Energy Policy 34 (2006) 32683283

va

,,1

Z Utr

idelbe

ine 8

To assess which biofuels have the better potential for the short-term or the longer term (2030), and what developments are

Bioenergy is seen as one of the key options to mitigate bioenergy use covers 914% of the global demand (of

more: up to 30% of the 2100 energy supply to

ARTICLE IN PRESS

www.elsevier.com/locate/enpol

Corresponding author. Tel.: +3130 2897414.E-mail address: carlohamelinck@yahoo.com (C.N. Hamelinck).0301-4215/$ - see front matter r 2005 Elsevier Ltd. All rights reserved.

doi:10.1016/j.enpol.2005.06.012

1Currently employed with Ecofys, P.O. Box 8408, 3503 RK Utrecht,

the Netherlands.

2Biofuels means liquid or gaseous fuel for transport produced from

biomass (EU, 2003).greenhouse gas emissions and to substitute fossilfuels (Hall et al., 1993; Goldemberg, 2000). Large-scale introduction of biomass energy could contributeto sustainable development on several fronts, envi-ronmentally, socially, and economic (Ravindranathand Hall, 1995; Turkenburg, 2000; van den Broek,2000).

about 400EJ in 1998), most of which as traditional, low-tech and inefcient cooking and heating in developingcountries (Hall et al., 1993; Turkenburg, 2000). Modernproduction of energy carriers from biomass (heat,electricity and fuels for transportation or biofuels)2

contributes a lower, but signicant 7 EJ (Turkenburg,2000). Different global energy scenario studies indicatethat in this century biomass may contribute muchsynthetic dieselis systematically analysed. This present paper summarises, normalises and compares earlier reported work. First,

the key technologies for the production of these fuels, such as gasication, gas processing, synthesis, hydrolysis, and fermentation,

and their improvement options are studied and modelled. Then, the production facilitys technological and economic performance is

analysed, applying variations in technology and scale. Finally, likely biofuels chains (including distribution to cars, and end-use) are

compared on an equal economic basis, such as costs per kilometre driven. Production costs of these fuels range 1622 h/GJHHV now,

down to 913 h/GJHHV in future (2030). This performance assumes both certain technological developments as well as the

availability of biomass at 3 h/GJHHV. The feedstock costs strongly inuence the resulting biofuel costs by 23 h/GJfuel for each h/

GJHHV feedstock difference. In biomass producing regions such as Latin America or the former USSR, the four fuels could be

produced at 711 h/GJHHV compared to diesel and gasoline costs of 7 and 8 h/GJ (excluding distribution, excise and VAT; at crude

oil prices of 35 h/bbl or 5.7 h/GJ). The uncertainties in the biofuels production costs of the four selected biofuels are 1530%.When applied in cars, biofuels have driving costs in ICEVs of about 0.180.24 h/km now (fuel excise duty and VAT excluded) and

may be about 0.18 in future. The cars contribution to these costs is much larger than the fuels contribution. Large-scale

gasication, thorough gas cleaning, and micro-biological processes for hydrolysis and fermentation are key major elds for RD&D

efforts, next to consistent market development and larger scale deployment of those technologies.

r 2005 Elsevier Ltd. All rights reserved.

Keywords: Biofuels; Prospects; Well-to-wheel

1. Introduction Abundant biomass resources are available in mostparts of the world (Rogner, 2000). The presentnecessary to improve the performance of biofuels, the production of four promising biofuelsmethanol, ethanol, hydrogen, andOutlook for ad

Carlo N Hamelincka

aAzielaan 774, 3526 SbUtrecht University, Copernicus Institute, He

Available onl

Abstractnced biofuels

, Andre P.C. Faaijb

echt, the Netherlands

rglaan 2, 3584 CS Utrecht, The Netherlands

August 2005

biomass (Intergovernmental Panel on Climate Change,2000), an average 50250EJ/yr in 2060 (2003); aglobal (technical) potential of primary biomass in2050 of 331135 EJ/yr (Hoogwijk et al., 2003a),depending on population growth and food demand(diet), economic development, food productionefciency, energy crop productivity on various landtypes, competing biomaterial products, and land usechoices. This range may be narrowed to 300675EJor 4060% of the energy demand in 2050, which couldbe produced on 410% of the terrestrial surface(Hoogwijk et al., 2003c). Large-scale bioenergy pro-duction also includes environmental, social andeconomic risks. They have not been evaluated here,but deserve attention in discussions about sustainabilityof bioenergy.Biomass is currently almost exclusively used for

the generation of heat and power. Only some 0.56EJof the biofuels are produced worldwide, largely ethanolfrom sugar/starch and a small amount of biodieselfrom oil crops (His, 2004), of which 62 PJ in theEuropean Union (EurObserER, 2004). Also, thepossibilities for electricity and heat productionfrom biomass (esp. combustion) are well known (Faaij,1997; van den Broek, 2000) and widely appliedin various markets. But, while there are many

other new or renewable technologies emergingfor large-scale electricity production with low or nocarbon emissions, the transportation sector, which isalmost entirely based on fossil oil use, has feweralternatives.Transportation represents about 27% of the worlds

secondary energy consumption (21% of primary) and isalmost exclusively fuelled by mineral oil. The share mayincrease to 2932% in 2050 (Intergovernmental Panelon Climate Change, 2000; IMAGE-team, 2001; EIA,2003). The rapidly increasing demand for transportationfuels is combined with rapidly decreasing mineral oilreserves of non-OPEC states. This increases dependencyon a limited number of oil-providing countries (Rogner,2000), with inherent risks for energy security and suddenprice distortions.Biofuels can play an important role in addressing

both the greenhouse gas emissions of transport and thedependency on mineral oil.A few main routes can be distinguished to produce

biofuels: extraction of vegetable oils, fermentation ofsugars to alcohol, gasication and chemical synthesis,and direct liquefaction. Many eventual fuels areconceivable: methanol, ethanol, hydrogen, syntheticdiesel, biodiesel, and bio oil (Fig. 1). All have verydifferent properties.

ARTICLE IN PRESS

Hydrogen(H2)

oil

Hydrogen(H2)

oil

C.N. Hamelinck, A.P.C. Faaij / Energy Policy 34 (2006) 32683283 3269Flash pyrolysis

Pressing orExtraction

Lignocellulosicbiomass

Gasification

Hydrothermalliquefaction

Hydrolysis

Anaerobicdigestion

Milling andhydrolysis

Sugar/starchcrops

Oil plants

Syngas

Bio oil

Biogas

Sugar

Vegetable

Flash pyrolysis

Pressing orExtraction

Lignocellulosicbiomass

Gasification

Hydrothermalliquefaction

Hydrolysis

Anaerobicdigestion

Milling andhydrolysis

Sugar/starchcrops

Oil plants

Syngas

Bio oil

Biogas

Sugar

VegetableFig. 1. Overview of conversion routes from crops toEsterificationBiodiesel

(alkyl esters)

Methanol(CH3OH)

FT Diesel(CxHy)

Ethanol(CH3CH2OH)

Biodiesel(CxHy)

Fermentation

Purification

DME(CH3OCH3)

SNG(CH4)

Bio oil(vegetable oil)

Hydro treatingand refining

Catalysedsynthesis

Water gas shift+ separation

EsterificationBiodiesel

(alkyl esters)

Methanol(CH3OH)

FT Diesel(CxHy)

Ethanol(CH3CH2OH)

Biodiesel(CxHy )

Fermentation

Purification

DME(CH3OCH3)

SNG(CH4)

Bio oil(vegetable oil)

Hydro treatingand refiningbiofuels (Elam, 1996; van den Broek, 2000).

