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Home , Biodiesel production, Biofuel

10 THE STATE OF FOOD AND 2008

2. and agriculture – a technical overview

Traditional , including fuelwood, poverty and who use this energy mainly charcoal and animal dung, continues to for cooking. More advanced and efficient provide important sources of energy in conversion technologies now allow the many parts of the world. is the extraction of biofuels – in solid, liquid and dominant energy source for most of the gaseous forms – from materials such as world’s population who live in extreme wood, and waste material. This chapter provides an overview of biofuels. What are they, what is their potential and what FIGURE 4 are their implications for agriculture? The Biofuels – from feedstock to end use main focus, however, is on liquid biofuels for transport, which are now gaining in prominence as a result of the rapid increase RESOURCES in their use.

Land Nutrients Water Energy Labour … Types of biofuels Seeds

PRODUCTION Biofuels are energy carriers that store the energy derived from biomass.2 A wide range of biomass sources can be used to produce bioenergy in a variety of forms. For example,

FEEDSTOCKS food, fibre and wood process residues from the industrial sector; energy crops, short- cane rotation crops and agricultural wastes from Jatropha Switchgrass the agriculture sector; and residues from the forestry sector can all be used to generate ... electricity, heat, combined heat and power, PROCESSING and other forms of bioenergy. Biofuels may be referred to as because they are a form of transformed . Biofuels can be classified according to BIOFUELS source and type. They may be derived from forest, agricultural or fishery products or municipal wastes, as well as from agro- Fuelwood ... industry, food industry and food service Charcoal by-products and wastes. They may be solid, CONSUMPTION such as fuelwood, charcoal and wood pellets; liquid, such as ethanol, biodiesel and oils; or gaseous, such as biogas. END USE

Transport Electricity Heating ...

2 For a review of terminology relating to biofuels, see FAO Source: FAO. (2004a). BIOFUELS: PROSPECTS, RISKS AND OPPORTUNITIES 11

FIGURE 5 Uses of biomass for energy

80% Residential use

18% Industrial use

2% Transport

Source: IEA, 2007.

A basic distinction is also made between Ethanol primary (unprocessed) and secondary Any feedstock containing significant amounts (processed) biofuels: of sugar, or materials that can be converted • Primary biofuels, such as firewood, wood into sugar such as or , can be chips and pellets, are those where the used to produce ethanol. Ethanol available in organic material is used essentially in its the market today is based on either natural form (as harvested). Such sugar or starch. Common sugar crops used as are directly combusted, usually to supply feedstocks are sugar cane, sugar beet and, cooking , heating or electricity to a lesser extent, sweet . Common production needs in small- and large- starchy feedstocks include maize, wheat scale industrial applications. and . The use of biomass containing • Secondary biofuels in the form of solids that can be fermented directly to (e.g. charcoal), liquids (e.g. ethanol, ethanol is the simplest way of producing biodiesel and bio-oil), or gases (e.g. ethanol. In and other tropical countries biogas, synthesis gas and ) currently producing ethanol, sugar cane is can be used for a wider range of the most widely used feedstock. In OECD applications, including transport and countries, most ethanol is produced from high-temperature industrial processes. the starchy component of cereals (although sugar beet is also used), which can be converted fairly easily into sugar. However, Liquid biofuels for transport3 these starchy products represent only a small percentage of the total mass. In spite of their limited overall volume Most plant matter is composed of cellulose, (see Figure 5), the strongest growth in hemicellulose and lignin; the first two can be recent years has been in liquid biofuels for converted into after they have first transport, mostly produced using agricultural been converted into sugar, but the process is and food commodities as feedstocks. The more difficult than the one for starch. Today, most significant are ethanol and biodiesel. there is virtually no commercial production of ethanol from cellulosic biomass, but substantial research continues in this area

3 This section is based on GBEP (2007, pp. 2–10) and IEA (see the section on second-generation (2004). biofuels on pp. 18–19). 12 THE STATE OF FOOD AND AGRICULTURE 2008

