biomass chp best practice guide - force...

Prepared by:Anders Evald, FORCE Technology, Denmark

Janet Witt, Institute for Energy and Environment, GermanyMarch 2006

Biomass CHP best practice guide

Performance comparison and recommendationsfor future CHP systems utilising biomass fuels

This Best Practice Guide presents theresults from the activities in theAltener project “Bio-CHP - EuropeanBiomass CHP in practice”, Altenercontract no. 4.1030/Z/02-150/2002.

The report contains results and re-commendations from analysis ofmonthly operational data from 63 bio-mass CHP plants during 24 months.

Information on individual plants can-not be recognized from data in this re-port. Due to the level of anonymity re-quired from a number of plants parti-cipating in the project all plants areanonymous, even if many plants haveaccepted full publication of individualdata. This is necessary to protect therequired anonymity for those plantswho cannot accept publication ofplant specific data.

Biomass CHP best practice guide2

To enable clear reading of the in-cluded graphics, we recommend thatprints made from the electronic ver-sion of the report should be made incolour.

For more information about the pro-ject please check web site at:

http://bio-chp.force.dk

- or contact the project co-ordinator:

Mr. Anders Evald, FORCE TechnologyE-mail: [email protected]

Anders Evald

March 2006

Disclaimer: A huge effort has beenput into assuring high quality of data.This has been done through carefulevaluation of primary data from theplants comparing them with data fromearlier months, through formal qualitycontrol in other project partner officesand through identification of outliers inthe total data system when files fromall plants are compared and analyzed.However even after this effort we arenot in a position where we can guaran-tee 100% correct data in this hugedataset covering more than 100 pa-rameters for 63 plants in 24 months.Thus we cannot guarantee individualfigures, and we cannot take responsi-bility for any actions taken on the basisof the information in this report.

Preface

The sole responsibility for the content of thispublication lies with the authors. It does notrepresent the opinion of the European Commu-nities. The European Commission is not respon-sible for any use that may be made of the infor-mation contained therein.

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Preface 2

Table of contents 3

Introduction 4

Best practice conclusions and recommendations 5

Definitions 7

Biogas and landfill gas plants 8

Gasification plants 10

Grate fired boilers 12

MSW grate fired boiler plants 14

CFB plants 16

BFB plants 18

Dust-fired steam boiler plant 20

Cross technology comparison 21

Environmental performance 23

Participating CHP-plants 24

Biomass CHP best practice guide 3

Table of contents

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The BIO-CHP project intends to con-tribute to an increased - and more ef-ficient - use of biomass for combinedheat and power (CHP) production inEurope.

From 2003 to 2006 the projectcollected and disseminated biomassCHP experience based on collecteddata from more than 60 existing CHPplants in Denmark, The Netherlands,Austria, Germany, Sweden and Fin-land.

BIO-CHP is partly funded by theEuropean Commission Altenerprogramme.

The Project aims are to:

• Promote biomass CHP in Europe bydisplaying experiences from solidbiomass (including co-firing), Mu-nicipal Solid Waste (MSW), anaero-bic digestion gas and landfill gasfuelled CHP plants and highlightingplants with the best operation

• Provide e.g. authorities and futureplant owners with information aboutwhat performance to expect frombiomass CHP plants and about bestavailable technologies. This willhelp ensuring high quality of futureplants

• Enable benchmarking and thusidentify the improvement potentialof the existing European CHP plants

• Replicate best practices on the op-eration of biomass CHP plants byextensive dissemination activities

• Create a network for exchange ofgood and not so good CHP experi-ences

Project partnersA total of 6 EU countries are partnersin the project, each covering CHPplants in their home country, as wellas other project activities.

Elvira Lutter, Östereichische Energieagentur - Austrian Energy Agency(AEA), Austria

Harrie Knoef, BTG Biomass Tech-nology Group BV, The Netherlands

Kati Veijonen, VTT Processes, Finland

Johan Vinterbäck, Swedish BioenergyAssociation Service AB, Sweden

Janet Witt, Institute for Energy andEnvironment, Germany

Anders Evald, FORCE Technology,Denmark

A few plants located in countries out-side the partner countries were in-cluded in the study.

MethodA large number of combined heatand power plants located in the par-ticipating countries are invited to takepart in the project as suppliers of keyplant data and specific monthly oper-ational figures and statistics. In re-turn the plants receive access to alarge data material covering similarinstallations in their home countryand in other countries, which enablesthem to compare their own perfor-mance with others. This way changescan be made in operational patterns,in installations etc. to enable theplants to achieve an improved eco-nomic and environmental perfor-mance.

For each plant a series of key per-formance indicators were calculated.These parameters are the key to as-sessing operational performance fromone month to the next, and in com-parison with other plants.

The participating plants cover awide range of technologies, which isclassified into 7 categories:


• Biogas and landfill plants (from di-gestion of animal manure, agricul-tural residues and MSW)

• Gasification plants (using woodfuels)

• CFB (circulating fluidized bed) plants(using wood fuels, bark and peat)

• BFB (bubbling fluidized bed) plants(using wood fuels, bark and peat)

• Grate-fired steam boiler plants (us-ing uncontaminated biomass suchas wood chips, bark etc.)

• Grate-fired steam boiler plants(using MSW as a fuel)

• Dust-fired steam boiler plants(using a combination of coal andstraw)

Information on key figures andmonthly data were collected in theparticipating partner countries, vali-dated and passed on to the centraldatabase system in FORCE Technol-ogy, Denmark.

The collection of monthly data coversa total of 24 month, starting September2003 and ending August 2005.

Environmental performance datawere collected. Due to incomparabledata sets, the analyses of these dataare limited to ash production and wa-ter consumption. A range of otheremission parameters were collected.

A project website on the addressbio-chp.force.dk has been estab-lished. The site covers all kinds of pro-ject related information, and includesan intermediate technical report, thee-mail newsletters, the best practiceguide, details on the participating CHPplants etc.

E-mail newsletters are being distrib-uted to a European target audience.

A project workshop presenting theresults to a European audience washeld in Vienna, Austria in March 2006.

Introduction

This section contains conclusions

and recommendations, which is

general to biomass CHP. Please refer

to the following chapters for more

detailed conclusions regarding the

individual CHP technologies.

Big is beautifulBiomass energy systems, being re-newable energy systems, are in somecontexts considered “green”, “alterna-tive” technology, which should developbased on a local urge to do somethingabout environmental problems. This“think globally, act locally” idea will of-ten point towards small scale techni-cal systems, that depend on fuel sup-ply from within a short distance, andcover relatively small energy demands.

For biomass CHP systems, this ideais in contradiction to the findings fromplants in operation. In general we ob-serve higher efficiency, lower own con-sumption and better availability for thelarger plants, which means that largerplants perform significantly better infossil fuel substitution and in opera-tional economic performance.

And even though our study does notcover investment cost for the CHPplants, it is evident from other studiesand from general economic mecha-nisms, that larger systems show lowerinvestment cost relative to the size ofthe plant. Thus the general perspectivefor development of biomass CHP sys-tems is “bigger is better”, meaning thatfor the resources given (capital, bio-mass, manpower) the bigger the plant,the more renewable energy is produced.

