Technologies Cost Analysis-Biomass

8/10/2019 Technologies Cost Analysis-Biomass

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Acknowledgement

This paper was prepared by the IRENA Secretariat. The paper benetted from an internal IRENAreview, as well as valuable comments and guidance from S uani Coelho ( CENBIO), Margaret Mann(NREL) and Martin Zeymer (Deutsches Biomasseforschungszentrum gemeinntzige ).

For further information or to provide feedback, please contact Michael Taylor, IRENA Innovationand Technology Centre, Robert-Schuman-Platz 3, 53175 Bonn, Germany; [email protected].

This working paper is available for download from www.irena.org/Publications

Copyright (c) IRENA 2012Unless otherwise indicated, material in this publication may be used freely, shared or reprinted,but acknowledgement is requested.

About IRENA

The International Renewable Energy Agency (IRENA) is an intergovernmental organisation dedicatedto renewable energy.

In accordance with its Statute, IRENA's objective is to "promote the widespread and increasedadoption and the sustainable use of all forms of renewable energy". This concerns all forms ofenergy produced from renewable sources in a sustainable manner and includes bioenergy,geothermal energy, hydropower, ocean, solar and wind energy.

As of May 2012, the membership of IRENA comprised 158 States and the European Union (EU), outof which 94 States and the EU have ratied the Statute.

The designations employed and the presentation of materials herein do not imply the expressionof any opinion whatsoever on the part of the Secretariat of the International Renewable Energy

Agency concerning the legal status of any country, territory, city or area or of its authorities, or con-cerning the delimitation of its frontiers or boundaries. The term country as used in this materialalso refers, as appropriate, to territories or areas.

Disclaimer


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ContentsKEY FINDINGS i

LIST OF TABLES AND FIGURES iii

1. INTRODUCTION 1 1.1 Different Measures of Cost and Data Limitations

1.2 Levelized Cost of Electricity Generation

2. BIOMASS POWER GENERATION TECHNOLOGIES 4 2.1 Biomass Combustion Technologies 2.2 Anaerobic Digestion 2.3 Biomass Gasication Technologies

3. FEEDSTOCK 17

4. GLOBAL BIOMASS POWER MARKET TRENDS 21 4.1. Current Installed Capacity and Generation 4.2 Future Projections of Biomass Power Generation Growth 4.3 Feedstock Market 5. CURRENT COSTS OF BIOMASS POWER 27 5.1 Feedstock Prices 5.2 Biomass Power Generation Technology Costs 5.3 Operation and Maintenance Expenditure (OPEX) 5.4 Cost Reduction Potentials for Biomass-red Electricity Generation

6. LEVELISED COST OF ELECTRICITY FROM BIOMASS 38

6.1 The LCOE of Biomass-red Power Generation

REFERENCES 45

ACRONYMS 49


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1. The total installed costs of biomass power generation technologies varies significantly bytechnology and country. The total installed costs of stoker boilers was between USD 1 880and USD 4 260/kW in 2010, while those of circulating fluidised bed boilers were betweenUSD 2 170 and USD 4 500/kW. Anaerobic digester power systems had capital costsbetween USD 2 570 and USD 6 100/kW. Gasification technologies, including fixed bedand fluidised bed solutions, had total installed capital costs of between USD 2 140 andUSD 5 700/kW. Co-firing biomass at low-levels in existing thermal plants typically requiresadditional investments of USD 400 to USD 600/kW. Using landfill gas for power generationhas capital costs of between USD 1 920 and USD 2 440/kW. The cost of CHP plants issignificantly higher than for the electricity-only configuration.

2. Operations and maintenance (O&M) costs can make a significant contribution to thelevelised cost of electricity (LCOE) and typically account for between 9% and 20% of theLCOE for biomass power plants. It can be lower than this in the case co-firing and greaterfor plants with extensive fuel preparation, handling and conversion needs. Fixed O&M costsrange from 2% of installed costs per year to 7% for most biomass technologies, with variableO&M costs of around USD 0.005/kWh. Landfill gas systems have much higher fixed O&Mcosts, which can be between 10% and 20% of initial capital costs per year.

3. Secure, long-term supplies of low-cost, sustainably sourced feedstocks are critical to theeconomics of biomass power plants. Feedstock costs can be zero for wastes which wouldotherwise have disposal costs or that are produced onsite at an industrial installation (e.g.black liquor at pulp and paper mills or bagasse at sugar mills). Feedstock costs may bemodest where agricultural residues can be collected and transported over short distances.However, feedstock costs can be high where significant transport distances are involved dueto the low energy density of biomass (e.g. the trade in wood chips and pellets). The analysisin this report examines feedstock costs of between USD 10/tonne for low cost residues toUSD 160/tonne for internationally traded pellets.

Ke f d gs

i est e t costs LCOE geUSD/kW USD/kWh

Stoke bo le 1 880 4 260 0.06 0.21

Bubbl g d c cul t g flu d sed bo le s 2 170 4 500 0.07 0.21

F ed d flu d sed bed g s f e s 2 140 5 700 0.07 0 24

Stoke CHP 3 550 6 820 0.07 0.29

G s f e CHP 5 570 6 545 0.11 0.28

L df ll g s 1 917 2 436 0.09 0.12

D geste s 2 574 6 104 0.06 0.15

Co-f g 140 850 0.04 0.13

TaBLE 1: TyPiCaL CaPiTaL COSTS anD THE LE vELiSED COST OF ELECTriCiTy OF BiO maSS POWEr TECHnO LOGiES


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4. The LCOE of biomass-fired power plants ranges from USD 0.06 to USD 0.29/kWhdepending on capital costs and feedstock costs. Where low-cost feedstocks are availableand capital costs are modest, biomass can be a very competitive power generation option.Where low-cost agricultural or forestry residues and wastes are available, biomass can oftencompete with conventional power sources. Even where feedstocks are more expensive, theLCOE range for biomass is still more competitive than for diesel-fired generation, makingbiomass an ideal solution for off-grid or mini-grid electricity supply.

5. Many biomass power generation options are mature, commercially available technologies(e.g. direct combustion in stoker boilers, low-percentage co-firing, anaerobic digestion,municipal solid waste incineration, landfill gas and combined heat and power). While othersare less mature and only at the beginning of their deployment (e.g. atmospheric biomassgasification and pyrolysis), still others are only at the demonstration or R&D phases (e.g.integrated gasification combined cycle, bio-refineries, bio-hydrogen). The potential for costreductions is therefore very heterogeneous. Only marginal cost reductions are anticipatedin the short-term, but the long-term potential for cost reductions from the technologies thatare not yet widely deployed is good.


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List of tablesTable 2.1: Biomass feedstocks 4Table 2.2: Thermo-chemical and bio-chemical conversion processes for biomass feedstocks 5Table 2.3: Steam turbine types and characteristics 7Table 2.4: Appropriate anaerobic digesters by waste or crop stream 10Table 2.5: Operational parameters of a representative anaerobic digester using energy crops 11Table 2.6: Advantages and disadvantages of uidised bed gasiers 15Table 2.7: Examples of producer gas contaminants 16Table 3.1: Heat content of various biomass fuels (dry basis) 17Table 3.2: Biomass power generation technologies and feedstock requirements 20Table 4.1: Details of fossil-fuel red power plants co-ring with biomass in the Netherlands 23Table 5.1: Biomass and pellet market prices, January 2011 27Table 5.2: Biomass feedstock prices and characteristics in the United States 28Table 5.3: Biomass feedstock costs including transpor t for use in Europe 30Table 5.4: Feedstock costs for agricultural residues in Brazil and India 31

Table 5.5: Estimated equipment costs for biomass power generation technologies by study 32Table 5.6: Fixed and variable operations and maintenance costs for biomass power 35Table 5.7: Long-run cost reduction potential opportunities for bioenergy power generation technologies 36Table 6.1: Assumptions for the LCOE analysis of biomass-red power generation technologies in Figure 6.4 43

Figure 1.1: Renewable power generation costs indicators and boundaries 1Figure 2.1: Biomass power generation technology maturity status 6Figure 2.2: An example of efciency gains from CHP 8Figure 2.3: Different biomass co-ring congurations 9Figure 2.4: Schematic of the gasication process 12Figure 2.5: Gasier size by type 13Figure 2.6: Small-scale updraf t and downdraf t xed bed gasiers 14Figure 3.1: Impact of moisture content on the price of feedstock cost on a net energy basis 18Figure 4.1: Global grid-connected biomass capacity in 2010 by feedstock and country/region (MW) 21Figure 4.2: Share of global installed biomass capacity in 2010 by feedstock and country/region 22Figure 4.3: Biomass power generation projects with secured nancing/under construction (GW) 24

Figure 4.4: Projected biomass and waste installed capacity for power generation and annual investment,2010 to 2030 24

Figure 5.1: Breakdown of biomass and waste availability by cost in the United States, 2012/2017 29Figure 5.2: Biomass feedstock preparation and handling capital costs as a function of throughput 30Figure 5.3: Installed capital cost ranges by biomass power generation technology 33Figure 5.4: Capital cost breakdown for biomass power generation technologies 34Figure 5.5: Biomass feedstock cost reduction potentiaL to 2020 in Europe 36Figure 6.1: The LCOE framework for biomass power generation 39Figure 6.2: LCOE ranges for biomass-red power generation technologies 40Figure 6.3: Share of fuel costs in the LCOE of bioenergy power generation for high and low feedstock prices 41Figure 6.4: Breakdown of the LCOE of selected bioenergy-red power generation technologies 42

List of figures


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1Cost Analysis of Biomass for Power Generation

Without access to reliable information on the relativecosts and benefits of renewable energy technologies,it is difficult, if not impossible, for governments toarrive at an accurate assessment of which renewableenergy technologies are the most appropriate fortheir particular circumstances. These papers fill asignificant gap in information availability becausethere is a lack of accurate, comparable, reliableand up-to-date data on the costs and performanceof renewable energy technologies. There is also asignificant amount of perceived knowledge about thecost and performance of renewable power generationthat is not accurate, or, indeed, is even misleading.Conventions on how to calculate cost can influencethe outcome significantly, and it is imperative thatthese are well-documented.

