, the new infrastructure

will also eliminate the losses caused

by transmitting coal-fred electricity

into the city from remote generating

plants.

Some 350 MWe of new trigen

schemes will eventually be needed

to deliver the planned carbon

reductions. Individual schemes are

likely to be based on gas engines,

will each be less than 30 MWe in size,

and will be developed by a variety

of energy services agreements. The

frst of these low-carbon precinct

agreements was signed in March

this year for plant to serve buildings

being developed in the Broadway

area of the city. Sydney acknowledges

that four-ffths of the buildings to be

present in the City in 2030 are already

built, so the local energy schemes will

have to connect existing, as well as

new buildings.

Theres still a long way to go in

Sydney, but the city is beneftting from

experience gained in London by its

Chief Development Offcer for Energy

& Climate Change, Allan Jones, who

previously did this type of work for the

London Climate Change Agency, in

pre-recession days. The UK capital

continues to work towards a target of

a quarter of its energy to be supplied

from decentralized sources by 2025. A

London Heat Map has been drawn-up

to highlight the best opportunities

for new cogeneration (less need for

cooling in London) schemes.

In both cities, the involvement of

private sector funding is, of course,

crucial. Costs for establishing new

district energy infrastructure mainly

underground hot and chilled water

pipelines can be very high indeed.

The standard practice is for local

government to commit its own

buildings to provide baseloads

for new district energy schemes;

simultaneously persuading private

sector operators to do the same.

So will Sydney realise its ambitions

for new decentralized energy

schemes? Theres no doubting the

scale of the ambition shown in the

plans. The city seems to have many of

the ingredients for success a bold,

ambitious plan, solid support from

local government, and the interest of

the private sector.

The case for cogeneration and

trigeneration is, of course, well-

understood by readers of COSPP. In

many cases, the effciency gains from

replacing old, ineffcient, remote and

electricity-only power generation with

modern, highly effcient, modular and

local technology are high indeed.

Whether high enough to attract

suffcient investment to fund initial

capital costs the City of Sydney is

currently fnding out.

Steve Hodgson

Contributing Editor

Steve Hodgson

1307cospp_8 8 7/18/13 4:41 PM

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Comment

For many reasons, historians

consider the city of Boston

in the British Colony of

Massachusetts, the birthplace

of the American Revolution.

While the US recently celebrated

Independence Day on 4 July in

honour of the ratifcation of the

Declaration of Independence, there

were in fact many other key events

and forces that moved the Colonies

to the tipping point where they were

willing to risk their lives and property

rather than continue under British

rule.

On December 16, 1773, the Sons

of Liberty in Boston rose up against

taxation without representation

and destroyed the cargo of the

East India Company by dumping

342 chests of tea into Boston Harbor.

Today, we may think of the Tea

Party as a conservative political

movement, however, for over 200

years it has been a symbol of

revolution and the ability of the

people to triumph against the forces

of government. Boston was also the

home of a silversmith and patriot

named Paul Revere, who became

famous for his midnight ride warning

of an imminent attack by the British

and for the intelligence strategy of

communicating whether the troops

were coming by the land route or

by sea across the Charles River. He

instructed the sexton of the North

Church to light one lantern in the

steeple to signal the land route and

two if they were coming by sea.

While Boston may be steeped

in revolutionary war history, it will

also be the site for discussion of

a much more modern revolution

and power struggle that is

taking place in the way that we

produce and deliver energy. From

19 November to 21 November, WADE

will be meeting with the Northeast

Clean Heat and Power Initiative

for a discussion of decentralized

energy policy, technology and

commercial opportunities.

Among the notable speakers and

guests will be Christoph Burger,

who along with Jens Weinmann,

authored The Decentralized Energy

Revolution, Business Strategies for

a New Paradigm. As they explain:

The value proposition offered by

decentralized generation differs

fundamentally from the current

energy system confguration: It turns

the one-way street from producer

to consumer upside-down. It

enables every household, as well

as all types of commercial and

industrial consumers, to become

active agents and autonomous

providers of energy, either for [their]

own consumption purposes or

to generate revenues by feeding

electricity into the central grid.

While this revolution is driven

not only by a search for self-

determination and control, it is also

fueled by a need for clean, reliable

and affordable electricity. The

developments in fossil and renewable

power generation technology and

in the production of abundant

supplies of natural gas are forcing

all consumers to take a fresh look at

the centralized grid model of power

delivery and question whether there

are better solutions for our energy

future. In the aftermath of Hurricane

Sandy, the need for a more resilient

and robust power system has never

been greater, and decentralized

energy technologies are in the lead

as potential answers.

We urge you to come to Boston

for this groundbreaking meeting

and dialogue and to meet with

customers, colleagues, friends and

industry leaders from the region

and around the globe. For those

with a thirst for knowledge, we will

be holding a technical workshop

on CHP and trigen systems at the

Harpoon Brewery, including a tour of

their CHP facility (and opportunities

for tasting the local brew).

We will also be discussing a

range of cutting edge issues and

topics, including: microgrids, smart

grids, community energy, distributed

renewables and intermittency,

innovative fnancial and business

models, the latest on policy issues

such as interconnection net

metering and standby charges, and

a global roundup on decentralized

energy developments around the

world. In addition, there will be

opportunities for quick pitches of

new and exciting technologies and

projects to this global audience.

We look forward to seeing you

in Boston and enlisting you in the

revolution. Please go the WADE

website, www.localpower.org for

more details or contact me if you

have any questions on how you and

your organization can get involved

with this conference.