Such a recommendation obviouslyhas limitations. One is, that biomassCHP systems are limited by the size ofthe heat market, they can be con-nected to. Another is that the conclu-sion might be slightly different forbiogas and landfill gas engine sys-tems, where the size dependency isless significant than for other technol-ogies. A third is that in a more maturemarket development, series produc-tion of energy systems might bringdown capital costs for smaller units. Afourth limitation arises from biomassavailability.

Capacity and utilisationLooking across the different CHP tech-nologies there seems to be a general

tendency that the CHP plants are builtwith a too high capacity. This is evi-dent from the relatively low utilisationfactor shown for the majority of theplants included in the survey.

Selecting the right size for a CHPsystem connected to a heat system isby no means trivial. A large plant, cov-ering close to or even more than thepeak heat demand in winter will showa low utilisation of installed capacitythe main part of the year, and it mighteven have to shut down during summerdue to limitation in low load operation.On the other hand a relatively largeplant can benefit from larger electricitysales, and when coupled to a heat ac-cumulator it can benefit from chang-ing electricity tariffs by producing theheat when the value of electricity isthe highest.

Also many plant owners, who pres-ently do not utilise the installed ca-pacity (plants too big for the heat mar-ket) argue that the size of the plantdoes not necessarily match the pres-ent heat demand, but rather a futureheat demand created by more heatconsumers being connected to thedistrict heating system.

A high utilisation of the installed ca-pacity can be achieved if the plant isrelatively small, covering only e.g. 40% of the peak winter heat demand.This generally gives a better payback

Best practice conclusions and recommendations


on the investment in the CHP system,but due to the need for a generallymore expensive peak load supplemen-tary heat production and due to asmaller impact from the CHP systemon the total heat production costs inthe heating system, a very small sys-tem is not optimal either.

The optimal CHP plant capacity in agiven heat distribution system dependson fuel costs, investment cost, peakload heat production costs, electricitytariffs, expected development in heatdemand and a number of other eco-nomic parameters. Optimal perfor-mance studies generally indicate thatthe economic optimal capacity is inthe order of 50 to 70 % of winterpeak heat load. Lower and higher endof this interval corresponds to 86 % to98 % of annual heat demand coveredby the CHP system and 74 % to 61 %utilisation factor (calculated figures,assuming Danish climatic conditionsand full availability - in Southern Eu-rope the different climate will lead todifferent optimal conditions).

The fuel and systems available tosupply peak heat demand and de-mand when CHP is out of operationalso influences optimal plant size andoperational pattern. This is discussedin further detail in the section onBFB-boiler, but is relevant for othertechnologies as well.

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CHP or not CHPWe have included some biogas andlandfill gas plants in the study, whichonly to a very limited extent utilisesthe heat associated with the powerproduction. One might argue thatsuch plants are not truly combinedheat and power plants; on the otherhand as long as a small fraction of theheat is actually utilised, the plants areat least partially CHP.

The point is emphasized by the factthat in some countries biogas andlandfill gas plants are subject to pre-mium price schemes for renewableelectricity no matter if the heat is uti-lised or not. In this way, supportschemes for renewable electricity pro-motes development of renewableelectricity, however not necessarily aselectricity produced with high total ef-ficiency in combined heat and powersystems.

Also for a few other plants based onsolid fuels the amount of heat con-nected to the plant is too small tomatch the potential heat productionfrom the plant. This is true especiallyfor a couple of large waste incinerationplants, which is connected to relativelysmall process heat demands, mostlikely because these plants for localiza-tion reasons are placed far from do-mestic district heating systems.

Generally combined heat and powerproduction is highly efficient. Nationalsupport schemes for renewable elec-tricity might support the developmentof biomass CHP systems, but if sup-port is given for electricity-only as wellas for combined production, there isno specific incentive to install CHPsystems and locate the plants near aheat demand. Such a support schememight initiate more renewable electric-ity, but not in the most efficient wayas CHP.

Balancing heat and powerFrom a general energy efficiency pointof view electricity is the more valuedof the two energy products from aCHP system. This is in most casesalso true when it comes to the salesvalue of the two products. However,for industrial plants, and for plants lo-cated where heat has a high value(e.g. in several Nordic countries,where taxes on fossil fuels makesheat a valuable energy service, com-parable in price to electricity) the twoproducts may be more balanced. In-

dustrial facilities might operate theCHP plant primarily for the sake of itsown steam consumption, and a NordicCHP plant might create by far the larg-est income from sales of heat to adistrict heating system.

Choosing the right technologyThe different CHP technologies arequite different when it comes to effi-ciency. While most perform well inheat utilisation (this is by far the easi-est from a technical point of view), dif-ference in electric efficiency might bevery big. Additional income from highelectricity sales must off course bebalanced against any additional in-vestment costs.

For all plant types that involve asteam cycle, the steam data are ex-tremely important for efficiency. This istrivial for the energy engineer, butmaybe not so much for the investor orplant management board. The higherpressure and the higher temperaturein the steam cycle the better. Gener-ally larger plants operate at highersteam data and modern plants arealso better in this context than olderplants. When decisions are to bemade on investment in CHP systems,the efficiency gain must be weighedagainst the costs of boiler, turbine andother equipment and against risk ofcorrosion and other operational prob-lems.

Retrofitting older equipment oftenpays back well. Increasing steam dataor changing an old inefficient turbineto a newer model might add very sig-nificantly to the operational perfor-mance of the plant.

Industrial systemsCHP plants built to provide steam andother heat demand for an industrialfacility seem to provide a less solidfoundation for an efficient biomassCHP operation. One CHP plant is indanger of closure due to its main in-dustrial steam user being closeddown; another has skipped completelythe heat sales part of what was fromthe outset a combined heat andpower plant. Several CHP plants in-stalled in industrial facilities haverather limited heat demand con-nected, and operate to a large extendafter this heat/steam demand leadingto low electric efficiency, extended pe-riods of stand still and general poorutilisation of the plant. Electric effi-


ciency in industrial power plants is of-ten lower simply because their mostimportant product is not electricity butsteam (or heat). They use bled steamfor industrial processes which naturallydecreases the electricity production.

Reducing own consumptionThe consumption of power for internalpurposes within the CHP plant is sig-nificant and needs to be addressed al-ready in the planning phase in orderto keep it as low as possible.

The different CHP technologiesshow rather large difference in ownconsumption, meaning a sensiblechoice of technology is important.

Modern plants show lower ownconsumption than older ones; this in-dicates a potential to reduce the ownconsumption by retrofitting importantauxiliary equipment in the plant.

Finally plants with a high electric ef-ficiency presents a relatively low ownconsumption. If the choice falls on alow budget turbine plant with lowsteam data, be prepared for using avery large fraction of the producedelectricity within the plant.

Operational problemsCo-firing common fossil fuels withsolid biomass and recycled fuelsposes new challenges for power plantoperators. E.g. sintering of bed-parti-cles has been observed in manybiofuel-fired fluidized bed boilers,which can lead to shutdown of theboiler due to decreased fluidization.Deposits on heat transfer surfaces re-duce the heat transfer, decrease theefficiency of the boiler and increasethe risks for high temperature corro-sion. Also the variations in the mois-ture content of biomass fuels set de-mands e.g. for combustion processand the auxiliary equipment (e.g. fluegas fans) of the boiler. Due to theseoperational problems boiler efficiencydecreases and the operating andmaintenance costs increase, signifi-cantly influencing the total economyof the plant.

