Biofuel

A bus fueled by biodiesel

Information on pump regarding ethanol fuel blend up to 10%,California

A biofuel is a fuel that contains energy from geologicallyrecent carbon fixation, such as plants. These fuels are pro-duced from living organisms. Examples of this carbonfixation occur in plants and microalgae. These fuels aremade by a biomass conversion (biomass refers to recentlyliving organisms, most often referring to plants or plant-derivedmaterials). This biomass can be converted to con-venient energy containing substances in three differentways: thermal conversion, chemical conversion, and bio-chemical conversion. This biomass conversion can resultin fuel in solid, liquid, or gas form. This new biomass canbe used for biofuels. Biofuels have increased in popular-ity because of rising oil prices and the need for energysecurity.Bioethanol is an alcohol made by fermentation, mostlyfrom carbohydrates produced in sugar or starch cropssuch as corn, sugarcane, or sweet sorghum. Cellulosicbiomass, derived from non-food sources, such as treesand grasses, is also being developed as a feedstock for

ethanol production. Ethanol can be used as a fuel for ve-hicles in its pure form, but it is usually used as a gasolineadditive to increase octane and improve vehicle emis-sions. Bioethanol is widely used in the USA and in Brazil.Current plant design does not provide for converting thelignin portion of plant raw materials to fuel componentsby fermentation.Biodiesel can be used as a fuel for vehicles in itspure form, but it is usually used as a diesel additiveto reduce levels of particulates, carbon monoxide, andhydrocarbons from diesel-powered vehicles. Biodiesel isproduced from oils or fats using transesterification and isthe most common biofuel in Europe.In 2010, worldwide biofuel production reached 105 bil-lion liters (28 billion gallons US), up 17% from 2009,[1]and biofuels provided 2.7% of the world’s fuels for roadtransport, a contribution largely made up of ethanol andbiodiesel. Global ethanol fuel production reached 86 bil-lion liters (23 billion gallons US) in 2010, with the UnitedStates and Brazil as the world’s top producers, account-ing together for 90% of global production. The world’slargest biodiesel producer is the European Union, ac-counting for 53% of all biodiesel production in 2010.[1]As of 2011, mandates for blending biofuels exist in31 countries at the national level and in 29 states orprovinces.[2] The International Energy Agency has a goalfor biofuels to meet more than a quarter of world demandfor transportation fuels by 2050 to reduce dependence onpetroleum and coal.[3] The production of biofuels also ledinto a flourishing automotive industry, where by 2010,79% of all cars produced in Brazil were made with a hy-brid fuel system of bioethanol and gasoline.[4]

There are various social, economic, environmental andtechnical issues relating to biofuels production and use,which have been debated in the popular media and scien-tific journals. These include: the effect of moderating oilprices, the "food vs fuel" debate, poverty reduction poten-tial, carbon emissions levels, sustainable biofuel produc-tion, deforestation and soil erosion, loss of biodiversity,impact on water resources, rural social exclusion and in-justice, shantytown migration, rural unskilled unemploy-ment, and nitrous oxide (NO2) emissions.

1 Liquid fuels for transportation

Most transportation fuels are liquids, because vehiclesusually require high energy density. This occurs naturally

1

2 1 LIQUID FUELS FOR TRANSPORTATION

in liquids and solids. High energy density can also be pro-vided by an internal combustion engine. These enginesrequire clean-burning fuels. The fuels that are easiest toburn cleanly are typically liquids and gases. Thus, liq-uids meet the requirements of being both energy-denseand clean-burning. In addition, liquids (and gases) canbe pumped, which means handling is easily mechanized,and thus less laborious.

1.1 First-generation biofuels

'First-generation' or conventional biofuels are made fromsugar, starch, or vegetable oil.

1.1.1 Ethanol

Main article: Ethanol fuelBiologically produced alcohols, most commonly ethanol,

Neat ethanol on the left (A), gasoline on the right (G) at a fillingstation in Brazil

and less commonly propanol and butanol, are producedby the action of microorganisms and enzymes through thefermentation of sugars or starches (easiest), or cellulose(which is more difficult). Biobutanol (also called bioga-soline) is often claimed to provide a direct replacementfor gasoline, because it can be used directly in a gasolineengines.Ethanol fuel is the most common biofuel worldwide, par-ticularly in Brazil. Alcohol fuels are produced by fermen-tation of sugars derived from wheat, corn, sugar beets,sugar cane, molasses and any sugar or starch from whichalcoholic beverages such as whiskey, can be made (suchas potato and fruit waste, etc.). The ethanol produc-tion methods used are enzyme digestion (to release sug-ars from stored starches), fermentation of the sugars,distillation and drying. The distillation process requiressignificant energy input for heat (sometimes unsustain-able natural gas fossil fuel, but cellulosic biomass such asbagasse, the waste left after sugar cane is pressed to ex-tract its juice, is the most common fuel in Brazil, whilepellets, wood chips and also waste heat are more commonin EuropeWaste steam fuels ethanol factory- where waste

heat from the factories also is used in the district heatinggrid.Ethanol can be used in petrol engines as a replacement forgasoline; it can be mixed with gasoline to any percentage.Most existing car petrol engines can run on blends of upto 15% bioethanol with petroleum/gasoline. Ethanol hasa smaller energy density than that of gasoline; this meansit takes more fuel (volume and mass) to produce the sameamount of work. An advantage of ethanol (CH3CH2OH) is that it has a higher octane rating than ethanol-freegasoline available at roadside gas stations, which allows anincrease of an engine’s compression ratio for increasedthermal efficiency. In high-altitude (thin air) locations,some states mandate a mix of gasoline and ethanol asa winter oxidizer to reduce atmospheric pollution emis-sions.Ethanol is also used to fuel bioethanol fireplaces. As theydo not require a chimney and are “flueless”, bioethanolfires[5] are extremely useful for newly built homes andapartments without a flue. The downsides to these fire-places is that their heat output is slightly less than electricheat or gas fires, and precautions must be taken to avoidcarbon monoxide poisoning.In the current corn-to-ethanol production model in theUnited States, considering the total energy consumedby farm equipment, cultivation, planting, fertilizers,pesticides, herbicides, and fungicides made frompetroleum, irrigation systems, harvesting, transport offeedstock to processing plants, fermentation, distillation,drying, transport to fuel terminals and retail pumps, thenet energy content value added and delivered to con-sumers is about 1.3 - 2 times higher than the total energyinput. The net climate benefit (all things considered) wasin the early 2000s between 15 and 30% net savings,[6]but have since improved and is now approaching theEuropean wheat and corn-based ethanol with typicalvalues of 65-67 % reduction of climate gasses. The bestEuropean production lines are however reducing climateemissions with 90-95 %.[7]

Corn-to-ethanol and other food stocks has led to the de-velopment of cellulosic ethanol. According to a jointresearch agenda conducted through the US Departmentof Energy,[8] the fossil energy ratios (FER) for cellulosicethanol, corn ethanol, and gasoline are 10.3, 1.36, and0.81, respectively.[9][10][11]

Ethanol has roughly one-third lower energy content perunit of volume compared to gasoline. This is partly coun-teracted by the better efficiency when using ethanol (in along-term test of more than 2.1 million km, the BESTproject found FFV vehicles to be 1-26 % more energyefficient than petrol cars The BEST project), but the vol-umetric consumption increases by approximately 30%, somore fuel stops are required.With current subsidies, ethanol fuel is slightly cheaper perdistance traveled in the United States.[12]