BOX 1 Other types of biomass for heat, power and transport

Biomass for heat and power significant environmental and health A range of biomass resources are used benefits. is a gas to generate electricity and heat through that has a global-warming potential that . Sources include various forms is 22–24 times more powerful than that of of waste, such as residues from agro- . By trapping and utilizing industries, post-harvest residues left on the methane, its impacts the fields, animal , wood wastes are avoided. In addition, heat generated from forestry and industry, residues from during the biodigestion process kills the food and paper industries, municipal pathogens present in manure, and the solid wastes, sewage sludge and biogas material left at the end of the process from the digestion of agricultural and provides a valuable fertilizer. other organic wastes. Dedicated energy crops, such as short-rotation perennials Gasification (, poplar, willow) and grasses Through the process of gasification, solid ( and switchgrass), are also biomass can be converted into a fuel gas used. or biogas. Biomass gasifiers operate by Several processes can be used for heating biomass in a low-, high- power generation. Most biomass-derived temperature environment that breaks it electricity is produced using a steam- down to release a flammable, energy-rich cycle process: biomass is burned in a synthesis gas or “”. This gas can be boiler to generate high-pressure steam burned in a conventional boiler, or used that flows over a series of aerodynamic instead of in a gas turbine to blades causing a turbine to rotate, turn electric generators. Biogas formed which in response turns a connected through gasification can be filtered to electric generator to produce electricity. remove unwanted chemical compounds Compacted forms of biomass such as and can be used in efficient “combined- wood pellets and can also cycle” power-generation systems that be used for combustion, and biomass combine steam and gas turbines to can also be burned with in the generate electricity. boiler of a conventional power plant to yield steam and electricity. The latter is Biogas for transport currently the most cost-efficient method Untreated biogas is unsuitable as a for incorporating renewable technology transport fuel owing to its low methane into conventional power production content (60–70 percent) and high because much of the existing power plant concentration of contaminants. However, infrastructure can be used without major it can be treated to remove carbon modifications. dioxide, water and corrosive hydrogen sulphide and to enhance its methane Biogas for heat, power and transport content (to over 95 percent). When compressed, treated biogas has properties Biogas can be created through the similar to those of , anaerobic digestion of food or animal making it suitable for use in transport. waste by bacteria in an oxygen-starved environment. The resulting biogas contains a high volume of methane along with carbon dioxide, which can be used for heating or for in a modified internal combustion . The conversion of animal wastes and manure to methane/biogas can bring Source: based on GBEP, 2007. BIOFUELS: PROSPECTS, RISKS AND OPPORTUNITIES 13