In the following sections on tech-nologies, more details on operationalproblems are listed for BFB and CFB.This might indicate that other technol-ogies are problem free, however oper-ational problems exist for all biomassCHP technologies; only more detailswere available from the BFB and CFBplants.

Utilisation factorThe extent, to which installed capacityis utilised, is studied using a perfor-mance indicator called the utilisation

factor. It is calculated from monthlyproduced power in MWh divided bythe plant capacity in MWh assumingthe plant runs continuously at full loadthe whole month. The utilisation pe-riod expresses the extent to which theplant capacity is utilised: a low figuremeans low capacity utilisation causedby stand still or part load operation, ahigh figure means constant full loadoperation.

The utilisation factor will generallybe higher for industrial CHP systems,where process related heat or steamdemand fluctuate less than outsidetemperature dependent heat load indistrict heating plants.

AvailabilityThe performance indicator availability

describes the extent to which the


plant is ready for operation (not nec-essarily in operation). It is calculatedas 100% minus (weighted hours ofout of operation due to damage +hours out of operation due to of revi-sion) divided by hours in a month.

Energy productionThe energy production is the total pro-duction of heat and electricity for theplant in the period.

Electric efficiencyAverage efficiency (monthly or annual)measured as net power produced di-vided by fuel consumption in the plantmeasured in energy units using lowerheating value.

Total efficiencyAverage efficiency (monthly or annual)measured as net power produced andnet heat produced divided by fuel con-sumption in the plant measured in en-ergy units using lower heating value.

Operational efficiencyThis is the actual electricity and heatefficiency observed in the plantsmonthly operational data. Nominal ef-ficiency This is the efficiency, as antic-ipated by designers and plant ownersas the expected nominal performanceof the plant.

Own consumptionInternal consumption of electricity atthe plant.

It should be noted, that while wehave attempted to include only inter-nal electricity consumption at theplant, we cannot rule out that a fewplants might give data that includesother electricity consumption as well.

Specific own powerconsumptionInternal consumption of electricity atthe plant as a ratio to the gross powerproduction.

Definitions

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Biogas and landfill gas plantsThis technology classification covers 19 gas based CHPsystems (gas engines) based on biogas from dedicatedbiogas plants or landfill gas. For plant no 26 only the first11 months data are included.

The analyses focus on the performance of the gas en-gine systems as such, because of the diversity of thebiogas raw materials used and the immeasurable nature ofthe landfill gas biomass consumption.

Some of the plants present virtually no heat production,either because there is no heat production, or because theheat used locally is not measured. Please refer to the gen-eral conclusions section for a detailed discussion of the im-plications of this.

Utilisation and availability

Utilisation factor and availability for 16 biogas and landfill

CHP plants. Figures are shown as average values for 24

months, September 2003 to August 2005.

Several plants uses the installed capacity only about 25%.This is a severe loss on invested capital. At least for someof the plants, it is caused by to large installed engine ca-pacity as compared to the biogas production potential.

There seems to be a tendency that the larger plants hasa lower utilisation of installed capacity (not shown ingraphics).

The majority of plants have a very high availability. Whencompared to the other types of CHP plants, the gas enginethemselves are not very technically complicated which givesshorter period of non-availability.

Efficiency

Nominal and operational efficiencies for 18 biogas and

landfill CHP systems. Operational figures are average valu-

es for 24 months, September 2003 to August 2005.

Except for two plants, the practical total efficiency is signifi-cantly lower than the nominal. For all plants, where datavalidation allows this comparison, the electric efficiency issignificantly lower than the nominal.

As income from sales of electricity is the main salesvalue for most plants (heat is less significant from an eco-nomic point of view) this has a great negative impact onthe economic performance of the plants.

Several plants have not been able to supply reliable dataon heat production. These are typically biogas plants inGermany with the highest income from electricity sales,connected to a very small local heat demand, which is of-ten not even measured.

For plant no. 32 the anticipated connection to a heatdemand in reality was much smaller, hence the low opera-tional heat efficiency.

Efficiency and annual energy production

Operational efficiencies for 19 biogas and landfill gas CHP

systems compared to the size of the plant shown as the

annual production of electricity and heat. Operational fi-

gures are average values for 24 months, September 2003

to August 2005.

There is no clear indication that operational performancefor larger plants are more efficient than smaller plants. This

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72 64 24 30 42 18 46 40 34 11 26 52 50 2 32 65

Utilisation factor Availability

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100Efficiency [per cent]

Operational electric efficiency Operational heat efficiency

Nominal electric efficiency Nominal total efficiency

Energy production [MWh/a] Efficiency [per cent]

72 64 24 30 42 18 46 40 36 34 11 26 52 50 47 2 32 65 29

Power production Heat production

Total efficiency Electric efficiency

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75

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is clearly different from the other CHP technologies, wherelarger plants generally present higher (electric) efficiency.

The size range between smallest and largest plant is verywide, illustrated by the difference in annual heat and powerproduction.

Efficiency over time

Total of heat and electric efficiencies for 19 biogas and land-

fill gas CHP systems. Operational figures are monthly data

shown for 24 months, September 2003 to August 2005.

Variation in efficiency from month to month is very high.This implies improvement options for the individual plant bycarefully following these data and copying operational pat-terns from the best months (choice of biomass raw mate-rial, operational pattern, load condition etc.).

Some plants shown do not have valid figures for heatproduction - these are the group of six plants showing datain the 20 to 40 % range, which must be then read as elec-tric efficiency and not directly comparable to the otherplants. Plant 42 had no heat sales in the first months, andalso other plants have irregular periods with very low heatproduction.

Total efficiency per month [per cent]

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29 32 30 46 24 26 34 40 64

42 2 47 72 36 52 18 50

Biogas production

Biogas production relative to the volume of biomass input

and to the digester capacity for 15 biogas CHP systems

(landfill gas systems not shown here). Operational figures

are monthly data shown for 24 months, September 2003

to August 2005.

The plants show huge variation in the efficiency of produc-ing gas the biomass raw material - from 25 to more than200. This is probably caused by different raw materialsused.

There is also an extreme variation in the gas productionbased on digester volume. From 17 to 102 m3/m3.

Smallest plants are shown to the left, largest to the right.There is no indication that plant size has any influence onthese important performance parameters.


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Biogas production/biomass input Biogas production/digester volume

72 64 24 30 42 18 46 40 36 34 26 52 47 32 32

Gasification plantsThis technology class consists of 4 plants, of highly variablesize. For plant no 54 only the first 12 month data are in-cluded.


Utilisation factor and availability for 4 gasification biomass



All gasification plants show low utilisation factor - two offour plants utilise the installed capacity less than 30 %.This is a loss on invested capital.

Plant no. 56 is out of operation for prolonged periodsduring the project period. This is caused by damage to vitalengine parts occurring three times in 24 months as well asintentional non-operational periods and periods with toolow heat demand. For plant no. 23 the low utilisation iscaused by a too large installed engine capacity. Total ca-pacity is 1.4 MW (electric power), while the gasifier gasproduction capacity only corresponds to about 0.8 MW(electric power).