1998; Wooley et al., 1999). However, often these studies

ARTICLE IN PRESSEner1.1. Advanced fuels

With the exception of sugar cane ethanol, the short-term (van den Broek et al., 2003) or traditional(Turkenburg, 2000) biofuels have a number of severedisadvantages that are related to the feedstock. Thecurrent costs of rapeseed biodiesel and ethanol fromcereals or beets are much higher than the costs ofgasoline and diesel. Substantial subsidies are needed tomake them competitive. These high costs are a result ofthe low net energy yield of most annual crops(100200GJ/ha yr in the long-term), the high-quality(valuable) agricultural land required, and the intensivemanagement. The lower productivity per hectare andhigh fertilizer requirement also limit the well-to-wheelreduction of fossil energy use, and the environmentalbenets are also limited (Ranney and Mann, 1994; VanZeijts et al., 1994; van den Broek, 2000; van Thuijl, 2002;Berndes et al., 2003).The net energy yield of perennial crops (220550GJ/

ha yr), grasses (220260) and sugar cane (400500) ismuch higher. These crops can be grown on less valuableland (Rogner, 2000). Compared with sugar, starch, andoil crops, the application of lignocellulosic biomass (e.g.wood and grasses) is more favourable and gives bettereconomic prospects to the future of biofuels. Also, moretypes of feedstock are in principle suitable to produce abroader range of fuels than when applying traditionalbiofuels feedstock.Higher overall (production, distribution and use)

energy conversion efciencies and lower overall costsare the key criteria for selecting biofuels for the longerterm. Various options are considered/developed thathave good potentials. Key examples are ethanolproduced from lignocellulosic biomass, synthetic dieselvia FischerTropsch (FT), methanol, and hydrogen(Katofsky, 1993; Williams et al., 1995; Arthur, 1999;Turkenburg, 2000). But the research, development anddemonstration status of all these fuels vary considerably.These fuels are selected for a detailed analysis of theirlong-term perspectives and RD&D needs.

1.2. Production of the selected biofuels

Methanol, hydrogen and FT diesel can be producedfrom biomass via gasication. Several routes involvingconventional, commercial, or advanced technologiesunder development are possible. Fig. 2 pictures ageneric conversion owsheet for this category ofprocesses. A train of processes to convert biomass torequired gas specications precedes the methanol or FTreactor, or hydrogen separation. The gasier producessyngas, a mixture of CO and H2, and few othercompounds. The syngas then undergoes a series ofchemical reactions. The equipment downstream of the

C.N. Hamelinck, A.P.C. Faaij /3270gasier for conversion to H2, methanol or FT diesel isincorporate only small biomass input scales (authorsassume that large scale is a priori not feasible) andexisting technologies. The potential for a better perfor-mance that could be obtained by applying improved ornew (non-commercial) technologies, combined fuel andpower production, and increasing scale giving higherefciencies and lower unit capital costs, has notexhaustively been explored.Another problem is the comparability of the results.

The capital analysis for biofuels producing facilities hasbeen done in different ways. The data quality is veryvariable. Also, the level of detail in analyses variesenormously: from very supercial, to thorough plantanalysis. In either case the inuence of individualparameters (e.g. feedstock costs) on the nal productprice is unclear.This study is for a large part based on our earlier

reported techno-economic studies on the production ofmethanol and hydrogen (Hamelinck and Faaij, 2002),FT diesel (Tijmensen et al., 2002; Hamelinck et al.,2004a) and ethanol (Hamelinck et al., 2005), and on thelong-distance transport of biomass (Hamelinck et al.,2004b), which have resulted in a PhD thesis (Hamelinck,the same as that used to make these products fromnatural gas (Williams et al., 1995), except for the gascleaning train. A gas turbine or boiler, and a steamturbine optionally employ the unconverted gas forelectricity co-production.Ethanol, instead, is produced via (largely) biochemical

processes (Fig. 3). Biomass is generally pretreated bymechanical and physical actions (steam) to clean andsize the biomass, and destroy its cell structure to make itmore accessible to further chemical or biologicaltreatment. Also, the lignin part of the biomass isremoved, and the hemicellulose is hydrolysed (sacchar-ied) to monomeric and oligomeric sugars. The cellulosecan then be hydrolysed to glucose. The sugars arefermented to ethanol, which is to be puried anddehydrated. Two pathways are possible towards futureprocesses: a continuing consolidation of hydrolysis-fermentation reactions in fewer reactor vessels and withfewer micro-organisms, or an optimisation of separatereactions. As only the cellulose and hemicellulose can beused in the process, the lignin is used for powerproduction.

1.3. Status of knowledge

Several studies exist that provide an overview of (partof) the biofuels eld (Van Zeijts et al., 1994; Arthur,1999; van den Broek et al., 2003). Other studies presentthe techno-economic performance of individual biofuels(Katofsky, 1993; Williams et al., 1995; De Jager et al.,

gy Policy 34 (2006) 326832832004).

ARTICLE IN PRESS

g, Shieparat

Turbine

, or F

ellulosydrolys

me gro

EnerGasification and gas cleaning

ReforminCO2 s

Drying and ChippingBiomass

Fig. 2. Generic owsheet for methanol, hydrogen

HemicellulosehydrolysisChippingBiomass

CH

Enzy

C.N. Hamelinck, A.P.C. Faaij /1.4. Objective

The central questions are as follows: Which of thebiofuel options have the better potential for the short-term and which have the best long-term (2030)prospects? And what developments are necessary toimprove the performance of advanced biofuels produc-tion and use?To answer these questions the short- and long-term

technological and economic performance of biofuels areanalysed and compared. This present study summarisesand normalises results for the four selected fuels(methanol, ethanol, hydrogen, and synthetic diesel)from the named earlier studies, compares their well-to-wheel performance, and indicates the key factorsinuencing that performance. First, the key technologiesfor the production of these fuels, such as gasication,gas processing, synthesis, hydrolysis, and fermen-tation, and their improvement options are studiedand modelled. Then, the production facilitys techno-logical and economic performance is analysed,applying variations in technology and scale. Finally,major biofuels chains (including distribution to cars,and end-use) are compared on an equal economicbasis, such as costs per kilometre driven. The results

Fig. 3. Ethanol production by hydrolT diesel production, via gasication of biomass.

Ethanol

Gas Turbine orboiler Electricity

eis Fermentation

wth

Distillationfting, ion

Catalysis,Separation

Catalysis,Separation

Separation

Gas Turbine orboiler

Steam

Electricity

Methanol

FT Diesel

Hydrogen

Recycle

Refining

gy Policy 34 (2006) 32683283 3271are compared with the reviewed performance of classicbiofuels such as rapeseed biodiesel and sugar/starchethanol.It is assessed which factors inuence the fuel produc-

tion and fuel chains performance most, and whichaspects are most uncertain. This gives insights both inthe possible barriers to implementation that need to beovercome, and in the technological improvementoptions that should be stimulated by research develop-ment and demonstration.

2. Research method

2.1. Modelling mass and energy balances

For analysing the production of methanol, hydrogenand FT diesel, Aspen Plus (Aspen Technology Inc.,2003) owsheet models were made and used foroptimisation purposes. The gasier, reformer and gasturbine deliver heat, whereas the dryer, gasier, refor-mer, and water gas shift reactor require steam. Thesupply and demand of heat (taking into account steamconditions) is added to or drawn from the steam turbine,such that the surplus heat is turned into electricity.