1.1 First-generation biofuels 3

1.1.2 Biodiesel

Main articles: Biodiesel and Biodiesel around the worldBiodiesel is the most common biofuel in Europe. It

In some countries, biodiesel is less expensive than conventionaldiesel.

is produced from oils or fats using transesterificationand is a liquid similar in composition to fossil/mineraldiesel. Chemically, it consists mostly of fatty acid methyl(or ethyl) esters (FAMEs). Feedstocks for biodiesel in-clude animal fats, vegetable oils, soy, rapeseed, jatropha,mahua, mustard, flax, sunflower, palm oil, hemp, fieldpennycress, Pongamia pinnata and algae. Pure biodiesel(B100) currently reduces emissions with up to 60% com-pared to diesel Second generation B100.Biodiesel can be used in any diesel engine when mixedwith mineral diesel. In some countries, manufactur-ers cover their diesel engines under warranty for B100use, although Volkswagen of Germany, for example, asksdrivers to check by telephone with the VW environmentalservices department before switching to B100. B100maybecome more viscous at lower temperatures, dependingon the feedstock used. In most cases, biodiesel is com-patible with diesel engines from 1994 onwards, which use'Viton' (by DuPont) synthetic rubber in their mechanicalfuel injection systems. Note however, that no vehicles arecertified for using neat biodiesel before 2014, as there wasno emission control protocol available for biodiesel before

this date.Electronically controlled 'common rail' and 'unit injector'type systems from the late 1990s onwards may only usebiodiesel blended with conventional diesel fuel. Theseengines have finely metered and atomized multiple-stageinjection systems that are very sensitive to the viscosityof the fuel. Many current-generation diesel engines aremade so that they can run on B100 without altering theengine itself, although this depends on the fuel rail de-sign. Since biodiesel is an effective solvent and cleansresidues deposited by mineral diesel, engine filters mayneed to be replaced more often, as the biofuel dissolvesold deposits in the fuel tank and pipes. It also effec-tively cleans the engine combustion chamber of carbondeposits, helping to maintain efficiency. In many Euro-pean countries, a 5% biodiesel blend is widely used andis available at thousands of gas stations.[13][14] Biodieselis also an oxygenated fuel, meaning it contains a reducedamount of carbon and higher hydrogen and oxygen con-tent than fossil diesel. This improves the combustionof biodiesel and reduces the particulate emissions fromunburnt carbon. However, using neat biodiesel may in-crease NOx-emissions Nylund.N-O&Koponen.K. 2013.Fuel and Technology Alternatives for Buses. Overall En-ergy Efficiency and Emission Performance. IEA Bioen-ergy Task 46. Possibly the new emission standards EuroVI/EPA 10 will lead to reduced NOx-levels also when us-ing B100.Biodiesel is also safe to handle and transport because itis non-toxic and biodegradable, and has a high flash pointof about 300 °F (148 °C) compared to petroleum dieselfuel, which has a flash point of 125 °F (52 °C).[15]

In the USA, more than 80% of commercial trucks andcity buses run on diesel. The emerging US biodiesel mar-ket is estimated to have grown 200% from 2004 to 2005.“By the end of 2006 biodiesel production was estimatedto increase fourfold [from 2004] to more than” 1 billionUS gallons (3,800,000 m3).[16]

1.1.3 Other bioalcohols

Methanol is currently produced from natural gas, a non-renewable fossil fuel. In the future it is hoped to be pro-duced from biomass as biomethanol. This is technicallyfeasible, but the economic viability is still pending[17] Themethanol economy is an alternative to the hydrogen econ-omy, compared to today’s hydrogen production from nat-ural gas.Butanol (C4H9OH) is formed by ABE fermentation (acetone, butanol,ethanol) and experimental modifications of the processshow potentially high net energy gains with butanol asthe only liquid product. Butanol will produce more en-ergy and allegedly can be burned “straight” in existinggasoline engines (without modification to the engine or

4 1 LIQUID FUELS FOR TRANSPORTATION

car),[18] and is less corrosive and less water-soluble thanethanol, and could be distributed via existing infrastruc-tures. DuPont and BP are working together to help de-velop butanol. E. coli strains have also been successfullyengineered to produce butanol by modifying their aminoacid metabolism.[19]

1.1.4 Green diesel

Main article: Vegetable oil refining

Green diesel is produced through hydrocracking biolog-ical oil feedstocks, such as vegetable oils and animalfats.[20][21] Hydrocracking is a refinery method that useselevated temperatures and pressure in the presence of acatalyst to break down larger molecules, such as thosefound in vegetable oils, into shorter hydrocarbon chainsused in diesel engines.[22] It may also be called renewablediesel, hydrotreated vegetable oil[22] or hydrogen-derivedrenewable diesel.[21] Green diesel has the same chemi-cal properties as petroleum-based diesel.[22] It does notrequire new engines, pipelines or infrastructure to dis-tribute and use, but has not been produced at a cost thatis competitive with petroleum.[21] Gasoline versions arealso being developed.[23] Green diesel is being developedin Louisiana and Singapore by ConocoPhillips, Neste Oil,Valero, Dynamic Fuels, and Honeywell UOP.[21][24] andalso by Preem in Gothenburg, Sweden Evolution Diesel

1.1.5 Biofuel gasoline

In 2013 UK researchers developed a genetically modi-fied strain of Escherichia coli (E.Coli), which could trans-form glucose into biofuel gasoline that does not need tobe blended.[25] Later in 2013 UCLA researchers engi-neered a new metabolic pathway to bypass glycolysis andincrease the rate of conversion of sugars into biofuel,[26]while KAIST researchers developed a strain capable ofproducing short-chain alkanes, free fatty acids, fatty es-ters and fatty alcohols through the fatty acyl (acyl carrierprotein (ACP)) to fatty acid to fatty acyl-CoA pathway invivo.[27] It is believed that in the future it will be possi-ble to “tweak” the genes to make gasoline from straw oranimal manure.

1.1.6 Vegetable oil

Main article: Vegetable oil used as fuel

Straight unmodified edible vegetable oil is generally notused as fuel, but lower-quality oil can and has been usedfor this purpose. Used vegetable oil is increasingly be-ing processed into biodiesel, or (more rarely) cleaned ofwater and particulates and used as a fuel.As with 100% biodiesel (B100), to ensure the fuel injec-

Filtered waste vegetable oil

tors atomize the vegetable oil in the correct pattern forefficient combustion, vegetable oil fuel must be heatedto reduce its viscosity to that of diesel, either by elec-tric coils or heat exchangers. This is easier in warm ortemperate climates. Big corporations like MAN B&WDiesel, Wärtsilä, and Deutz AG, as well as a number ofsmaller companies, such as Elsbett, offer engines that arecompatible with straight vegetable oil, without the needfor after-market modifications.Vegetable oil can also be used in many older diesel en-

