rapid assessment biofuels

8/12/2019 Rapid Assessment Biofuels

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Bi o f u e ls: E n vi ro n m e n t a l C o n s e q u e n c e s & I m p l ic a t i o n s o f C h a n g i n g L a n d U se

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E xe c u t i v e S u m m a r y

Many countries and companies are investingheavily in biofuels for transport, motivated byconcerns and opportunities related to globalclimate change, energy security, and ruraldevelopment. Production targets andmandates for biofuels vary by country, butmany governments have adopted goals tosubstitute 10% or more of transportationdemand for liquid fossil fuels with biofuelswithin 10 to 20 years (Chapters 2 and 11).Governmental energy policies have focused

largely on liquid biofuels (ethanol andbiodiesel) rather than solid biofuels (wood andcharcoal) in part because the liquid fuels canreadily replace conventional transportationfuels without major modifications in currenttransportation technologies. The convenienceof liquid fuels for transportation has longresulted in a price differential between liquidand solid fuels, and as of 2007, crude oil was

worth some 12-times more than coal per unitenergy (Chapter 1).

Global production of liquid biofuels has grownexponentially in recent years, and 2007production was 3-fold greater than that in2000 (Figure 1a). Despite this growth, liquidbiofuels are still small contributors to theglobal energy supply. As of 2006, they supplied1.8% of the global use of liquid transportationfuels. This is equivalent to 1% of the total

liquid fuel use globally (including liquid fuelsused other than for transportation), or 0.4% ofthe total global energy consumption from allsources. By comparison, solid biofuelssupplied approximately 10% to 13% of totalglobal energy consumption, or some 30-foldmore energy than liquid biofuels (Chapter 1).

Although many countries anticipate largeincreases in production, the current global

Rapid Assessment on Biofuels andthe Environment: Overview and Key Findings

Robert W. Howartha, Stefan Bringezub, Mateete Bekundac, Charlotte de Fraitured,Luc Maenee, Luiz Martinellif, and Osvaldo Salag

aCornell University, Ithaca, New York, USA, bWuppertal Institute for Climate, Environment, and Energy,Wuppertal, Germany, cMakerere University, Kampala, Uganda, dInternational Water ManagementInstitute,Colombo, Sri Lanka, eInternational Fertilizer Industry Association, Paris, France, fUniversity ofSo Paulo, Piracicaba, Brazil, gBrown University, Providence, Rhode Island, USA

The Scientific Committee on Problems of the Environment (SCOPE) of the International Council for Science(ICSU) established the International SCOPE Biofuels Project to provide a comprehensive and objective, science-based analysis of the effects of biofuels on the environment. The SCOPE Biofuels Project held a workshop inGummersbach, Germany from September 22-24, 2008 to develop a rapid assessment of these environmentalconsequences. More than 75 scientists from 21 countries and representing a diversity of disciplines participated inthis assessment, either in person at Gummersbach, as co-authors or reviewers of chapters in the report, or asadvisors to the Project. Here we summarize the report and provide the key findings of the rapid assessment. Theinformation provided in this overview is fully supported with references in the reports chapters. For ease ofreading, the only references used here are citations to the pertinent chapters. The full report is available athttp://cip.cornell.edu/biofuels/


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R a p i d a s se s sm e n t o n b i o f u e l s a n d e n v i ro n m e n t : o v e r v i e w a n d k e y f i n d i n g s

Sc i e n t i f ic C o m m i t te e o n P ro b l e m s o f t h e E n v ir o n m e n t

production of liquid biofuels is dominated by

just a handful of countries. Brazil and in theUnited States combined have accounted for75% or more of the global ethanol productionfor decades (Figure 1b). Ethanol is the majorliquid biofuel globally, with a production ofapproximately 1.2 EJ (1.2 x 1018 joules, or 55billion liters) in 2007. China and India are thenext largest producers, together accounting for12% of global ethanol production in 2006. Theglobal production of biodiesel in 2007 wasapproximately 0.4 EJ (12 billion liters) per year,about one-third the rate of ethanol production(by energy content). Almost 80% of the worldsproduction of biodiesel occurs in the EuropeanUnion, with almost 50% of global productionin Germany alone (Chapter 1).