Steam Turbine

ysis fermentation schematically.

changes, but the heat integration focussed on the majorheat sources and sinks. In the FT process, pressure,

variety of chains, comprising different biomass produc-tion systems, pre-treatment and conversion operations,and transport of raw (chips, logs, bales) and renedbiomass (pellets) by different means (truck, train, ship).The projected costs for delivered biomass feedstock

has been analysed separately (Hamelinck et al., 2004b).It has been shown that 300MWHHV (8.6 PJHHV over8000 h) solid biomass in the compressed form (pellets orbales) could be delivered to a Western Europeanlocation from Latin America (11,000 km sea transport)at about 3.1 h/GJHHV, adding 2 h/GJHHV to the localproduction costs of 1 h/GJ (Hamelinck et al., 2004b), ofwhich only 0.5 h/GJHHV is in the actual internationalshipping. The present paper further assumes that

ARTICLE IN PRESS

Table 1

Unieda set of input parameters

Scale 400-2000MWHHV input (short-term-long-term)

Electricity price (supply and 0.03 h/kWh

3All costs in this introductory essay are in h2003, ination 2.5%

annually, 1 h2003 1 US$2003.4Energy is preferably expressed on Higher Heating Value basis,

indicated by the subscript HHV. LHV indicates Lower Heating Value,

Energy Policy 34 (2006) 32683283temperature, and (relative) concentration of the reac-tants inuence the product quality and yield, and thiswas also accounted for. Ethanol production has notbeen modelled in Aspen Plus (though the power isle was)because it incorporates biological rather than chemicalprocesses. They were analysed at a lower level of detailbecause only generic information (mostly conversionefciencies per step) was available. The studies havebeen made comparable by applying a unied set of inputEthanol production was for the greater part modelledin Excel (except for the power isle, which was modelledin Aspen Plus). For each process step in the hydrolysisfermentation process, conversion extents (of hydrocar-bons to sugars, of sugars to ethanol, of energygeneration, etc.) and losses were applied, so that eachstep yielded intermediate amounts of sugar, ethanol andsolid residuals.

2.2. Economic evaluation

The resulting mass and energy balances served as abasis for economic evaluation. Fuel production costs arecalculated by dividing the total annual costs of a systemby the annually produced amount of fuel. The totalannual costs consist of annual capital costs, operatingand maintenance (including maintenance, consumables,labour, waste handling), biomass feedstock costs andcosts of electricity supply/demand (xed power price).The Total Capital Investment, or TCI, is calculated byfactored estimation, based on known costs for majorequipment as found in the literature or estimated byexperts, and translated to the actual equipments size.Scaling-up has been done by using individual scalefactors for each piece of equipment. The uncertaintyrange of such estimates is up to 730% (Peters andTimmerhaus, 1980).For some of the process equipment costs are known

from current practical reality (e.g. compressors, heatexchangers, reactor vessels, reformers, etc.). Other costshave been estimated in the literature, or by consultedexperts.While largely the same method was applied in the

analysis of the selected fuels, there are differences in thedegree of detail. The methanol and hydrogen conceptswere rst chosen for their expected technical perfor-mance, then individually modelled and optimised forefciency, and eventually economically evaluated; theyincluded far reaching heat integration. The model of thesecond FT study allowed for far going optimisation, byvariation of gasier oxygen level and pressure, andapplying many step-by-step process conguration

C.N. Hamelinck, A.P.C. Faaij /3272parameters (Table 1).2.3. Feedstock costs

The biomass feedstock costs are a major inputparameter for the calculation of the biofuel productioncosts. Hoogwijk et al. (2003b) found that in the year2050, 170290EJHHV may annually be produced at costsbelow 2 h3/GJ4HHV. In Latin America, Africa, Asia andEastern Europe signicant amounts of biomass arealready supplied at 0.52.0 h/GJHHV (Williams andLarson, 1993; Marrison and Larson, 1995, 1996; Perlackand Wright, 1995; Phillips et al. 1995; Azar and Larson,2000; van den Broek, 2000). For the rst decade, forestor agricultural residues and waste will play an importantrole, as they are potentially available in large amounts(3090EJ/yr in 20202050) at mostly low costs. Large-scale international transport from bioenergy producingregions to Western Europe can be done via a broad

demand)e

Economic lifetime (depreciation

time)

15 yr

Technical lifetime 25 yr

Interest rate 10%

Load 8000 h (91% of time)

Investment path 20% in rst year, 30% in second

and 50% in last year

aSeveral input parameters were slightly different between the

original papers, which may complicate direct comparison. Therefore,

the results have been recalculated from the separate studies by using

this unied set of parameters.if no subscript is given, the denition is unknown.

biomass in compressed form can be delivered in WesternEurope at 3 h/GJHHV. In biomass producing regions asBrazil and Eastern Europe, biomass can be delivered tolocal plants at 2 h/GJHHV.

2.4. Selection for comparison

Based on the earlier broader evaluations, for each ofthe four fuels we select one concept for the short-term,and one concept for the longer term. For the short-term,we choose the best performing from concepts that arepossible with currently available technology. For thelong-term, we compare the ultimately best performingconcepts, which may need further technological devel-opment. The study on methanol and hydrogen (Hame-linck and Faaij, 2002) yielded six promising concepts forthe production of methanol and ve for the productionof hydrogen. About half of these concepts made use oftechnologies already available now, the other halfassumed technologies that are still under development.Of each category, the best performing concept waschosen. The study on ethanol (Hamelinck et al., 2005) incontrast yielded a development pathway with oneplausible concept for the short-, one for the medium-,and one for the long-term. The study on FT diesel, via atree of process choices and directly visible economicresults, yielded one best performing concept for the

short-term. Plausible improvement options were sum-marised, and their effect estimated. The concepts fromthe background articles that will be compared here aresummarised in Table 2.

3. Results and discussion

3.1. Technological insights

3.1.1. Gasification-based fuels

The ndings of the previously published papers can besummarised as follows: gasication-based fuel produc-tion systems that apply pressurised gasiers have higherjoint fuel and electricity energy conversion efcienciesthan atmospheric gasier-based systems. The totalefciency is also higher for once-through congurations,than for recycling congurations that aim at maximisingfuel output. This effect is strongest for FT production,where (costly) syngas recycling not only introducestemperature and pressure leaps, but also material leapsby reforming part of the product back to syngas. Formethanol and hydrogen, however, maximised fuelproduction, with little or no electricity co-production,generally performs economically somewhat better thanonce-through concepts.