1.1 First-generation biofuels 5

Walmart’s truck fleet logs millions of miles each year, and thecompany planned to double the fleet’s efficiency between 2005and 2015.[28] This truck is one of 15 based atWalmart’s Buckeye,Arizona distribution center that was converted to run on a bio-fuel made from reclaimed cooking grease produced during foodpreparation at Walmart stores.[29]

gines that do not use common rail or unit injection elec-tronic diesel injection systems. Due to the design of thecombustion chambers in indirect injection engines, theseare the best engines for use with vegetable oil. This sys-tem allows the relatively larger oil molecules more timeto burn. Some older engines, especially Mercedes, aredriven experimentally by enthusiasts without any conver-sion, a handful of drivers have experienced limited suc-cess with earlier pre-"PumpeDuse” VWTDI engines andother similar engines with direct injection. Several com-panies, such as Elsbett or Wolf, have developed profes-sional conversion kits and successfully installed hundredsof them over the last decades.Oils and fats can be hydrogenated to give a diesel sub-stitute. The resulting product is a straight-chain hydro-carbon with a high cetane number, low in aromatics andsulfur and does not contain oxygen. Hydrogenated oilscan be blended with diesel in all proportions. They haveseveral advantages over biodiesel, including good perfor-mance at low temperatures, no storage stability problemsand no susceptibility to microbial attack.[30]

1.1.7 Bioethers

Bioethers (also referred to as fuel ethers or oxygenatedfuels) are cost-effective compounds that act as octanerating enhancers."Bioethers are produced by the reac-tion of reactive iso-olefins, such as iso-butylene, withbioethanol.”[31] Bioethers are created by wheat or sugarbeet.[32] They also enhance engine performance, whilstsignificantly reducing engine wear and toxic exhaustemissions. Though bioethers are likely to replacepetroethers in the UK, it is highly unlikely they willbecome a fuel in and of itself due to the low energydensity.[33] Greatly reducing the amount of ground-levelozone emissions, they contribute to air quality.[34][35]

When it comes to transportation fuel there are six ether

additives- 1. Dimethyl Ether (DME) 2. Diethyl Ether(DEE) 3. Methyl Teritiary-Butyl Ether (MTBE) 4.Ethyl ter-butyl ether (ETBE) 5. Ter-amyl methyl ether(TAME) 6. Ter-amyl ethyl Ether (TAEE)[36]

The European Fuel Oxygenates Association (aka EFOA)credits Methyl Tertiary-Butyl Ether (MTBE) and Ethylter-butyl ether (ETBE) as the most commonly used ethersin fuel to replace lead. Ethers were brought into fu-els in Europe in the 1970s to replace the highly toxiccompound.[37] Although Europeans still use Bio-ether ad-ditives, the US no longer has an oxygenate requirementtherefore bio-ethers are no longer used as the main fueladditive.[38]

1.1.8 Biogas

Pipes carrying biogas

Main article: Biogas

Biogas is methane produced by the process of anaerobicdigestion of organic material by anaerobes.[39] It can beproduced either from biodegradable waste materials orby the use of energy crops fed into anaerobic digestersto supplement gas yields. The solid byproduct, digestate,can be used as a biofuel or a fertilizer.

• Biogas can be recovered frommechanical biologicaltreatment waste processing systems.

Note: Landfill gas, a less clean form of biogas,is produced in landfills through naturally occur-

6 1 LIQUID FUELS FOR TRANSPORTATION

ring anaerobic digestion. If it escapes into theatmosphere, it is a potential greenhouse gas.

• Farmers can produce biogas frommanure from theircattle by using anaerobic digesters.[40]

1.1.9 Syngas

Main article: Gasification

Syngas, a mixture of carbon monoxide, hydrogen andother hydrocarbons, is produced by partial combustionof biomass, that is, combustion with an amount of oxygenthat is not sufficient to convert the biomass completely tocarbon dioxide and water.[30] Before partial combustion,the biomass is dried, and sometimes pyrolysed. The re-sulting gas mixture, syngas, is more efficient than directcombustion of the original biofuel; more of the energycontained in the fuel is extracted.

• Syngas may be burned directly in internal com-bustion engines, turbines or high-temperature fuelcells.[41] The wood gas generator, a wood-fueledgasification reactor, can be connected to an internalcombustion engine.

• Syngas can be used to produce methanol, DME andhydrogen, or converted via the Fischer-Tropsch pro-cess to produce a diesel substitute, or a mixture ofalcohols that can be blended into gasoline. Gasifi-cation normally relies on temperatures greater than700 °C.

• Lower-temperature gasification is desirable whenco-producing biochar, but results in syngas pollutedwith tar.

1.1.10 Solid biofuels

Examples include wood, sawdust, grass trimmings,domestic refuse, charcoal, agricultural waste, nonfoodenergy crops, and dried manure.When raw biomass is already in a suitable form (such asfirewood), it can burn directly in a stove or furnace toprovide heat or raise steam. When raw biomass is in aninconvenient form (such as sawdust, wood chips, grass,urban waste wood, agricultural residues), the typical pro-cess is to densify the biomass. This process includesgrinding the raw biomass to an appropriate particulatesize (known as hogfuel), which, depending on the densi-fication type, can be from 1 to 3 cm (0.4 to 1.2 in), whichis then concentrated into a fuel product. The current pro-cesses produce wood pellets, cubes, or pucks. The pelletprocess is most common in Europe, and is typically a purewood product. The other types of densification are largerin size compared to a pellet, and are compatible with abroad range of input feedstocks. The resulting densified

fuel is easier to transport and feed into thermal generationsystems, such as boilers.Industry has used sawdust, bark and chips for fuel fordecades, primary in the pulp and paper industry, andalso bagasse (spent sugar cane) fueled boilers in the sugarcane industry. Boilers in the range of 500,000 lb/hr ofsteam, and larger, are in routine operation, using grate,spreader stoker, suspension burning and fluid bed com-bustion. Utilities generate power, typically in the rangeof 5 to 50 MW, using locally available fuel. Other in-dustries have also installed wood waste fueled boilers anddryers in areas with low cost fuel.[42]

One of the advantages of biomass fuel is that it is often abyproduct, residue or waste-product of other processes,such as farming, animal husbandry and forestry.[43] Intheory, this means fuel and food production do not com-pete for resources, although this is not always the case.[43]

A problem with the combustion of raw biomass is thatit emits considerable amounts of pollutants, such asparticulates and polycyclic aromatic hydrocarbons. Evenmodern pellet boilers generate muchmore pollutants thanoil or natural gas boilers. Pellets made from agriculturalresidues are usually worse than wood pellets, producingmuch larger emissions of dioxins and chlorophenols.[44]

In spite of the above noted study, numerous studies haveshown biomass fuels have significantly less impact on theenvironment than fossil based fuels. Of note is the USDepartment of Energy Laboratory, operated by MidwestResearch Institute Biomass Power and Conventional Fos-sil Systems with and without CO2 Sequestration – Com-paring the Energy Balance, Greenhouse Gas Emissionsand Economics Study. Power generation emits significantamounts of greenhouse gases (GHGs), mainly carbondioxide (CO2). Sequestering CO2 from the power plant flue gas can significantly reducethe GHGs from the power plant itself, but this is not thetotal picture. CO2 capture and sequestration consumes additional energy,thus lowering the plant’s fuel-to-electricity efficiency. Tocompensate for this, more fossil fuel must be procuredand consumed to make up for lost capacity.Taking this into consideration, the global warming poten-tial (GWP), which is a combination of CO2, methane (CH4), and nitrous oxide (N2O) emissions,and energy balance of the system need to be examinedusing a life cycle assessment. This takes into account theupstream processes which remain constant after CO2 sequestration, as well as the steps required for additionalpower generation. Firing biomass instead of coal led to a148% reduction in GWP.A derivative of solid biofuel is biochar, which is pro-duced by biomass pyrolysis. Biochar made from agricul-tural waste can substitute for wood charcoal. As woodstock becomes scarce, this alternative is gaining ground.In eastern Democratic Republic of Congo, for exam-