David Sweet

Executive Director, WADE

[email protected]

David Sweet

Theres going to be a revolution

1307cospp_10 10 7/18/13 4:41 PM


1307cospp_11 11 7/18/13 4:41 PM


Promoting biogasse cogeneration in Pakistan

After many false

starts and delays,

Pakistan appears

to be ready to

expand its bagasse-based

cogeneration output.

It was in March, ahead of

the countrys general election,

which saw the frst handover

of one elected government to

another, that a policy to scale

up cogeneration through

the use of sugar mills was

announced by the cabinets

Economic Co-ordination

Committee. Pakistan is aiming

to persuade its 83 sugar mills

to start producing electricity

on a commercial basis, The

expansion would build on the

experience of some pioneering

cogeneration projects already

built in Pakistans sugar sector,

which have demonstrated

such development is feasible.

The incentives planned

by the government include

Pakistan would gain much if it greatly scaled up its cogeneration fred by this sugar mill

by-product. But is its new plan to do so more promising than previous failed initiatives,

ask Rahimullah Yusufzai and Robert Stokes

Bagasse,sweet success this time round?

Sugarcane being crushed in a rudimentary machine in Charsadda, a rural area near Peshawar, Khyber Pakhtunkhwa Credit: Mohammad Sajjad

1307cospp_12 12 7/18/13 4:41 PM

www.cospp.com Cogeneration & OnSite Power Production | July - August 2013 13


an attractive upfront power

purchase tariff and help

towards capital fnancing.

A widespread sense of

urgency exists among most

political parties in Pakistan to

overcome bureaucratic red

tape and make use of every

resource to generate electricity

to meet the acute shortages

that are causing social unrest,

affecting industrial production

and slowing down the

economy.

For this reason the new

policy framed within

the Framework for Power

Cogeneration 2013 Bagasse

and Biomass, itself an annex to

the governments renewable

energy policy is expected

to be continued in the new

government of Mohammad

Nawaz Sharif and his Pakistan

Muslim League (N) party,

which came to power in the 11

May election.

One of the frst things that the

two-time former premier Sharif

did when he came to power

and even before assuming the

position of prime minister was

to set up a team of experts to

come up with short and long-

term proposals to tackle the

countrys crippling energy

crisis. Plans to diversify the

sources of energy also came

under discussion because the

rising prices of fossil fuels are

hitting the already depressed

economy hard.

A few days later, Sharifs

younger brother Shahbaz

Sharif called a meeting of

government offcials, sugar

mills owners and experts to

discuss proposals for electricity

generation from bagasse, or

crushed sugarcane. Shahbaz

Sharif is the chief minister of

Pakistans most populous

and economically advanced

province, Punjab. He gave

a committee of government

offcials and members of the

Pakistan Sugar Mills Owners

Association (PSMA) until 29

May to fnalise and submit a

plan to this effect.

Previous attempts

However, this is not the frst

time that the Sharif brothers

and others in power have

focused attention on bagasse

in a bid to diversify Pakistans

energy sources. Four years

ago, Shahbaz Sharif invited

sugar mill owners to work out

a plan for utilizing their plants

and waste feedstock to fuel

the cogeneration of electricity

and heat on a commercial

basis to meet the growing

demand for energy. However,

discussions stalled over issues

such as setting the tariff for

the electricity that the mills

would produce and sell to

the state-owned Water and

Power Development Authority

(WAPDA).

Today, the team of the

Pakistan Muslim League (N),

headed by Nawaz Sharif in

the central government, and

Shahbaz Sharif in the Punjab,

appears keen to use every

resource to produce more

electricity and stave off protests

by consumers. However,

unluckily for them, the general

election took place when the

weather becomes hot and

the demand for electricity

increases. The two brothers

were installed in power in

the frst week of June when

the temperatures in most of

the country rise to over 40C

and shortfalls in power reach

phenomenal levels.

On 27 May, for example,

the total generation from

all sources, including hydro,

thermal and nuclear, was

10,500 MW against a demand

of 17,500 MW. Inevitably a

series of load-shedding power

cuts followed.

Promising option

The bagasse option does have

promise, however. Pakistan

is the ffth largest sugarcane

producer in the world. Forty-

fve of its 83 sugar mills are

located in Punjab, with most

of the remaining mills in Sindh

province and some in Khyber

Pakhtunkhwa, which borders

Afghanistan and was formerly

called North West Frontier

province. The total installed

sugarcane crushing capacity

in the country is around

65 million tonnes per season.

Pakistans annual sugar

production is reported to be

5 million tonnes.

In addition there are

19 distilleries that process

the molasses by-product

1307cospp_13 13 7/18/13 4:41 PM



into ethanol. These have a

combined capacity of around

400,000 tonnes. Until 2005 most

of the molasses was exported

but the situation changed as

companies adjusted to the

demands of the market and

began exporting ethanol as a

value-added product instead

of molasses. Thus, some could

now be used as a domestic

power feedstock.

All the sugar mills have

an in-house bagasse-based

power generation capability

but they use ineffcient boilers

and primitive back-pressure

small turbines to generate

power. A Punjab government

offcial has said a sugar mill

produces on average of

23 MW of electricity to meet

its energy requirements.

Hussain Ahmad Siddiqui,

former chairman of the State

Engineering Corporation,

opined that a sugar mill

crushing 2000 tonnes of

cane daily could, if the waste

is effectively harnessed,

generate 11 MW of electricity.

He said a mill could use 2 MW

for its own consumption and

sell the remaining electricity to

the grid.