ARTICLE IN PRESS

, wet g

react

, wet

addit

-site

ferme

nt, C

eacto

wet g

d gas

sier,

conv

sier,

conv

of m

e is the fourth and overall best of those concepts, but it applies a technology

cost reduction through learning, which was not incorporated in that study.

of ethanol via hydrolysis fermentation for short-, medium-, and long-term.

ong-t

n of h

re is t

cost

the p

echno

C.N. Hamelinck, A.P.C. Faaij / Energy Policy 34 (2006) 32683283 3273Table 2

Denition of the selected processes for biofuels production

Fuel Technical description

Methanola Now Atmospheric indirect gasier

pressure gas phase methanol

Future Atmospheric indirect gasier

methanol reactor with steam

Ethanolb Now Dilute acid pre-treatment, on

(cellulose hydrolysis and C6

Future Liquid hot water pre-treatme

and co-fermentation in one r

Hydrogenc Now Atmospheric indirect gasier,

and a combined cycle

Future Pressurised direct oxygen re

combined cycle

FT dieseld Now Direct 25 bar oxygen red ga

synthesis at 60 bar with 90%

Future Direct 25 bar oxygen red ga

synthesis at 60 bar with 90%

aHamelinck and Faaij (2002) assessed six concepts for the production

that performs best with currently available technology. Methanol futur

that is not yet available. The quoted results are compensated for 15%bHamelinck et al. (2005) assessed three concepts for the production

Ethanol now is ethanol short-term concept, and ethanol future is the lcHamelinck and Faaij (2002) assessed ve concepts for the productio

that performs best with currently available technology. Hydrogen futu

that are not yet available. The quoted results are compensated for 15%dHamelinck et al. iteratively assessed a broad range of concepts for

concept is the concept that was found to perform best; it incorporates twith 15% and 5% cost reduction (learning+process improvement).erm concept of that study.

ydrogen. Hydrogen now is the fth of those concepts; it is the concept

he third and overall best of those concepts, but it applies technologies

reduction through learning, which was not incorporated in that study.

roduction of FT diesel (Hamelinck et al., 2004a). The FT diesel now

logy that is currently available. The future concept is the same conceptas cleaning, steam reforming (partly fed by off gas), shift reactor, low-

or with recycle, and a steam turbine

gas cleaning, steam reforming (partly fed by off gas), a liquid phase

ion and recycle, and a steam turbine

enzyme production, enzymatic cellulose hydrolysis, SSF conguration

ntation integrated in one reactor vessel), boiler and steam turbine

BP conguration (enzyme production, enzymatic cellulose hydrolysis

r vessel), boiler and steam turbine

as cleaning, shift reactor, pressure swing adsorption for H2 separation,

ier, hot gas cleaning, ceramic membrane with (internal) shift, and a

tar cracker, wet gas cleaning, no reforming, and once-through FT

ersion

tar cracker, wet gas cleaning, no reforming, and once-through FT

ersion

ethanol. Methanol now is the sixth of those concepts; it is the concept

Hot (dry) gas cleaning generally improves the totalefciency, but the economical effects are ambivalent,since the investments also increase. Similarly, CO2removal does increase the total efciency (and in theFT reaction also the selectivity), but due to theaccompanying increase in investment costs this doesnot decrease the product costs. The bulk of the capitalinvestment is in the gasication and oxygen productionsystem, syngas processing and power generation units.These parts of the investment especially prot from

cost reductions at larger scales. Also, combinations withenriched air gasication (eliminating the expensiveoxygen production assumed for some methanol andhydrogen concepts) may reduce costs further.Several technologies considered here are not yet fully

proven or commercially available. Pressurised (oxygen)gasiers still need further development. At present, onlya few pressurised gasiers, operating at relatively smallscale, have proved to be reliable (Larson et al., 2001).Consequently, the reliability of cost data for large-scalegasiers is uncertain. A very critical step in all thermalsystems is gas cleaning. It still has to be proven whetherthe (hot) gas cleaning section is able to meet the strictcleaning requirements for reforming, shift and synthesis.

important for high overall energy efciencies. Severalunits may be realised with higher efciencies thanconsidered in this paper: new catalysts and carrierliquids could improve liquid phase methanol single passefciency. At larger scales, conversion and powersystems (especially the combined cycle) have higherefciencies, but this has not been researched in depth.

3.1.2. Ethanol

The assumed conversion extent of (hemi)cellulose toethanol by hydrolysis fermentation is close to thestoichiometric maximum. There is only little residualmaterial (mainly lignin), while the steam demand for thechosen concepts is high. This makes the application ofBIG/CC unattractive at 400MWHHV. Developments ofpre-treatment methods and the gradual ongoing reactorintegration are independent trends and it is plausiblethat at least some of the improved performance will berealised in the medium-term. The projected long-termperformance depends on development of technologiesthat have not yet passed laboratory stage, and that maybe commercially available earlier or later than 20 yrfrom now. This would mean either a more attractiveethanol product cost in the medium-term, or a less

ARTICLE IN PRESS

for no

and re

O&M

4.0

4.0

6.4

3.6

4.0

4.0

4.4

4.4

or the

e), or

tion a

metha

ital R

8%).

d her

ler R

e Fisc

etha

C.N. Hamelinck, A.P.C. Faaij / Energy Policy 34 (2006) 326832833274Liquid phase reactors (methanol and FT) are likely tohave better economies of scale. The development ofceramic membrane technology is crucial to reach theprojected hydrogen cost level. For FT diesel production,high CO conversion, either once through or after recycleof unconverted gas, and high C5+ selectivity are

Table 3

Technological and economic performance of biomass to fuels facilities

factor, annual O&M costs, and fuel production costs are summarised

Fuel ZHHVa (%) TCIb (Mh) Rc

Fuel Electricity

Methanol Now 58.9 4.0 235 0.79Future 57.0 0.1 188 0.84

Ethanol Now 34.9 4.1 291 0.84

Future 47.3 4.0 218 0.82

Hydrogen Now 34.8 16.9 247 0.81

Future 41.3 19.7 207 0.86

FT diesel Now 42.1 3.2 292 0.85

Future 42.1 3.2 235 0.85

Parameters hold at 400MWHHV biomass input. The production costs f

costs 0.03h/kWhe. Delivered feedstock costs 3h/GJHHV (Western Europ

wet (30% moisture) chipped biomass, drying to 1015% and pulverisaaElectricity is co-produced in most processes (Paper 2 also shows

electricity.bFrom the Total Capital Investment (TCI) follows the Total Cap

investment path (20%, 30% and 50%, in rst, second and last year: 11

study (Paper 4) did not include an investment path; the values presente

annual capital costs.cR value found for upscaling from 400 to 2000MWHHV input, smaldO&M for the methanol and hydrogen processes is xed at 4%. In th

part decreasing with scale (0.4% at 400MWHHV, R 0:85). O&M in

eThe time path also incorporates a scale increase: now: 400MWHHV andattractive cost in the long-term.The investment costs for advanced hemicellulose

hydrolysis methods need to be assessed more exactly.Continuing development of new micro-organisms isrequired to ensure fermentation of xylose and arabinose,and decrease the cellulase enzyme costs.

w-future: efciencies to fuel and electricity, capital investment, scalecalculated from the background articles

d (% of TCI) Production costse (h/GJHHV)

Now - future Local future

12

9 8

22

11 9

16

9 7

18

13 11

future include a larger scale (2000MWHHV input). Electricity buy/sell

2 h/GJHHV (local in biomass producing region). The processes assume

re included in the concepts.

nol concepts co-producing electricity). Some processes require extra

equirement (TCR) assuming a correction for lifetime (90.4%) and

The methanol and hydrogen study (Paper 2) and the Fischer-Tropsch

e are therefore somewhat higher. The TCR is used for determining the

are found for downscaling.

herTropsch process, O&M consists of a xed part (4% of TCI) and a

nol production is very dependent on cellulase required.future: 2000MWHHV.