7

ple, biomass briquettes are being marketed as an alter-native to charcoal to protect Virunga National Park fromdeforestation associated with charcoal production.[45]

1.2 Second-generation (advanced) biofuels

Main article: Second-generation biofuels

Second generation biofuels, also known as advanced bio-fuels, are fuels that can be manufactured from varioustypes of biomass. Biomass is a wide-ranging term mean-ing any source of organic carbon that is renewed rapidlyas part of the carbon cycle. Biomass is derived from plantmaterials but can also include animal materials.First generation biofuels are made from the sugars andvegetable oils found in arable crops, which can be easilyextracted using conventional technology. In comparison,second generation biofuels are made from lignocellulosicbiomass or woody crops, agricultural residues or waste,which makes it harder to extract the required fuel.

1.3 Sustainable biofuels

Biofuels in the form of liquid fuels derived from plant ma-terials, are entering the market, driven mainly by the needto reduce climate gas emissions, but also by factors suchas oil price spikes and the need for increased energy se-curity. However, many of the biofuels that are currentlybeing supplied have been criticised for their adverse im-pacts on the natural environment, food security, and landuse.[46][47]

The challenge is to support biofuel development, includ-ing the development of new cellulosic technologies, withresponsible policies and economic instruments to help en-sure that biofuel commercialization is sustainable. Re-sponsible commercialization of biofuels represents an op-portunity to enhance sustainable economic prospects inAfrica, Latin America and Asia.[46][47][48]

2 Biofuels by region

Main article: Biofuels by regionSee also: Biodiesel around the world

There are international organizations such as IEABioenergy,[49] established in 1978 by the OECDInternational Energy Agency (IEA), with the aim of im-proving cooperation and information exchange betweencountries that have national programs in bioenergy re-search, development and deployment. The UN Inter-national Biofuels Forum is formed by Brazil, China,India, Pakistan, South Africa, the United States andthe European Commission.[50] The world leaders in bio-fuel development and use are Brazil, the United States,

France, Sweden and Germany. Russia also has 22% ofworld’s forest,[51] and is a big biomass (solid biofuels)supplier. In 2010, Russian pulp and paper maker, Vy-borgskaya Cellulose, said they would be producing pelletsthat can be used in heat and electricity generation from itsplant in Vyborg by the end of the year.[52] The plant willeventually produce about 900,000 tons of pellets per year,making it the largest in the world once operational.Biofuels currently make up 3.1%[53] of the total roadtransport fuel in the UK or 1,440 million litres. By 2020,10% of the energy used in UK road and rail transportmust come from renewable sources – this is the equiva-lent of replacing 4.3 million tonnes of fossil oil each year.Conventional biofuels are likely to produce between 3.7and 6.6% of the energy needed in road and rail transport,while advanced biofuels could meet up to 4.3% of theUK’s renewable transport fuel target by 2020.[54]

3 Debates regarding the produc-tion and use of biofuel

Main article: Issues relating to biofuels

There are various social, economic, environmental andtechnical issues with biofuel production and use, whichhave been discussed in the popular media and scien-tific journals. These include: the effect of moderat-ing oil prices, the "food vs fuel" debate, poverty reduc-tion potential, carbon emissions levels, sustainable bio-fuel production, deforestation and soil erosion, loss ofbiodiversity,[55] impact on water resources, the possiblemodifications necessary to run the engine on biofuel, aswell as energy balance and efficiency. The InternationalResource Panel, which provides independent scientificassessments and expert advice on a variety of resource-related themes, assessed the issues relating to biofuel usein its first report Towards sustainable production and useof resources: Assessing Biofuels.[56] “Assessing Biofuels”outlined the wider and interrelated factors that need tobe considered when deciding on the relative merits ofpursuing one biofuel over another. It concluded that notall biofuels perform equally in terms of their impact onclimate, energy security and ecosystems, and suggestedthat environmental and social impacts need to be assessedthroughout the entire life-cycle.Another issue with biofuel use and production is the UShas changed mandates many times because the produc-tion has been taking longer than expected. The Renew-able Fuel Standard (RFS) set by congress for 2010 waspushed back to at best 2012 to produce 100 million gal-lons of pure ethanol (not blended with a fossil fuel).[57]

8 4 CURRENT RESEARCH

4 Current research

Research is ongoing into finding more suitable biofuelcrops and improving the oil yields of these crops. Usingthe current yields, vast amounts of land and fresh waterwould be needed to produce enough oil to completely re-place fossil fuel usage. It would require twice the landarea of the US to be devoted to soybean production, ortwo-thirds to be devoted to rapeseed production, to meetcurrent US heating and transportation needs.Specially bred mustard varieties can produce reasonablyhigh oil yields and are very useful in crop rotation withcereals, and have the added benefit that the meal left overafter the oil has been pressed out can act as an effectiveand biodegradable pesticide.[58]

The NFESC, with Santa Barbara-based Biodiesel Indus-tries, is working to develop biofuels technologies for theUS navy and military, one of the largest diesel fuel usersin the world.[59] A group of Spanish developers workingfor a company called Ecofasa announced a new biofuelmade from trash. The fuel is created from general urbanwaste which is treated by bacteria to produce fatty acids,which can be used to make biofuels.[60]

4.1 Ethanol biofuels

Main articles: Ethanol fuel and Cellulosic ethanolcommercialization

As the primary source of biofuels in North Amer-ica, many organizations are conducting research in thearea of ethanol production. The National Corn-to-Ethanol Research Center (NCERC) is a research divi-sion of Southern Illinois University Edwardsville dedi-cated solely to ethanol-based biofuel research projects.[61]On the federal level, the USDA conducts a large amountof research regarding ethanol production in the UnitedStates. Much of this research is targeted toward the effectof ethanol production on domestic food markets.[62] A di-vision of the U.S. Department of Energy, the NationalRenewable Energy Laboratory (NREL), has also con-ducted various ethanol research projects, mainly in thearea of cellulosic ethanol.[63]

Cellulosic ethanol commercialization is the process ofbuilding an industry out of methods of turning cellulose-containing organic matter into fuel. Companies, such asIogen, POET, and Abengoa, are building refineries thatcan process biomass and turn it into bioethanol. Com-panies, such as Diversa, Novozymes, and Dyadic, areproducing enzymes that could enable a cellulosic ethanolfuture. The shift from food crop feedstocks to wasteresidues and native grasses offers significant opportuni-ties for a range of players, from farmers to biotechnologyfirms, and from project developers to investors.[64]

As of 2013, the first commercial-scale plants to pro-

duce cellulosic biofuels have begun operating. Multiplepathways for the conversion of different biofuel feed-stocks are being used. In the next few years, the costdata of these technologies operating at commercial scale,and their relative performance, will become available.Lessons learnt will lower the costs of the industrial pro-cesses involved.[65]