The absence of accurate and reliable data on the costand performance of renewable power generationtechnologies is therefore a significant barrier tothe uptake of these technologies. Providing thisinformation will help governments, policy-makers,investors and utilities make informed decisions aboutthe role renewables can play in their power generationmix. This paper examines the fixed and variablecost components of biomass power, by country

and by region, and provides the levelised cost ofelectricity from biomass power given a number of keyassumptions. This up-to-date analysis of the costs ofgenerating electricity from biomass will allow a faircomparison of biomass with other power generatingtechnologies. 1

1.1 DIFFERENT MEASURES OF COST AND DATA LIMITATIONS

Cost can be measured in a number of different ways,and each way of accounting for the cost of powergeneration brings its own insights. The costs thatcan be examined include equipment costs (e.g. windturbines, PV modules, solar reflectors), financingcosts, total installed cost, fixed and variable operatingand maintenance costs (O&M), fuel costs and thelevelised cost of energy (LCOE), if any.

The analysis of costs can be very detailed, but forcomparison purposes and transparency, the approachused here is a simplified one. This allows greaterscrutiny of the underlying data and assumptions,improved transparency and confidence in the analysis,as well as facilitating the comparison of costs bycountry or region for the same technologies in orderto identify what are the key drivers in any differences.

The three indicators that have been selected are:

Equipment cost (factory gate FOB anddelivered at site CIF);

Total installed project cost, including fixedfinancing costs 2; and

The levelised cost of electricity LCOE.

The analysis in this paper focuses on estimatingthe cost of biomass power from the perspective ofan investor, whether it is a state-owned electricitygeneration utility, an independent power producer or

1. i t oduct oR enewable energy technologies can help countries meet their policy goals for secure, reliable andaffordable energy to expand electricity access and promote development. This paper is part of a serieson the cost and performance of renewable energy technologies produced by IRENA. The goal of these papersis to assist government decision-making and ensure that governments have access to up-to-date and reliableinformation on the costs and performance of renewable energy technologies.

1 IRENA, through its other work programmes, is also looking at the costs and benefits, as well as the macro-economic impacts , of renewable power generation technologies . See WWW.IRENA.ORG for further details. 2 Banks or other financial institutions will often charge a fee, usually a percentage of the total funds sought, to arrange the debt financing of a project. These costs are often reported separately under project development costs.


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2 Cost Analysis of Biomass for Power Generation

an individual or community looking to invest in small-scale renewables (Figure 1.1). The analysis excludesthe impact of government incentives or subsidies,system balancing costs associated with variablerenewables and any system-wide cost-savings fromthe merit order effect. Further, the analysis does nottake into account any CO2 pricing, nor the benefitsof renewables in reducing other externalities (e.g.reduced local air pollution and contamination ofthe natural environment). Similarly, the benefits ofrenewables being insulated from volatile fossil fuelprices have not been quantified. These issues areimportant but are covered by other programmes ofwork at IRENA.

It is important to include clear definitions of thetechnology categories, where this is relevant, to

ensure that cost comparisons are robust and provideuseful insights (e.g. biomass combustion vs. biomassgasification technologies). Similarly, it is importantto differentiate between the functionality and/ or qualities of the renewable power generationtechnologies being investigated (e.g. ability to scale-up, feedstock requirements). It is important to ensurethat system boundaries for costs are clearly set andthat the available data are directly comparable. Otherissues can also be important, such as cost allocationrules for combined heat and power plants and gridconnection costs.

The data used for the comparisons in this paper comefrom a variety of sources, such as business journals,industry associations, consultancies, governments,auctions and tenders. Every effort has been made toensure that these data are directly comparable andare for the same system boundaries. Where this is notthe case, the data have been corrected to a commonbasis using the best available data or assumptions.It is planned that these data will be complementedby detailed surveys of real world project data inforthcoming work by the agency.

An important point is that although this paper triesto examine costs, strictly speaking, the data availableare actually prices, and not even true market averageprices, but price indicators. The difference betweencosts and prices is determined by the amount above,

or below, the normal profit that would be seen in acompetitive market. The rapid growth of renewablesmarkets from a small base means that the market forrenewable power generation technologies is rarelywell-balanced. As a result, prices, particularly forbiomass feedstocks, can rise significantly above costsin the short-term if supply is not expanding as fast asdemand, while in times of excess supply losses canoccur and prices may be below production costs.This makes analysing the cost of renewable powergeneration technologies challenging and every effortis made to indicate whether costs are above or belowtheir long-term trend.

T spo t costi po t le els

Factor gateEquipme t

O siteEquipme t Project cost LCOE

P ojectde elop e t

S te p ep t oG d co ect oWo k g c p t l

au le u p e t

no -co e c lcost

Ope t o &m te ce

Cost of f ceresou ce u l tC p c t f cto

L fe sp

LCOE: Le el ed C ost o f Elect c t (D scou ted l fet e cost d ded b d scou ted l fet e ge e t o )

FiGUrE 1.1: rEnEWaBLE POWEr GEnEraTiOn COSTS inDiCaTOrS anD BOUnDariES


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The cost of equipment at the factory gate is oftenavailable from market surveys or from other sources.A key difficulty is often reconciling different sourcesof data to identify why data for the same perioddiffer. The balance of capital costs in total project

costs tends to vary even more widely than powergeneration equipment costs, as it is often based onsignificant local content, which depends on the coststructure of where the project is being developed.Total installed costs can therefore vary significantlyby project, country and region, depending on a widerange of factors.

1.2 LEVELISED COST OF ELECTRICITY

GENERATION

The LCOE of renewable energy technologiesvaries by technology, country and project, basedon the renewable energy resource, capital andoperating costs and the efficiency/performance ofthe technology. The approach used in the analysispresented here is based on a discounted cash flow(DCF) analysis. This method of calculating thecost of renewable energy technologies is basedon discounting financial flows (annual, quarterly ormonthly) to a common basis, taking into considerationthe time value of money. The weighted averagecost of capital (WACC), often also referred to as thediscount rate, is an important part of the informationrequired to evaluate biomass power generationprojects and has an important impact on the LCOE.

There are many potential trade-offs to be consideredwhen developing an LCOE modelling approach. Theapproach taken here is relatively simplistic, given

the fact that the model needs to be applied to awide range of technologies in different countriesand regions. However, this has the additionaladvantage that the analysis is transparent and easy tounderstand. In addition, more detailed LCOE analysisresults in a significantly higher overhead in terms ofthe granularity of assumptions required. This oftengives the impression of greater accuracy, but when

it is not possible to robustly populate the model withassumptions, or to differentiate assumptions based onreal world data, then the accuracy of the approachcan be misleading.

The formula used for calculating the LCOE ofrenewable energy technologies is 3:

Where:LCOE = the average lifetime levelised cost of

electricity generation;It = investment expenditures in the year t;Mt = operations and maintenance expenditures in

the year t;F t = fuel expenditures in the year t;Et = electricity generation in the year t;r = discount rate; andn = life of the system.

All costs presented in this paper are real 2010 USD,unless otherwise stated, 3 that is to say after inflationhas been taken into account. 4 The LCOE is the priceof electricity required for a project where revenueswould equal costs, including making a return onthe capital invested equal to the discount rate. Anelectricity price above this would yield a greaterreturn on capital while a price below it would yield alower return on capital or even a loss.

As already mentioned, although different costmeasures are useful in different situations, the LCOEof renewable energy technologies is a widely used

measure by which renewable energy technologiescan be evaluated for modelling or policy developmentpurposes. Similarly, more detailed DCF approaches,taking into account taxation, subsidies and otherincentives, are used by renewable energy projectdevelopers to assess the profitability of real world

nt = 1

nt = 1

I t + M t + F t (1+r) t

E t

(1+r) t

LCOE =

3 Note that for biomass CHP, a credit is allocated for the steam produced. The methodology used for allocating costs betweenelectricity and heat production can have an important impact on the estimated LCOE (Coelho, 1997)..4 The 2010 USD/Euro exchange rate was 1.327 and the USD/GBP exchange rate was 1.546. All data for exchange rates and GDPdeflators were sourced from the International Monetary Funds databases or from the World Banks World Economic Outlook.5 An analysis based on nominal values with specific inflation assumptions for each of the cost components is beyond the scope ofthis analysis. Project developers will develop their own specific cash-flow models to identify the profitability of a project from their

perspective.


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The o-Che c l P ocess

Combustio The c cle used s the co e t o l k e c cle w th b o ss be g bu ed (o d sed) h g h p essu e bo le to ge e te ste . The et powe c cle eff c e c es th t c

be ch e ed e bout 23% to 25%. The e h ust of the ste tu b e c e the be

full co de sed to p oduce powe o used p tl o full fo othe useful he t gct t . i dd t o to the e clus e use of b o ss co bust o to powe stetu b e, b o ss c be co-f ed w th co l co l-f ed powe pl t.D ect co-f g s the p ocess of dd g pe ce t ge of b o ss to the fuel co l-f ed powe pl t. it c be co-f ed up to 5-10% of b o ss ( e e g te s)d 50-80% 6 w th e te s e p e-t e t e t of the feedstock ( .e. to ef ct o ) w th o lo ch ges the h dl g e u p e t. Fo pe ce t ges bo e 10% o f b o ssd co l e bu g sep tel d ffe e t bo le s, k ow s p llel co-f g, the

ch ges lls, bu e s d d e s e eeded.