Ethanol can be blended with petrol or As with ethanol, diesel also contains only a burned in its pure form in slightly modified negligible amount of sulphur, thus reducing spark-ignition . A litre of ethanol sulphur oxide emissions from vehicles. contains approximately 66 percent of the energy provided by a litre of petrol, but has Straight a higher octane level and when mixed with Straight vegetable oil (SVO)4 is a potential petrol for transportation it improves the fuel for diesel engines that can be produced performance of the latter. It also improves from a variety of sources, including oilseed fuel combustion in vehicles, thereby crops such as rapeseed, sunflower, reducing the emission of , and palm. Used from restaurants unburned and carcinogens. and animal fat from meat-processing However, the combustion of ethanol also industries can also be used as fuel for diesel causes a heightened reaction with nitrogen vehicles. in the atmosphere, which can result in a marginal increase in nitrogen oxide gases. In comparison with petrol, ethanol contains Biofuel feedstocks only a trace amount of sulphur. Mixing ethanol with petrol, therefore, helps to There are many supply sources of biomass reduce the fuel’s sulphur content and for energy purposes, scattered across large thereby lowers the emissions of sulphur and diverse geographical areas. Even oxide, a component of rain and a today, most energy derived from biomass carcinogen. used as fuel originates from by-products or co-products of food, fodder and fibre . For instance, the main by- Biodiesel is produced by combining products of forest industries are used to vegetable oil or animal fat with an alcohol produce fuelwood and charcoal, and black and a catalyst through a chemical process liquor (a by-product of pulp mills) is a major known as transesterification. Oil for biodiesel fuel source for bioelectricity generation in production can be extracted from almost countries such as Brazil, Canada, Finland, any oilseed ; globally, the most popular and the United States of America. sources are rapeseed in Europe and soybean A considerable amount of heat and power in Brazil and the United States of America. In is derived from recovered and/or recycled tropical and subtropical countries, biodiesel woody biomass and increasing amounts of is produced from palm, coconut and jatropha energy are recovered from biomass derived oils. Small amounts of animal fat, from from cropland ( and cotton stalks) and fish- and animal-processing operations, forest land (wood chips and pellets). In sugar- are also used for biodiesel production. The and coffee-producing countries, bagasse and production process typically yields additional coffee are used for direct combustion by-products such as crushed bean “cake” (an and to produce heat energy and steam. animal feed) and glycerine. Because biodiesel In terms of bioenergy, however, the big can be based on a wide range of oils, the growth area in recent years has been in the resulting fuels can display a greater variety production of liquid biofuels for transport of physical properties, such as and using agricultural crops as feedstocks. The combustibility, than ethanol. bulk of this has taken the form of ethanol, Biodiesel can be blended with traditional based on either sugar crops or starchy crops, or burned in its pure form in or biodiesel based on oil crops. compression ignition engines. Its energy As shown in Figure 6, a range of different content is 88–95 percent of that of diesel, crops can be used as feedstock for ethanol but it improves the lubricity of diesel and and biodiesel production. However, most raises the cetane value, making the fuel global ethanol production is derived from economy of both generally comparable. The sugar cane or maize; in Brazil, the bulk of higher oxygen content of biodiesel aids in ethanol is produced from sugar cane and in the completion of fuel combustion, reducing the United States of America from maize. emissions of particulate air pollutants, carbon monoxide and hydrocarbons. 4 Also referred to as pure plant oil (PPO). 14 THE STATE OF FOOD AND AGRICULTURE 2008

FIGURE 6 Conversion of agricultural feedstocks into liquid biofuels

SUGAR CROPS Fermentation Sugar cane and Sugar beet

STARCHY CROPS

Maize Wheat ETHANOL Rye Potatoes Saccarification, Cassava fermentation and distillation CELLULOSIC MATERIALS

Switchgrass Miscanthus Willow Poplar Crop

OIL CROPS

Rapeseed Extraction Oil palm and BIODIESEL Soybean esterification Sunflower Peanut Jatropha

Source: FAO.

Other significant crops include cassava, , significant is the sector’s increasing role as a sugar beet and wheat. For biodiesel, the provider of feedstock for the production of most popular feedstocks are rapeseed in the liquid biofuels for transport – ethanol and EU, soybean in the United States of America biodiesel. Modern bioenergy represents a and Brazil, and palm, coconut and castor oils new source of demand for farmers’ products. in tropical and subtropical countries, with a It thus holds promise for the creation of growing interest in jatropha. income and employment. At the same time, it generates increasing competition for natural resources, notably land and water, Biofuels and agriculture especially in the short run, although yield increases may mitigate such competition The current expansion and growth of in the longer run. Competition for land energy markets, as a result of new energy becomes an issue especially when some of and environment policies enacted over the the crops (e.g. maize, oil palm and soybean) past decade in most developed countries that are currently cultivated for food and and in several developing countries, is feed are redirected towards the production reshaping the role of agriculture. Most of biofuels, or when food-oriented BIOFUELS: PROSPECTS, RISKS AND OPPORTUNITIES 15