Availability is low: the plants are not ready for operationmore than 10% of the time; one plant even 41% of thetime. However the dataset is too limited to draw a generalconclusion from this.

Availability and utilisation are shown for the power pro-ducing part of the plant (engine or turbine). When lookingat the gasifier alone, the situation might be somewhat dif-ferent.

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Average utilisation factor & average availability [per cent]


Efficiency

Nominal and operational efficiencies for 4 biomass gasifi-

cation CHP systems. Operational figures are average values

for 24 months, September 2003 to August 2005.

The operational total efficiency is significantly lower thanthe nominal. Further, the electric efficiency is significantlylower than the nominal.


Further the heat efficiency for two of the four plants islow. This is linked to limitations in the heat market as wellas to technical constraints at the plants.

The plant to the right in the graphics consists of a com-bination of a biomass gasifier and a coal fired boiler, whichshare one steam turbine. For this plant, the efficiency de-scription covers the combined system.


Operational efficiencies for 4 biomass gasifier CHP systems

compared to the size of the plant shown as the annual pro-

duction of electricity and heat. Operational figures are

average values for 24 months, September 2003 to August

2005.

Compared with the very large plant (no. 1), the threesmaller plants show significantly lower electric efficiency,between 14 and 17 % based on operational data from 24months.

Plant no. 1 is special as mentioned above.

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Average energy production [MWh/a] Efficiency [per cent]


Total efficiency Electric efficiency

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Heat production: 1036 GWh/aPower production: 753 GWh/a

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Total of heat and electric efficiencies for 4 biomass gasifier

CHP systems. Operational figures are monthly data shown


Seasonal variation in efficiency is very high. This implies im-provement options for the individual plant by carefully fol-lowing these data and copying operational patterns fromthe best months (choice of biomass raw material, opera-tional pattern, load condition etc.).

Further there seems to be a seasonal variation, showinglower efficiency during the summer. This is most likelycaused by part load operation during the summer, whereheat demand is low or by reduced heat sales during sum-mer, where some plants (e.g. plant no. 1) cool of excessheat. Condensing power operation or cooling off excessheat places a question mark to the classification as a CHPplant. It does however makes sense when the plant canhave a a high income from the electricity sales, or avoidbuying electricity (industrial applications).

Plant no. 56 is completely out of operation for extendedperiods (explained above).

Own power consumption

Own power consumption for 3 biomass gasification CHP

plants. Data are shown as averages for the 24 month

period September 2003 to August 2005.

For the 3 plants where valid data are available, the internalpower consumption are 9 to 17 % of the power produced.The two higher values raise concern about the economic


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Specific own consumtion to fuel input

Specific own consumtion to gross power output


performance of the plants as a significant fraction of theelectricity produced is used internally.

Fuels used

Division between biomass fuels and fossil fuels used in 4

biomass gasification CHP plants. Average figures for 24


The figures illustrate the very large difference in the type ofthe plants. Plant no. 1 is a dedicated combined fuels plant,where biomass fuels is only a minor fraction. In plant no.56 the engine operates on as well gasification gas as dieseloil. When the owners need the power production, but doesnot operate the gasifier, diesel substitutes biomass.

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Biomass input Fossil energy input

Grate fired boilersA total of 14 plants are included in the survey categorized asgrate fired boilers. The majority of the plants are wood firedsteam boilers with one or more steam turbines. For plants no4 and 6 only the first 12 months of data are included.


Utilisation factor and availability for 13 grate fired biomass



Some plants utilise installed capacity very badly, less than50 %, and one is even below 25 %. General reasons forthis is explained in the initial conclusive chapter.

Plant no. 14 shows very low utilisation due to extensiveand repeated periods out of operation. 4 out 24 month wasstand still caused by a damaged superheater, and 2.5 ad-ditional months was spend on planned revision work.

Another reason for the utilisation to be low is that thenominal installed capacity is never achieved during operation- the plant was simply sold as bigger than it is in reality.

Finally the utilisation is low for some plants due to ex-tended periods out of operation due to damage to criticalparts in the plant such as superheater, turbine etc.

Availability for most plants is acceptable. When com-pared to other CHP technologies, grate fired systems per-form relatively well.

There are no indications that larger plants are betterthan smaller plants.

EfficiencyWhile the total of heat and electricity show acceptable val-ues in the order of 80% for most plants, the electric effi-ciency found from operational data are by no means im-pressive. 10 to 15% electric efficiency seems to the normfor this technology.

The practical total efficiency is significantly lower thanthe nominal. More important however is that the electricefficiency is many cases much lower than nominal, underpractical condition less than 10 %!

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41 4 6 20 60 14 57 82 5 16 22 45 35


Nominal and operational efficiencies for 13 grate fired bio-

mass CHP systems. Operational figures are average values


There are a long range of explanations for the electric effi-ciency to be lower than the nominal value. Part load opera-tion is one; turbines generally perform best at 100 % load.Some plants operates in on/off mode, taking advantages ofthe highest tariff for electricity during peak hours, operatingat high efficiency (full load) and storing heat in a heat accu-mulator for continuous heat supply. Such plants howeverhave reduced average efficiency due to losses during start-up and shutdown procedures, even though such procedu-res can be relatively short (50 to 120 minutes) for modernplants.

As income from sales of electricity is the main salesvalue for most plant (heat is less significant from an eco-nomic point of view) this has a great negative impact onthe economic performance of the plants.

Some plants show efficiencies above 100% - these areequipped with flue gas condensing systems.


Operational efficiencies for 13 grate fired biomass CHP sy-

stems compared to the size of the plant shown as the an-

nual production of electricity and heat. Operational figures

are average values for 24 months, September 2003 to

August 2005.

While the total efficiency (heat plus electricity) is in thesame order of magnitude for most plants it is evident, thatthe larger plants show significantly better electric efficiency(approximately twice) than the smaller ones. This confirms

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041 4 6 20 60 14 57 82 5 16 22 45 35

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60

90

120

5,000

10,000

15,000

20,000

25,000

30,000

35,000

40,000Average energy production [MWh/a] Efficiency [per cent]


Electric efficiency Total efficiency

Heat production: 606 GWh/a


the general conclusion that larger plants generally performbetter.

Electric efficiency for steam cycle plants is largely deter-mined by the basic steam data (pressure and temperature)from the boiler. Generally larger plants will operate in highersteam data, and also technology development in steamboiler steel quality etc. enables higher steam data and con-sequently higher efficiency in newer plants as compared toolder plants.

Some plants show efficiencies near or above 100% –these are equipped with flue gas condensing systems.


Total of heat and electric efficiencies for 13 grate fired bio-

mass CHP systems. Operational figures are monthly data

shown for 24 months, September 2003 to August 2005

This class of CHP plants shows more stable efficiency dur-ing the year than the other classes.

A few plants show efficiencies above 100 % in somemonths. These plants are equipped with flue gas condens-ing systems, which gives a higher heat production, butdoes not influence electric efficiency. It should be noted,that the high heat efficiency means that in a given heatmarket (district heating system) less electricity productionis possible.

Some plants exhibit months with much lower than usualefficiency. This should be investigated by the plant owners.