The vast majority of current production ofliquid biofuels is based on crops that can alsobe used for food: corn (i.e. maize) in theUnited States (the worlds largest producer),sugarcane in Brazil (the worlds second largestproducer), and rapeseed (i.e. canola) in

Germany (the worlds third largest producer).In 2007, the United States used 24% of itsnational corn harvest to produce ethanol,which contributed 1.3% of national liquid fueluse (transportation fuels plus other uses ofliquid fuels) (Chapter 1). This illustrates thedifficulty of reaching current mandates forproduction of liquid biofuels. Meeting a goalof 10% substitution of liquid transportationfuels globally would require some combinationof a large increase in the area devoted to

biofuels crops and an unprecedented increasein the yield of biofuel crops per unit of land,water, and fertilizers (Chapter 4). Estimates ofthe range of new agricultural land required tomeet a global target of 10% biofuelsubstitution range from 118 to 508 millionhectares, depending on the crop type andassumed productivity level. This compareswith the current area of arable land in theworld of 1,400 million hectares (Chapter 6).

Because of constraints on the productivity ofbiofuel crops such as water availability, thehigher end of estimates for land-use needs maybe most reasonable (Chapters 4 and 16).

The challenge of meeting land needs for theexpansion of biofuel production must beconsidered in the context of a growingdemand for food. The global population hasmore than doubled since 1960, and worldagricultural area per person decreased 2-fold.In the past, food production per personincreased due to dramatic improvements incrop productivity per area. However, the abilityto increase crop productivity is not infinite and

Figure 1. Global production of ethanol and biodiesel(1a, top) and comparison of production of ethanol in

the the USA and Brazil with global production (1b,

bottom) from 1975 to 2007. A petajoule is 1015(one

quadrillion) joules. One thousand petajoules equals

an exajoule (EJ ). Reprinted from Chapter 1

Ethanol Production

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population growth and improved, higher

protein diets are placing ever-greater demandson land for food production. Thus,competition and conflict with biofuelproduction using current methods will likelyincrease in a world where some one billionpeople are already underfed (Chapter 4).

Biofuel production and consumption have avariety of effects on the local and regionalenvironment. Growing crops is essentially thesame for biofuels as for other agriculturalpurposes. However, the environmental impacts

of crop production often increase as more landis used, land is farmed more intensively, andso-called marginal lands are placed intoagricultural production. The environmentalconsequences of biofuels depend on whatcrops or materials are used, where and howthese feedstocks are grown, how the biofuel isproduced and used, and how much isproduced and consumed. Effects on theenvironment are both positive and negative.

Biofuels and the Emission ofGreenhouse Gases

Biofuels are often promoted as a way to reduceglobal warming. However, some biofuelsystems can increase the release of greenhousegases relative to the fossil fuels they replace,thus aggravating global warming. Greenhousegas emissions from biofuels occur fromfarming practices, refining operations, and theconversion of ecosystems to cropland forbiofuel production. The details of how andwhere crops are grown, how crops aretransported before being processed into fuels,and how fuels are made are all important indetermining the net effect on greenhouse gasemissions. Most recent studies based on life-cycle analysis conclude that when ethanolfrom sugar cane is used to replace fossil fuelsin transportation, a substantial reduction innet greenhouse gas emissions may result: 80%

to greater than 100% savings are recorded

(when low emissions of nitrous oxide areassumed). On the other hand, using ethanolfrom corn is less favorable: 30% to a maximumof 50% savings or even an increase ofgreenhouse gas emissions relative to fossilfuels, depending on process-energy sources.Savings from rapeseed biodiesel fall betweenvalues reported for ethanol from sugar caneand ethanol f rom corn (20% to 85% relative tofossil fuels). The wide range of greenhouse-gassavings for all types of biofuels can be largelyattributed to differences in co-productallocation methods (for example, whether ornot waste products are used for animal feeds)and the type of energy inputs used to makebiofuels and transport crops to processingsites. Greenhouse gas emissions are far higherwhen coal, rather than natural gas, is used asthe energy source to distill ethanol, and thelowest values result when plant residues areused as an energy source (e.g. bagasse fromsugarcane). In general, the agricultural andtransformation phases account for the vastmajority of total greenhouse gas emissionsfrom biofuels (Chapter 5).