According to government

offcials and experts, it could

be possible to produce

20003000 MW of electricity

from local bagasse during the

sugarcane crushing season,

which normally begins in

October and continues for

about 120 days. However, last

year the former chief offcial for

the Ministry of Water and Power,

Secretary Zafar Mahmood,

was more conservative. He

said Pakistan could generate

1500 MW of electricity daily by

using bagasse once the sugar

mills were able to acquire

effcient machinery. Other

government offcials, such as

Jehanzeb Khan, the secretary

of the Punjab governments

energy department, feel a

more realistic fgure would be

8001000 MW to begin with,

which could be increased

gradually to 15002000 MW.

Mill owners have said

rice husk, cotton and wheat

stocks, coal and other locally

available raw materials could

be used to generate electricity

during the rest of the year.

A more appealing aspect

of power generation by sugar

mills would be to bring much-

needed electricity to rural

communities because the mills

are mostly in those areas. The

power would also be available

during the winter, when

hydropower is reduced due

to the decreased fow of rivers.

As one offcial put it, it would

be nice to complement the

countrys power generation

by making available bagasse-

generated electricity to the

national grid at a time when

there is less production of

hydroelectric power, which

is a major power source in

Pakistan.

Slow progress

Although successive

governments in Pakistan

began paying attention to

the potential of bagasse

producing electricity many

years ago, the progress in

making this happen has

been slow. In November

2005, the cabinet Economic

Co-ordination Committee

approved plans for increasing

the existing capacity of the

cogeneration power plants to

700 MW but, as with the more

recent arguments on the issue

in Punjab, the sugar industry

was not keen as it wanted a

higher tariff for power sales to

cover the cost of investment

for upgrading their boilers and

related machines.

In January 2006, the

government released its

National Policy for Power

Co-Generation by Sugar

Industry, which offered

incentives to sugar mills.

However, only one major

company showed interest,

Fatima Sugar Mills. It wanted to

build a dual-fuel power plant

to generate 125 MW, using

natural gas as a secondary

fuel. The project, however, did

not take off. The policy was

revised in January 2008 in

consultation with the PSMA,

with government backing for

a series of 60+ MW projects to

produce a total of 1000 MW on

a commercial basis by 2010

and doubling the capacity by

2012, yet Fatimas project still

stalled.

In June 2008, the National

Electric Power Regulatory

Authority (NEPRA) announced

an indicative tariff of

US$0.083/kWh for a period

of 30 years of a projects life.

The PSMA however found it

unacceptable. Subsequently,

NEPRA offered an upfront tariff

of $0.093/kWh, but the PSMA

wanted $0.11/kWh.

These failures represent

one reason why the outgoing

Pakistan Peoples Party-led

coalition government has

been criticised for neglecting

the energy sector during its

fve-year rule after the 2008

general election. But on

8 February, towards the end

of its rule, Chaudhry Ahmad

Mukhtar, the water and

power minister, presided over

a meeting in Islamabad on

the fast-track development

of bagasse-based power

generation projects. It aimed

Villagers in Charsadda, in Khyber Pakhtunkhwa, carrying sugarcane stalks (left) and bagasse (right) Credit: Mohammad Sajjad

1307cospp_14 14 7/18/13 4:41 PM

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to approve a draft national

policy for cogeneration by

utilising bagasse and biomass

the policy released in March.

A delegation headed by

PSMA chairman Shunaid

Qureshi also attended

the meeting and received

assurances that a reasonable

upfront tariff would be given

for fast-track projects and

the producers would have

the option to sell electricity

to distribution companies

working under WAPDA or the

Central Power Purchasing

Agency.

The meeting heard that

around 12 million tonnes of

bagasse annually generated

by the sugar mills should

be used for cogeneration

rather than being wastefully

incinerated. It would reduce

imports of costly furnace oil

and save foreign exchange,

the meeting also noted. It has

been calculated by experts

and the PSMA that $500 million

could be saved in fuel costs

by consumers if 2000 MW is

generated from bagasse. The

foreign exchange savings for

the country through the use of

this indigenous fuel in place of

imported heavy fuel oil is said

to exceed $1 billion annually.

Immediately after the

election, NEPRA approved

PKR10.5 ($0.11) per kWh as

an upfront tariff for sugar mills

utilising bagasse, and the

Alternate Energy Development

Board was tasked to progress

bagasse-based projects under

the governments umbrella

renewable energy policy. A

NEPRA spokesman said at

the time that the move could

encourage sugar mills to

generate around 1500 MW

of electricity on a fast-track

basis. Government offcials

and experts have calculated

that the cost of hydropower is

PKR2.50 ($0.02) per kWh while

it is around PKR5 ($0.5) per

kWh if gas is used to generate

power. Electricity generated by

standard thermal plants cost

PKR1418 ($0.140.18), while

diesel-based generation costs

PKR2328 ($0.230.28) per kWh.

Scepticism remains

Some of the sugar mill owners

remain sceptical of the

governments promises and

wish they had been made

earlier. Iskander Khan, a director

at the privately-owned Premier

Sugar Mills, Frontier Sugar Mills

and Chashma Sugar Mills, in

Khyber Pakhtunkhwa, says if

NEPRA had offered $0.11 in

2008, the sugar mills would

have started operations by

now, saving precious foreign

exchange due to reduced

demand for furnace oil.

Khan also says his aim

is to make electricity the

main product and sugar

the by-product of the sugar

mills in due course. We are

producing enough electricity

from bagasse to run our sugar

mills and would be happy to

produce more by installing

pressure boilers, provided the

tariff being offered is attractive,

he says. Lamenting the missed

opportunities, he adds that

the new government should

streamline its policies and

adhere to decisions taken in

meetings with the corporate

sector to overcome the crises

facing the economy.