In parts of Asia and Africa where drylands prevail, sweetsorghum is being investigated as a potential source offood, feed and fuel combined. The crop is particularlysuitable for growing in arid conditions, as it only extractsone seventh of the water used by sugarcane. In India, andother places, sweet sorghum stalks are used to producebiofuel by squeezing the juice and then fermenting intoethanol.[66]

A study by researchers at the International Crops Re-search Institute for the Semi-Arid Tropics (ICRISAT)found that growing sweet sorghum instead of grainsorghum could increase farmers incomes by US$40 perhectare per crop because it can provide fuel in additionto food and animal feed. With grain sorghum currentlygrown on over 11 million hectares (ha) in Asia and on23.4million ha in Africa, a switch to sweet sorghum couldhave a considerable economic impact.[67]

4.2 Algae biofuels

Main articles: Algaculture and Algal fuel

From 1978 to 1996, the US NREL experimented withusing algae as a biofuels source in the "Aquatic SpeciesProgram".[68] A self-published article by Michael Briggs,at the UNH Biofuels Group, offers estimates for the re-alistic replacement of all vehicular fuel with biofuels byusing algae that have a natural oil content greater than50%, which Briggs suggests can be grown on algae pondsat wastewater treatment plants.[69] This oil-rich algae canthen be extracted from the system and processed into bio-fuels, with the dried remainder further reprocessed to cre-ate ethanol. The production of algae to harvest oil forbiofuels has not yet been undertaken on a commercialscale, but feasibility studies have been conducted to ar-rive at the above yield estimate. In addition to its pro-jected high yield, algaculture — unlike crop-based bio-fuels — does not entail a decrease in food production,since it requires neither farmland nor fresh water. Manycompanies are pursuing algae bioreactors for various pur-poses, including scaling up biofuels production to com-mercial levels.[70][71] Prof. Rodrigo E. Teixeira from theUniversity of Alabama in Huntsville demonstrated the ex-traction of biofuels lipids from wet algae using a simpleand economical reaction in ionic liquids.[72]

4.6 Greenhouse gas emissions 9

4.3 Jatropha

Main article: Jatropha curcas

Several groups in various sectors are conducting researchon Jatropha curcas, a poisonous shrub-like tree that pro-duces seeds considered by many to be a viable source ofbiofuels feedstock oil.[73] Much of this research focuseson improving the overall per acre oil yield of Jatrophathrough advancements in genetics, soil science, and hor-ticultural practices.SG Biofuels, a San Diego-based jatropha developer, hasused molecular breeding and biotechnology to produceelite hybrid seeds that show significant yield improve-ments over first-generation varieties.[74] SG Biofuels alsoclaims additional benefits have arisen from such strains,including improved flowering synchronicity, higher resis-tance to pests and diseases, and increased cold-weathertolerance.[75]

Plant Research International, a department of theWageningen University and Research Centre in theNetherlands, maintains an ongoing Jatropha Evalua-tion Project that examines the feasibility of large-scale jatropha cultivation through field and labora-tory experiments.[76] The Center for Sustainable EnergyFarming (CfSEF) is a Los Angeles-based nonprofit re-search organization dedicated to jatropha research in theareas of plant science, agronomy, and horticulture. Suc-cessful exploration of these disciplines is projected to in-crease jatropha farm production yields by 200-300% inthe next 10 years.[77]

4.4 Fungi

A group at the Russian Academy of Sciences in Moscow,in a 2008 paper, stated they had isolated large amounts oflipids from single-celled fungi and turned it into biofuelsin an economically efficient manner. More research onthis fungal species, Cunninghamella japonica, and others,is likely to appear in the near future.[78] The recent discov-ery of a variant of the fungus Gliocladium roseum pointstoward the production of so-called myco-diesel from cel-lulose. This organism was recently discovered in the rain-forests of northern Patagonia, and has the unique capabil-ity of converting cellulose into medium-length hydrocar-bons typically found in diesel fuel.[79]

4.5 Animal Gut Bacteria

Microbial gastrointestinal flora in a variety of animalshave shown potential for the production of biofuels.Recent research has shown that TU-103, a strain ofClostridium bacteria found in Zebra feces, can convertnearly any form of cellulose into butanol fuel.[80] Mi-crobes in panda waste are being investigated for their

use in creating biofuels from bamboo and other plantmaterials.[81]

4.6 Greenhouse gas emissions

Some scientists have expressed concerns about land-usechange in response to greater demand for crops to usefor biofuel and the subsequent carbon emissions.[82] Thepayback period, that is, the time it will take biofuels topay back the carbon debt they acquire due to land-usechange, has been estimated to be between 100 and 1000years, depending on the specific instance and location ofland-use change. However, no-till practices combinedwith cover-crop practices can reduce the payback periodto three years for grassland conversion and 14 years forforest conversion.[83]

A study conducted in the Tocantis State, in northernBrazil, found that many families were cutting downforests in order to produce two conglomerates of oilseedplants, the J. curcas (JC group) and the R. communis(RC group). This region is composed of 15% Ama-zonian rainforest with high biodiversity, and 80% Cer-rado forest with lower biodiversity. During the study, thefarmers that planted the JC group released over 2193 MgCO2, while losing 53-105 Mg CO2 sequestration fromdeforestation; and the RC group farmers released 562MgCO2, while losing 48-90Mg CO2 to be sequestered fromforest depletion.[84] The production of these types of bio-fuels not only led into an increased emission of carbondioxide, but also to lower efficiency of forests to absorbthe gases that these farms were emitting. This has to dowith the amount of fossil fuel the production of fuel cropsinvolves. In addition, the intensive use of monocroppingagriculture requires large amounts of water irrigation, aswell as of fertilizers, herbicides and pesticides. This doesnot only lead to poisonous chemicals to disperse on waterrunoff, but also to the emission of nitrous oxide (NO2)as a fertilizer byproduct, which is three hundred timesmore efficient in producing a greenhouse effect than car-bon dioxide (CO2).[85]

Biofuels made from waste biomass or from biomassgrown on abandoned agricultural lands incur little to nocarbon debt.[86]

5 See also• Aviation biofuel

• Sustainable aviation fuel

• BioEthanol for Sustainable Transport

• Biofuels Center of North Carolina

• Biofuelwatch

• Biogas powerplant

10 6 REFERENCES

• Bioheat, a biofuel blended with heating oil.

• Biomass briquettes

• Cellulosic ethanol

• Clean Cities

• Biomass to liquid bio-oil

• Dimethyl ether

• Energy forestry

• Ecological sanitation

• Energy content of biofuel

• Environmental impact of aviation

• Green crude

• IRENA

• Life cycle assessment

• List of biofuel companies and researchers

• List of emerging technologies

• List of vegetable oils section on oils used as biodiesel

• Low-carbon economy

• Sustainable transport

• Syngas

• Table of biofuel crop yields

• Vegetable oil economy

6 References[1] “Biofuels Make a Comeback Despite Tough Economy”.

Worldwatch Institute. 2011-08-31. Retrieved 2011-08-31.

[2] REN21 (2011). “Renewables 2011: Global Status Re-port”. pp. 13–14. Retrieved 2015-01-03.

[3] “Technology Roadmap, Biofuels for Transport”. 2011.