The studies summarized in the paragraphabove may underestimate the release of onegreenhouse gas nitrous oxide (N2O) frombiofuel production, and therefore are probablytoo optimistic. Nitrous oxide is not asabundant as carbon dioxide in the atmosphere,and is not as important as a driver of globalwarming. However, for an equivalent mass, it is

almost 300-fold greater in its ability to warmthe planet, and it is currently the third mostimportant gas in causing global warming, aftercarbon dioxide and methane. Most studies onbiofuels and greenhouse gas emissions haveused the Intergovernmental Panel on ClimateChange (IPCC) approach for estimatingemissions of nitrous oxide. Recent evidencesuggests that nitrous oxide emissions may wellbe 4-fold greater than this, with high


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emissions both from agricultural fields and

from downstream aquatic ecosystemsresulting from the use of synthetic nitrogenfertilizer. If so, the increased N2O fluxassociated with producing ethanol from cornis likely to more than offset any positiveadvantage from reduced carbon dioxidefluxes (compared to burning fossil fuels).Even for ethanol from sugar cane or biodieselfrom rapeseed, emissions of nitrous oxideprobably make these fuels less effective as anapproach for reducing global warming thanhas been previously believed (Chapter 1).

A major criticism of the life-cycle analysisapproaches described above is that they donot include indirect effects associated withthe scaling up of production. There aremultiple indirect effects of increased biofuelsproduction, and researchers are only startingto unfold those effects and measure theirenvironmental implications (Chapter 14).One of the greatest concerns is the effect ofindirect land-use change on emission of

greenhouse gases. The rapidly growingproduction of biofuels requires additionalcropland. In some cases, this additional landcomes from agricultural land previously usedto grow food or feed crops. In a hungryworld, these diverted crops must be made upelsewhere, thus driving land conversionperhaps in different countries and ondifferent continents to compensate for theloss of food-crop production. Additional landfor food and feed production usually comes

from the conversion of native ecosystems suchas grasslands, savannahs, and forests, or byreturning permanent fallow or abandonedcroplands to production. These landconversions can have a substantial impact onthe greenhouse-gas balances of biofuels. Ingeneral, when biofuel cropping is associatedwith the conversion of native ecosystems(particularly forests, and especially peat land),the net greenhouse-gas balance is negative,

and more greenhouse gases are emitted to theatmosphere than if fossil fuels were usedinstead. The carbon debt of this conversion intheory can eventually be re-paid through theextended use of biofuels over time, but thisrequires many decades or even hundreds ofyears to balance out the initial carbon losses.In the meanwhile, the biofuel system hasaggravated rather than helped to mitigateglobal warming, even for systems where thelife-cycle analyses indicate a positive inf luenceon net greenhouse gas emissions (Chapter 6).

Figure 2. Oil palms can be an excellent source of oilfor biodiesel when grown on previously degraded

land. On the other hand, palm plantations

established on newly cleared tropical forests result in

loss of biodiversity from one of the worlds hot spots

of diversity and huge emissions of greenhouse

gases, especially when grown on peat soils as is

prac ticed in much of Southeast Asia. (photo by J eff

McNeeley).


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As one example, LCA studies indicate a

greenhouse gas savings for palm oil, withoutconsidering emissions from land-use change,of approximately 80%. However, conversion ofrainforests with peat soils to palm plantationscan increase the net emissions of greenhousegas emissions by 20-fold relative to simplyusing fossil fuels instead (Figure 2), reducingthe greenhouse gas savings to a range of -800%to -2000% (Chapter 5). Plans for suchdevelopment in Indonesia could cause aglobally significant increase in emissions ofcarbon dioxide to the atmosphere (Chapter 1).If global warming is the primary concern,leaving natural ecosystems (particularlyforests) alone is often a better strategy thanclearing them to grow crops. Currently, theglobal emissions of greenhouse gases fromdeforestation are roughly equal to thoseemitted while burning fuels for transportation(Chapter 14).