Gasificatio G s f c t o s ch e ed b the p t l co bust o of the b o ss low o gee o e t, le d g to the ele se of g seous p oduct (p oduce g s o s g s). So-c lled llothe l o d ect g s f c t o s lso poss ble. The g s f e c e the beof f ed bed, flu d sed bed o e t ed flow co f gu t o . The esult g g s s tu e of c bo o o de, w te , CO 2, ch , t d h d oge , d t c be used co bust o e g es, c o-tu b es, fuel cells o g s tu b es. Whe used tu b esd fuel cells, h ghe elect c l eff c e c es c be ch e ed th those ch e ed ste tu b e. it s poss ble to co-f e powe pl t e the d ectl ( .e. b o ss dco l e g s f ed togethe ) o d ectl ( .e. g s f g co l d b o ss sep tel fouse g s tu b es).

P rolsis P ols s s subset of g s f c t o s ste s. i p ol s s, the p t l co bust o sstopped t lowe te pe tu e (450C to 600C), esult g the c e t o of l u db o-o l, s well s g seous d sol d p oducts. The p ol s s o l c the be used s fuel to ge e te elect c t .

B o-Che c l P ocess

A aerobic Digestio a e ob c d gest o s p ocess wh ch t kes pl ce l ost b olog c l te lth t s deco pos g d s f o ed b w , wet d less co d t o s. The esult gg s co s sts l of eth e d c bo d o de d s efe ed to s b og s. Theb og s c be used, fte cle -up, te l co bust o e g es, c o-tu b es,g s tu b es, fuel cells d st l g e g es o t c be upg ded to b o eth e fod st but o .

TaBLE 2.2: THErmO-CHEmiCaL anD BiO-CHEmiCaL COnvErSiOn PrOCESSES FOr BiOmaSS FEEDSTOCKS

Source: BaSed on ePrI, 2012

Power generation from biomass can be achieved witha wide range of feedstocks and power generation

technologies that may or may not include anintermediate conversion process (e.g. gasification).In each case, the technologies available range fromcommercially proven solutions with a wide rangeof technology suppliers (e.g. solid fuel combustion)through to those that are only just being deployed

at commercial scale (e.g. gasification). There areother technologies that are at an earlier stage of

development and are not considered in this analysis(Figure 2.1). In addition, different feedstocks andtechnologies are limited or more suited to differentscales of application, further complicating the picture.The following sections discuss each of the majortechnology groups and their technical parameters.

6 See for example, http://www.topellenergy.com/product/torrefied-biomass/


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2.1 BIOMASS COMBUSTIONTECHNOLOGIES

Direct combustion of biomass for power generation isa mature, commercially available technology that canbe applied on a wide range of scales from a few MWto 100 MW or more and is the most common form ofbiomass power generation. Around the globe, over90% of the biomass that is used for energy purposesgoes through the combustion route. Feedstockavailability and costs have a strong influence on

project size and economics, since with increasingscale the increased transport costs for the biomassfeedstock may outweigh economies of scale from

larger plants. However, this is very project-specificand pre-treatment (e.g. torrefaction) to achieve higherenergy densities can help to reduce this impact andallow larger-scale plant.

There are two main components of a combustionbased biomass plant: 1) the biomass-fired boiler thatproduces steam; and 2) the steam turbine, which isthen used to generate electricity.

The two most common forms of boilers are stoker and

fluidised bed (see Box 1). These can be fuelled entirelyby biomass or can be co-fired with a combination ofbiomass and coal or other solid fuels (EPA, 2008).

a t c p t e d C o s t o f F u l l - S c l e a p p l c t o

rese ch De elop e t De o st t o

T e

Deplo e t m tu e Tech olog

I tegrated BiomassGasificatio Fuel Cell

Bio-H droge

Biorefi eries

H brid Biomass-Solar/Geothermal

PressurizedGasificatio

Torrefied Pellet Productio

High-RateCofiri g

AtmosphericBiomass Gasificatio

Refuse-Derived &Process-E gi eered Fuels

100% Biomass Repoweri g Optio s

P rol sis

Medium-Rate Cofiri g

MSWI ci eratio

CHPA aerobic Digestio

Low-RateCofiri g

Stoker/FBCSteam-Electric

Combustio

LFG

Source: ePrI, 2011

FiGUrE 2.1 : BiOmaSS POWEr GEnE raTiOn TECHnOLOGy maTUriTy STaTUS


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Stoker boilers burn fuel on a grate, producing hotflue gases that are then used to produce steam.The ash from the combusted fuel is removedcontinuously by the fixed or moving grate. Thereare two general types of stokers. Underfeedboilers supply both the fuel and the air from underthe grate. Overfeed boilers supply the fuel fromabove the grate and the air from below.

Fluidised bed boilers suspend fuels on upwardblowing jets of air during the combustion process.They are categorised as either atmospheric orpressurised units. Atmospheric fluidised bedboilers are further divided into bubbling-bed and

circulating-bed units; the fundamental differencebetween bubbling-bed and circulating-bed boilersis the fluidisation velocity (higher for circulating).Circulating fluidised bed boilers (CFB) separateand capture fuel solids entrained in the high-velocity exhaust gas and return them to the bedfor complete combustion. Pressurised CFB areavailable, although atmospheric-bubbling fluidisedbed boilers are more commonly used when thefuel is biomass. They can also be a more effectiveway to generate electricity from biomass with ahigher moisture content than typical in a stokerboiler (UNIDO, 2009).

Box 1

BOILER TYPES

These e des g ed to obtthe u ou t of sh ftwo k out of g e ste put o de to se elect c l

eff c e c . Th s s the def ult cho cefo st d lo e ste elect cge e t g pl t.

Co de s g Ste Tu b eTh s s t o of st ghtco de s g tu b e. it s des g edto llow ste to be e t ctedf o the tu b e t te ed tep essu es the ddle p t ofthe tu b e. Th s s des ble foco b ed he t d powe s ste s,s the he t d powe ge e t ole els c be djusted to thed ffe e t e u e e ts. Th s t peof tu b e offe s h gh fle b l t

of ope t o but t the e pe se ofelect c l eff c e c .

E t ct o Ste Tu b eTh s des g s ostl used whe co st t suppl of he t s e u edto p o de ste to dust l oco e c l p ocess. B ckp essu etu b es d sch ge ste t h ghte pe tu es d p essu es. Dueto the h ghe p essu e d sch ge, b ckp essu e tu b e w ll p oducelowe ou ts of sh ft powe dh e lowe elect c l eff c e c .Co o l used B l the

sug c e dust , the eche pe but less fle ble thco de s g d e t ct o stetu b es.

B ckp essu e Ste Tu b e

TaBLE 2.3: STEam TUrBinE TyPES anD CHaraCTEriSTiCS

Source: M Hale, 2010.

The steam produced in the boilers is injected intosteam turbines. These convert the heat contained inthe steam into mechanical power, which drives the

generation of electricity. There are three major typesof turbines with each one having its own specificcharacteristics (Table 2.3).


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The co-firing of biomass with coal in large coal-firedpower plants is becoming increasingly common.Around 55 GW of coal-fired capacity is now co-firedwith biomass in North America and Europe (IEABioenergy, 2012). In Europe, approximately 45 GW ofthermal power generation capacity is co-fired withbiomass with from as little as 3% to as much as 95%

biomass fuel content. The advantage of biomassco-firing is that, on average, electric efficiency inco-firing plants is higher than in dedicated biomasscombustion plants. The incremental investment costsare relatively low although they can increase the costof a coal-fired power plant by as much as a third.

Combined heat and power (CHP), also known asa co-generation, is the simultaneous productionof electricity and heat from one source ofenergy. CHP systems can achieve higher overallefficiencies than the separate production ofelectricity and heat when the heat produced isused by industry and/or district heating systems(Figure 2.2). Biomass-fired CHP systems canprovide heat or steam for use in industry (e.g. thepulp and paper, steel, or processing industries) orfor use for space and water heating in buildings,directly or through a district heating network.

The viability of biomass CHP plants is usuallygoverned by the price of electricity and theavailability and cost of the biomass feedstock.Although many sources of biomass are availablefor co-generation, the greatest potential lies in thesugar cane and wood processing industries, as thefeedstock is readily available at low cost and theprocess heat needs are onsite (UNIDO, 2008).

Box 2

COMBINED HEAT AND POWER

Source: BaSed on Iea, 2008.

FiGUrE 2.2: an ExamPLE OF EFFiCiEnCy GainS FrOm CHP

Heat Heat

CHPfuel

2 1 5

Losses (40)Losses (20)

Losses (60)

Losses (5)

Combi edheat a d

power

CHP

Boiler fuel (100)

Power statiofuel (115)

Co ve tio al ge eratio Combi ed heat a d power

Efficie c : 48%

Efficie c : 80%

TOTA L E F F I C I E n Cy 6 0 % TOTA L E F F IC I E n Cy 76 , 5%

1 7 0

Gas powerpla t

Gasboiler

5 0

8 0


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There are three possible technology set-ups for co-firing (Figure 2.3):

Direct co-firing, whereby biomass and coalare fed into a boiler with shared or separate

burners;

Indirect co-firing, whereby solid biomassis converted into a fuel gas that is burnedtogether with the coal; and

Parallel co-firing, whereby biomass is burnedin a separate boiler and steam is supplied tothe coal-fired power plant.