agricultural land is converted to biofuel topping the list of in terms of biofuel output production. per hectare and India not far behind. Yields Currently, around 85 percent of the global per hectare are somewhat lower for maize, production of liquid biofuels is in the form but with marked differences between yields, of ethanol (Table 1). The two largest ethanol for example, in China and in the United States producers, Brazil and the United States of of America. The data reported in Table 2 refer America, account for almost 90 percent only to technical yields. The cost of producing of total production, with the remainder biofuels based on different crops in different accounted for mostly by Canada, China, countries may show very different patterns. the EU (mainly France and ) and This is discussed further in Chapter 3. India. Biodiesel production is principally concentrated in the EU (with around 60 percent of the total), with a significantly The biofuels life cycle: energy smaller contribution coming from the balances and greenhouse gas United States of America. In Brazil, biodiesel emissions production is a more recent phenomenon and production volume remains limited. Two of the main driving forces behind Other significant biodiesel producers include policies promoting biofuel development China, India, Indonesia and Malaysia. have been concerns over and Different crops vary widely in terms a desire to reduce . of biofuel yield per hectare, both across Just as different crops have different yields in feedstocks and across countries and terms of biofuel per hectare, wide variations production systems, as illustrated in Table 2. also occur in terms of energy balance and Variations are due both to differences in crop greenhouse gas emission reductions across yields per hectare across crops and countries feedstocks, locations and technologies. and to differences in conversion efficiency The contribution of a biofuel to energy across crops. This implies vastly different land supply depends both on the energy content requirements for increased biofuel production of the biofuel and on the energy going depending on the crop and location. into its production. The latter includes the Currently, ethanol production from sugar energy required to cultivate and harvest cane and sugar beet has the highest yields, the feedstock, to process the feedstock into with sugar-cane-based production in Brazil biofuel and to transport the feedstock and

TABLE 1 Biofuel production by country, 2007

COUNTRY/COUNTRY ETHANOL BIODIESEL TOTAL GROUPING

(Million litres) (Mtoe) (Million litres) (Mtoe) (Million litres) (Mtoe)

Brazil 19 000 10.44 227 0.17 19 227 10.60

Canada 1 000 0.55 97 0.07 1 097 0.62

China 1 840 1.01 114 0.08 1 954 1.09

India 400 0.22 45 0.03 445 0.25

Indonesia 0 0.00 409 0.30 409 0.30

Malaysia 0 0.00 330 0.24 330 0.24 United States of 26 500 14.55 1 688 1.25 28 188 15.80 America

European Union 2 253 1.24 6 109 4.52 8 361 5.76

Others 1 017 0.56 1 186 0.88 2 203 1.44

World 52 009 28.57 10 204 7.56 62 213 36.12

Note: Data presented are subject to rounding. Source: based on F.O. Licht, 2007, data from the OECD–FAO AgLink-Cosimo database. 16 THE STATE OF FOOD AND AGRICULTURE 2008

TABLE 2 Biofuel yields for different feedstocks and countries

GLOBAL/NATIONAL CROP BIOFUEL CROP YIELD CONVERSION EFFICIENCY BIOFUEL YIELD ESTIMATES

(Tonnes/ha) (Litres/tonne) (Litres/ha)

Sugar beet Global Ethanol 46.0 110 5 060

Sugar cane Global Ethanol 65.0 70 4 550

Cassava Global Ethanol 12.0 180 2 070

Maize Global Ethanol 4.9 400 1 960

Rice Global Ethanol 4.2 430 1 806

Wheat Global Ethanol 2.8 340 952

Sorghum Global Ethanol 1.3 380 494

Sugar cane Brazil Ethanol 73.5 74.5 5 476

Sugar cane India Ethanol 60.7 74.5 4 522

Oil palm Malaysia Biodiesel 20.6 230 4 736

Oil palm Indonesia Biodiesel 17.8 230 4 092

United States of Maize Ethanol 9.4 399 3 751 America

Maize China Ethanol 5.0 399 1 995

Cassava Brazil Ethanol 13.6 137 1 863

Cassava Nigeria Ethanol 10.8 137 1 480

United States of Soybean Biodiesel 2.7 205 552 America

Soybean Brazil Biodiesel 2.4 205 491

Sources: Rajagopal et al., 2007, for global data; Naylor et al., 2007, for national data.