Biofuel crops offer their greatest promise forgreenhouse gas benefits if grown on

abandoned, degraded, or marginal lands. Onthese lands, carbon losses f rom conversion tobiofuels are often small. Of course, if the landshave the potential to revert to forests,conversion to biofuels represents a lostopportunity for carbon storage. Theenvironmental consequences of inputs(irrigation water, fertilizer) required to makedegraded and marginal lands productive mustalso be considered. Using wastes andagricultural and forest residues for biofuels is

also likely to produce greenhouse gas benefits,but care must be taken to assure that enoughresiduals are left behind to protect soil healthand productivity which depend on carbonlevels.

Other Environmental Effects

Biodiversity:Increased biofuel production willhave negative impacts on biodiversity due to

habitat loss, enhanced dispersion of invasive

species, and agrochemical pollution. Theconsequences are likely to be veryheterogeneous depending on the biodiversitycharacteristics and impact history of theregion and the type of biofuel production. Inalready heavily impacted areas, a modestexpansion of biofuel production could havelarge, negative effects on biodiversity.Communities with high species densities maylose more species than species-poorcommunities as a result of a similardisturbance. The degree of intensification ofbiofuel production has a direct impact onbiodiversity, with larger losses scalingpositively with increasing intensification(Chapter 7).

Land conversions are perhaps the greatestthreat to biodiversity, particularlydeforestation and conversion of grasslands andsavannas to biofuel crops. Agro-ecologicalmodeling indicates the expansion of sugarcaneand crops for biofuels in Brazil will likely be

focused on the Cerrado region of CentralBrazil. This area represents about 9 % of thetotal area of tropical savannas in the world andis one of the worlds biodiversity hotspots(Chapter 16). Biodiversity losses also occurfrom the conversion of rain forest to palm oilplantations in Southeast Asia, another globallyimportant hotspot of biodiversity (Chapter 1).In the United States and European Union,some lands currently set aside for conservationreasons, including protection of biodiversity,

are expected to be converted and used to growcrops for increased biofuel production(Chapter 16).

Small-scale biofuel production systems inwhich biodiversity is maintained are possible.Particularly promising is the management ofnatural grasslands and forests for harvest ofbiofuel material at moderate levels, providing


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reasonable protection for biodiversity (Chapter

7).Competition for freshwater: Freshwater isincreasingly in short supply and may not meetfuture demands for food production in manyregions. Using irrigation to grow biofuel cropswill aggravate these shortages, reducing wateravailable for other uses and further impactingfreshwater (and in some cases coastal marine)ecosystems. The water requirements ofbiofuel-derived energy are 70 to 400 timeslarger than other energy sources such as fossil

fuels, wind or solar. Roughly 45 billion cubicmeters of irrigation water were used for biofuelproduction in the 2007, or some 6 times morewater than people drink globally. The greatestuse is for the production of the feedstockcrops. Several approaches exist which couldimprove water productivity of agriculture forboth biofuel and food crops. Also, alternativefeedstock crops can be used to reduce thedemand for water in biofuel production.However, the water implications of future

large-scale biofuel production remain

uncertain (Chapter 8).Local and regional air pollution: The use ofethanol and biodiesel as fuels or as fueladditives to fossil fuels can reduce theemissions of some pollutants from vehicleexhaust such as fine particles and carbonmonoxide, but tends to increase otherpollutant emissions such as nitrogen gases(Chapters 1 and 10). One of the largest sourcesof air pollution from biofuel production comesfrom the practice of burning sugarcane before

harvest. The resulting smoke, fine particles,and nitrogen gases in the atmosphere causeacid rain and contribute to a variety of humanhealth impacts (Figure 3). Burning as apractice is used to facilitate the cut ofsugarcane stalks by manual harvesting and toreduce the risk to harvesters of being bitten bysnakes, and can be avoided if mechanicalharvesting equipment is used. However,manual harvesting remains dominant, andmost sugarcane fields are burned before

Figure 3. In Brazil, air pollution is severely affected from ethanol production, particularly

from the burning of sugar cane before manual harvest. Ac id rain is occurring as a result.

(photo by Edmar Mazzi).


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harvest. Also during the cultivation phase,large amounts of polluting nitrogen gases areemitted to the atmosphere from volatilizationof fertilizers and nitrogen-containing wastes(Chapters 10 and 16).