Plant no. 20 presents very low total efficiency. This is anindustrial facility, where heat demand is limited to dryingand local space heating, without connection to a districtheating network. Surplus heat is cooled off in a coolingtower. As steam demand is limited, so is the heat effi-ciency; one might argue that the plant is not truly a CHPsystem. Similarly plant no. 22 has no heat demand for thefirst 8 months shown as the heat demand was not con-nected initially.


Own power consumption for 10 grate fired biomass CHP

plants. Data are shown as averages for the 24 month


8 to 15% own consumption seems to be the rule for thistype of CHP plant. This is less than the CFB and BFBplants, but still a significant and a high figure.

The highest specific own consumption is found in thesmallest plants, because these have the lowest electric ef-ficiency. There would also be a tendency, that older plantsshow higher specific own consumption.

Some plants show extremely high own consumption. Forplant 6 and 14 this is probably caused by industrial powerconsumption being included, while plant 41 suffers from avery low electric efficiency, which results in a high relativefigure for own consumption.

Fuels used


grate fired biomass CHP plants. Average figures for 24


Generally gratefired systems are independent of fossils fu-els, however two plants (6 and 35) are specifically de-signed for co-firing fossil fuels with wood. Plant no. 35 is adedicated co-firing unit combining wood chips and naturalgas. This plant also shows the highest electric efficiency inthe group.


120

100

80

60

40

20

0

Sep03

Oct03

Nov03

Dec03

Jan 04

Feb04

Mar04

Apr04

Maj04

June

04

July

04

Aug04

Sep04

Oct04

Nov04

Dec04

Jan 05

Feb05

Mar05

Apr05

Maj05

June

05

JUly

05

Aug05

41 6 60 57 5 22 35

4 20 14 82 16 45

0

0.10

0.20

0.30

0.40


41 6 20 14 57 5 16 22 45 35

Specific own consumption to fuel input

Specific own consumption to gross power output

041 4 6 20 60 14 57 82 5 16 22 45 35

20

40

60

80




MSW grate fired boiler plantsA total of 8 CHP plants based on combustion of municipalsolid waste (MSW) are included in the study. Although of adifferent size the plants are built on more or less the sametechnology: combustion on a grate and steam cycle forpower production. Thus this technology class is more ho-mogeneous than the others.


Utilisation factor and availability for 8 MSW grate fired bio-

mass CHP plants. Figures are shown as average values for

24 months, September 2003 to August 2005.

Availability is rather low, but more even between the plants.A low figure here must be attributed to the use of MSW,which causes regular maintenance work on the boiler.

Utilisation is better than other technologies. The mainpurpose of the plant operation is to handle waste, whichcreates additional income as compared to other CHP tech-nologies, where fuel is a cost.

There is no tendency that larger plants perform betterthan smaller ones.

The lowest utilisation factor of 34% is certainly low for atechnology with such high investment costs; for this partic-ular plant it is caused by less incentive for operation ascompared to other plants due to a low value of electricity(no special feed-in tariff valid for this plant).

Efficiency

Nominal and operational efficiencies for 8 MSW grate fired

biomass CHP systems. Operational figures are average va-

lues for 24 months, September 2003 to August 2005.

Like other CHP plants no one is over performing, all plantsare to a larger or smaller extent performing poorer than an-ticipated in the nominal data. For 3 plants the averageelectric efficiency is less than half of what is stated as thenominal efficiency of the plant. It seems that 20 % electricefficiency, or just above this figure, is what can be expectedas an annual average for this technology.

The plant to the right in the graphics has only a verysmall heat demand connected, which causes very low heatefficiency.

The plant to the left in the graphics has flue gas con-densing system, this causing efficiencies above 100%.


Operational efficiencies for 8 grate fired biomass CHP sy-

stems compared to the size of the plant shown as the an-

nual production of electricity and heat. Operational figures

are average values for 24 months, September 2003 to

August 2005.

There is a clear tendency that the bigger plants perform sig-nificantly better than the smaller ones in electric efficiency.Looking at the total of heat and electric efficiency this ten-dency does not exist - the smaller plants gain from higherheat utilisation, and the larger ones might even be limitedon the possibility to connect sufficient heat demand.

Plant no. 8 show very low heat utilisation - the potentialfor additional income is significant if a large district heatingnetwork could be connected, making the plant truly a com-bined heat and power plant. Also plant no. 38 present lowheat utilisation caused by limitations in the connected pro-cess heat demand.

Some plants (e.g. no. 3, 12 and 28) clearly have morefocus on heat production and waste incineration than opti-mizing electricity production. Low steam data (35 to 40 barand temperature below 400 degrees is part of the technicalcause for low electric efficiency in these plants.

0

20

40

60

80

100Per cent

3 12 28 59 38 27 53 8


0

20

40

60

80

100




03 12 28 59 38 27 53 8

0

50

25

75

100

300,000

150,000

450,000

600,000Average energy production [MWh/a] Efficiency [per cent]






Total of heat and electric efficiencies for 8 MSW grate fired

biomass CHP systems. Operational figures are monthly data

shown for 24 months, September 2003 to August 2005.

Most plants show stable operating performance. Seasonalvariations are observed; less heat sales during summer.Operational problems can be observed in some months(plant no. 3 and no. 59).


Own power consumption for 7 MSW grate fired biomass

CHP plants. Data are shown as averages for the 24 month


Two plants seem to operate fine with low internal powerconsumption, two plants are intermediate, and two plants,no. 3 and 12, show extremely high own consumption ofelectricity. This is caused to some extend by external elec-tricity consumption being included (district heating pumpsetc.), and it is also one of several reasons for the sameplants showing very low net electric efficiency.


120

100

80

60

40

20

0

Sep03

Oct03

Nov03

Dec03

Jan

04

Feb

04

Mar

04

Apr04

Maj

04

June

04

July

04

Aug04

Sep04

Oct04

Nov04

Dec04

Jan

05

Feb

05

Mar

05

Apr05

Maj

05

June

05

July

05

Aug05

3 12 28 59 38 27 53 8

0

0.1

0.2

0.3

0.4

0.5

0.6


3 12 28 38 27 53 8



Fuels used


MSW grate fired biomass CHP plants. Average figures for

24 months, September 2003 to August 2005.

Small fractions of fossil fuel are used in the MSW boilersfor start-up and support fuel. In a few plants natural gas isused also for flue gas cleaning processes.

03 12 28 59 38 27 53 6

20

40

60

80




Availability for most plants are acceptable, however a fewplants is only 70 % to 85 % or lower, thus these plants arenot ready for operation 15-30 % of the time.

There are no indications that larger plants are betterthan smaller plants.

The participating CFB plants present also an insight tothe operational problems that are often seen in bio-mass-fired CFB boiler. In general problems are observed incombustion and fuel feeding because of bad fuel quality.Sintering of the bed is a problem, likewise blocked super-heaters and excessive deposit formation. Sometimes highmoisture content in the biofuel limits plant total capacitybecause flue gas blowers are running at their upper limits(moisture in flue gas ad to the flue gas volume).

Further plant operators report occasional problems withfuel feeding equipments, steam leaks, malfunction in dis-trict heating pump operation, turbine shut-downs, electricalfailures, and in periods of low heat demand, part load oper-ation can cause operational problems.