3.2. Selected processes

Table 3 gives the resulting key parameters for biomassto fuel conversion facilities in the short- and long-term,the latter includes process improvements and technolo-gical learning. In the short-term ethanol and FT dieselfacilities are the most expensive. These processes alsohave the lowest total (fuel+electricity) efciency in theshort-term. This, in combination with high operatingcosts, makes cellulose ethanol the most expensive ofthese biofuels in the short-term. Through expectedprocess improvements, technological learning and scaleenlargement, production costs can decrease and/orefciencies can go up. Technological learning can takeplace through increasing production capacity andexperience.A breakdown of the production costs into capital,

O&M, feedstock and power costs is shown in Fig. 4. A30% uncertainty should be applied to the total capitalinvestment of methanol, hydrogen, and FT dieselconcepts. The capital costs for the ethanol conceptsare estimated to have a higher uncertainty (50%),

because of the less detailed analysis. The uncertaintybars in Fig. 4 show that the eventual inuence of theseuncertainties to the production costs could be up to3050%.The bare inuence of scale (for all concepts of Table

3) on the biofuel production costs is made visible in Fig.5. Analysis of the curves yields different overall scalefactors for the production facilities capital investmentsfor the different technologies. Also, these scale factorschange over the whole 802000MWHHV range. Allthermal gasication-based processes experience a stron-ger inuence of scale between 80 and 400MWHHV, thanethanol production. The hydrolysis fermentation takesplace in vessels that have a small maximum size,decreasing scale advantages at larger scales comparedto gasication-based processes.In the base situation (Fig. 4) feedstock (at 3 h/GJHHV)

accounts for 4558% of the total product costs. Theinuence of biomass feedstock price depends on theconversion efciency from feedstock to fuel, e.g. aZHHV,fuel of 35% (ethanol-now) implies that with every hfeedstock cost reduction, the production costs reduce

ARTICLE IN PRESS

20

25CapitalO&MBiomassCosts/Income Power

Now Future

ol, eth

HV, m

C.N. Hamelinck, A.P.C. Faaij / Energy Policy 34 (2006) 32683283 3275-5

0

5

10

15

Methanol Ethanol Hydrogen FT diesel

Fuel

pro

duct

ion

cost

s ( /

GJ H

HV)

Fig. 4. Breakdown of the production costs of selected biofuels (methan

GJHHV. Time path also incorporates a scale increase: now 400MWH

ranges of 30% are applied to capital (and O&M, because this is a linear funMethanol Ethanol Hydrogen FT diesel

anol, hydrogen and FT diesel) now and in future. Feedstock costs 3 h/

edium-term: 1000MWHHV, and ultimate: 2000MWHHV. Uncertaintyction of capital), 50% for the ethanol concepts.

ARTICLE IN PRESS

WHH

fuels

Ener0

5

10

15

20

25

0 400 800

Input scale (M

MeOH nowMeOH futureEtOH nowEtOH futureH2 nowH2 futureFT nowFT future

Fuel

pro

duct

ion

cost

s ( /

GJ H

HV)

Fig. 5. Inuence of input scale on the production costs of selected bio

2000MWHHV input.

C.N. Hamelinck, A.P.C. Faaij /3276with 1/0.35 or 2.9 h. A much more efcient process, suchas methanol now thus becomes relatively moreattractive at high feedstock costs (refer to Fig. 6). Sincecheap feedstock will be used rst (up to 3 h/GJ at gate),process improvements may initially focus on capital,O&M and power cost reduction.

3.3. Broader comparison

Table 4 presents the estimated production costs for abroader range of biofuels, calculated from informationon TCI, scale, and efciencies, by using the same baseassumptions. For ethanol production from sugar cane a3840 h operation window is used (limited harvest seasonand impossibility to store cane for longer time) (Damen,2001).The calculated ethanol from sugar cane production

costs are higher than the current prices in SouthEast Brazil (79 h/GJHHV currently without subsidies(Goldemberg et al., 2004)). The (large) difference maybe explained by the fact that many existing installationswere built with subsidies in the eighties, and are atpresent completely depreciated, and by the direct linkbetween the sugar and ethanol production, which allowsfor cost allocation over the two products. Internationalalcohol shipment from Latin America to Europe will notadd more than 0.5 h/GJ. If road tanker transport from1200 1600 2000

V)

2000 MWHHVand

2 /GJHHVfeedstock

costs

. Feedstock costs 3 h/GJHHV, with a sensibility towards 2h/GJHHV at

gy Policy 34 (2006) 32683283an inland production location to the harbour werenecessary, this would add half a euro extra per GJ per100 km (Hamelinck et al., 2004b).The calculated production costs of most fuels agree

with the literature: delivered costs are reported toamount 2138 h/GJHHV for ethanol from wheat,1529 h/GJHHV for RME, and 13 h/GJHHV for dimethy-lether (DME). Sugar beet ethanol is often projectedcheaper, than calculated here, at a delivered cost of2640 h/GJHHV, and substitute natural gas (SNG) moreexpensive at 13 h/GJHHV (Van Zeijts et al., 1994; Arthur,1999; Reinhardt and Zemanek, 2000; van den Broek etal., 2003).The fuels could also be produced in the biomass

supplying countries, provided that the amount ofcheaply available biomass locally sufces, after whichthe biofuel is internationally shipped. This has twoadvantages: the elimination of the costly densi-cation step (pellets) otherwise necessary to minimiselong-distance transport costs, and the higher energydensity of the transported commodity. The joint costreduction is about 9% for methanol (Hamelincket al., 2004b). Although ethanol has a higherenergy density than methanol, the cost advantagewill be practically the same. It can be concludedthat this route is very attractive for sugar cane ethanolfrom Brazil.

ARTICLE IN PRESS

tock co

Energy Policy 34 (2006) 32683283 32770

5

10

15

20

25

0 1 2

Feeds

Fuel

pro

duct

ion

cost

s ( /

GJ H

HV)

C.N. Hamelinck, A.P.C. Faaij /3.3.1. Distribution and dispensing

The fuels physical properties have a strong inuenceon costs and energy use during distribution to the end-user (Table 5). The energy density of ethanol andmethanol is lower than that of gasoline and diesel, whichresults in proportionally higher costs. Hydrogen is byfar the most challenging commodity to distribute andstore. Pipeline transport in gaseous form is the cheapestand the most energy efcient approach at present, butonly suitable for large-scale, e.g. at national to regionallevel. Supplying individual gas stations require thetransport of liquid hydrogen by road tankers, whichincreases the costs (van Walwijk et al., 1996). Chemicalproperties of individual fuels require special materialsand safety precautions. Alcohols and RME can best beblended with gasoline and diesel right at the reneries,or at intermediate depots between reneries and gasstations (van den Broek et al., 2003). The choice dependsmainly on the biofuel production facilitys location(s),on the blends stability (van den Broek et al., 2003), and,in the case of alcohols, on whether or not they are alsodispensed as neat fuels.The resulting delivered costs at the car are shown in

Fig. 7, left. In the short-term, lignocellulosic methanoland sugar cane ethanol are the cheapest biofuels. Theymay be delivered at 1314 h/GJHHV. RME from rape-seed is very expensive, but as has been reported by

Fig. 6. Inuence of feedstock costs on the production3 4 5

sts ( /GJHHV)

MeOH nowMeOH futureEtOH nowEtOH futureH2 nowH2 futureFT nowFT future

others (van den Broek et al., 2003), it has a very broadcost uncertainty range. Hydrogen has very highdistribution costs (De Jager et al., 1998; Ogden et al.,1999), so end consumers costs are about 20 h/GJHHV,which is comparable with FT diesel. In the long-term thedelivered costs range from 10 to 15 h/GJHHV for mostbiofuels, but the traditional biofuels lag behind. Forcomparison: gasoline over the last decennium cost2.57.2 h/GJHHV at Rotterdam port and diesel2.46.6 h/GJHHV (BP, 2003), while distribution to gasstations adds about 1.4 h/GJHHV (van Walwijk et al.,1996), so that the high ends of the delivered costs5 wereabout 9 h/GJHHV. This corresponded with oil prices of1234 h/bbl (1 bbl equals 6.12GJHHV). At the currentcrude oil prices of above 35 h/bbl or 5.7 h/GJ, diesel andgasoline cost over 7 and 8 h/GJ (excluding distribution,excise and VAT), at 50 h/bbl, diesel and gasoline costs.As projections for future fossil fuels costs are highly

costs of selected biofuels (400MWHHV input).