Javed Kiyani, who served

as PSMA chairman from

201012, is also critical of

the government for failing

to offer a reasonable tariff

to the sugar industry in

the past. The previous

government was interested

in projects [involving] rental

power and those proposed

by independent power

producers, he says, as

those in authority could

demand commissions to fll

their pockets. There was little

interest in cheaper sources of

energy and renewable energy

projects. He also points out

that Pakistan has lacked a

comprehensive sugar policy

while neighbouring India

devised one many years ago,

increasing sugar exports and

encouraging sugar mills to

produce 3500 MW of electricity

from bagasse and biomass.

According to Kiyani,

Pakistan had the potential

to substantially increase

bagasse-generated electricity

from the current 225250 MW

by pursuing realistic policies.

From the 48 million tonnes

of sugarcane that is crushed,

Pakistan produces 15 million

tonnes of bagasse, he says.

One tonne of steam is

generated from two tonnes

of bagasse. By installing

high-pressure boilers in place

of low-pressure [types], our

sugar mills would be able to

effciently use bagasse for

electricity generation and sell

it to the national grid.

When reminded that NEPRA

had offered a better upfront

tariff to the sugar mills owners

by raising it from $0.098/

kWh to $0.11, Kiyani says the

20% devaluation of Pakistani

currency and the rising costs

of machinery mean that the

tariff had to be raised to make

it competitive and attractive to

the owners.

Kiyani and other mills

owners also complain that

they can no longer sell their

surplus electricity to the

national grid because NEPRA

last year instructed the mills to

frst obtain a power generation

licence. More than 200 MW of

our surplus electricity is being

Pakistans neighbour India can offer good practice on bagasse cogen if the new government succeeds in improving Indo-Pakistani relations. Here trucks unload sugarcane at the Khatauli sugar mill in Uttar Pradesh, India, which generates renewable heat and power from the waste bagasseCredit: Land Rover Our Planet (Flickr)

The high-pressure boilers of the fagship Almoiz bagasse-fred cogeneration plant Credit: D.I. Khan, AEDB

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wasted as the mills couldnt

sell it last year, he says, adding

that mill owners did not apply

for generation licences as they

frst wanted the tariff issue to be

sorted out with NEPRA.

Good reception

Pakistans progress towards

a more supportive policy for

cogeneration in general and

bagasse or biomass co-fred

projects in particular has been

welcomed by international

groups promoting these forms

of heat and power production.

As our own reports

show, theres an abundant

opportunity for the wider

use of bagasse-based

cogeneration in sugarcane-

producing countries and to

contribute substantially to high

effciency energy production,

but this potential remains

largely unexploited, says Syed

Hassan, programme director

at the World Alliance for

Decentralized Energy (WADE),

which works to increase the

market share of cogen and

on-site renewables in the

global power mix.

Hassan summarises the

Pakistani situation in this way:

The governments framework

for power generation based

on bagasse offers a very

attractive power purchase

agreement, high price per

unit, tax holidays, accelerated

depreciation, almost 20%

return on investment, and

import duty exemption on

plants and equipment. The

government agencies are

also being directed to look at

assistance with fnancing and

feasibility studies.

He adds that the time is

ripe to raise global awareness

of what Pakistan has to offer

in this regard. Bagasse and

biomass power generation

offers great potential for global

vendors, says Hassan.

Opportunities

Pakistan does have native

companies that are more than

capable of making equipment

for cogeneration and on-site

power plants that use

bagasse, biomass or biogas

produced from molasses. They

include Descon Engineering, a

Karachi-based multinational,

which has worked worldwide

to help equip cogeneration

projects.

However, if the new policy

unlocks new domestic

projects and results in the

upgrading of older generating

equipment, there will be

greater opportunities for

foreign suppliers or designers

of equipment such as stokers,

boilers and steam turbines,

and for consultants of various

kinds.

As of 31 January, seven

cogen proposals linked to

sugar mills and totalling

585 MW were on the table,

according to the private

power and infrastructure

board of Pakistans Ministry

of Water and Power, with the

majority in Punjab These are:

JDWP/JSMLs 80 MW JDW

project near Rahim Yar Khan;

the Ramazan Energy/Sharif

Groups and Ramaz Sugar

Mills 100 MW plant planned

for Bhawana; Janpur Energy/

RYK Mills 60 MW scheme

at Rahim Yar Khan; Fatima

Energy/Fatima Sugar Mills

100 MW proposal for

Sanawan; CPL/CSMLs

Chistia 65 MW project at

Sargodha; Dewan Energys

120 MW plan for Dewan City

near Sujawal in Sindh province;

and Etihad Power Generations

60 MW facility for Rahim Yar

Khan.

One UK turbine maker told

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currently consider Pakistan

because of security concerns.

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However, foreign frms with recent direct

experience of selling into the country

include Brazilian equipment maker NG

Metalurgica, which in 2005 made an HB 420

model 9 Type B multi-stage steam turbine

for the Almoiz bagasse cogen project,

a 27-MW facility generating power for

Lahore-based Almoiz Industries Paharpur

sugar mill, in Khyber Pakhtunkhwa.

The output of the NG Metalurgica back-

pressure turbine is 12 MW, with rotation

speeds of 9250 rpm for the turbine and

1500 rpm for other equipment. The steam

conditions are: a temperature of 480C,

an inlet pressure 4500 kPa and an exhaust

pressure of 300 kPa.