Efficiency

Nominal and operational efficiencies for 10 CFB biomass

CHP systems. Operational figures are average values for 24


The electric efficiency achieved is not impressive, less than30% in all cases, and in most cases in the order of 10 %to 15 %.

The practical total efficiency is also for CFB-plants signifi-cantly lower than the nominal. Further and more importantfrom an economic point of view, the electric efficiency issignificantly lower than the nominal.


Four of the plants showing electric efficiency around orbelow 10 % are installed in wood manufacturing industry.Focus might be more on getting rid of wood waste and pro-ducing steam rather than operation of an efficient energyplant. Low feed-in tariff for electricity for such plants add tothis picture.

Added to results seen in other technology classes itseems that industrial CHP plants, while operating at anacceptable total efficiency are less focussed on high elec-tric efficiency and long operation periods, and more fo-cussed on the production demands in the industry, such

CFB plantsThis technology classification includes 10 circulating fluidbed boiler plants with steam boiler and steam turbine. Mostof the plants are relatively big, 8 out 10 is above 7 MW(electric capacity).


Utilisation factor and availability for 10 CFB biomass CHP

plants. Figures are shown as average values for 24


Several plants utilise installed capacity very badly. A utilisa-tion factor in the range 30 to 60 % for 7 of the 10 plantsindicates that these might be rather large in installed ca-pacity for the heat market connected or out of operation forextended periods.

One example of the operational logic behind a relativelylow utilisation factor would be CHP systems shut downcompletely during the summer period. In Nordic climatethere is a large difference between load in summer andwinter - the maximum load in winter might be 10 timeshigher than in the summer. Even if the plant is designed ata sensible size, covering in the order of 40 to 80 percent ofwinter peak heat demand, the summer conditions wouldrequire plants to operate at less than 30 percent load,which is from a technically point not possible. Such a plantwill shut down during summer, unless the heat can becooled of, but then it no longer a 100 percent combinedheat and power. Several Swedish systems follow this oper-ational pattern, and still perform well economically due tothe fact, that old biomass heat-only boilers, and not oil,cover the summer heat demand. A similar operational pat-tern might be chosen for summer operation due to lowmarket value for electricity produced during the summer-time.

Other examples are plant no. 62 and 66, both arestopped during weekends as the plant is installed in an in-dustrial facility and dependent on the energy demand andworking hours in the industry.

The very high utilisation and availability seen for plant no.10 is caused partially by this plant being virtually independ-ent of the limitations of a heat market (no heat produc-tion). One has to stretch the definition to call this plant aCHP-system; however the plant was originally built as aCHP plant, and we have kept it in the study to illustrate e.g.the influence on utilisation.

0

20

40

60

80

100

62 66 61 15 17 9 10 25 33 51



0

20

40

60

80

100





as working hours, steam demand or getting rid of wasteproducts.

Some plants show efficiencies near or above 100% -these are equipped with flue gas condensing systems.


Operational efficiencies for 10 CFB biomass CHP systems




2005.

It is significant, that the electric efficiency is far better forthe larger plants. Total efficiency is not dependent on size,showing that smaller plants compensate for lower electricefficiency by higher heat utilisation.


Total of heat and electric efficiencies for 10 CFB biomass

CHP systems. Operational figures are monthly data shown

for 24 months, September 2003 to August 2005

Variation in efficiency from month to month for this tech-nology is smaller than other CHP technologies. This indi-cates less influence from part load operation, and generallystable operating conditions. However, when the number ofoperational hours in a certain month is very low due to an-

0

800,000

700,000

600,000

500,000

400,000

300,000

200,000

100,000

Average energy production [MWh/a]




0

50

25

75



120

100

80

60

40

20

0

Sep03

Oct03

Nov03

Dec03

Jan 04

Feb04

Mar04

Apr04

Maj04

June

04

July

04

Aug04

Sep04

Oct04

Nov04

Dec04

Jan 05

Feb05

Mar05

Apr05

Maj05

June

05

July

05

Aug05

62 61 17 10 33

66 15 9 25 51


nual revision, this may affect strongly the efficiency of thatmonth as start-up and shut-down are reasonably excep-tional moments in power plant operation.

Plant no. 10 is operating at exceptionally stable condi-tions. The plant runs continuous full load and it is not yetdependent on heat demand. Other plants present a fewmonths with exceptionally poor results. These are in mostcases caused by revision or operational problems at theplant.

Plant 25 presents much lower total efficiency in thesummer months. Due to low heat summer demand theplants operates partially condensing power in the summer,thus reducing heat efficiency these months.


Own power consumption for 10 CFB biomass CHP plants.

Data are shown as averages for the 24 month period Sep-

tember 2003 to August 2005.

10 to 20 % or even 25 % own consumption seems to bethe rule for this type of CHP plant. This is significant and ahigh figure.

0

0.10

0.20

0.30

0.40


62 66 61 15 17 9 10 25 33 51



BFB plantsThis CHP technology classification includes 11 plants inthis study. All of these are located in Finland or Sweden.For plant no 43 only the first 10 month data are included.


Utilisation factor and availability for 10 BFB biomass CHP

plants. Figures are shown as average values for 24 months,

September 2003 to August 2005.

Several plants utilise installed capacity very badly, less than50% is common. Some explanations for this are identicalto those given for CFB plants. Several of the BFB plants arerelatively new, which means that the connected heat de-mand has not yet developed to the anticipated figures,leading to a low utilisation of installed capacity in the firstyears of the plant life.

Revision period of typically one month also has severeinfluence on as well availability as utilisation factor.

Availability for some plants is only 75 % to 85 %, thisshould give cause for action by these plants. There are noindications that larger plants are better than smaller plants.

Operational problems reported by BFB operator mostlyinvolve problems related to fuel quality. Poor fuel qualityhave caused problems such as bed de-fluidization, exces-sive slagging and fouling, superheater blocking, unplannedplant shut-downs, additional costs due to thorough boilercleaning, limited power output, and bad fuel quality havealso speeded up bed material replacement frequency etc.Further the plants list problems in bed material removalsystem, grate blockages due to stones in fuel, problems infuel silos and fuel silo unloading screws, fuel conveyors,etc., most of these problems are also related to the fuelquality issue.

The plant operators also report occasional problems re-lated to e.g. misuse failures specially at start-up, electricalfault related to the external grid, generator and turbinefaults, turbine automation failures, electric precipitatorblockage, additional turbine revisions, steam leak in boiler,DH-exchanger leak, HP water pre-heater leak, automationsystem problems, fire in ash silo, high silicate level insuperheated steam, problems with flue gas blowers, turbineautomation, ash dampening equipment and feed waterpumps.

0

20

40

60

80

100

63 21 37 7 13 43 39 55 31 19



Fuels used


CFB biomass CHP plants. Average figures for 24 months,


Virtually all CFB units use fossil fuels to some extent, show-ing that these are certainly versatile boilers. Fossil fuels aregenerally used for start-up and process stabilisation (e.g.some sulphur is required when burning wood to neutralizethe alkali compounds in wood ash).

Peat fuel is here shown as biomass fuel using the Finn-ish definition of peat being a slowly renewable biomassbased fuel (please note that under emission tradingschemes peat is treated as fossil fuel).

Plant 17 is designed and operated as a co-firing plantwith an intentional large fraction of fossil fuels; this doesnot however make this plant perform better or worse in anyother key performance indicator.