Technically it is possible to co-fire up to about 20%of capacity without any technological modifications;however, most existing co-firing plants use up toabout 10% biomass. The co-firing mix also depends onthe type of boiler available. In general, fluidised bed

boilers can substitute higher levels of biomass thanpulverised coal-fired or grate-fired boilers. Dedicatedbiomass co-firing plants can run up to 100% biomassat times, especially in those co-firing plants that areseasonally supplied with large quantities of biomass

(IRENA, 2012).

However, co-firing more than 20% will usuallyrequire more sophisticated boiler process controland boiler design, as well as different combustionconsiderations, fuel blend control and fuel handlingsystems due to the demanding requirements ofbiomass-firing and the need to have greater controlover the combustion of mixed-feedstocks.Biomass is also co-fired with natural gas, but inthis case the natural gas is often used to stabilisecombustion when biomass with high-moisturecontent (e.g. municipal solid waste) is used and thepercentage of natural gas consumed is generally low(US EPA, 2007).

Source: euBIoneT, 2003.

FiGUrE 2.3: DiFFErEnT BiOmaSS CO-FirinG COnFiGUraTiOnS

D ect Co-f g i d ect Co-f g P llel Co-f g

Biomass

BiomassBiomass

Gasificatio gas

Coal CoalCoal

GR

An important source of electricity generation frombioenergy today is found in the pulp and paper

industry in the form of black liquor. Black liquoris a by-product of the paper-making processand consists of the remaining components aftercellulose fibres have been cooked out of the woodfeedstock. Although initially weak (15% solids), thissolution is concentrated by evaporation until it has

a solid content of around 75% to 80%. It can thenbe combusted in an energy recovery boiler or, less

commonly, gasified. The black liquor then provideselectricity and heat for the process needs of theplant and possibly for export. Combustion in boilersis a mature technology, but commercial gasificationtechnologies are only just being deployed.

Boiler Boiler BoilerBoi-ler


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2.2 ANAEROBIC DIGESTION

Anaerobic digestion (AD) converts biomassfeedstocks with a relatively high moisture content intoa biogas. Anaerobic digestion is a naturally occurring

process and can be harnessed to provide a veryeffective means to treat organic materials, includingenergy crops (although this is often at the R&Dstage, depending on the crop), residues and wastesfrom many industrial and agricultural processes andmunicipal waste streams (Table 2.4). AD is mostcommonly operated as a continuous process and thusneeds a steady supply of feedstock. The feedstock

needs to be strictly checked and usually needssome form of pre-treatment to maximise methaneproduction and minimise the possibility of killing thenatural digestion process. Co-digestion of multiplefeedstocks is most commonly practised to achieve the

best balance of biogas yield and process stability. Thetwo main products of AD are biogas and a residuedigestate, which, after appropriate treatment, can beused as a bio-fertiliser. Biogas is primarily a mixtureof methane (CH 4) and carbon dioxide (CO 2), as wellas some other minor constituents including nitrogen,ammonia (NH 3), sulfur dioxide (SO 2), hydrogen sulfide(H2S) and hydrogen.

app op te d geste

Desc pt o

Co e ed l goo d geste /Upflow e ob c sludgebl ket/F ed F l

Co e ed l goo o sludgebl ket-t pe d geste se used w th w stes

d sch ged to w te .The deco pos t o ofw ste w te c e tes tu ll e ob c

e o e t.

Plug flow d geste

Plug flow d geste s eused fo sol d u eo w ste (ge e llwhe the w stes sol dsco pos t o s 11% og e te ). W stes edepos ted lo g,

he ted t k th t st p c ll s tu ted belowg ou d. B og s e s the t k u t l use o

fl g.

Co plete d geste

Co plete d geste swo k best w th slu

u e o w stes th te se -l u d (ge e ll ,

whe the w stes sol dsco pos t o s less th10%). These w stes e

depos ted he tedt k d pe od c lled. B og s th t s

p oduced e s thet k u t l use o fl g

T pe of W ste L u d W ste Slu W ste Se -sol d W ste

TaBLE 2.4: aPPrOPriaTE anaErOB iC DiGESTErS By WaSTE Or CrOP STrEam

Source: cenTr e for clIMaTe and energy SoluTIonS, 2012.

Biogas is readily used as a fuel in power or combinedheat and power units and has the potential to beused as a substitute for natural gas after appropriate

cleaning and upgrading (IEA Bioenergy, 2011). Large-scale plants using municipal solid waste (MSW),agricultural waste and industrial organic wastesrequire between 8 000 and 9 000 tonnes of MSW/

MW/year. Landfill gas and digesters are proventechnologies, but they can be limited in scale byfeedstock availability. Table 2.5 provides an indication

of the quantities of three different crop feeds thatwould be required to power a 500 kW electrical primemover and its electrical and thermal output.


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In Europe in mid-2011, Germany, with 7 090 digesters,was the leading country for both the number andinstalled capacity of ADs (Linke, 2011). The totalinstalled electrical capacity of these plants is2 394 MW. Virtually all of this capacity is locatedin the agricultural sector where maize sillage, othercrops and animal slurry are used. This importantcontribution is driven by a feed-in tariff in Germanythat supports electricity generation from biogas fromAD.

2.3 BIOMASS GASIFICATIONTECHNOLOGIES

Gasifier technologies offer the possibility ofconverting biomass into a producer gas, which canbe burned in simple or combined-cycle gas turbines

at higher efficiencies than the combustion of biomassto drive a steam turbine. Although gasificationtechnologies are commercially available, more needsto be done in terms of R&D and demonstration topromote their widespread commercial use, as onlyaround 373 MW th of installed large-scale capacitywas in use in 2010, with just two additional projectstotaling 29 MW th planned for the period to 2016(US DOE, 2010). The key technical challenges that

require further R&D include improving fuel flexibility,removing particulates, alkali-metals and chlorine; andthe removal of tars and ammonia (Kurkela, 2010).From an economic perspective, reducing complexityand costs, and improving performance and efficiencyare required.

There are three main types of gasification technology 7:

Fixed bed gasifiers;

Fluidised (circulating or bubbling)bed gasifiers; and

Entrained flow gasifiers. 8

However, there are a wide range of possibleconfigurations, and gasifiers can be classifiedaccording to four separate characteristics:

Oxidation agent: This can be air, oxygen,steam or a mixture of these gases.

Heat for the process: This can be eitherdirect (i.e. within the reactor vessel by thecombustion process) or indirect (i.e. providedfrom an external source to the reactor).

pe e

TaBLE 2.5: OPEraTiOnaL ParamETErS OF a rEPrESE nTaTivE anaErOBiC DiGESTEr USi nG EnErGy CrOPS

Source: MurPHy eT al., 2010.

7 One additional option is the use of air as the reactive agent, but this yields a very low energy content gas, albeit suitable for use in boilers

or internal combustion engines.8 Entrained flow gasifiers are not discussed in detail in this paper, as their main advantage is the possibility to work at large scales (from100 MW to over 1 000 MW), which arent common for biomass-fired power generation projects.

i put of e s l ge (to es) 5 940

i put of g ss s l ge (to es) 2 181

i put of clo e s l ge (to es) 1 374Tot l feedstock (to es) 9 495

B og s p oduct o ( ll o 3) 1.88

Elect c t p oduced (mWh) 4 153

The l e e g p oduced (mWh) 4 220

Ow elect c t co su pt o (mWh) 161

Ow the l e e g co su pt o (mWh) 701

Elect c t l ble fo s le (mWh) 3 992

The l e e g l ble fo s le (mWh) 1 697


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FiGUrE 2. 4: SCHEmaTiC OF THE GaSiFiCaTiOn PrOCESSSource: BaSed on Sadaka, 2010; BelgIorno, 2003; an d McHale, 2010.


The pressure level: Gasification can occur atatmospheric pressure or at higher pressures.

Reactor type: As already discussed, these canbe fixed bed, fluidised bed or entrained flow.

Gasification comprises a two-step process. The firststep, pyrolysis, is the decomposition of the biomassfeedstock by heat. This yields 75% to 90% volatilematerials in the form of liquids and gases, with theremaining non-volatile products being referred toas char. The second step is the gasification process,where the volatile hydrocarbons and the char aregasified at higher temperatures in the presence ofthe reactive agent (air, oxygen, steam or a mixture ofthese gases) to produce CO and H 2 , with some CO 2,methane, other higher hydrocarbons and compoundsincluding tar and ash. These two steps are typicallyachieved in different zones of the reactor vesseland do not require separate equipment. A thirdstep is sometimes included: gas clean-up to removecontaminants, such as tars or particulates.

Air-based gasifiers are relatively cheap and typicallyproduce a hydrogen/carbon monoxide producer gaswith a high nitrogen content (from the air) and a lowenergy content (56 MJ/m 3 on a dry-basis). Gasifiersusing oxygen or steam as the reactive agent tend to

produce a syngas with relatively high concentrationsof CO and H 2 with a much higher energy content(919 MJ/m 3), albeit at greater cost than an air-blowngasifier

The gasification process is a predominantlyendothermic process that requires significantamounts of heat. The producer gas, once produced,will contain a number of contaminants, some ofwhich are undesirable, depending on the powergeneration technology used. Tars, for example,can clog engine valves and accumulate on turbineblades, leading to increased maintenance costs anddecreased performance. Some producer gas clean-up will therefore usually be required. After cleaning,the producer gas can be used as a replacement fornatural gas and injected in gas turbines or it canproduce liquid biofuels, such as synthetic diesel,ethanol, gasoline or other liquid hydrocarbons viaFischer-Tropsch synthesis.