A separate condensing extraction

turbo-generator of 15 MW for Almoiz

was made in 2006 by the Guangzhou

Guangzhong Enterprise Group of

Guangzhou, China.

The Almoiz project demonstrates what

scope there is to do business in Pakistan

without necessarily being there. Descon

Engineering, for example, provided two

80 tonnes/h, 6500 kPa high-pressure

boilers for the plant. These were based

on the latest designs from Eckrohrkessel

of Berlin, Germany, which licenses out

engineering designs to manufacturers

worldwide. Similarly, ipro Consulting of

Kalsruhe, Germany, was the engineering

consultant on the project.

Det Norske Veritas Certifcation of

Norway has conducted validation

analysis and reports for bagasse and

biomass cogeneration and on-site power

production in Pakistan, and Ecoenergy

of Sao Paolo, Brazil, has provided

carbon market consultancy for bagasse

cogeneration in Pakistan and South

America.

First Climate of Zurich, Switzerland, a

world-leading carbon asset management

and consultancy company, was involved

in a recent project that established

cogeneration from biogas produced

from molasses left over in sugar refning at

Shakarganj Mills in Jhang, Punjab. While,

GE Jenbacher of Austria, has supplied

eight 1 MW JGS320 gas generators

and the gas dehumidifcation unit for

the project. A desulphurisation unit to

sweeten the gas came from Denmarks

ScanAirclean.

Trailblazer projects such as Almoiz

and Shakarganj could encourage other

Pakistani sugar mills to consider new

or upgraded cogeneration plants as

part of the new government policy. And

international suppliers and consultants

may be encouraged to participate in

such cogen projects in Pakistan because

they know that external development

agencies are likely to support the projects.

These include international development

fnancial institutions such as the Asian

Development Bank, which already has

in place incentives that include debt

fnancing and meeting part of the cost

of initial feasibility studies. Its priorities for

co-operation and investment in Pakistan

include the all-important energy security.

Rahimullah Yusufzai and Robert Stokes

are freelance journalists specializing in

energy matters. Rahimullah is based in

Peshawar.

This article is available

on-line. Please visit

www.cospp.com

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Biomass-fred CHP plant optimization

Various fees, taxes

and incentives

facing power

plant owners have

given them an increasing

interest in the effcient

operation of their facilities in

general. Even though these

stick-and-carrot stimuli vary

from country to country, the

trend is towards the better

use of renewable resources.

One way to achieve this is

to improve the economics

of operating a plant, which

depend mainly on the

energy sold compared to

operating costs.

Swedish utility Kalmar

Energi has turned to fue gas

condensing and combustion

air humidifcation to optimize

the operation of its biomass-

fred CHP plant in Moskogen.

Experience there has shown

the company how the latter

process enhances the heat

recovery from the former. But

when is their employment

economically justifed, what

are the operating hours of

these processes at Moskogen

and how do they affect the

plants capacity profle?

The CHP plant

Kalmar Energi has been

operating Moskogen

since 2009. It comprises a

90 MWth bubbling fuidized

bed (BFB) boiler that produces

30 MW of electrical power and

85 MW of district heat. Bark,

forest residue and wood chips

are the main fuels, and its total

Flue gas condensing and combustion air humidifcation can beneft a CHP plant.

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Kalmar Energis Moskogen CHP plant provides about 90% of the district heating consumed in the city of Kalmar Credit: Kalmar Energi

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output is about 400 GWh of

district heating and 130 GWh

of electricity per year, providing

about 90% of the district

heating consumed in the city

of Kalmar.

When biomass or other

high-moisture fuel are fred, it

is quite common to boost the

effciency of a plant by using

fue gas condensing systems,

which can help to raise the

overall plant effciency to 110%

or more.

The heat effect of fue gas

condensing depends on the

fuel moisture content and

the temperature of the return

water in the district heating.

High fuel moisture content and

low return temperature of the

district heating water enable a

high heat effect, which makes

fue gas condensing very

interesting in an economic

sense.

Figure 1 shows how a

greater content of moisture in

the fuel means the fue gas

contains more moisture and

has a higher dew point. The

process of condensing fue

gas produces hot water at a

dew point temperature that

again depends mainly on the

fuel moisture content.

Biomass-fred boilers

produce fue gas that contains

plenty of heat (mainly latent

heat) because the moisture

content of the fuel is relatively

high. As the fue moisture is

in a vapour form, it has high

enthalpy, which is measured

in kJ/kg.

Energy is released when the

water vapour condenses, a

process that occurs when the

temperature of the fue gas

falls to that of the water dew

point, in other words when the

relative humidity is 100%. About

1 m3 of condensed water per

hour corresponds to 1 MW of

recovered heat.

In the case of biomass-

fuelled plants the temperature

of the hot water produced

in the fue gas condensing

process is typically 6570C.

Although a CHP plant

commonly uses this hot water

to raise the temperature of

the return water in the district

heating system, there can be

other consumers of the heat,

such as large-scale industrial

processes. So the higher the

temperature of the water

produced by the fue gas

condensing process, the more

energy can be transferred to

the district heating system.

Figure 2 shows how a

typical district heating systems

return water temperature

varies according to the heat

demand in the network. A

high return temperature limits

heat transfer from the fue

gas condensate to the district

heating water.

In the case of Kalmar, the

high temperature of the return

water in summer occurs when

the CHP plant is shut down

and the heat plant provides

hot water to the Moskogen

plant. Figure 3 shows the

approximate heat recovery

potential at Moskogen as

the temperature of the return

water changes.