062 66 61 15 17 9 10 25 33 51

20

40

60

80




Efficiency

Nominal and operational efficiencies for 10 BFB biomass

CHP systems. Operational figures are average values for 24


The practical total efficiency is significantly lower than thenominal. Further and more important from an economicpoint of view, the electric efficiency is significantly lowerthan the nominal for 10 plants out of 11.

Operational electric efficiency is about 20 % for mostplants; the best plants present an average electric effi-ciency from 24 month of operation of 26 %.

As income from sales of electricity is the main salesvalue for most plant (heat is less significant from an eco-nomic point of view) this has a great negative impact onthe economic performance of the plants.

Some plants show efficiencies above 100% - these areequipped with flue gas condensing systems. Flue gas con-densing systems tends to be the standard in locationswhere the value of heat is high and the value of electricitylow. And in locations with a relatively high electricity priceand a lower heat price, the loss of electricity productionfrom the increased heat efficiency does not justify installa-tion of a flue gas condenser.


Operational efficiencies for 10 BFB biomass CHP systems




2005.

0

20

40

60

80

100




0

200,000

400,000

600,000

800,000

1,000,000Average energy production [MWh/a]



0

20

40

60

80


Heat production:999 GWh/a


The electric efficiency is not impressive, less than 30% inmost cases.

Even though the plants are quite different in size, lesssize dependency for electric efficiency is observed as com-pared to other biomass CHP technologies.

Some plants operate wholly or partly as condensingpower. This reduces heat production as well as the heatpart of total efficiency.


Total of heat and electric efficiencies for 10 BFB biomass

CHP system. Operational figures are monthly data shown


Several plants show lower efficiency during the summermonths, caused by the plants operating part load, and forsome plant because the plant is operating as condensingpower (no or low utilised heat production) during the warmmonths (e.g. plant no. 31).

Some plants exhibit large variations in efficiency monthby month, while other, like the older plant no. 19 are verystable.


Own power consumption for 10 BFB biomass CHP plants.

Data are shown as averages for the 24 month period Sep-


10 to 20% own consumption seems to be the rule also forthis type of CHP plant. This is significant and a high figure,and higher than other biomass CHP technologies.


120

100

80

60

40

20

0

Sep03

Oct03

Nov03

Dec03

Jan 04

Feb04

Mar04

Apr04

Maj04

June

04

July

04

Aug04

Sep04

Oct04

Nov04

Dec04

Jan 05

Feb05

Mar05

Apr05

Maj05

June

05

July

05

Aug05

63 37 13 39 31

21 7 43 55 19

0

0.05

0.10

0.15

0.20


63 21 37 7 13 43 39 55 31 19



Dust-fired steam boiler plantThis technology class contains only dataset from one plant.The general anonymity methodology cannot be appliedhere, however, plant in question, Studstrupvaerket in Den-mark, has no objection to any publication of data.


0

20

40

60

80


Operational electric efficiency

Operational heat efficiency

Nominal electric efficiency

Nominal total efficiency

71

0

20

40

60

80

100Per cent

71

Utilisation factor

Availability

Utilisation factor and availa-

bility for the dust-fired co-

firing CHP plant. Average

figures for 24 months, Sep-

tember 2003 to August

2005.

Utilisation and availability are comparable to what isachieved for other technologies, however 80 % availabilityis not impressive. By far the majority of unavailable hoursare caused by one major revision of the plant.

Efficiency

Nominal and operational

efficiencies for the dust-

fired CHP plant. Operational

figures are average values

for 24 months, September

2003 to August 2005.

Plant no. 43 and 55 are industrial installations. Internalpower consumption other than the in the CHP plant itselfmight explain the high own consumption here.

Plant no. 37 is a new installation, where more efficienttechnology has reduced own consumption of electricity sig-nificantly.

Fuels used


BFB biomass CHP plants. Average figures for 24 months,


Virtually all BFB units use fossil fuels to a small extent,showing that these are certainly versatile boilers. Fossil fu-els as well as peat are generally used for start-up and pro-cess stabilisation.

Peat fuel is here included in biomass fuel.

063 21 37 7 13 43 39 55 31 19

20

40

60

80




Cross technology comparisonKey operational data for the technology classifications hasbeen put together to enable a direct comparison betweendifferent technologies. The single dust-fired plant is not in-cluded in the graphics as it does not consist of a group ofplants like the other technologies, thus average and minand max values are not defined.

Plant size

Comparison of the size, shown as min, max and average

net electric capacity, for the different technologies.

Biogas and landfill gas plants are much smaller than theothers. Gasification plants would generally be smaller thanshown here because one very large plant is included among4 units.

The dust-fired plant (not shown) is 260 MW net electriccapacity. Representing ordinary coal power plant technol-ogy this type of plant would generally be this big; thus for aCHP plant this is only an option when connected to verylarge district heating systems.

Electric efficiency

Comparison of min, max and average electric efficiency for

the different technologies based on operational performance

data for 24 months.

Biogas and landfill gas plants show significantly higher effi-ciency than other technologies. However these are not ex-actly comparable as the gas-based systems usually in-cludes just a gas engine while the other technologies in-

Netpower output [MWel]

0

20

40

60

80

100

Max. value:200 MWel

Bio- andlandfill gas

plants

Gasificationplants

CFBplants

BFBplants

Grate firedboilerplants

MSW gratefired boiler

plants

Average

Per cent

0

10

20

30

40


plants

Gasificationplants

CFBplants

BFBplants



plants

Average

Both electric and heat efficiencies are significantly lower inactual operational data compared to the plant nominaldata.


Total of heat and electric efficiencies for the dust-fired CHP

plant. Figures are monthly data shown for 24 months, Sep-


Total efficiency drops significantly in summer months,where heat demand falls below the plant production capac-ity. From May 2005 the plant is out of operation for majorrevision works.

Own power consumptionThe average own power consumption for this plant is calcu-lated to 0.09 MWh pr. MWh gross electric production, andto 0.03 MWh pr. MWh fuel consumption.

As the own consumption is calculated for the plant inclu-sive 90 % coal consumption it does not however illustratewith accuracy of the performance of the biomass fraction ofthe CHP plant.

Fuels usedThe average monthly biomass fuel input is 35511 MWh

along with 351800 MWh fossil fuels. A 10 % biomass frac-tion (in this case straw) is normal for CHP plants co-firingbiomass and coal in a dust-fired boiler.


0

20

40

60

80

100

Sep03

Oct03

Nov03

Dec03

Jan

04

Feb

04

Mar

04

Apr04

Maj

04

June

04

July

04

Aug04

Sep04

Oct04

Nov04

Dec04

Jan

05

Feb

05

Mar

05

Apr05

Maj

05

June

05

JUly

05

Aug05


volves more complicated equipment to convert energy fromsolid biomass into electricity.

The dust-fired system (not shown) performs best of all:33 %.

Total efficiency

Comparison of the total of electric and heat efficiencies for

the different technologies based on operational data for 24

months.

When adding heat and power, the different technologiesare much more even. This is caused by the general thermo-dynamics in the plant: whatever energy input (fuel) notturned into electricity will convert into heat in one way orother.

The BFB plants generally perform best, also better thanthe dust-fired plant (not shown) at 71%.