Local and regional water pollution: Severewater pollution can result from runoff fromagricultural fields and from waste producedduring the production of biofuels. Nitrogenlosses from cornfields are a particular problem(Figure 4). Compared to most crops, corn isespecially leaky of nitrogen because of ashallow rooting system and a very short time

period of active nutrient uptake. In regionswhere soils have artificial drainage such asmuch of the corn belt of the upperMississippi River basin in the United States,the nitrogen loss associated with growing corncan be quite high. This is the single largestsource of nutrient pollution leading to thedead zone, or area of low-oxygen water in theplume of the Mississippi River in the Gulf ofMexico. The increase in corn to support

ethanol goals in the United States is predictedto increase nitrogen inputs to the MississippiRiver by 37%. This works against the nationalgoal of reducing nitrogen inputs by at least40% to mitigate the dead zone. Whenperennial crops such as switchgrass are usedinstead of annual ones such as corn, waterpollution is much less (chapter 9).

Organic waste from the sugar cane-ethanolsystem (vinasse) is another serious problem.This waste is nutrient rich, and can thus berecycled onto fields as an effective fertilizer.However, excessive fertilization with vinasse

results in polluted runoff to surface water andcontamination of groundwater. Sometimesvinasse is directly discharged into surface waterbodies. The high organic content of the vinasserapidly consumes oxygen, severely degradingwater quality. In Brazil, the government hasenacted environmental laws that if followedwill greatly reduce the potential impacts of theethanol industry on water quality (chapter 9).

Figure 4. Because of a shallow rooting system and short time period of active

nutrient uptake, corn is a crop that is particularly leaky of nutrients. In regions

where soils have artificial drainage, the nitrogen loss assoc iated with growing corn

can be quite high. This is the single largest source of nutrient pollution leading to

the dead zone, or area of low-oxygen water in the plume of the Mississippi River

in the Gulf of Mexico (Photo by Robert Howarth).


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Future Biofuel Crops and Expansion of

Lands Used for Biofuel ProductionA small number of food-crop species such ascorn, sugarcane, oil palm and rapeseed arecurrently used globally to produce biofuels.Their continued use as biofuel feedstocks inlight of increasing food demand, limited landresources, and stagnant agricultural yields isproblematic. Dedicated energy crops such asswitchgrass in temperate areas and jatropha inthe tropics have been proposed as a way toproduce energy without impacting food

security or the environment. However, suchspecial energy crops require land, water,nutrients, and other inputs, and thereforecompete with food crop for these resources.This competition contributes to conversion ofgrasslands, to deforestation, to and other land-use changes, with the associated adverseenvironmental effects (Chapter 4).

Use of marginal and degraded land (oftenabandoned farmland) has been proposed as away to decrease competition with foodproduction, although there is no evidence thatnon-food crops can be grown efficiently forenergy production on land that could not alsogrow crops for food (Chapter 4). Nonetheless,some of these lands, which became marginalthrough human influence, may provide anopportunity to produce crops for biofuelswhile also restoring the landscape (Chapters 6and 15). To use degraded lands productivelywill often require substantial investment inirrigation and fertilizer. The availability ofwater for irrigation is a particular concern, asirrigation for agriculture is already the largestsingle use of water by societies globally, andwater is increasingly in short supply for allhuman uses. The processing of biofuels canalso consume substantial quantities of water(Chapter 8).

There is substantial uncertainty over themagnitude of lands that could be farmed in a

sustainable, environmentally beneficial way for

biofuels. Because of the high demand for landfor other valuable purposes (including food,carbon storage and biodiversity), the area leftfor environmentally benign use by biofuelproduction is necessarily restrictive (Chapter16). Lands classified as marginal are oftensites of high biodiversity (Chapter 7) or landsthat serve other conservation purposes, such asprotecting water quality (Chapter 9). Landlimits have a very strong social-economiccomponent, sometimes more important thanbiophysical constraints, and in this sense localand regional contexts are critical (Chapters 11,12, and 16).