5The sale price at the gas station further usually includes excise duty,

in the Netherlands this is currently 18 h/GJHHV (0.64 h/l) for gasoline

and 9h/GJHHV (0.34 h/l) for diesel (van den Broek et al., 2003), and

value added tax (VAT, 20%). (Partial) duty exemption for biofuels

could make their price competitive with gasoline and diesel. VAT is

compulsory and the same percentage for all vehicle fuels. The current

sale prices in the Netherlands are about 33h/GJHHV (1.15h/l) for

gasoline and 21 h/GJHHV (0.80h/l) for diesel.

ARTICLE IN PRESS

Table 4

Production costs of fuels from various crops, not analysed further in this pa

Fuel Feedstocka (h/GJHHV) ZHHV (%) TCI (

Fuel Electricity

Ethanol Maizec 8.3 18 16 289 0.75 8.3 25 - 19Wheatc 10 19 15 280 0.75 8.3 29 - 24Sugar beetd 14 37 2.2 149 0.75 5.0 40 - 39Sugar canee 2.4 43 0 48 0.8 13 11

Now

Sugar cane 2.4 89 1.2 153 0.8 10 8

397 0.95 0.9 25 - 23306 0.7 7 15 - 11242 0.7 4 15 - 11141 0.7 4 9 - 7

rm (400MWHHV input), and production costs for short-term-long-term.thanol from cane at Brazil conditions, all other fuels European conditions.

ree at eld) (De Jager et al., 1998). All include 100 km truck transport of the

C.N. Hamelinck, A.P.C. Faaij / Ener3278Future

Biodiesel (RME) Rapeseedf 6.6 31 12

DMEg Lignocellulose 3 58 3.6DMMh Lignocellulose 3 46.4 0

SNGh Lignocellulose 3 60 0

Technological and economic fuel production parameters for short-te

Efciencies are on whole used feedstock basis (see notes 3, 4 and 6). EaCosts for maize, wheat and rapeseed are for grain+straw (straw is funcertain,6 they may well come in the range of biofuelscosts.

3.4. Biofuels use in cars

Different fuels perform differently in various drivechains. Therefore, the various biofuels should be

raw material (0.5h/GJHHV). Sugar cane feedstock price at conversion installbThe production costs are recalculated from total capital requirement an

interest, 15 yr lifetime, the relation between TCR and TCI was explained in T

and long-term 2000MWHHV input. Long-term includes cost reductions by lcEthanol from maize and wheat by the same wet milling-fermentation proce

to electricity is 37-45% by HHV (BIG-CC). The milling-fermentation p0.20GJth/GJHHVfuel. Efciencies and costs reported in this table are for the to

the milling-fermenting part is 72-62Mh for 104MWHHV grain input, for twhich is settled with the O&M (Elam, 1996; De Jager et al., 1998; Faaij et a

dEthanol from sugar beet conversion is 43%, but requires heat 0.35GJ

deducted from the feedstock, the electricity supplied by the grid. A 139MWHfuture. Co-produced fodder has value, which is deducted from the O&M (E

eConversion efciency for an average Brazilian sugar/ethanol mill is 85 l/to

17.35GJHHV/tonnedry) but could increase to 177 litre/tonnewet (mc 73%) or 8

in the short-term, but in the long-term produce electricity 55.4MJe/tonnewet (

now is 63.2Mh, for a future 1951MWHHV input 581Mh (Damen, 2001).fEfciencies and costs reported in this table are for the total process of seed

49% by HHV. The extraction-esterication requires electricity 0.05GJe/GJHH1.9Mh (10% cost reduction by learning), costs and efciencies for the BIG/

gDimethylether. Efciency and capital costs from Elam (Elam, 2002).hDMM is dimethoxymethane; SNG is substitute natural gas; Efciency an

6The worlds oil supplies are not unlimited (Meadows et al., 1972),

and although the insights differ from increasing oil production until at

least 2025 (EIA, 2003), down to declining oil production within the

next 20 (Cavallo, 2002) or 510 yr (Campbell and Laherrere, 1998;

Deffeyes, 2001). The differences are partly explained by the denition

of supplies. This may or may not include unconventional oil that

although it cannot be exploited economically at presentcould

eventually be exploited economically depending on both technology

improvement and the markets demand (Rogner, 2000). After a

production peak, the world does not run out of oil, but the oil prices

likely rise (EIA, 2003). For comparison, over the last hundred years the

crude oil price has usually been between 1.6 and 4.9 h/GJ (BP, 2003),

and up to 13 h/GJ during the oil crisis.per, based on literature

Mh) R O&M (% of TCI) Production costsb (h/GJHHV)

gy Policy 34 (2006) 32683283compared on an equal basis, such as driving costs, theirenergy saving potential, or specic costs as CO2reducing option. Moreover, the prospects for biofuelscannot be seen apart from (the future of) vehiclepropulsion. A selection of fuels, shown in Fig. 7 (left),is used for further comparison. Table 6 sums up the

ation in Latin America, leaves are left in the eld (Damen, 2001).

d efciency, assumptions: 8000 h load (3840h for sugar cane), 10%

able 3, note 2. Electricity buy/sell 0.03 h/kWhe, short-term 400MWHHVearning (see respective notes).

ss. Conversion grain to ethanol is 37-40% by HHV, conversion strawrocess requires electricity 0.06-0.05GJe/GJHHVfuel, and heat 0.24-tal process of grain and straw to ethanol and electricity. Investment for

he BIG/CC 2986-2398 h/kWhe. The co-produced fodder has a value,l., 1998).

th/GJHHVfuel and electricity 0.06GJe/GJHHVfuel. The heat demand is

HV input facility has TCR of 72Mh now, and 10% reduction towards

lam, 1996; De Jager et al., 1998).

nnewet (mc 73%) or 7.4MJHHV/tonnedry or 42.8% by HHV (sugar cane

9% HHV. Sugar mills assumed to produce or consume no extra energy

electric efciency 1.2% by HHV). TCR for a 523MWHHV input facility

and straw to RME and electricity. Conversion of rapeseed to RME is

Vfuel. A 1.875MWHHV input esterication facility has a TCR of 2.1-CC as in note 3 (De Jager et al., 1998).

d capital costs from Arthur D. Little (Arthur, 1999).