Utilisation factor

Comparison of the utilisation factor for the different tech-

nologies, based on operational data for 24 months

Annual total efficiency [per cent]

0

20

40

60

80

100

120


plants

Gasificationplants

CFBplants

BFBplants



plants

Average

Annual electric utilisation period [per cent]

0

20

40

60

80

100


plants

Gasificationplants

CFBplants

BFBplants



plants

Average

Gasification plants perform significantly poorer than theother technologies; do keep in mind however that thisgroup includes only four plants. Again the biogas and land-fill gas plants are the best for the same reason as de-scribed above.

The dust-fired plant (not shown) is 68 %, better than anyaverage for the other technologies.

From a general economic performance perspective, andlooking at the achieved averages across technologies, theutilisation is generally not impressive. The utilisation couldbe seen as the use of invested capital, and the general lowfigures show that many CHP systems either operate partload much of the time or is out of operation for longer periods.

Availability

Comparison of the availability for the different technologies,

based on operational data for 24 months

Gas engine systems are very reliable compared to the othertechnologies, while gasification plants are unavailable foroperation more than 20% of the year (note: average foronly 4 plants).

The dust-fired plant is available 80% of the time in the24 months.

Annual availability [per cent]

50

60

70

80

90

100


plants

Gasificationplants

CFBplants

BFBplants



plants

Average


Environmental performanceA range of environmental performance indicators has beencollected in order to present a “normal” range, and to pres-ent variation between individual plants and between tech-nologies.

Most parameters however were given in incomparableunits and based on incomparable measurement methods,leaving only the following few parameters for comparison.

Ash productionThe amount of ash produced from the plant depend to alarge extent of the fuel used, but also on the technology,including it’s capability to sustain complete burn-out of theorganic matter in the fuel.

Amount of ash produced in the plants shown in metric ton-

nes pr. GWh fuel input. Ash weight includes any water

mixed into the ashes.

BFB and CFB plant produce significantly more ash thangratefired plants; these figures may include some sand(bed material), however most of the CFB and BFB plantsuse a large share of peat with an ash content about 5 %,while 1 - 1.5 % is normal for wood fuels. The extremelyhigh CFB plant in the graphics uses waste paper and bark,both with high mineral content as a fuel.

The MSW plants show much higher ash production fig-ures than other plants. This is due to the nature of thewaste, consisting of as well combustible organic and inor-ganic compounds as large fractions of metals and other in-combustible materials.

Water consumptionWater is consumed internally in the plants in largeamounts, some for process purposes, some for steam pro-duction and some for other purposes.

20

0

40

60

80

100

120Tonnes ash/GWh fuel input

Gasification

CFB

BFB

Grate Wood

Grate MSV

Dust


Consumption of water in the plants shown in m3 pr. GWh

fuel input.

Some plants shopwing higher figures than average produceprocess steam, and thus consume more water, while at thesame time not generating waste water.

Waste water generation

Waste water generation from the plants shown in m3 pr.

GWh fuel input

The variation between plants is higher than other perfor-mance parameters.

Bed materialFor CFB plants the consumption of bed materials is signifi-cant, and counts in this technology performance both as aneconomic operational cost and as an environmental cost.

0

50

100

150

200

250

300

350Cubic metre water consumed/GWh fuel input

Biogas and landfill gas

Gasification CFB

BFB

Grate Wood

Grate MSV

Dust

0

50

100

150

200

250

300

350Cubic waste water produced/GWh fuel input

CFB

BFB Grate MSV

Grate Wood

Anaerobic DigestionNahvärme Antiesenhofen (A)Nahvärme Atzbach (A)NEGH Bio-Strom (A)De Scharlebelt (NL)Ecopark De Wierde (NL)Biogasanlage Preut (DE)Graspower (A)Biogasanlage Klaus Uidl (A)GF-Bio-Energie Hasetal GmbH (DE)Hashoej Power and Heat Supply (DK)Kirchhorster Biogas GbR (DE)ENR GmbH - LOICK Bioenergie (DE)Linko Gas A.m.b.a (DK)Projekt Neustrom (A)Gedea-Novatech Biogasanlagen GmbH & Co. KG (DE)

Landfill gas plantsARN Beuningen (NL)Afvalverwerkingsinrichting de Meersteeg (NL)Ecopark De Wierde (NL)Glatved Landfill Gas Plant (DK)Stige Oe Landfill Gas Plant (DK)

Gasification plantsRural Generation (UK)Biomassekraftwerk Güssing (A)Harbooere District Heating Plant (DK)Lahti Energia Oy, Kymijärvi Power Plant (FIN)

CFB plantsBiomasse-KWK-Anlage Wiesner Hager (A)Etelä-Savon Energia Oy, Pursiala Power Plant (FIN)Grenaa CHP plant (DK)Jämtkraft AB, Lugnvik (SE)Karlstad Energi AB, Heden (SE)Nässjö Affärsverk AB (SE)Perlen Papier AG (CH)PROKON Nord Biomasseheizkraftwerk PapenburgGmbH & Co. KG (DE)Vapo Oy, Lieksa power plant (FIN)Växjö Energi AB, Sandvik 2 (SE)

BFB plantsE.ON Finland, Joensuu Power Plant (FIN)Eskilstuna Energi & Miljö AB (SE)Falu energi AB, Västermalmsverket (SE)Forssan Energia Oy (FIN)Jyväskylän Energiantuotanto Oy, Rauhalahti Power Plant (FIN)Kokkolan Voima Oy, Kokkola power plant (FIN)M-Real Oyj, Simpeleen kartonkitehdas (FIN)Sala-Heby Energi AB, Silververket (SE)Savon Voima Lämpö Oy, Iisalmi power plant (FIN)UPM-Kymmene, Jämsänkoski power plant (FIN)UPM-Kymmene, Kaukas (FIN)

Grate fired boiler plantsAssens District Heating (DK)Bio Energiecentrale Schijndel VOF (NL)Biomassa-centrale Lelystad (NL)Biomasse-KWK-Anlage Lienz (A)Biomasse-Heizkraftwerk Dresden-Niedersedlitz (DE)Biomasse-Heizkraftwerk Mann Naturenergie GmbH& Co. KG (DE)Biomasse-Heizkraftwerk Pfaffenhofen (DE)Elsam A/S Herningvaerket (DK)Enköpings Värmeverk AB (SE)Hjordkaer District Heating Plant (DK)SFW Biomasse-Heizkraftwerk Neufahrn (DE)STIA-ORC-Admont (A)Trans Energi AB, Södra Vakten (SE)VKW Kaufmann (A)

MSW grate fired boiler plantsAfval Energie Bedrijf Gemeente Amsterdam (NL)ARN Nijmegen (NL)Odense CHP Plant (DK)Renova AB, Sävenäs (SE)Roskilde Incineration Plant, Line 5 (DK)Thermische Abfallbehandlungsanlage Spittelau (A)Umeå Energi AB, Dåva (SE)Zweckverband Restmüllheizkraftwerk Böblingen (DE)

Dust fired steam boiler plantsElsam A/S Studstrupvaerket, unit 4 (DK)

Participating CHP-plants

Altener contract no. 4.1030/Z/02-150/2002

biomass chp best practice guide - force...

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