* n t : c mm i is i s th q ipm t v i b s with missi p m t s t i mm i p ti with v i bi it q iv t t mm i ti q ipm t b p t th

th th m t v p th t h .

Reactiveage t

Biomass

Gas without treatme t Co-ge eratio

Power

AlcoholMeha olGasoli eMetha eAmmo ia

Commercial Pilot or Lab concept Near commercialisation

Air

Steam

or ox ge

or a mixtureof air,steam

a dox ge

Step 1:P rolisis ~500 C

C clo e filtersWet scrubber

etc

Boilers

Low energy gas Producer gas

Mediume erg gas

S gas

Catal ticcracki g

Gas turbi eStirli g motor

Fuel cell

I ter alCombustioe gi es ICE

Thermalcracki g

Co versioReform of s gasFischer-Tropsch

S thsis

Step 2:Gasificatio

~1000 C


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FiGUrE 2. 5: GaSiFiEr SizE By TyPE

Source: r enSfelT, 2005.


One of the key characteristics of gasifiers, in additionto the producer gas they produce, is the size rangeto which they are suited. Fixed bed downdraftgasifiers do not scale well above around 1 MW th in size due to the difficulty in maintaining uniform

reaction conditions (Lettner, 2007). Fixed bed updraftgasifiers have fewer restrictions on their scale whileatmospheric and pressurised fluidised bed andcirculating bed, and entrained flow gasifiers canprovide large-scale gasification solutions. 9

10 kW 100 kW 1 mW 10 mW 100 mW 1000 mW

9 The entrained flow gasifier is based on even higher velocities in the reactor where the material is picked up and carried off in the airflow.They arent considered here, as there principle benefits of larger scale-up make feedstock sourcing problematic. Other options provide the

scale required for biomass power generation10 See for instance http://www.volund.dk/solutions_references/gasification_solutions

Dow draft Fixed Bed

Updraft Fixed Bed

Atm, BFB a d CFB

Pressurised BFB a d CFB

Pressurised E trai ed Flow

Fixed bed gasifiersFixed bed gasifiers typically have a grate to supportthe gasifying biomass and maintain a stationaryreaction bed. They are relatively easy to design andoperate and generally experience minimum erosion ofthe reactor body.

There are three types of fixed bed designs:

In an updraft fixed bed gasifier, biomassenters at the top of the reactor and thereactive agent (i.e. air, steam and/or oxygen)below the grate. The producer gas, togetherwith tars and volatiles, exits from the topwhile chars and ashes fall through the grate(at the bottom). These gasifiers are oftenused for direct heating, but gas clean-up can

remove the relatively high levels of tar andother impurities to allow electricity generationor CHP, albeit with increased capital costs. 10 Slagging problems can also arise if high-ashbiomass is used.

In a downdraft fixed bed gasifier, the biomassand the reactive agent are introduced at thetop of the reactor and the tars pass throughthe oxidation and charcoal reduction zones,

meaning levels of tar in the gas are muchlower than in updraft gasifiers. They tend torequire a homogenous feedstock to achievethe best results.

Cross-draft fixed bed gasifiers are similar todowndraft gasifiers and are often used to


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FiGUrE 2.6: SmaLL-SCaLE UPDraFT anD DOWnDraFT FixED BED GaSiFiErS

Source: BrandIn, eT al. 2011.


gasify charcoal, but the reactive agent entersat the side, low down in the reactor vesseland parallel to the biomass movement. Theyrespond rapidly to load changes, are relativelysimple to construct and the gas produced

is suitable for a number of applications.However, they are more complicated tooperate and if a fuel high in volatiles andtars is used, very high amounts of tar andhydrocarbons will be present in the producergas.

Fixed bed gasifiers are the preferred solution forsmall- to medium-scale applications with thermalrequirements up to 1 MW th (Klein, 2002). Updraftgasifiers can scale up to as much as 40 MW th .However, down-draft gasifiers do not scale wellbeyond 1 MW th .

Biomass gasification is successfully applied in India,and rice-husk gasification is a widely deployedtechnology. To produce electricity, piles of rice husksare fed into small biomass gasifiers, and the gasproduced is used to fuel internal combustion engines.The operations by-product is rice-husk ash, whichcan be sold for use in concrete. Several equipmentsuppliers are active and one, Husk Power Systems(HPS), has installed 60 mini-power plants that

power around 25 000 households in more than 250communities. Investment costs are low (USD 1 000 toUSD 1 500/kW) and overall efficiencies are between7% and 14%, but they are labour-intensive in O&M asthere is significant fouling. One of the keys to their

success has been the recruitment of reliable staff witha vested interest in the ongoing operation of the plantto ensure this regular maintenance.

Although they do not meet OECD air pollutionstandards and some developing country standardsas well, they can be an important part of off-gridelectricity access in rural areas. These systemsare being promoted by The International FinanceCorporation (IFC) and HPS in Kenya and Nigeria.In Benin, GIZ (Germany) is promoting biomassgasification for combined heat and power (CHP)generation in decentralised settings as an economicalternative to grid extension in remote areas of thecountry.

The critical factors for these gasification systemsare the reliability of the gasifier and the cost of thebiomass supply. While feedstock may be free whenthe first plant begins operating, prices can quicklyrise if the technology takes off and competition forfeedstock arises. This often places a limit on thepotential of waste-based power generation.

B o ssSto ge

B o ssSto ge

P oduce g s

P oduce g s

B o ss B o ss

a

ashash

a


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24/60


Tars 13 are a major problem, as they can build upon turbine blades and/or foul turbine systems.One solution to this problem is to crack the tars.Cracking can be either thermal or catalytic. Anotheroption is wet scrubbing of the gas to remove up tohalf the tar and, when used in conjunction with aventuri scrubber, can remove up to 97% of the tar. Thedisadvantage of simple scrubbing systems is that theycool off the biogas and create a waste stream thathas to be disposed of. However, the OLGA tar removalprocess is based on multiple scrubbers and effectivelyrecycles almost all of the tar to the gasifier to beeliminated. 14

Biomass integrated combined cycle gasificationBiomass integrated combined cycle gasification(BIGCC), or biomass integrated gas turbinetechnology (BIG-GT), as it is sometimes referred to,has the potential to achieve much higher efficienciesthan conventional biomass-powered generationusing steam cycles by creating a high quality gas in apressurised gasifier that can be used in a combinedcycle gas turbine. Significant R&D was conducted andpilot-scale plants were built in the late 1990s and theearly 2000s. Several demonstration plants were alsobuilt. However, performance has not been as good as

hoped for, and the higher feedstock costs for large-scale BIGCC and the higher capital costs due to fuelhandling and biomass gasification has resulted in acooling of interest.

PyrolysisPyrolysis is a subset of the gasification system.Essentially, pyrolysis uses the same process asgasification, but the process is limited to between300C and 600C. Conventional pyrolysis involvesheating the original material in a reactor vessel inthe absence of air, typically at between 300C and500C, until the volatile matter has been releasedfrom the biomass. At this point, a liquid bio-oil isproduced, as well as gaseous products and a solidresidue. The residue is char more commonly knownas charcoal a fuel which has about twice the energydensity of the original biomass feedstock and whichburns at a much higher temperature. With moresophisticated pyrolysis techniques, the volatiles canbe collected, and careful choice of the temperature atwhich the process takes place allows control of theircomposition. The liquid bio-oil produced has similarproperties to crude oil but is contaminated with acidsand must be treated before being used as fuel. Boththe charcoal and the oil produced by this technologycould be used to produce electricity (although this isnot yet commercially viable) and/or heat.

13 Tars are the name given to the mostly poly-nuclear hydrocarbons, such as pyrene and anthracene, that form as part of the gasification process .14 For a description of the process see http://www.renewableenergy.nl/index.php?pageID=3220&n=545&itemID=351069

P t cles ash, ch , flu d bed te l E os o g s f e d p e o e

alk l et ls Sod u d Pot ss u co pou ds Hot co os o

n t oge co pou ds nH3 d HCn Loc l pollut t e ss o s

T s ref ct e o t cs Clogg g of f lte s d othe foul g

Sulphu , chlo e H 2S d HC1 Co os o , e ss o s

Co t ts E ples Pote t l p oble

TaBLE 2.7: ExamPLES OF PrODU CEr GaS COnTaminanTS

Source: WIanT, eT al. 1998.


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3. FeedstockB iomass is the organic material of recently living plants from trees, grasses and agricultural crops. Biomassfeedstocks are very heterogenous and the chemical composition is highly dependent on the plant species.This highly hetrogenous nature of biomass can be a problem since, although some combustion technologiescan accept a wide range of biomass feedstocks, others require much more homogenous feedstocks in order tooperate.

Agricultural Residues

Co st lks/sto e 17.6 20.5 16.8 18.1

Sug c e b g sse 15.6 19.4 15 17.9

Whe t st w 16.1 18.9 15.1 17.7Hulls, shells, p u gs 15.8 20.5

F u t p ts

Herbaceous Crops

m sc thus 18.1 19.6 17.8 18.1

Sw tchg ss 18.0 19.1 16.8 18.6

Othe g sses 18.2 18.6 16.9 17.3

B boo 19.0 19.8

Wood Crops

Bl ck locust 19.5 19.9 18.5

Euc l ptus 19.0 19.6 18.0

H b d popl 19.0 19.7 17.7

Dougl s f 19.5 21.4

Popl 18.8 22.4

m ple wood 18.5 19.9

P e 19.2 22.4

W llow 18.6 20.2 16.7 18.4

Forest Residues

H dwood wood 18.6 20.7

Softwood wood 18.6 21.1 17.5 20.8Urba Residues

mSW 13.1 19.9 12.0 18.6

rDF 15.5 19.9 14.3 18.6

newsp pe 19.7 22.2 18.4 20.7

Co ug ted p pe 17.3 18.5 17.2

W ed c to s 27.3 25.6

H ghe he t g lue mJ/kg Lowe he t g lue mJ/kg

TaBLE 3.1: HEaT COnTEnT OF variOUS BiOm aSS FUELS (Dry BaSiS)

SourceS: uS doe, 2012; JenkInS, 1993; JenkInS, eT al. , 1998; TIlMan,1978; BuS Hnell, 1989; ecn, 2011; an d cIolkoSz, 2010.