Table 5

Costs assumed for distribution and dispensing different fuels from a

central production facility to gas stations (van Walwijk et al., 1996; De

Jager et al., 1998; Ogden et al., 1999)

Fuel Costs (h/GJHHV)

Gasoline 1.41

Diesel 1.33

Methanol 2.12

Ethanol 1.84

Compressed hydrogen 4.50

LPG, DME 2.40

ARTICLE IN PRESS

051015202530

fossil gasolinefossil diesel

rapeseed biodieselmaize ethanolsugarcane ethanol

lignocellulose ethanollignocellulose ethanollignocellulose methanollignocellulose diesel (FT)lignocellulose hydrogenlignocellulose DME

lignocellulose hydrogenlignocellulose methanollignocellulose DME

fossil gasolinefossil diesel

rapeseed biodieselsugarcane ethanol

lignocellulose ethanollignocellulose methanollignocellulose diesel (FT)lignocellulose DME

lignocellulose hydrogenfossil gasolinefossil diesellignocellulose methanollignocellulose DME

Fuel delivered costs ( /GJ) Fuel production Fuel deliveryNo

wFu

ture

0.00

0.05

0.10

0.15

0.20

0.25

0.30

in ICEV-SIin ICEV-CI

as RME5 in ICEV-CIas E10 in ICEV-SIas E10 in ICEV-SI

as E10 in ICEV-SIin ICEV-SIin ICEV-SIin ICEV-CIin ICEV-SIin ICEV-CI

in FCV-PEMin FCV-SR-PEMin FCV-SR-PEM

in ICEV-SIin ICEV-CI

as RME5 in ICEV-CIas E10 in ICEV-SI

in ICEV-SIin ICEV-SIin ICEV-CIin ICEV-CI

in FCV-PEMin FCV-POX-PEMin FCV-POX-PEM

in FCV-SR-PEMin FCV-SR-PEM

Costsof driving ( /km) Car Car O&M FuelN

ow

Future

Dies

eli

nc

l. du

ty ex VA

T

Gaso

line

incl

. du

ty ex

VAT

Fig. 7. Delivered biofuels costs (left), and marginal costs of driving (right) for different fuelcar combinations for now-future. Costs exclude exciseduty, fuel VAT and road tax. Both fuel and driving costs are on pure biofuels basis: all extra or avoided costs of blends, relative to pure gasoline or

diesel, are allocated to the biofuel. Mineral oil-derived gasoline costs 5-5.3h/GJHHV and diesel 4.4-4.9 h/GJHHV. For all vehicles (100 kW wheelpower passenger cars), annual distance is 20,000 km, lifetime is 10 yr, annual O&M is 400h. RME5 means 5% biodiesel in diesel, E10 means 10%

ethanol in gasoline.

Table 6

Car costs and fuel efciencya (km/GJHHV) on short-term-long-term, for passenger cars (about 100 kW wheel power), for various fuels in variousengine systems

Engine system Fuel Car costsa (h) Efciencyb (km/GJfuel)

Short-term -Long-term Short-term -Long-term

ICEV-SI Gasoline 16,500 430 -950Methanol M100 17,800 540 -950Ethanol E10 16,500 440 -950

E85 (FFV) 18,500 520 -950H2 21,450 510

ICEV-CI Diesel (fossil, synthetic, RME) 18,000 -17,750 470 -760M100 18,000 470

FCV-PEM H2 25,400 -18,750 880 -1690

FCV-SR-PEM M100 26,050 -22,100 760 -840

FCV-POX-PEM Gasoline/diesel/E100 26,500 -22,500 630 -960

Annual O&M is assumed 400 h/car.aCosts for the gasoline ICEV SI and diesel ICEV CI are set; the others are derived from absolute costs (extra costs for drive train) and relative costs

in literature (van Walwijk et al., 1996; De Jager et al., 1998; Arthur, 1999; Ogden et al., 1999).bBesides the fuel and engine, the fuel efciency depends on other car features (weight, form, energy regeneration options) and the drive cycle

(Ogden et al., 1999; Maclean and Lave, 2003). Efciency is found expressed in many different ways: mile per gallon (mpg), 100 km per certain litres of

gasoline equivalent, %, MJ/km. To calculate from km per litre gasoline equivalent to km per GJ, multiply by 28.4 l/GJ (1 l for 15 km equals 430 km/

GJ). Efciencies estimated from average drive cycles in literature (Williams et al., 1995; Lynd, 1996; van Walwijk et al., 1996; De Jager et al., 1998;

Arthur, 1999; Weiss et al., 2003). Efciencies for blends are allocated to the biofuel only.

C.N. Hamelinck, A.P.C. Faaij / Energy Policy 34 (2006) 32683283 3279

performance of (bio)fuels in different engines and carcosts. Parameters have been derived from relativenumbers in the literature that compared the drive trainsrunning on biofuels with comparable drive trains onfossil fuels. The fuel cell vehicle has been included as an(expensive) option for the short-term, and is assumed tobe available at projected costs in the future.The engine efciency (measured in km/GJ fuel) of

ICEVs can be improved for both spark and compressionignition engines. Alcohols may have a higher efciencyin spark-ignition ICEVs than gasoline, if the vehicles areadapted to prot from the slightly higher octane7

ARTICLE IN PRESSC.N. Hamelinck, A.P.C. Faaij / Ener3280number. Efciency differences found for different fuelsin compression-ignition (diesel) ICEVs are so small thatthey will not be reckoned with (van Walwijk et al.,1996). Vehicle efciency improvements in transmissionand aerodynamics are generally independent of the fueltype (Lynd, 1996) and are not anticipated here. Theefciencies in Table 6 hold for a drive chain of 100 kWwheel power. Because of differences in energy contentbetween the fuels, equal driving ranges require differentfuel and tank loads (volume or mass), which indirectlyinuences the performance (Elam, 1996; Ogden et al.,1999). It is not known to what extent this is dealt with inthe literature.All biofuels require adaptations in ICEV cars, leading

to extra costs. Only relative costs from comparisons ofdifferent fuelcar combinations in the literature areused.Many advantages are attributed to future fuel cell

vehicles8 over ICEVs. Potentially, they have a highenergy efciency (not limited to the Carnot efciency ofthermal energy processes), hardly produce emissions,operate silently, require little maintenance (no movingparts), and would be cheap in owning and operation(Katofsky, 1993; Williams et al., 1995; van Walwijket al., 1996; Ogden et al., 1999; E-lab, 2000). However,fuel cells are not commercial yet and expected expensivein the short-term, large and heavy per kiloWatt output.Also, exible car operation (changing load) requires theuse of very efcient batteries. Short-term efciency maynot be so high compared to hybrid vehicles. Whether

7The octane number expresses a fuels quality rating, indicating the

ability of the fuel to resist premature detonation and to burn evenly

when exposed to heat and pressure in an (spark ignited) internal

combustion engine. Normal gasoline has an octane number of 8789.

The cetane number is a primary measure of fuel suitability for diesel

engines (compression ignited), but not related to fuel efciency. It

essentially expresses the delay before ignition. The shorter the delay the

betterand the higher the cetane number.8Different types of fuel cells are considered for vehicles: Alkaline

Fuel Cell (AFC) and Proton Exchange Membrane (aka Polymer

Electrolyte Membrane PEM) fuel cell that process hydrogen, and the

Direct Methanol Fuel Cell (DMFC) that processes methanol. All have

low operation temperatures (20120 1C). Most literature and demon-stration programs focus on PEM FCVs. The AFC is extremelyexpensive and requires very pure H2.and when FCVs will really perform better than futureICEVs is not clear (Weiss et al., 2003).To use a fuel other than hydrogen in PEM Fuel cells,

it must be converted into H2 (and CO2) onboard thevehicle. The most simple fuels methanol and DME canbe steam reformed (SR) at relatively low temperatures(van Walwijk et al., 1996), while others require (harsher)partial oxidation (POX) or autothermal reforming.Onboard reforming implies an energy (direct and viavehicle weight) and cost penalty. The total fuel efciencyof a fuel cell system must then take into account theefciency of the reforming process as well as theefciency of the fuel cell. The heat generated as a by-product of the fuel cell can be used to increase thesystems energy efciency. Onboard reforming is only anoption if the reformer is exible in providing hydrogento the fuel cell, as fast or slow as it is being consumed bythe fuel cell. If additional hydrogen storage would benecessary, the onboard reformer loses its advantage(Brydges, 2000). Direct methanol fuel cells (DMFC)circumvent reforming, thereby offering lower systemcomplexity. Although the methanol to electricity ef-ciency is theoretically high, results reported so far arenot optimistic, and the catalyst is very expensive (Dillonet al., 2004).For a 100 kW wheel power passenger car with annual