A combustion air humidifer

uses waste heat from the fue

gas to raise the temperature

of the combustion air, which

allows additional moisture

to transfer into it. After the

humidifer, the relative moisture

content of the combustion air

can reach 100%.

Figure 4 shows how the

addition of moisture to the

combustion air which

increases the fue gas moisture

content increases the

condensing heat effect.

Combustion air

humidifcation is an effective

method to increase heat

production. However, its use

requires some optimization of

the operation of a CHP plant

because the increase in the

condensing heat effect can

reduce the electrical effect.

Two-stage scrubbing

At Moskogen, an electrostatic

precipitator removes particles

from the fue gas coming

from the BFB. The fue gas

then passes to a two-stage

condensing scrubber. A frst

washing process occurs in a

spray stage, with a packed bed

performing the fnal cleaning.

The scrubber removes oxides

of sulphur, ammonia slip and

any remaining particles.

Condensation takes place

in the scrubber, where the

condensate is pumped over

a packed bed layer. In the

packed bed, heat from the

water-saturated fue gas is

transferred to the condensate.

The condensate is continuously

pumped through a set of plate

Figure 1. The direct correlation between the moisture content of the fuel and the moisture level in the fue gas and its dew point temperature

Figure 3. The heat recovery potential as the temperature of the district heating return water at the Moskogen CHP plant changes

Figure 2. The variability in the return temperature of the district heating water at the Moskogen CHP plant over a year

1307cospp_22 22 7/18/13 4:41 PM


1307cospp_23 23 7/18/13 4:41 PM



heat exchangers to transfer

the heat to the district heating

return water its temperature

after the heat exchangers is

typically 60C.

After the fue gas condenser,

the district heating water

fows through the turbine

condensers and is heated to

the actual temperature set

point of the departing district

heating water, which typically

ranges from 85C to 100C.

Operational profle

Moskogen typically starts

up for the heating season

in September, when heat

demand is high enough for

the minimum load operation

of the boiler. The plant is in

operation through the entire

heating season, and typically

shuts down in early June, when

heat demand is too low for

operation at minimum load.

In winter, the heat effect

from fue gas condensing

amounts to nearly 30% of

the total plant heat effect.

Figure 5 shows how the plants

production of electricity and

district heat varied between

the plants startup in 2009

and summer 2012. The fgure

also displays the change in

the district heat effect from

fue gas condensing over the

same period.

Moskogen employs

combustion air humidifcation

most of the time, but not in

early autumn and late spring.

The CHP plant operates for

about 260 days annually, with

the duration of the scheduled

summer shutdown in the

region of 100 days.

Optimizing operations

The most important variable

for heat and electricity

production in a CHP plant is

the heat demand in the district

heating system, which in turn

depends on the weather. At

ambient air temperatures of

0C or lower, the heat demand

load is high enough to allow

full operation of the CHP plant,

the fue gas condenser and

the air humidifer.

This heat demand

decreases at higher ambient

temperatures, when the CHP

cannot run at full load. In this

situation there are alternative

ways to optimize the energy

production of the plant.

The most important

variables are the price

achieved for the electricity

sold and the cost of fuel. If the

ratio of the two is high enough,

it becomes proftable to limit

fue gas condensing and

keep up steam production

in the boiler. This enables full

electricity production, even

though the plants full heat

output potential cannot

be delivered to the district

heating system. Moskogen

is also equipped with a hot

water accumulator to enable

shorter term optimization

between heat and electricity

production.

The limitation of heat

recovery in the fue gas

condensing process is

carried out in steps. The frst

step involves turning off the

air humidifer. In the second,

condensate fow from the

condensing scrubber to the

heat exchangers is reduced

and the minimum heat output

from the fue gas condensing

is determined on the basis of

the maximum temperature of

the packed bed layer or the

minimum condensate fow of

about 5 m3/h.

The minimum condensate

fow is maintained to avoid the

concentration of solids in the

scrubber. It is also possible to

stop the condensate fow to the

heat exchangers, but then the

scrubber consumes expensive

city water for cooling and

makeup, so this is done only

at minimum load just before

plant shutdown. This strategy

avoids starting up other boilers

that use more expensive fuels,

such as dry wood powder.

Planning of the operation

takes place on a weekly basis.

Plans are reviewed daily and

adjusted for weather and

ambient temperature.

In summary

Thus in winter, the CHP plant

is operated at a full load with



in full operation. At this time

of year fue gas condensing

produces about 28% of the

plant heat effect. Without


the additional heat effect

would be slightly lower at 22%.

At the end of the heating

season, the operation of



is adjusted. When summer

approaches and heat

demand in the district heating

system decreases towards the

minimum load of the boiler,

fue gas condensing is limited.

The frst step is to turn off the

air humidifer, then reduce the

condensate fow.