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FiGUrE 3.1 : imPaCT OF mOiSTUrE COnTE nT On THE PriCE OF FEEDSTOCK COST On a nET EnErGy BaSiS


Biomass chemical composition is comprised ofa generally high (but variable) moisture content,a fibrous structure, which is comprised of lignin,carbohydrates or sugars and ash. Ligno-cellulose isthe botanical term used to describe biomass from

woody or fibrous plant materials. It is a combinationof lignin, cellulose and hemicellulose polymersinterlinked in a heterogenous matrix. The chemicalcomposition of the biomass feedstock influences itsenergy density. Table 3.1 presents the energy densityon a dry basis of different feedstocks. Hardwoodstend to have higher energy densities but tend to growmore slowly.

The main characteristics that affect the quality ofbiomass feedstock are moisture content, ash contentand particle size, and density.

Moisture contentThe moisture of biomass can vary from 10% to 60%,or even more in the case of some organic wastes.Stoker and CFB boilers can accept higher moisturecontent fuel than gasifiers. In anaerobic digestion,several options are available, including high solids-dry, high solids-wet or low solids-wet. In the case ofa low solids-wet configuration, such as with manure

slurry, the solids content can be 15% or less. 15 Thekey problem with a high moisture content, evenwhen it is destined for anaerobic digestion, is thatit reduces the energy value of the feedstock. Thisincreases transportation costs and the fuel cost on an

energy basis, as more wet material is required to betransported and provide the equivalent net energycontent for combustion. 16 Figure 3.1 presents theimpact of moisture content on the price per unit ofenergy (net) of a wood feedstock for a range of pricesof the wet feedstock per tonne.

Improving the energy density of the feedstockhelps to reduce transportation costs and canimprove combustion efficiency. The principal meansof achieving this is through drying by natural oraccelerated means. Other options include torrefaction,pelletising or briquetting, and conversion to charcoal.The trade-off is that these processes increasefeedstock prices, and the energy balance decreasessignificantly due to the energy consumption used forthe pre-treatment of the biomass. However, althoughthis increases the costs per tonne of feedstock, it cansometimes reduce the price of the feedstock per unitof energy.

15 Although virtually any organic material can be used as a feedstock for anaerobic digestion, the more putrescible (digestible) thefeedstock the higher the potential gas yield.16 That is to say the remaining energy of the fuel after the energy required to evaporate the water contained in the feedstock.

10 %

2 0 1 0 U S D / G J

moisture co te t (%)

20 % 30 % 40 % 50 % 60 %

USD 160 pe to e

USD 140 pe to e

USD 120 pe to e

USD 100 pe to e

USD 80 pe to e

USD 60 pe to e

USD 40 pe to e

USD 20 pe to e

35

30

25

20

15

10

5

0


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Ash content and slaggingAn important consideration for feedstocks is theash content, as ash can form deposits inside thecombustion chamber and gasifier, called slaggingand fouling, which can impair performance and

increase maintenance costs. Grasses, bark and fieldcrop residues typically have higher amounts of ashthan wood.

Slagging occurs in the boiler sections that aredirectly exposed to flame irradiation. Slaggingdeposits consist of an inner powdery layer followedby deposits of silicate and alkali compounds. Foulingdeposits form in the convective parts of the boiler,mainly due to condensation of volatile compoundsthat have been vaporised in previous boiler sectionsand are loosely bonded (Masi, 2005).

Slagging and fouling can be minimised by keepingthe combustion temperature low enough to preventthe ash from fusing. Alternately, high-temperaturecombustion could be designed to encourage theformation of clinkers (hardened ash), which couldthen be more easily disposed of.

Some types of biomass have problems with the ashgenerated. This is the case for rice husks that needspecial combustion systems due to the silica contentof the husks. 17

Feedstock sizeThe size and density of the biomass is also importantbecause they affect the rate of heating and dryingduring the process (Ciolkosz, 2010). Large particlesheat up more slowly than smaller ones, resulting inlarger particles producing more char and less tar(Sadaka, 2010). In fixed bed gasifiers, fine-grained

and/or fluffy feedstock may cause flow problemsin the bunker section, resulting in an unacceptablepressure drop in the reduction zone and a highproportion of dust particles in the gas. In downdraftgasifiers, the large pressure drop can also reduce thegas load, resulting in low temperatures and higher tarproduction.

The type of handling equipment is also determinedby the size, shape, density, moisture content andcomposition of the fuel. The wrong design will havean impact on the efficiency of the combustion/ gasification process and may cause damage to the

handling system.

Biogas from anaerobic digestion and landfill gasIn anaerobic digestion and landfill gas, the presenceof non-fuel substances reduces the amount of gasproduced. The biogas is primarily methane and CO 2,and more methane means more energy content ofthe biogas. The methane formation is influencedby parameters like moisture content, percentage oforganic matter, pH and temperature. Hence, control ofthese characteristics is a crucial prerequisite to havinga good quality gas for electricity generation.

Overview of biomass power generation technologiesand biomass feedstock characteristicsTable 3.2 gives an overview of biomass technology,feedstock and the requirements on particle size andmoisture content. Co-firing in coal-fired power plantshas the most stringent requirements for moisturecontent and feedstock size if efficiency is not to bedegraded.

17 For experience in Brazil, see Hoffman et al.(undated) http://www.ufsm.br/cenergia/arte_final.pdf


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FiGUrE 4 .1: GLOBaL GriD-COn nECTED BiOmaSS CaPaCiTy in 2010 By FEEDSTOCK anD COUnTry/rEGiOn (mW)

Source: PlaTTS, 2011.


4.1 CURRENT INSTALLED CAPACITY AND GENERATION

In 2010 the global installed capacity of biomass powergeneration plants was between 54 GW and 62 GW(REN21, 2011 and Platts, 2011). The range suggests thatpower generation from biomass represents 1.2% oftotal global power generation capacity and providesaround 1.4% to 1.5% of global electricity production(Platts, 2011 and IEA, 2011).

Europe, North America and South America accountfor around 85% of total installed capacity globally.In Europe, 61% of total European installed capacityusing solid biomass (excluding wood chips) is inEngland, Scotland and Sweden. Wood-fired biomasspower capacity is concentrated in Finland, Sweden,

England and Germany. Together these four countriesaccount for 67.5% of European wood-fired biomasspower generation capacity. Landfill gas capacity isconcentrated in England with 45% of the Europeantotal, while biogas capacity is concentrated inGermany with 37% of total European capacity. InNorth America wood accounts for 65% of totalinstalled capacity and landfill gas 16% (Platts, 2011).In South America, Brazil is the largest producer ofbiomass electricity as a result of the extensive use ofbagasse for co-generation in the sugar and ethanolindustry.

Despite the large biomass resources in developingand emerging economies, the relative contributionof biomass is small, with the majority of biomasscapacity located in Europe and North America. The

4. Glob l B o ss Powe

m ket T e ds

E u o p e

n o t h

a e c

a f c

C h

i d

r e s t a s /

O c e

B z l

r e s t S o u t h

a e c

r e s t w o l d

M W

woodg s

wood

l df ll g s

sew ge g s

l u d fuel

b og s

b g sse

b o ss

20000

18000

16000

14000

12000

10000

8000

60004000

2000

0


30/60

Source: PlaTTS, 2011.

P oduce g s

P oduce g s

B o ss B o ss

a

FiGUrE 4 .2: SH arE OF GLOBaL inSTaLLED BiOmaSS CaPaCiTy in 2010 By FEEDSTOCK anD COU nTry/rEGiOn


combustion of bagasse is the dominant source ofelectricity from bioenergy in non-OECD countries.In Brazil, the combustion of bagasse from the largesugar cane industry accounted for around 4.4 GW ofgrid-connected capacity in 2010 (Figure 4.1)

Around 84% of total installed biomass power gene-ration today is based on combustion with steamturbines for power generation, with around half ofthis capacity also producing heat (combined heatand power) for industry or the residential and service

sectors.

The co-firing of thermal plants with biomass isbecoming increasingly common. By the end of 2011,around 45 GW of thermal capacity was being co-fired with biomass to some extent in Europe. In NorthAmerica, around 10 GW of capacity is co-firing withbiomass (IEA Bioenergy, 2012 and Platts, 2011). 18

Table 4.1 presents examples of the co-firing ofbiomass in coal-fired power plants in the Netherlands.The level of co-firing ranges from 5% to 35% and thereis a range of technologies and feedstocks being used.

4.2 FUTURE PROJECTIONS OF BIOMASSPOWER GENERATION GROWTH

Biomass currently accounts for a significant, butdeclining share of total renewable power generationcapacity installed worldwide, but significant growth is

expected in the next few years due to support policiesfor renewable energy in Europe and North America.In addition to the environmental and energy securitybenefits all renewables share, biomass has theadditional advantage that is a schedulable renewablepower generation source and can complement thegrowth in other variable renewables. Biomass forCHP can also greatly improve the economics of

18 The Platts data identifies power plants with the capacity to co-fire, unfortunately no statistics are available on the amount of biomass

used in co-firing. Another source of data is the co-firing database, created by IEA Bioenergy, which can be found at http://www.ieabcc.nl/ database/cofiring.php.