Many developing countries in the tropics haveadvantages for expansion of biofuel productionin that biomass production potential is muchhigher and production costs lower than that ofdeveloped countries in the temperate zone.Further, the prospects of increased farmincome and rural economic development inthe less developed countries is used as an

argument for government intervention topromote biofuels production (Chapter 11).Export or internal markets will influence thetype of biofuels grown as well as the potentiallocal economic benefits, and ruraldevelopment. Biofuel productionopportunities in developing countries arebeing fuelled by the apparent relativeavailability of land to grow the feedstock crops.However, a biofuel boom in these countriesraises concerns about the impacts of potential

increases in food prices and food security inthese low-income societies, as well as othereffects resulting from land-use and land-coverchange including greenhouse gas emissions,water stress, and loss of biodiversity. Theseimpacts are poorly understood, but seem todepend on the premise that biofuelsproduction can be sustained at a reasonablelevel, and with transparent and fair market


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prices to allow appropriate investment(Chapter 15).

Biofuel programs can be small-, medium- andlarge-scale with production for local use,national use, or export. These different scales

have varied impacts on rural populations andenvironments and require different types ofinstitutions and planning to assure positiveoutcomes (Chapter 15). Large-scale productionposes the greatest social risks. In thedeveloping world, the most capitalizedproducers will be able to compete on theinternational market and make money sellingbiofuel feedstock or processed biofuels, butlikely at the cost of displacing small farmers,

increasing prices for food, and decreasing food

security. Alternatively, small amounts ofbiofuel feedstock on small (and perhapscurrently marginal for agriculture) pieces ofland can provide easily processed and adequatefuels for local consumption. The choice offeedstock can be based on complementaryroles, for example using jatropha as a biofuelcrop but also as stakes for the valuable vanillacrop or as boundary markers, therebymaximizing the utility of resource inputs to thesystem. Negative social impacts are largelyabsent in such a system as long as thisproduction does not compete with foodproduction for land (Chapter 12).

Successful development will requireinvestment. In contrast to the global pattern,yields of food crops in Africa have beenstagnant, largely as a consequence of limitedinfrastructure and nutrient inputs.Investments in agriculture in Africa could, ifmanaged properly, help increase production ofbiofuels as well as food (Chapter 13). For

example, oil f rom jatropha grown on degradedlands in Mali powers generators for electricityfor cell phone microwave towers and provideslocal jobs with low environmental impact(Figure 5). This and other expanded biofuelproduction can be an important engine of ruraldevelopment. However, the distribution ofwealth is very uneven in many developingcountries, in Africa and elsewhere. Policiesshould be crafted to ensure equity in incomedistribution along the production chain, and

key environmental goals will need to becarefully managed (Chapters 15 and 16).

Future Biofuel Technologies andSystems

The current methods for making biofuels,often called first-generation biofuels, relyeither on fermentation of sugars to produceethanol or transesterfication of plant oils to

Figure 5. Oil from jatropha grown on degraded

lands in Mali powers generators for electricity for

cell phone microwave towers and provides local

obs with low environmental impact. This and other

expanded biofuels production can be animportant engine of rural development. Policies

should be crafted to ensure equity in income

distribution along the production chain. (photo by

J eff McNeeley)


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produce biodiesel. A variety of other fuels,

including other liquid fuels as well as solid andgaseous fuels, are possible, and these can beproduced through a variety of technologiesbased on both thermal and biologicalprocesses (Chapter 3). Limitations with firstgeneration biofuels are widely acknowledged,particularly for producing ethanol from corn.Looking into the future, much of the interestis with second-generation fuels, often calledadvanced biofuels. As one example, the UnitedStates has set a national goal of producing 70billion liters (1.5 EJ, assuming ethanol is thefuel) of advanced biofuels by 2020, an amountroughly equal to the global production of allbiofuels in 2007 (Chapter 1). Examples ofadvanced biofuels include ethanol made fromcellulose (cellulosic ethanol) and non-oxygenated, pure hydrocarbon fuels such asbiomass-to-liquid (or BtL) fuel. Bothcellulosic ethanol and BtL are made fromcellulose-rich feedstock such as wood orgrasses. Also, methane gas (or biogas) andhydrogen show great promise as biofuels, andcan be produced from a variety of feedstocks,including cellulose but also animal and humanwastes (Chapters 1 and 3).