Daniel Jedfelt is operation

manager at Kalmar

Energi Vrme AB, Sweden,

Risto Etelaho is product

manager at BFB Metso

Power Oy, Finland and

Tarja Korhonen is product

manager, Environmental

Systems, at Metso Power Oy,

Finland.

www.metso.com



www.cospp.com

0

5

10

15

20

25

30

35

35 40 45 50 55 60 65

Condensing heat efect, %

of plant heat efect

District heating return temperature, C

Efect of combustion air humidifcation

@50% fuel moisture content

Without humidier

With humidier

Figure 4. The temperature of the returning district heating water affects the condensing heat effect, with and without the use of a humidifer

0

10

20

30

40

50

60

70

80

90

100

1.8.2009

1.9.2009

1.10.2009

1.11.2009

1.12.2009

1.1.2010

1.2.2010

1.3.2010

1.4.2010

1.5.2010

1.6.2010

1.7.2010

1.8.2010

1.9.2010

1.10.2010

1.11.2010

1.12.2010

1.1.2011

1.2.2011

1.3.2011

1.4.2011

1.5.2011

1.6.2011

1.7.2011

1.8.2011

1.9.2011

1.10.2011

1.11.2011

1.12.2011

1.1.2012

1.2.2012

1.3.2012

1.4.2012

1.5.2012

1.6.2012

1.7.2012

District heating efect [MW]

Generator active power [M

W]

Turbine condenser district heat power[MW] Turbine electric power [MW]

Flue gas condenser power [MW] Total district heat power [MW]

Figure 5. The variability of the Moskogen CHP plants heat and electrical effects between 2009 and 2012

1307cospp_24 24 7/19/13 9:58 AM


1307cospp_25 25 7/18/13 4:42 PM


Growing popularity of self-generation in the UK

Co g e n e r a t i o n

specialist ENER-G

has seen an

a c c e l e r a t e d

uptake of its discount energy

scheme as the economic

downturn continues to hit

the UKs small-to-medium

(SME) enterprises and

organizations hard.

According to the company,

its pay-as-you-save Discount

Energy Purchase scheme,

which was pioneered in the

1990s, gives cash-strapped

organizations access to

energy-effcient combined

heat and power (CHP)

technology, without any

upfront investment. The cost of

the CHP system is paid for via

a competively-priced metered

energy charge.

ENER-G reported earlier this

year that it had now sold

more than half its small-

scale cogen systems to UK

business customers under

the scheme.

The discount energy

purchase concept is simple

and places virtually no risk on

our clients, says sales director

Ian Hopkins, explaining that

customers at times of recession

do not want to tap into capital

savings or take out expensive

loans.

He adds, that because

the cogeneration system is

highly effcient ENER-G is able

to charge customers less for

electrical output than from

the grid and provide free

heat, while still recouping

adequate funds to cover the

investment cost and ongoing

maintenance of the system.

Our clients can use their

capital to fund core projects

and sit back and enjoy bottom-

line savings from CHP, which

can achieve cost savings of

up to 40% compared with

electricity from the grid and

heat generated by on-site

boilers.

Furthermore, CHP systems

primed by natural gas, or other

fossial fuels, can cut carbon

emissions by about 20%,

compared with conventional

plants, according to ENER-G

calculations, he adds.

ENER-Gs cogeneration

systems on offer range from

just 4 kWe to over 5 MWe. CHP

is typically 90% effcient for

on-site energy consumption

around twice as effcient

as conventional plants, where

the generated heat is wasted,

while another 7% in effciency

losses occur by transmitting

electricity from remote power

stations to end-users, Hopkins

concludes.

Among the businesses

that are benefting from

funded cost and carbon

savings is Tangerine

Confectionery, which has fve

ENER-G cogeneration and

trigeneration systems funded

through the Discount Energy

Purchase scheme.

ENER-G reports an acceleration in the uptake of its pay-as-you-save

discount energy purchase scheme in the UK, and more businesses are

warming to the idea of green power self-generation, writes Richard Baillie.

On-site powercontinues to gain favour in the UK

ENER-Gs 230 kWe CHP system installed at Tangerine Confectionary under its Discount Energy Purchase scheme Credit: ENER-G

1307cospp_26 26 7/18/13 4:51 PM


Growing popularity of self-generation in the UK

Peter Sanders, operations

director for Tangerine, says, We

are continually seeking ways

to raise our environmental

performance and this move to

on-site generation of power is

a key element of our carbon

cutting strategy.

ENER-G is able to provide

us with a total service, from

initial design to long-term

care of the systems. This has

required no capital investment

as the technology is supplied

by ENER-G in return for us

purchasing the generated

electricity at a favourable rate.

ENER-Gs Hopkins adds, We

have clients that have enjoyed

the benefts of Discount Energy

Purchase for 15 years and are

now replacing their equipment

under the same simple

contract structure. It is a very

effective way for companies to

regain some control over their

energy costs while electricity

rates continue to rise.

Growth in renewable

self-generation

Recent research from Opus

Energy, a business energy

supplier, also suggests a

growing level of interest

among UK frms in generating

renewable energy on their

premises, compared with 2011.

More than a third of those

surveyed 39%, up from 32%

in 2011 expect to introduce

solar panels, wind turbines,

or anaerobic digestion, for

example, and almost half

(48%) expect to generate their

own green electricity within

two years.

In 2011, just 26% were

looking to introduce on-site

renewables within fve years.

Of those surveyed, 15% are

already generating renewable

power, versus 6% in 2011.

Interestingly, SME owners aged

55+ are leading the charge

20% already generate green

power on site.

Opus Energy is also seeing

more companies sign up

to its renewable power

purchase agreements (PPAs),

which enable the supplier to

purchase excess renewable

power from businesses for

its customers. This means

companies can generate an

extra income and enhance

their corporate responsibility.

In the survey, the three main

benefts stated by businesses

for self-generation were: self-

suffciency (28%), generation

of income (23%), and doing

our bit to combat climate

change (17%).

Successful PPA signings

In December, Opus Energy

announced the signing of its

500th renewable PPA.

A relatively recent signing

is with Knocknain Farm in

Scotland, which now sells all

its 330 kW wind-generated

power to Opus Energy. The

Port of Milford Haven also

signed an agreement last year,

enabling the energy supplier

to buy excess power from solar

photovoltaic (PV) systems

installed on multiple buildings.