[4] Hall, Jeremy, Stelvia Matos, Bruno Silvestre, and MichaelMartin. “Managing Technological and Social Uncertain-ties of Innovation: The Evolution of Brazilian Energyand Agriculture” Technological Forecasting and SocialChange 78 (2011): 1147-1157. Accessed October 30,2014. doi: 10.1016/j.techfore.2011.02.005

[5] Bio ethanol fires information bio ethanol fireplace. (2009)

[6] Wang, Michael, May Wu and Hong Huo. Life-cycle en-ergy and greenhouse gas emission impacts of differentcorn ethanol plant types. Environ. Res. Lett. 2007

[7] Energimyndigheten 2013. Hållbara biodrivmedel och fly-tande biobränslen 2013

[8] see “Breaking the Biological Barriers to CellulosicEthanol”

[9] Brinkman, N. et al., “Well-to-Wheels Analysis of Ad-vanced/Vehicle Systems”, 2005.

[10] Farrell, A.E. et al. (2006) “Ethanol can Contribute to En-ergy and Environmental Goals”, Science, 311, 506-8.

[11] Hammerschlag, R. 2006. “Ethanol’s Energy Return on In-vestment: A Survey of the Literature 1999-Present”, En-viron. Sci. Technol., 40, 1744-50.

[12] http://www.e85prices.com/. Missing or empty |title=(help)

[13] “ADM Biodiesel: Hamburg, Leer, Mainz”. Biodiesel.de.Retrieved 2010-07-14.

[14] RRI Limited for Biodiesel Filling Stations. “Welcome toBiodiesel Filling Stations”. Biodieselfillingstations.co.uk.Retrieved 2010-07-14.

[15] “Biofuels Facts”. Hempcar.org. Retrieved 2010-07-14.

[16] THE FUTURIST, Will Thurmond. July–August 2007

[17] Börjesson.P. et al. 2013, REPORT f3 2013:13, p 170

[18] “ButylFuel, LLCMain Page”. Butanol.com. 2005-08-15.Retrieved 2010-07-14.

[19] Evans, Jon (14 January 2008). “Biofuels aim higher”.Biofuels, Bioproducts and Biorefining (BioFPR). Retrieved2008-12-03.

[20] Brown, Robert; Jennifer Holmgren. “Fast Pyrolysis andBio-Oil Upgrading”. Retrieved 15 March 2012.

[21] “Alternative & Advanced Fuels”. US Department of En-ergy. Retrieved 7 March 2012.

[22] Knothe, Gerhard (2010). “Biodiesel and renewable diesel:A comparison”. Progress in Energy and Combustion Sci-ence

[23] Jessica, Ebert. “Breakthroughs in Green Gasoline Pro-duction”. Biomass Magazine. Retrieved 14 August 2012.

[24] Albrecht, KO; Hallen, RT (March 2011). “A Brief Liter-ature Overview of Various Routes to Biorenewable Fuelsfrom Lipids for the National Alliance of Advanced Bio-fuels and Bio-products NAAB Consortium”. Prepared bythe US Department of Energy

[25] Summers, Rebecca (24 April 2013) Bacteria churn outfirst ever petrol-like biofuel New Scientist, Retrieved 27April 2013

[26] Bogorad, I. W.; Lin, T. S.; Liao, J. C. (2013). “Syntheticnon-oxidative glycolysis enables complete carbon conser-vation”. Nature. doi:10.1038/nature12575.

[27] Choi, Y. J.; Lee, S. Y. (2013). “Microbial production ofshort-chain alkanes”. Nature. doi:10.1038/nature12536.

[28] Nishimoto, Alex (March 10, 2014). “Walmart DebutsTurbine-Powered WAVE Semi Truck Prototype”. MotorTrend.

11

[29] “Wal-Mart To Test Hybrid Trucks”. Sustainable Business.February 3, 2009.

[30] Evans, G. “Liquid Transport Biofuels - Technology StatusReport”, National Non-Food Crops Centre, 2008-04-14.Retrieved on 2009-05-11.

[31] Rock, Kerry; Maurice Korpelshoek (2007).[<http://www.digitalrefining.com/article_1000210“Bioethers Impact on the Gasoline Pool"]. DigitalRefining. Retrieved 15 February 2014.

[32] beet.http://biofuel.org.uk/bioethers.html

[33] http://biofuel.org.uk/bioethers.html

[34] “Council Directive 85/536/EEC of 5 December 1985 oncrude-oil savings through the use of substitute fuel com-ponents in petrol”. Eur-lex.europa.eu. Retrieved 2010-07-14.

[35] “Microsoft Word - IA 55 EN.doc” (PDF). Retrieved2010-07-14.

[36] Sukla, Mirtunjay Kumar; Thallada Bhaskar,A.K. Jain, S.K. Singal, and M.O. Garg. [<http://www.ascension-publishing./BIZ/DMEoverview.pdf>“Bio-Ethers as Transportation Fuel: A Review"]. IndianInstitute of Petroleum Dehradun. Retrieved 15 February2014.

[37] [<http://www.petrochemistry.eu/ftp/pressroom/EFOA_2008_def.pdf> “What are Bio-Ethers?"]. . The EuropeanFuel Oxygenates Association.

[38] [< http://www.epa.gov/mtbe/gas.htm> “Gasoline"]. En-vironmental Protection Agency.

[39] Redman, G., The Andersons Centre. “Assessment of on-farm AD in the UK”, National Non-Food Crops Centre,2008-06-09. Retrieved on 2009-05-11.

[40] “BIOGAS: No bull, manure can power your farm.” Farm-ers Guardian (25 September 2009): 12. General OneFile.Gale.

[41] Electricity from wood through the combination of gasi-fication and solid oxide fuel cells, Ph.D. Thesis by Flo-rian Nagel, Swiss Federal Institute of Technology Zurich,2008

[42] Biomass and Alternate Energy Fuel Systems: An Engi-neering and Economic Guide

[43] Frauke Urban and Tom Mitchell 2011. Climate change,disasters and electricity generation. London: OverseasDevelopment Institute and Institute of Development Stud-ies

[44] Cedric Briens, Jan Piskorz and Franco Berruti, “BiomassValorization for Fuel and Chemicals Production -- A Re-view,” 2008. International Journal of Chemical ReactorEngineering, 6, R2

[45] “Threat to Great Apes Highlighted at Virunga Meeting”.America.gov. Retrieved 2010-07-14.

[46] The Royal Society (January 2008). Sustainable biofuels:prospects and challenges, ISBN 978-0-85403-662-2, p.61.

[47] Gordon Quaiattini. Biofuels are part of the solutionCanada.com, April 25, 2008. Retrieved December 23,2009.

[48] EPFL Energy Center (c2007). Roundtable on SustainableBiofuels Retrieved December 23, 2009.

[49] “IEA bioenergy”. IEA bioenergy. Retrieved 2010-07-14.

[50] “Press Conference Launching International Biofuels Fo-rum”. United Nations Department of Public Information.2007-03-02. Retrieved 2008-01-15.

[51] Greenpeace - The Russian Forests

[52] “World’s Largest Pellet Plant to Start by Year-End”.Moscow Times

[53] UK falls short of biofuel targets for 2010/2011

[54] National Non-Food Crops Centre. “Advanced Biofuels:The Potential for a UK Industry, NNFCC 11-011”, Re-trieved on 2011-11-17

[55] Fletcher Jr., Robert J.; Bruce A Robertson; JasonEvans; Patrick J Doran; Janaki RR Alavalapati; Dou-glas W Schemske (2011). “Biodiversity conservationin the era of biofuels: risks and opportunities”. Fron-tiers in Ecology and the Environment 9 (3): 161–168.doi:10.1890/090091. Retrieved 10 December 2013.