20,000 km driving cycle, the resulting costs per kilometredriven are shown in Fig. 7. Biomass alternatives to dieselare all slightly more expensive than fossil diesel in theshort-term, but synthetic diesel and DME becomecompetitive in the longer term. Most fuel cell optionsare signicantly more expensive than gasoline/dieselICEVs; only hydrogen in a future FCV PEM maybecome competitive.In this gure, excise duty and VAT are excluded, and

the resulting fuel contribution may become strikinglysmall: only 9% of the total driving costs for hydrogen inFCVs. This agrees well with values reported by others(Arthur, 1999; Ogden et al., 1999). Considering thesendings with the fact that car costs are dictated by otherfactors than engine and fuel system costs, and with theobserved uncertainty in future fossil fuel-derived gaso-line and diesel costs, there are no a priori economicbarriers to develop and introduce cars that run onadvanced biofuels.For indication, estimated distances that could be

driven on fuel produced on 1 ha of feedstock are given inTable 7. The larger distances driven in the long-term arecaused by the higher yields per hectare combined withthe higher engine efciencies projected. Compared tothese, the increase in conversion efciency plays amarginal role. Although the ranges found are broad, itcan be concluded that much larger distances can bedriven on fuels from lignocellulosic biomass than onfuels from sugar beet or rapeseed, and that these

gy Policy 34 (2006) 32683283differences become more pronounced in the long-term.

ARTICLE IN PRESS

(Hamelinck, 2004, Tables 7 and 8).b

EnerIt seems that modern ICEVs (e.g. hybrids) combined

Derived from net energy yield, energy conversion efciency and

vehicle energy use in Faaij and Hamelinck (2002, Tables 2, 3 and 5).

From short- to long-term, the feedstock yield increases from 11 to

30 tonnedry/ha for lignocellulose crops, from 13 to 19 tonnedry/ha for

sugar beet and from 3 to 4 tonnedry/ha for rapeseed.Table 7

Distance that can be driven per hectare of feedstock for several

combinations of fuels and engines, derived from the net energy yield

and vehicle efciency as reported in Hamelinck and Faaij (2002), and

Hamelinck (2004)

Feedstock Fuel Engine Distance (thousands km/ha)

Short-term Long-term

Lignocellulose Hydrogen ICEV 26a37b 80b97a

FCV 44a140b 189b321a

Methanol ICEV 34b49a 75b287a

FCV 68a83b 113b252a

FT ICEV 22b38a 56b167a

FCV 50a67b 97b211a

Ethanol ICEV 29b30a 82b238a

FCV 38a72b 129b240a

Sugar beet Ethanol ICEV 15a37b 57a88b

FCV 19a93b 58a138b

Rapeseed RME ICEV 5a28b 15a79b

FCV 6a84b 19a137b

aDerived from area net fuel yield and vehicle efciency in Hamelinck

C.N. Hamelinck, A.P.C. Faaij /with advanced biofuels have a very strong position ascarbon neutral alternative for the transport sectorcompared to hydrogen fuelled FCVs for a long periodto come. The distance that can be driven on hydrogen ismore than double, when FCVs are applied instead ofICEVs.

4. Conclusion

4.1. Main conclusions

Biomass could play a large and important role in afuture sustainable energy supply as a source for modernenergy carriers as electricity and transportation fuels.Especially the introduction of biofuels is attractivebecause it is one of very few options for low CO2emission transport systems against (eventually) reason-able costs, and because it decreases or spreads fueldependency. Of the many conceivable biofuels, fuelsfrom lignocellulose biomass are the most attractive,because they allow for a higher fuel yield per hectare,have better projected economics, their feedstock requiresless additional energy for growth and harvest and can begrown under many different circumstances in contrast toannual crops that require good-quality land.In the present study, the production of four promising

biofuelsmethanol, ethanol, hydrogen, and syntheticdieselwas systematically analysed, based on detailedpre-engineering analyses. Production costs of these fuelsrange 1622 h/GJHHV now, down to 913 h/GJHHV infuture (2030). This performance assumes both certaintechnological developments as well as the availability ofbiomass at 3 h/GJHHV. The feedstock costs stronglyinuence the resulting biofuel costs by 23 h/GJfuel foreach h/GJHHV feedstock difference. In biomass produ-cing regions such as Latin America or the former USSR,the four fuels could be produced against 711 h/GJHHV.The uncertainties in the biofuels production costs of thefour selected biofuels are 1530%, which is small whenconsidering the large uncertainty in future (2030)gasoline and diesel prices.The production costs of other biofuels were calculated

using the same assumptions on feedstock costs, scale,load, and capital depreciation. This showed that alsodimethoxymethane (DMM), DME and SNG fall in thesame cost range. These fuels were however not analysedat a similar level of detail.When applied in cars, biofuels have driving costs in

ICEVs of about 0.180.24 h/km now and may be about0.18 in future (fuel excise duty and VAT excluded). Thisis only slightly higher than the driving costs of currentgasoline/diesel. Moreover, the cars contribution tothese costs is much larger than the fuels contribution,and the differences in the fuels contributions are onlyabout 1 cent/km (which is small compared to theuncertainties). The driving costs for fuel cell vehicles arehigher because of the projected larger vehicle costs.From this perspective one can conclude that cars thatrun on advanced fuels can be brought on the market atcompetitive prices, and that the biofuels driving costscould compete with those of fossil-derived fuels.Furthermore, much larger distances per hectare can bedriven on fuels from lignocellulosic biomass than onfuels from sugar beet or rapeseed, and these differencesbecome more pronounced in the long-term. Thedistances that can be driven on hydrogen more thandouble, when FCVs are applied instead of ICEVs.The key fuel chains for the short-term seem to be

methanol and FT diesel, while ethanol from lignocellu-lose emerges in the medium-term. Ultimately, hydrogenmay offer the best perspective; but requires break-throughs in hydrogen storage technology to tick thebalance. Compared with these advanced biofuels,biodiesel from rapeseed and ethanol from sugar beetor starch crops, already available today, are expensiveand inefcient with very little room for improvement.

4.2. RD&D issues

The gasication-derived fuels require the developmentof large (about 400MWHHV input) pressurised gasiers,a gas cleaning section that matches the catalysts

gy Policy 34 (2006) 32683283 3281specication, increased catalyst selectivity (for FT diesel

Wim Turkenburg (promoter) for detailed commenting

5158.

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Outlook for advanced biofuelsIntroductionAdvanced fuelsProduction of the selected biofuelsStatus of knowledgeObjective

Research methodModelling mass and energy balancesEconomic evaluationFeedstock costsSelection for comparison

Results and discussionTechnological insightsGasification-based fuelsEthanol

Selected processesBroader comparisonDistribution and dispensing

Biofuels use in cars

ConclusionMain conclusionsRD&D issues

AcknowledgementsReferences