C p c t st lled b feedstock C p c t st lled b cou t

B g sse 20%

no th a e c 30 %

Eu ope 34%

rest Wo ld 2%

B l 9%

rest as /Oce 10%

i d 5%

Ch 4%

af c 3%

rest South a e c 2%

B o ss 20%

Woodg s 1%

Wood 44%

L dflll g s 8%

Sew ge g s 1%L u d fuel 3%

B og s 3%


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biomass power generation, particularly when thereare low cost sources (e.g. residues from industry oragriculture) located next to industrial heat processheat needs. Another important synergy for biomasspower generation is with the biofuels industry, as theresidues from biofuels feedstock (e.g. bagasse, cornstover and straw) and biofuels process residues canbe used as raw material for co-generation systems.

The total capacity of proposed biomass powergeneration projects that are either under constructionor have secured financing and will be completed by

2013 is 10 GW. The vast majority of these projects(87%) are for combustion technologies, but plans fornew biogas capacity in Germany (due to its feed-intariff schemes for biogas) and the United States arealso in the pipeline (BNEF, 2011). However, when co-firing plans are also considered, projects based onbiomass combustion account for 94% of the projectsthat will be built by 2013.

In the longer term, biomass and waste 19 powergeneration could grow from 62 GW in 2010 to 270GW in 2030 (BNEF, 2011). The expected annualinvestment to meet this growth would be betweenUSD 21 billion and USD 35 billion (Figure 4.4). Thiswould represent around 10% of new renewablescapacity and investment until 2030. China and Brazilappear to have the largest potential: growth in Brazilwill be based on the continuing development of thebiofuel industry and the possibilities for using theresulting bagasse for electricity generation, whilein China better utilisation of the large quantities of

agricultural residues and waste produced is possible.In Europe, Germany and the United Kingdom are likelyto be the largest markets for biomass technologies,especially co-firing. The United States and Canadawill be important sources of biomass feedstock,particularly wood chips and pellets (BNEF, 2011).

19 Considering biogas combustion from agriculture animal waste and landfill gas; energy from waste in solid municipal waste facilities,including incineration and gasification; combustion of biomass pellets, either in dedicated facilities or co-firing in coal plants; and combustionof bagasse in sugar-cane producing plants

Gelde l d 13

a e 8

a e 9

a e 9

Bo ssele 12

m s l kte 1&2

W lle ale d e

m sb cht

D ect co-co bust o w th sep te ll g,ject o of pul e sed wood the pf-l es d

s ult eous co bust o

D ect co-co bust o : sep te ded c tedll g d co bust o ded c ted b o ss

bu e s

D ect co-f g: b o ss s lled sep tel ded c ted lls d co busted sep te

bu e s

i d ect co-f g : g s f c t o t osphe c c cul t g bed g s f e d co-f g of the fuel g s the co l-f ed bo le

P ct ce 1: d ect co-f g b sep te ll gd co bust o

P ct ce 2: d ect co-f g b g w th thew co l befo e the lls

P ct ce 1: d ect co-f g of b o ss,pul e sed sep te h e ll, ject oto the pf-l es d s ult eous co bust o .

P ct ce 2: l u d o g cs f ed sep te o lbu e s

D ect co-g s f c t o

D ect co-f g of p l -o l ded c ted bu e s

635

645

600

33

403

1040

253

640

5%

20%

35%

/

16%

12%

30%

15%

Powe pl t T pe of co bust o mW Co-f g

Source: euBIa, 2011.

TaBLE 4.1: DETaiLS OF FOSSiL-FUEL FirED POWEr PLanTS CO-FirinG WiTH BiOmaSS in THE nETHErLanDS


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The main assumptions driving the scenario to 2030are:

The abundance of forest residues and theirproven exploitation in Scandinavian countries;

The supportive policy environment forbiomass-fired power generation, for instancefrom the EU directives on the promotion ofrenewable energy;

The targets adopted by the ChinasGovernment to incentivise waste-to-energycapacity due to a need to dispose ofagricultural residues and waste; and

The future increase of co-firing, especially inEurope and North America.

4.3 FEEDSTOCK MARKET

With some notable exceptions, there are few formalprice markets for biomass. The biomass marketis primarily focused on the trade of wood chipsand pellets. However, the vast majority of biomassfeedstock is not traded, as it is used for domesticcooking, heating and lighting. In addition, the lowenergy content of biomass, its bulky nature andthe costs of handling and transporting biomassfeedstocks also tends to mean that local marketsoften are not integrated.

The majority of the biomass used for powergeneration therefore comes from non-traded sources,such as wastes and residues from agricultural andindustrial processes, forestry arisings, etc. that are

consumed locally. In certain regions, this may notbe the case, and significant commercial markets forbiomass feedstocks may exist. However, in general,the local nature of feedstock sources means thatbiomass power generation plants tend to be small inscale (up to 50 MW is typical), as securing enoughlow-cost feedstock for large-scale plants oncetransportation is taken into account is challenging.

However, a small but growing trade is emerging inpellets and wood chips. The support policies forrenewable power generation in many regions willsupport further growth in these markets. First usedfor district and household heating, wood chips and

pellets are increasingly being used to co-fire fossilfuel power plants or to displace them entirely. In thefirst nine months of 2010, the EU 27 imported 1.7million tonnes of wood pellets, which does not includeintra-EU trade (Forest Energy Monitor). Currently, theNetherlands is the largest EU importer of wood pelletswith 0.77 million tonnes (Mt) imported in 2010 (ForestEnergy Monitor, 2011).

The trade in wood chips is much larger than that ofpellets for the moment and tends to be more regionaland international. Japan is the main market for woodchips and accounted for 77% of the 19.4 million ovendry tonnes (ODT) shipped in 2008 (Junginger, 2011).Although data exist for the wood chip and pelletstrade, limited data on the amount that is being burnedin co-fired coal power plants are available.

China appears as an important forest biomassimporter from North America. In 2010 it imported29 Mt, twice that of in the previous year (14 Mt), butthe primarily use of this biomass is for heating andcharcoal production as co-firing and direct burning ofbiomass is still in the commencement stage.

An analysis of the world market estimates that 8 Mtof pellets was traded internationally in 2008, as wellas 1.8 Mt in the United States and 1.4 Mt in Canadafor a total of 11.2 Mt. Canada, the United States andWestern Russia are the major exporters to Europe.The largest consumers are Sweden, Denmark, theNetherlands, Belgium, Germany and Italy. Scenarios

for development of supply and demand for powerproduction until 2015 suggest that pellet demand forthe electricity market will be approximately 8 Mt in2015 although this is highly dependent on supportpolicies, logistics and the possible introduction ofsustainability criteria. The British and Dutch marketswill experience the strongest expected growthbetween 20112015, growing to 1.5 Mt per year in theNetherlands and 4.5 Mt per year in the UK (Junginger,2011).


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For non-traded biomass, the only costs for theraw material are often the transport, handling andstorage required to deliver the biomass wastes orresidues to the power plant. Some local marketsdo exist, but these are based on bilateral contracts

and data are often not available on prices paid. Forinstance, prices in Brazil for bagasse can range fromUSD 7.7 to USD 26.5/tonne. The problem with low-cost feedstocks that are associated with agriculturalproduction is that, in the case of an independentpower producer, the amount of bagasse available

depends on the ethanol and sugar markets. Thismakes it difficult to negotiate long-term contractsthat are designed to reduce price risk and guaranteesecurity of feedstock supply that will be required toallow access to financing. The same issues can often

occur with other waste and residue streams, suchas sawdust, bark, chips, black liquor, etc. This is oneof the reasons why many biomass power projects,particularly for CHP, are promoted by the industrywhich controls the process that produces the wastesand residues.


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5.1 FEEDSTOCK PRICES

Unlike wind, solar and hydro biomass electricitygeneration requires a feedstock that must beproduced, collected, transported and stored. Theeconomics of biomass power generation are criticallydependent upon the availability of a secure, longterm supply of an appropriate biomass feedstock at acompetitive cost.

Feedstock costs can represent 40% to 50% of thetotal cost of electricity produced. The lowest costfeedstock is typically agricultural residues like strawand bagasse from sugar cane, as these can becollected at harvest (ECF, 2010). For forest arising, thecost is dominated by the collection and transportationcosts. The density of the forestry arisings has a directimpact on the radius of transport required to deliver agiven energy requirement for a plant. The low energydensity of biomass feedstocks tends to limit thetransport distance from a biomass power plant thatit is economical to transport the feedstock. This canplace a limit on the scale of the biomass power plant,meaning that biomass struggles to take advantage ofeconomies of scale in the generating plant becauselarge quantities of low-cost feedstock are notavailable.

The prices of pellets and woodchips are quotedregularly in Europe by ENDEX and PIX (Table 5.1). Theprices are for delivery to Rotterdam or North/BalticSea ports and do not include inland transport to otherareas.

Prices for biomass sourced and consumed locallyare difficult to obtain and no time series data ona comparable basis are available. Prices paid willdepend on the energy content of the fuel, its moisturecontent and other properties that will impact thecosts of handling or processing at the power plantand their impact on the efficiency of generation. Table5.2 presents price estimates for biomass feedstocks inthe United States.

The 2011 U.S. Billion-ton Update: Biomass Supplyfor a Bioenergy and Bioproducts Industry providesvery detailed estimates of the amount of biomassfeedstocks available at different prices in the UnitedStates. Figure 5.1 presents the results of this analysisfor forest and wood wastes, agricultural biomass andwastes, and dedicated energy crops, respectively.