the resulting biofuel at the various phases sometimes, for a feedstock/fuel combination, of its production and distribution. The fossil depending on factors such as feedstock energy balance expresses the ratio of energy productivity, agricultural practices and contained in the biofuel relative to the fossil conversion technologies. energy used in its production. A fossil energy Conventional petrol and diesel have fossil balance of 1.0 means that it requires as much energy balances of around 0.8–0.9, because energy to produce a litre of biofuel as it some energy is consumed in refining crude contains; in other words, the biofuel provides oil into usable fuel and transporting it to no or loss. A markets. If a biofuel has a fossil energy energy balance of 2.0 means that a litre of balance exceeding these numbers, it biofuel contains twice the amount of energy contributes to reducing dependence on as that required in its production. Problems fossil fuels. All biofuels appear to make a in assessing energy balances accurately derive positive contribution in this regard, albeit to from the difficulty of clearly defining the widely varying degrees. Estimated fossil fuel system boundary for the analysis. balances for biodiesel range from around 1 Figure 7 summarizes the results of several to 4 for rapeseed and soybean feedstocks. studies on fossil energy balances for different Estimated balances for palm oil are higher, types of fuel, as reported by the Worldwatch around 9, because other oilseeds must be Institute (2006). The figure reveals wide crushed before the oil can be extracted, variations in the estimated fossil energy an additional processing step that requires balances across feedstocks and fuels and, energy. For crop-based ethanol, the estimated BIOFUELS: PROSPECTS, RISKS AND OPPORTUNITIES 17

FIGURE 7 Estimated ranges of fossil energy balances of selected fuel types

FUEL FEEDSTOCK

Crude oil PETROL

Crude oil

Soybean

Rapeseed

Waste vegetable oil

Palm oil

Sweet sorghum

Maize

Sugar beet

Wheat ETHANOL BIODIESEL DIESEL

Sugar cane

Cellusosic

01 2345678910 Fossil energy balance (ratio)

Note: The ratios for cellulosic biofuels are theoretical. Sources: based on Worldwatch Institute, 2006, Table 10.1; Rajagopal and Zilberman, 2007. balances range from less than 2 for maize to Biofuels are produced from biomass; in around 2–8 for sugar cane. The favourable theory, therefore, they should be carbon fossil energy balance of sugar-cane-based neutral, as their combustion only returns ethanol, as produced in Brazil, depends not to the atmosphere the carbon that was only on feedstock productivity, but also on sequestered from the atmosphere by the the fact that it is processed using biomass plant during its growth – unlike fossil fuels, residues from the sugar cane (bagasse) as which release carbon that has been stored energy input. The range of estimated fossil for millions of years under the surface of fuel balances for cellulosic feedstocks is even the earth. However, assessing the net effect wider, reflecting the uncertainty regarding of a biofuel on greenhouse gas emissions this technology and the diversity of potential requires analysis of emissions throughout feedstocks and production systems. the life cycle of the biofuel: planting and Similarly, the net effect of biofuels on harvesting the crop; processing the feedstock greenhouse gas emissions may differ widely. into biofuel; transporting the feedstock 18 THE STATE OF FOOD AND AGRICULTURE 2008