[56] Towards sustainable production and use of resources:Assessing Biofuels, 2009, International Resource Panel,United Nations Environment Programme

[57] Bracmort, Kelsi. “Meeting the Renewable Fuel Standard(RFS)Mandate for Cellulosic Biofuels:Questions andAn-swers”. Washington, DC: Congressional Research Ser-vice.

[58] “Mustard Hybrids for Low-Cost Biofuels and OrganicPesticides” (PDF). Retrieved 2010-03-15.

[59] Future Energies (2003-10-30). “PORT HUENEME,Calif: U.S. Navy to Produce its Own Biofuels :: FutureEnergies :: The future of energy”. Future Energies. Re-trieved 2009-10-17.

[60] “Newsvine - Ecofasa turns waste to biofuels using bacte-ria”. Lele.newsvine.com. 2008-10-18. Retrieved 2009-10-17.

[61] Ethanol Research (2012-04-02). “National Corn-to-Ethanol Research Center (NCERC)". Ethanol Research.Retrieved 2012-04-02.

[62] American Coalition for Ethanol (2008-06-02).“Responses to Questions from Senator Bingaman”.American Coalition for Ethanol. Retrieved 2012-04-02.

[63] National Renewable Energy Laboratory (2007-03-02).“Research Advantages: Cellulosic Ethanol”. National Re-newable Energy Laboratory. Retrieved 2012-04-02.

12 7 FURTHER READING

[64] Pernick, Ron and Wilder, Clint (2007). The Clean TechRevolution p. 96.

[65] HLPE (2013). “Biofuels and food security”.

[66] “Sweet Sorghum : A New “Smart Biofuel Crop"". Agri-culture Business Week. 30 June 2008.

[67] Sweet sorghum for food, feed and fuel New Agricultural-ist, January 2008.

[68] Sheehan, John; et al. (July 1998). “A Look Back at theU. S. Department of Energy’s Aquatic Species Program:Biofuels from Algae”. National Renewable Energy Labo-ratory. Retrieved 16 June 2012.

[69] Briggs, Michael (August 2004). “Widescale BiodieselProduction from Algae”. UNH Biodiesel Group (Univer-sity of New Hampshire). Archived from the original on24 March 2006. Retrieved 2007-01-02.

[70] “Valcent Products Inc. Develops “Clean Green” VerticalBio-Reactor”. Valcent Products. Retrieved 2008-07-09.

[71] “Technology: High Yield Carbon Recycling”. GreenFuelTechnologies Corporation. Retrieved 2008-07-09.

[72] R. E. Teixeira (2012). “Energy-efficient extraction of fueland chemical feedstocks from algae”. Green Chemistry 14(2): 419–427. doi:10.1039/C2GC16225C.

[73] B.N. Divakara, H.D. Upadhyaya, S.P. Wani, C.L. Laxmi-pathi Gowda (2010). “Biology and genetic improvementof Jatropha curcas L.: A review”. Applied Energy 87 (3):732–742. doi:10.1016/j.apenergy.2009.07.013.

[74] Biofuels Digest (2011-05-16). “Jatropha blooms again:SG Biofuels secures 250K acres for hybrids”. BiofuelsDigest. Retrieved 2012-03-08.

[75] SG Biofuels (2012-03-08). “Jmax Hybrid Seeds”. SGBiofuels. Retrieved 2012-03-08.

[76] Plant Research International (2012-03-08). “JATROPT(Jatropha curcas): Applied and technical research intoplant properties”. Plant Research International. Retrieved2012-03-08.

[77] Biofuels Magazine (2011-04-11). “Energy FarmingMethods Mature, Improve”. Biofuels Magazine. Re-trieved 2012-03-08.

[78] Sergeeva, Y. E.; Galanina, L. A.; Andrianova, D.A.; Feofilova, E. P. (2008). “Lipids of filamen-tous fungi as a material for producing biodiesel fuel”.Applied Biochemistry and Microbiology 44 (5): 523.doi:10.1134/S0003683808050128.

[79] Strobel, G.; Knighton, B.; Kluck, K.; Ren, Y.; Living-house, T.; Griffin, M.; Spakowicz, D.; Sears, J. (2008).“The production of myco-diesel hydrocarbons and theirderivatives by the endophytic fungus Gliocladium roseum(NRRL 50072)". Microbiology (Reading, England) 154(Pt 11): 3319–3328. doi:10.1099/mic.0.2008/022186-0.PMID 18957585.

[80] Kathryn Hobgood Ray (August 25, 2011). “Cars CouldRun on Recycled Newspaper, Tulane Scientists Say”. Tu-lane University news webpage. Tulane University. Re-trieved March 14, 2012.

[81] USA (2013-09-10). “Panda PoopMight Help Turn PlantsInto Fuel”. News.nationalgeographic.com. Retrieved2013-10-02.

[82] Searchinger, Timothy; Ralph Heimlich, R.A. Houghton,Fengxia Dong, Amani Elobeid, Jacinto Fabiosa, SimlaTokgoz, Dermot Hayes, Tun-Hsiang Yu (2011). “Use ofU.S. Croplands for Biofuels Increases Greenhouse GasesThrough Emissions from Land-Use Change”. Science 319(5867). pp. 1238–1240. doi:10.1126/science.1151861.Retrieved 8 November 2011.

[83] Kim, Hyungtae; Seungdo Kim; Bruce E. Dale (2009).“Biofuels, Land Use Change, and Greenhouse Gas Emis-sions: Some Unexplored Variables”. Environmental Sci-ence 43 (3). pp. 961–967. doi:10.1021/es802681k.

[84] Alves Finco, Marcus V., and Werner Doppler. “Bioen-ergy and Sustainable Development: The Dilemma ofFood Security and Climate Change in the BrazilianSavannah.” Energy for Sustainable Development 12(2010): 194-199. Accessed October 30, 2014. doi:10.1016/j.esd.2010.04.006

[85] Runge, Ford, and Benjamin Senauer. “How BiofuelsCould Starve the Poor” Foreign Affairs 86 (2007): 41-53. Accessed October 30, 2014. from: http://www.jstor.org/stable/20032348

[86] fargione, Joseph; Jason Hill; David Tilman; Stephen Po-lasky; Peter Hawthorne (2008). “Land Clearing andthe Biofuel Carbon Debt”. Science 319 (5867). pp.1235–1238. doi:10.1126/science.1152747. Retrieved 12November 2011.

7 Further reading

• Caye Drapcho, Nhuan Phú Nghiêm, Terry Walker(August 2008). Biofuels Engineering Process Tech-nology. [McGraw-Hill]. ISBN 978-0-07-148749-8.

• IChemE Energy Conversion Technology SubjectGroup (May 2009). A Biofuels Compendium.[IChemE]. ISBN 978-0-85295-533-8.

• Fuel Quality Directive Impact Assessment

• Biofuels Journal

• James Smith (November 2010). Biofuels and theGlobalisation of Risk. [Zed Books]. ISBN 978-1-84813-572-7.