5. Cu e t Costs of

B o ss Powe

i dust l wood pellets (1) 166 9.8

i dust l wood pellets (2) 11.1

E e g Ch ps/ es du ls-no th E st U.S. (3) 3.7

Eu ope

no th a e c

USD / to e

USD / to e

USD /

TaBLE 5.1: BiOmaSS anD PELLET mar KET PriCES, JanUary 2011

Source: for eST energy MonITor, 2011.

n t s: (1) endeX cIf r tt m; (2) PIX cIf B ti S n th S p t; (3) Mix s, iv .

GJ

USD /GJ


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This analysis for the United States is based on detailedgeographic simulations and includes supply curves forthe different biomass feedstocks by region. Detailedanalysis of this nature helps to give policy-makersconfidence in resource availability and costs when

developing support policies for biomass. Significantquantities of bioenergy feedstocks are available fromforestry arisings and other residues while significantresidues and wastes from corn production areavailable at USD 55/tonne and above. Dedicatedenergy crop availability is strongly related to cost,

representing the important impact that the best crop,land and climate conditions can have on feedstockcosts.

Other important cost considerations for biomass

feedstocks include the preparation the biomassrequires before it can be used to fuel the powerplant. Analysis suggests that there are significanteconomies of scale in biomass feedstock preparationand handling (Figure 5.2). 20 The capital costs fall fromaround USD 29 100/tonnes/day for systems with 90

20 The fuel preparation systems analysed (receiving, processing, storage and fue l metering conveyors, meters and pneumatic transport)were based on three separate systems: 100 tons/day, manual handling, 50% moisture content; 450 tons/day and 680 tons/day, automatichandling, 30% moisture content; which allowed drawing a trend line of the handling costs system based on the quantity of fuel being

prepared per day (ton/day).

Forest residues

Wood waste (a)

Ariculturalresidues (b)

E erg crops (c)

La dfill gas

11.5

19.9

11.35 11.55

14.25 18.25

18.6 29.8(d)

30% 40%

5% 15%

20% 35%

10% 30%

1.30 2.61

0.50 2.51

1.73 4.33

4.51 6.94

0.94 2.84)

15 30

10 50

20 50

39 60

0.017 0.051(d)

Collect g, h est g,ch pp g, lo d g,

t spo t t o du lo d g. Stu p gefee d etu fo p of t

d sk.

Cost c f oe o, whe e the ewould othe w se bed spos l costs, to u teh gh, whe e the e s est bl shed ket fothe use the eg o .

Collect g, p e up d to f e s,

t spo t t o .not d sclosed.

G s collect o dfl e.

He t luemJ / kg(LHv)

T c lmo stu eco te t

P ce(USD / GJ)

P ce(USD / to e)

Cost st uctu e

TaBLE 5.2: BiOmaSS FEEDSTOCK PriCES anD CHaraCTEriSTiCS in THE U niTED STaTES

n t s:

( ) S wmi s, p p p p m p i s (b , hip, s st, s w st). M ist t t is t w b s th h v b th h m t i p ss. I s s wh isp s is q i , p i s b s th v i sts

isp s m it w thwhi t i p tiv s th st .

(b) c st v st w.

( ) P p , wi w swit h ss. dis v t s ps hi h v st th m ssi s, hi h -vt tiv s s th t th iv p sts.

( ) f i s th h t v p i is i MJ/m 3 uSd/m 3 .

Source: BaSed on uS ePa, 2007.


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FiGUrE 5.1 : BrEaKD OWn OF BiOmaSS anD WaSTE avaiLaBiLiTy By COST in THE U niTED STaTES, 2012/2017

Source: uS doe, 2011.


tonnes/day throughput to USD 8 700/tonnes/day forsystems with 800 tonnes/day. The capital costs forpreparation and handling can represent around 6%to 20% of total investment costs of the power plant

for systems above 550 tonnes/day. Assuming a heatvalue of forest residue with 35% moisture contentto be 11 500 kJ/kg, the handling capital costs couldtherefore range from a low of USD 772/GJ/day to ashigh as USD 2 522/GJ/day.

In Europe, recent analysis of four biomass sources andsupply chains identified feedstock costs of betweenUSD 5.2 and USD 8.2/GJ for European sourcedwoodchips (European Climate Foundation et al.,

2010). Local agricultural residues were estimated tocost USD 4.8 to USD 6.0/GJ. Imported pellets fromNorth America are competitive with European woodchips if they must be transported from Scandinaviato continental Europe. 21 These are representativeexamples, and there will be significant variation inactual feedstock costs, depending on the actualproject details. 22

n t : S si s w st s i i i h s si s, tt i si s i t sh, s

si , h vi p i s, wh t st im m . oth ps i w ps ps . e p t 2017, th t 2012.

21 According to the report, at present forest residues and agricultural residues are only utilised to a significant extent in Scandinavia andDenmark respectively and there are only two pellet mills in the world with a production capacity of 500 000 tons per year or more.

22 For pel lets the heat value considered was 16 900 kJ/kg and moisture content of 10%.

F o e s t s g d

e s d u e s

Forest biomassa d residues

Agricultural residuesa d wastes

E erg crops

P y

C o

P e e l g s s e s

l o w

m l l e s d u e s

P y

W h e t , b l e y

,

o t s d w s t e s

P e e l g s s e s

h g h

U b w o o d w s t e

S e c o d y e s d u e s

d w s t e s

O t h e e e g y c o p s

l o w

O t h e e e g y c o p s

h g h

M i l l i o n t o n n e

s

USD / to e

44

55

66

160

140

120

100

80

60

40

20

0


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FiGUrE 5. 2: BiOmaSS FEEDSTOCK PrEParaTiOn anD HanD LinG CaPiTaL COSTS aS a FUnCTiOn OF THrOU GHPUT

Source: u S ePa, 2007.


Prices for feedstocks in developing countries areavailable but relatively limited. In the case of Brazil,the price of bagasse 23 varies significantly, dependingon the harvest period. It can range from zero toUSD 27/tonne 24 with the average price being aroundUSD 11/tonne, where a market exists. These lowbagasse prices make the economics of bioenergy

power plants with other feedstocks extremelychallenging, except where a captive feedstock exists(i.e. in the pulp and paper industry). As a result, mostof the other bioenergy power generation projects inBrazil rely on black liquor and woodwaste for co-generation in industry with the surplus electricity soldto the market. 25

300 500 700 900100

C a p i t a l C o s t ( U S D / t o n

n e

s / d a y

)

Biomass feedstock (to s / da )

30000

25000

20000

15000

10000

5000

0

23 Which is a residue from process and has no transportation costs if used in the same alcohol/sugar plant for electricity generation 24 1 USD = 1.80 R$

Woodch ps f o loc le e g c ops

Woodch ps f oSc d fo estes dues to co t e t lEu ope

Loc l g cultu l es dues

i po tedpellets(f o U.S. toco t e t lEu ope)

5.2 8.2 60 94 5.2 8.2 60 94

5.6 6.7 64 77 3.0 3.4 34 38 8.6 10.1 98 115

4.8 6.0 55 68 4.8 6.0 55 68

3.0 3.7 50 63 3 3.7 50-63

3 3.4 50 56 3.0 3.4 50-56

6.0 7.1 100 119 3.4 3.7 56 63 9.3 10.8 157-182

T spo tUSD / GJ

FeedstockUSD / GJ

Tot l costsUSD / GJ

Source: eur oPean clIMaTe foundaTIon eT al., 2010.

TaBLE 5.3: BiOmaSS FEEDSTOCK COSTS inCLUDinG TranSPOrT FOr USE in EUrOPE

Feedstock

Pellet s g

Tot l

USD / to e

USD / to e

USD / to e


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FiGUrE 5. 3: inSTaLLED CaPiTaL COST ranGES By BiOmaSS POWEr GEnE raTiOn TECHnOLOGy


The total investment cost capital expenditure(CAPEX) consists of the equipment (primemover and fuel conversion system), fuel handlingand preparation machinery, engineering andconstruction costs, and planning (Figure 5.3). It canalso include grid connection, roads and any kindof new infrastructure or improvements to existinginfrastructure required for the project. Differentprojects will have different requirements for each ofthese components with infrastructure requirements/ improvements in particular being very project-sensitive.

Figure 5.4 presents a breakdown of the typical coststructure of different biomass power generationtechnologies 28 . The feedstock conversion systemcomprises boilers (stoker, CFB, BFB, etc.), gasifiersand anaerobic digesters with a gas collection system,as well as the gas cleaning systems for gasifiers andgas treatment systems for AD systems. The primemover is the power generation technology and

includes any in-line elements, such as particulatematter, filters etc. As can be seen, the prime mover,feedstock conversion technology and feedstockpreparation and handling machinery account forbetween 62% and 77% of the capital costs for thebiomass power generation technologies presented.

The total installed cost range, including all balanceof plant equipment (e.g. electrical, fuel handling, civilworks), as well as owners costs including consultancy,design and working capital is presented in Figure 5.3.

The contribution of the prime mover to the totalcosts is very low and ranges from 5% to 15% (MottMacDonald, 2011). The converter system (e.g. stokerboiler, gasifier) usually accounts for the largestshare of capital costs, although fuel handling andpreparation is also an important contributor to totalcosts (Figure 5.4).

28 Transmission lines , road and any kind of infrastructure are not being considered in the costs breakdown as they are site/location specific

S t o k e

G s f e

G s f e C H P

B F B / C F B

S t o k e C H P

C o - f

g

D g e s t e

L F

Technologies Cost Analysis-Biomass

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