and the final fuel; and storing, distributing on developing efficient and cost-effective and retailing the biofuel – including the ways of carrying out the process. The lack impacts of fuelling a vehicle and the of commercial viability has so far inhibited emissions caused by combustion. In addition, significant production of cellulose-based any possible co-products that may reduce second-generation biofuels. emissions need to be considered. Clearly, As cellulosic biomass is the most therefore, fossil energy balances are only abundant biological material on earth, the one of several determinants of the emissions successful development of commercially impact of biofuels. Critical factors related viable second-generation cellulose-based to the agricultural production process biofuels could significantly expand the include fertilizing, pesticide use, irrigation volume and variety of feedstocks that can technology and soil treatment. Land-use be used for production. Cellulosic wastes, changes associated with expanded biofuel including waste products from agriculture production can have a major impact. For (straw, stalks, leaves) and forestry, wastes example, converting forest land to the generated from processing (nut shells, sugar- production of biofuel crops or agricultural cane bagasse, sawdust) and organic parts crops displaced by biofuel feedstocks of municipal waste, could all be potential elsewhere can release large quantities of sources. However, it is also important to carbon that would take years to recover consider the crucial role that decomposing through the emission reductions achieved biomass plays in maintaining soil fertility and by substituting biofuels for fossil fuels. texture; excessive withdrawals for bioenergy Chapter 5 discusses further the relationship use could have negative effects. between biofuels and greenhouse gas Dedicated cellulosic energy crops hold emissions and reviews the evidence that the promise as a source of feedstock for second- impact of biofuels on may generation technologies. Potential crops vary and may not necessarily be positive – or include short-rotation woody crops such as positive as is often initially assumed. as willow, hybrid poplars and eucalyptus or grassy species such as miscanthus, switchgrass and reed canary grass. These Second-generation liquid biofuels5 crops present major advantages over first- generation crops in terms of environmental Current liquid biofuel production based on . Compared with conventional sugar and starch crops (for ethanol) and starch and oilseed crops, they can produce oilseed crops (for biodiesel) is generally more biomass per hectare of land because referred to as first-generation biofuels. A the entire crop is available as feedstock for second generation of technologies under conversion to fuel. Furthermore, some fast- development may also make it possible growing perennials such as short-rotation to use . Cellulosic woody crops and tall grasses can sometimes biomass is more resistant to being broken grow on poor, degraded soils where food- down than starch, sugar and oils. The crop production is not optimal because of difficulty of converting it into liquid fuels erosion or other limitations. Both these makes the conversion technology more factors may reduce competition for land with expensive, although the cost of the cellulosic food and feed production. On the downside, feedstock itself is lower than for current, several of these species are considered first-generation feedstocks. Conversion of invasive or potentially invasive and may cellulose to ethanol involves two steps: the have negative impacts on water resources, cellulose and hemicellulose components and agriculture. of the biomass are first broken down Second-generation feedstocks and into sugars, which are then fermented to biofuels could also offer advantages in obtain ethanol. The first step is technically terms of reducing greenhouse gas emissions. challenging, although research continues Most studies project that future, advanced fuels from perennial crops and woody and 5 This section is based on GBEP (2007), IEA (2004) and agricultural residues could dramatically Rutz and Janssen (2007). reduce life-cycle greenhouse gas emissions BIOFUELS: PROSPECTS, RISKS AND OPPORTUNITIES 19