As with the first generation biofuels, theenvironmental consequences of the nextgeneration depend significantly on the type offeedstock and how and where the feedstock isproduced. The net greenhouse gas emissionsfrom using either cellulosic ethanol or BtL aresubstantially less than for ethanol produced

from corn, particularly if the feedstock comesfrom wood or from perennial grasses grown onnon-agricultural lands (Chapters 1 and 5). Theuse of indigenous woody and grass species isparticularly promising, both because these arelikely to be well suited to the localenvironment and because they are less likely toadversely affect biodiversity than are non-native species, which are f requently invasive(Chapters 7 and 13). Using methane gas

produced from animal wastes as a fuel is

among the most favourable alternatives forbiofuels in terms of greenhouse gas emissions,with net reductions of up to 170% compared tofossil fuels (Chapters 1 and 5).

Also as with the first generation of biofuels,indirect land-use changes associated with arapid expansion in area used to producefeedstock for second-generation biofuels maybe problematic. These indirect effects result ina less favourable consideration of netgreenhouse gas emissions and can be

detrimental for biodiversity and water quality(Chapters 6 and 13). Hydrocarbon liquid fuels(BtL) and gases such as methane and hydrogenemerge with better environmental profilesrelative to cellulosic ethanol when indirectland-use change is considered. Since thesefuels can be produced from biomass withmuch greater efficiencies than ethanol can,less land is needed to produce an equivalentamount of energy. Greenhouse gas emissionsand other environmental consequences

associated with land conversions and intensiveagriculture are reduced accordingly, as is thepotential competition with food production.One further inherent problem with ethanol isthe large amount of energy needed to distilethanol from water after fermentation, withthe consequent release of greenhouse gases(Chapter 1).

Another approach for biofuels is to burn solidbiofuels or gases in stationary facilities to

produce heat or to co-generate heat andelectricity, rather than producing liquid fuelssuch as ethanol. This may be the most effectivestrategy for biofuels if the goal is to reduceconsumption of crude oil. Globally, only 60%of liquid fossil fuels are used in thetransportation sector, and the remainder isburned in stationary uses. Substitution ineither sector can reduce overall crude-oilconsumption. However, due to differences in


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conversion efficiencies, the reduction is far

greater if biofuels are used in stationeryfacilities. The conversion of biomass to liquidbiofuels is 2.3 to 3-fold less efficient than thatfor converting crude oil to liquid fuels, whilecrude oil and solid biofuels are converted toheat and electricity in stationery plants withalmost equal efficiencies (Chapter 1). Theamount of biofuel that can be producedglobally in an environmentally responsible wayis limited, and land needs provide one of themajor constraints. Per area of land required toproduce biofuels, using switchgrass for directstationary combustion can provide 2.6-foldmore energy than can producing ethanol fromswitchgrass and 9-fold more energy than canproducing ethanol from corn (Chapter 1), thusreducing the area of land required to meet anequivalent target for energy production. If thegoal of using biofuels is to reduce globalwarming, stationary use makes even moresense, as long as it can displace burning ofcoal. Coal releases more greenhouse gases perunit of useful energy than crude oil. Thereduction in greenhouse gas emissions is morethan 10-fold greater when using switchgrassfor heating - replacing coal - than whenproducing ethanol from corn - replacinggasoline (Chapter 1).

The direct combustion of biomass can also beused to generate electricity for electricpropulsion, substituting liquid fuels fortransportation, though recent researchindicates that the energy conversion efficiency

and environmental impact of electric vehiclesvaries greatly with different energy sourcesand further technological developments areneeded (Chapter 3).

Key Findings and Recommendations

Many of the adverse effects of biofuels onthe environment could be reduced by usingbest agricultural management practices, if

production is kept below sustainable

production limits, although choice offeedstocks and the overall demand forbiofuel and level of production remaincritical.

In general, biofuels made from organicwaste are environmentally more benignthan those from energy crops. Usingbiomass primarily for material purposes,reusing and recycling it, and thenrecovering its energy content can gainmultiple dividends.

Low-input cultivation of perennial plants,e.g. from short-rotation forestry andgrasslands, may be an effective source ofcellulosic biomass and provideenvironmental benefits (reduced pollutionand lower greenhouse gas emissions).Careful attention to maintaining the long-term productivity of these systems throughnutrient additions (particularly potassium)is required.

New liquid hydrocarbon fuels (BtL)produced from cellulosic biomass are underdevelopment, and seem likely to offerseveral advantages over producing ethanolfrom cellulose in terms of more efficientyields and less environmental impact. Theeconomic viability of this technology stillneeds to be proven, and potential conf lictswith traditional wood-based industriesshould be considered.