• Mitchell, Donald (2010). Biofuels in Africa: Op-portunities, Prospects, and Challenges (Available inPDF). The World Bank, Washington, D.C. ISBN978-0-8213-8516-6. Retrieved 2011-02-08.

13

• Li, H.; Cann, A. F.; Liao, J. C. (2010). “Biofuels:Biomolecular Engineering Fundamentals and Ad-vances”. Annual Review of Chemical and Biomolec-ular Engineering 1: 19–36. doi:10.1146/annurev-chembioeng-073009-100938. PMID 22432571.

8 External links• EFOA

• Alternative Fueling Station Locator (EERE)

• Towards Sustainable Production and Use of Re-sources: Assessing Biofuels by the United NationsEnvironment Programme, October 2009.

• Biofuels guidance for businesses, including permitsand licences required on NetRegs.gov.uk

• How Much Water Does It Take to Make Electric-ity?—Natural gas requires the least water to produceenergy, some biofuels the most, according to a newstudy.

• International Conference on Biofuels Standards -European Union Biofuels Standardization

• International Energy Agency: Biofuels for Transport- An International Perspective

• Biofuels from Biomass: Technology and PolicyConsiderations Thorough overview from MIT

• The Guardian news on biofuels

• The U.S. DOE Clean Cities Program - links to all ofthe Clean Cities coalitions that exist throughout theU.S. (there are 87 of them)

• Biofuels Factsheet by the University of Michigan'sCenter for Sustainable Systems

• Learn Biofuels - Educational Resource for Students

14 9 TEXT AND IMAGE SOURCES, CONTRIBUTORS, AND LICENSES

9 Text and image sources, contributors, and licenses

9.1 Text• Biofuel Source: http://en.wikipedia.org/wiki/Biofuel?oldid=644104178 Contributors: Bryan Derksen, Timo Honkasalo, Youssefsan,

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Saturn, Lightbot, Acschwim, Teles, Gail, TeH nOmInAtOr, Wireless friend, Jarble, Pomie, Blablablob, Economyweb, Ben Ben,PlankBot, Astropata, Luckas-bot, TheSuave, Yobot, AzureFury, GGByte, Fraggle81, Les boys, Legobot II, PMLawrence, THEN WHO

9.2 Images 15

WAS PHONE?, Pganas, SwisterTwister, Food&fuel, Zozzie 9t9, Hontonikawaiidesu, Alexkin, Thameshead, Vesco77, AnomieBOT, Jane187, DemocraticLuntz, Four Doors, Darrell Smith1010, Jim1138, IRP, Petercascio, Darking764, Jamescp, Kingpin13, Gordino0, Flewis,Bolling1, Materialscientist, ImperatorExercitus, Gatorfuel, Citation bot, Maxis ftw, Clark89, Aarnjb, Htomfields, LilHelpa, Photonyte,Stlwebs, Em0299, Mićo, Goc sk, Sionus, Capricorn42, Tomsperoni, Gigemag76, Benny7820, NFD9001, J04n, GrouchoBot, MarieEuro,RibotBOT, SassoBot, H falcon, Shattered Gnome, Enigmatist23, Tonydomrep, Centonup, Linkman21, Cedric Briens, MLauba, Sewblon,Shadowjams, Jkander59, Azxten, Niljay, Appeltree1, FrescoBot, AlexSun123, Illustria, Lac10528, Docdik, Mikima, Sambhar, Silvert89,NadimChaudhry, Julpics, Muissus, Finalius, BenzolBot, Roycombya, Coltsfan126, Fiddler on the green, Citation bot 1, SuperJew, Swine-Flew?, Mikal42, NachshonR, Biker Biker, Ussbham, Pinethicket, Mr Who 0, Edderso, Okbicknell, ThePillock, Rushbugled13, Whentann,Mikershniker, Mistapopsicle, Brian Everlasting, Geronimo2k, Saayiit, Ambarprakashan, Elekhh, Trappist the monk, Zhernovoi, Solntsa,Vrenator, Intern8, Lanza33, Waynersampson69, Rebekah Hamrick, Infobios, Reaper Eternal, TheGrimReaper NS, Cookiemonsterhat,A4MES1, Beno795, Marissa leitman, Reach Out to the Truth, Derild4921, Keegscee, DARTH SIDIOUS 2, Civic Cat, RjwilmsiBot,Emilio lopez king, Djkhalad, Ccrazymann, Salvio giuliano, Jrsandor, EmausBot, Energy Dome, John of Reading, JeffreyLMason, Look-tothisday, Gfoley4, Willwin0001, Heracles31, Katherine, ScottyBerg, Awatten, Dewritech, Amandawutnn, NoisyJinx, K6ka, Greenzen,Oakmedia, Its snowing in East Asia, Peter reimers, Lberghmans, Darkman101, Josve05a, Buckston, Bisi77, Ihatedylan, KuduIO, EverardProudfoot, Potassium-39, Wayne Slam, Ocaasi, Michellebentham, L Kensington, Greentechguru, Orange Suede Sofa, Rangoon11, G9th,VictorianMutant, Longshevius, Rocketrod1960, Ncbiofuels, Arunesh85, Cgtdk, Farmjustice2010, ClueBot NG, Smtchahal, MIKHEIL,Coastwise, Georgina31Green, Monsoon Waves, Skubeska, Widr, Nmabraha, Helpful Pixie Bot, Electriccatfish2, Skierno1tiger, BG19bot,Mohamed CJ, Vagobot, Jon.sry, Fedor Babkin, Northamerica1000, Cyberpower678, Wiki13, Mark Arsten, SamC1404, CitationCleaner-Bot, Clarikaa, NotWith, Blonder1, Glacialfox, Fgmartinelli, Gcarrosio, TBrandley, SexyJeeves1, ArticLeaf, Klilidiplomus, Rutebega,Garkhedkar, Lovetousewiki, BattyBot, Ehr1Ros2, Riley Huntley, Minionice, StarryGrandma,Wikiukleeds, Editzzz, Pariswikiuser, Xcar71,Gilborrego, Lkjpoiuytrewq, Sha-256, MKR125188, Cambiaelmundo, Haby87, Sminthopsis84, Lca css, Tobijane2000, TwoMartiniTues-day, Terencedavidw, TwoTwoHello, Lugia2453, Diego Meneses, Cupco, The Triple M, Kjtermaat, Kevin12xd, Ross Hill, MrSpetsnaz,Magnolia677, Thoandgue, Mudassarhusain01, Tonymatthewsboy, Tyoii88, Nugey14, Gargcoolboy2117, CensoredScribe, Hannah.dimich,Hetrop, Ginsuloft, Tommcgowanwiki, Quenhitran, Manul, AddWittyNameHere, Adattaway, Sophoclesmm, Man of Steel 85, Bradyd-callahan, Timothymich99, Monkbot, Indiamonsoon, Jacksonclifton14, Clifton00101, Bumbbb, LetsGetNerdy, Scarlettail, Kiskanamjoker,Zman1383, Wikiman1981, Mexican Undertaker, Milkboy237, Mrislam.che, Poonreply, Rrocketeer, AesopSmart, Whoisjoking, Gyokeeg,Meme123123, Sanchezpatterson, Camilogil and Anonymous: 1465

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16 9 TEXT AND IMAGE SOURCES, CONTRIBUTORS, AND LICENSES

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