This includes the Ports fagship

100.8 kW Phoenix Power PV

plant the largest integrated

solar PV system in Wales

located on the roof of a tenpin

bowling centre.

According to Charlie

Crossley Cooke, managing

director of Opus Energy:

Its great to see companies

warming to the idea of

generating their own

renewable energy adding

that Opus Energy can work

with companies to help them

realise the extra revenue and

benefts to be gained by

entering this market.



www.cospp.com


1307cospp_27 27 7/18/13 4:51 PM

Project Profle:


Project profle: Optimization of industrial CHP in Portugal

The operators of a CHP plant at a large petrochemcial facility in Portugal were struggling to run the

plant in the most economic way because of the requirement for high operational fexibility, liquidity of

the cost and constantly varying site demands. Joo Coelho and Pascal Stijns explain how this issue

has been successfully resolved.

How to optimally runa complex industrial CHP plant

The Sines petrochemical complex is Repsols largest chemical facility in Portugal Credit: Repsol

1307cospp_28 28 7/18/13 4:51 PM

Repsol is an

integrated global

energy company

with a presence in

more than 30 countries. It

operates in the upstream

areas of exploration and

production of hydrocarbons,

as well as downstream

refning and the production

of chemicals, and new

energy.

Repsols largest chemical

facility in Portugal is a

petrochemical complex in

Sines, which manufactures

polymers. The heat and

power requirements for this

large chemical complex are

provided by a cogeneration

facility. The CHP plant consists of

three high-pressure boilers and

one medium-pressure auxiliary

boiler, and has a maximum

steam production capacity of

600 tonnes, which is used to

meet the sites electricity and

heat requirements.

The boilers are able to

combust six different fuels of

varying quality, availability and

cost simultaneously. The steam

is reduced and distributed via

fve steam headers within the

site via a 35 MW back-pressure

turbine or pressure reducing

stations. A 24 MW condensing

turbine is also available to

produce extra electrical power

when needed. The site has two

different electrical contracts, of

which the condensing turbine

contract is the most complex.

However, due to the

requirement for operational

fexibility, liquidity of cost

and constantly varying site

demands it was proving almost

impossible for operations to

make the right economical

decisions to achieve the

optimal utility production cost.

Thus, the Sines facility,

working with Honeywell,

decided to develop and

install an on-line and real-

time thermodynamic and

economic model that could

determine the optimal

production settings, and

thereby enable operations to

run the CHP plant in the most

economical way.

The optimization model

The plants Honeywell Experion

PKS distributed control system

(DCS) enabled the use of

various Microsoft standard

tools such as Task Scheduler,

Excel and Visual Basic,

which helped to simplify the

optimization application.

Furthermore, three MicroSoft

Excel add-ins are employed:

the Honeywell Water and

Steam Physical Properties,

the FrontSys Premium Solver

and the Microsoft Excel Data

Exchange. Figure 1 shows a

sample optimization window

from the application.

Data are read from the

DCS into an Excel workbook

via Honeywells Medex

OPC-based add-in. On-line

values, pricing information,

physical properties, etc, are

linked to the model. The Solver

add-in executes and inputs

the results into the model

tab. From there the values

are written to defned SCADA

points in the DCS for further

display, historization, reporting

and alarming via OPC.

A copy of the workbook,

without the input and output

sheets, can be used for off-line

optimization too, enabling

the user to run various multi

periods (i.e. hours, days, weeks,

months, years) and analyse

what if scenarios.

The Solver add-in enables

the use of various solving

techniques, ranging from

Mixed Integer Linear

Programming (MILP) to Mixed

Integer Quadratic Constraint

Programming (MIQCP), as

well as the more commonly

used, Mixed Integer Non Linear

Programming (MINLP).

The objective function of

the model represents the

sum of the variable and fxed

costs, including depreciation,

personnel, insurance and

fxed charges. The user is

able to view the impact of

various optimization modes,

constraints and loading,

including switching devices

on or off. The model also

provides the operating cost of

the CHP in actual mode and

optimum mode in a real-time

environment.

Positive outcome

Repsol Sines found some

surprising results. Running the

station with a 1 MW electrical

feedwater pump instead of

a turbo pump delivered an

astonishing saving of more

than 9%. Even more surprising

was the 13% saving by running

the station with two feedwater

lines and a turbo pump,

compared to running with a

single feedwater line and one

electrical pump.

Comparing several different

operational scenarios before

and after the optimizer also

proved to be an eye opener,

as can be seen in Figure 2.

The vertical axis represents the

cost (%) relative to the way the

CHP plant was operated in the

past at low loads.

The difference in Scenarios

1 (frst left, red) and 2 (second

left, red) is small in terms of

cost , although a 2% difference

does represent a considerable

amount of money on a yearly

basis. However, these were

rejected by Repsol due to

environmental considerations.

Scenarios 3, 4 and 5 (in

blue) all comply to Repsols

sustainability targets (i.e. no

faring and steam venting)

and clearly show signifcant

differences in operating

cost close to 22% between

operating the power station

with only the condensing set

at a minimum and one boiler

(scenario 3) and scenario

5, i.e. running the station as it

used to run.



Figure 1. A representative screenshot

1307cospp_29 29 7/18/13 4:51 PM



In addition, users are able to

justify improvements, including

various effciency improvement

projects by changing the layout

of the plant and comparing it

with previous scenarios over a

certain ope

Documents

Cogeneration July August 2013