relative to fuels and first- generation biofuels. This stems from both Potential for bioenergy the higher energy yields per hectare and the different choice of fuel used in the What is the potential for bioenergy conversion process. In the current production production? The technical and economic process for ethanol, the energy used in potential for bioenergy should be discussed processing is almost universally supplied in the context of the increasing shocks by fossil fuels (with the exception of sugar- and stress on the global agriculture sector cane-based ethanol in Brazil, where most and the growing demand for food and of the energy for conversion is provided by agricultural products that is a consequence sugar-cane bagasse). For second-generation of continuing population and income growth biofuels, process energy could be provided by worldwide. What is technically feasible to left-over parts of the (mainly lignin). produce may not be economically feasible While cellulosic biomass is harder to break or environmentally sustainable. This section down for conversion to liquid fuels, it is also discusses in more detail the technical and more robust for handling, thus helping to economic potential of bioenergy. reduce its handling costs and maintain its Because bioenergy is derived from quality compared with food crops. It is also biomass, global bioenergy potential is easier to store, especially in comparison with ultimately limited by the total amount of sugar-based crops, as it resists deterioration. energy produced by global . On the other hand, cellulosic biomass can Plants collect a total energy equivalent of often be bulky and would require a well- about 75 000 Mtoe (3 150 Exajoule) per year developed transportation infrastructure for (Kapur, 2004) – or six to seven times the delivery to processing plants after harvest. current global energy demand. However, this Significant technological challenges includes vast amounts of biomass that cannot still need to be overcome to make the be harvested. In purely physical terms, production of ethanol from lignocellulosic biomass represents a relatively poor way of feedstocks commercially competitive. It is harvesting solar energy, particularly when still uncertain when conversion of cellulosic compared with increasingly efficient solar biomass into advanced fuels may be able to panels (FAO, 2006a). contribute a significant proportion of the A number of studies have gauged the world’s liquid fuels. Currently, there are a volume of biomass that can technically number of pilot and demonstration plants contribute to global energy supplies. either operating or under development Their estimates differ widely owing around the world. The speed of expansion to different scopes, assumptions and of biochemical and thermochemical methodologies, underscoring the high conversion pathways will depend upon the degree of uncertainty surrounding the development and success of pilot projects possible contribution of bioenergy to future currently under way and sustained research global . The last major study funding, as well as world oil prices and of bioenergy conducted by the International private-sector investment. Energy Agency (IEA) assessed, on the basis In summary, second-generation biofuels of existing studies, the range of potential based on lignocellulosic feedstocks present bioenergy supply in 2050 from a low of a completely different picture in terms 1 000 Mtoe to an extreme of 26 200 Mtoe of their implications for agriculture and (IEA, 2006, pp. 412–16). The latter figure . A much wider variety of was based on an assumption of very rapid feedstocks could be used, beyond the technological progress; however, the IEA agricultural crops currently used for first- indicates that a more realistic assessment generation technologies, and with higher based on slower yield improvements energy yields per hectare. Their effects on would be 6 000–12 000 Mtoe. A mid-range commodity markets, land-use change and estimate of around 9 500 Mtoe would, the environment will also differ – as will according to the IEA, require about one- their influence over future production and fifth of the world’s agricultural land to be transformation technologies (see Box 2). dedicated to biomass production. 20 THE STATE OF FOOD AND AGRICULTURE 2008

BOX 2 applications for biofuels

Many existing can be Application of biotechnologies for applied to improve bioenergy production, second-generation biofuels for example, in developing better biomass Lignocellulosic biomass consists mainly feedstocks and improving the efficiency of of lignin and the polysaccharides converting the biomass to biofuels. cellulose (consisting of hexose sugars) and hemicellulose (containing a mix of Biotechnologies for first-generation hexose and pentose sugars). Compared biofuels with the production of ethanol from The plant varieties currently used for first- first-generation feedstocks, the use generation biofuel production have been of lignocellulosic biomass is more selected for agronomic traits relevant complicated because the polysaccharides for food and/or feed production and are more stable and the pentose not for characteristics that favour their sugars are not readily fermentable use as feedstocks for biofuel production. by Saccharomyces cerevisiae. In order Biotechnology can help to speed up the to convert lignocellulosic biomass to selection of varieties that are more suited biofuels the polysaccharides must to biofuel production – with increased first be hydrolysed, or broken down, biomass per hectare, increased content into simple sugars using either acid or of oils (biodiesel crops) or fermentable . Several biotechnology-based sugars (ethanol crops), or improved approaches are being used to overcome processing characteristics that facilitate such problems, including the development their conversion to biofuels. The field of of strains of Saccharomyces cerevisiae genomics – the study of all the genetic that can ferment pentose sugars, the material of an organism (its genome) – is use of alternative species that likely to play an increasingly important naturally ferment pentose sugars, and the role. Genome sequences of several first- engineering of enzymes that are able to generation feedstocks, such as maize, break down cellulose and hemicellulose sorghum and soybean, are in the pipeline into simple sugars. or have already been published. Apart Apart from agricultural, forestry and from genomics, other biotechnologies that other by-products, the main source can be applied include marker-assisted of lignocellulosic biomass for second- selection and genetic modification. generation biofuels is likely to be from Fermentation of sugars is central to “dedicated biomass feedstocks”, such as the production of ethanol from biomass. certain perennial grass and forest tree However, the most commonly used species. Genomics, genetic modification industrial fermentation micro-organism, and other biotechnologies are all being the yeast Saccharomyces cerevisiae, cannot investigated as tools to produce plants directly ferment starchy material, such as with desirable characteristics for second- maize starch. The biomass must first be generation biofuel production, for broken down (hydrolysed) to fermentable example plants that produce less lignin sugars using enzymes called amylases. (a compound that cannot be fermented Many of the current commercially into liquid biofuel), that produce enzymes available enzymes, including amylases, themselves for cellulose and/or lignin are produced using genetically modified degradation, or that produce increased micro-organisms. Research continues on cellulose or overall biomass yields. developing efficient genetic yeast strains that can produce the amylases themselves, so that the and fermentation Sources: based on FAO, 2007a, and The Royal steps can be combined. Society, 2008. BIOFUELS: PROSPECTS, RISKS AND OPPORTUNITIES 21