Opportunities for biofuel production thatmaximize social benefits while minimizingenvironmental impacts exist, but the extentof these win-win situations is limited, andtheir contribution to societys energybudget will be very small. As total biofuelproduction grows, the environmental costsincreasingly overshadow societal benefits.


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Increasing evidence suggests that biomass

can be used much more efficiently (andtherefore with less environmental impact)through direct combustion to generateelectricity and heat, rather than beingconverted to liquid fuels such as ethanol.

Current mandates and targets for liquidbiofuels should be reconsidered in light ofthe potential adverse environmentalconsequences, potential displacement orcompetition with food crops, and difficultyof meeting these goals without large-scale

land conversion.

The first steps towards sustainable energyand resource management should aim forsignificant reductions on the demand side,with greater conservation and improvedefficiency. Government mandates andeconomic incentives aimed at expandingbiofuel production should be coupled withpolicies that manage the overall demandfor energy.

On the production side, options exist forimproving technologies in terms of newfeedstocks and conversion technologies aswell as more efficient use of biomass.Policies to enhance performance of biofuelproduction comprise:

4 guidelines for sustainable biofuelproduction and tools to monitor theirimplementation;

4 product-oriented certification ofbiofuels.

The utility of guidelines for sustainablebiofuel production and certificationprograms may be reduced if they are basedonly on product life-cycle and farmingstandards, as these cannot address thedifficult issue of indirect land use resultingfrom growing demand. The risk of land

displacement and conversion far from the

site of biofuel production increases withthe overall consumption of biomass-basedproducts. Criteria that account for theeffects of land-use change, or that restrictthe types of biofuel feedstocks, could havegreater utility. The development of suchcriteria is a difficult challenge, but anecessary one if biofuels are to beenvironmentally sustainable.

Policy instruments are needed to helpadjust the overall demand for (non-food)

biomass at levels which can be supplied bysustainable production such as:

4 effective incentives to significantlyincrease efficient use of biomass andmineral resources;

4 incentives to reduce fuel consumptionfor transportation.

Comprehensive land-use guidelines areneeded that target biofuel production on

marginal and degraded lands and preserveareas for agriculture, forestry, settlements/infrastructure, and nature conservation onthe regional, national, and internationallevels to avoid unintended consequences.This requires a spatial inventory of landresources and their potential competinguses at scales appropriate to cropproduction and nature conservation.

National programs for sustainable resource

management will also have to consider theglobal land use associated with thedomestic consumption of biomass products(agriculture, forestry) in order to limit theshift of environmental pressure to otherregions.

Biofuels based on low input cultivation ofnon-food crops offers promise indeveloping countries as a source of energy,


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in part because energy use is often very low

at present. Biofuel markets can serve as anopportunity to trigger additionalinvestments that could lead to increasedproduction of food as well as biofuel cropsby small-scale farmers. Further research onthe use of indigenous non-food cropsshould be encouraged.

The distribution of wealth is very uneven in

many countries, and a high potential existsfor the benefits of biofuels to accrue largelyto those with wealth. Policies should beestablished to assure that rural poorpopulations would benefit from biofueldevelopments.

Acknowledgements

The International SCOPE Biofuels Project gratefully acknowledges support from the United NationsFoundation, Deutsche Forschungsgemeinschaft, the Packard Foundation, UNEP, the Cornell Center for aSustainable Future, the Biogeochemistry & Biocomplexity Initiative at Cornell University, an endowmentprovided to Cornell University by David R. Atkinson, and the Wuppertal Institute for Climate,

Environment, and Energy.

Suggested citation:

Howarth, R.W., S. Bringezu, M. Bekunda, C. de Fraiture, L. Maene, L. Martinelli, O. Sala. 2009. Rapidassessment on biofuels and environment: overview and key findings. Pages 1-13 in R.W. Howarth and S.Bringezu (eds), Biofuels: Environmental Consequences and Interactions with Changing Land Use.Proceedings of the Scientific Committee on Problems of the Environment (SCOPE) International BiofuelsProject Rapid Assessment, 22-25 September 2008, Gummersbach Germany. Cornell University, Ithaca NY,USA. (http://cip.cornell.edu/biofuels/)

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