More important than the purely technical production. Nevertheless, this illustrates that, viability is the question of how much of the even under a second-generation scenario, a technically available bioenergy potential hypothetical large-scale substitution of liquid would be economically viable. The long-term biofuels for fossil-fuel-based petrol would economic potential depends crucially on require major conversion of land. See also assumptions concerning the prices of fossil Chapter 4 for a further discussion, including energy, the development of agricultural regional impacts. feedstocks and future technological The potential for current biofuel innovations in harvesting, converting and technologies to replace fossil fuels is also using biofuels. These aspects are discussed in illustrated by a hypothetical calculation further detail in Chapter 3. by Rajagopal et al. (2007). They report A different way of looking at the potential theoretical estimates for global ethanol for biofuel production is to consider the production from the main cereal and sugar relative land-use requirements. In its crops based on global average yields and “Reference Scenario” for 2030 in World commonly reported conversion efficiencies. Energy Outlook 2006, the IEA projects an The results of their estimates are summarized increase in the share of the world’s arable in Table 3. The crops shown account land devoted to growing biomass for liquid for 42 percent of total cropland today. biofuels from 1 percent in 2004 to 2.5 percent Conversion of the entire crop production in 2030. Under its “Alternative Policy to ethanol would correspond to 57 percent Scenario”, the share in 2030 increases to of total petrol consumption. Under a more 3.8 percent. In both cases, the projections are realistic assumption of 25 percent of each based on the assumption that liquid biofuels of these crops being diverted to ethanol will be produced using conventional crops. production, only 14 percent of petrol Should second-generation liquid biofuels consumption could be replaced by ethanol. become widely commercialized before 2030, The various hypothetical calculations the IEA projects the global share of biofuels underline that, in view of their significant in transport demand to increase to 10 percent land requirements, biofuels can only rather than 3 percent in its Reference be expected to lead to a very limited Scenario and 5 percent in the Alternative displacement of fossil fuels. Nevertheless, Policy Scenario. Land-use requirements would even a very modest contribution of biofuels go up only slightly, to 4.2 percent of arable to overall energy supply may yet have land, because of higher energy yields per a strong impact on agriculture and on hectare and the use of waste biomass for fuel agricultural markets.

TABLE 3 Hypothetical potential for ethanol from principal cereal and sugar crops

GLOBAL GLOBAL BIOFUEL MAXIMUM PETROL SUPPLY AS SHARE OF 2003 CROP AREA PRODUCTION YIELD ETHANOL EQUIVALENT GLOBAL PETROL USE1

(Million ha) (Million tonnes) (Litres/ha) (Billion litres) (Billion litres) (Percentage)

Wheat 215 602 952 205 137 12

Rice 150 630 1 806 271 182 16

Maize 145 711 1 960 284 190 17

Sorghum 45 59 494 22 15 1

Sugar cane 20 1 300 4 550 91 61 6

Cassava 19 219 2 070 39 26 2

Sugar beet 5.4 248 5 060 27 18 2

Total 599 ...... 940 630 57

Note: ... = not applicable. Data presented are subject to rounding. 1 Global petrol use in 2003 = 1 100 billion litres (Kim and Dale, 2004). Source: Rajapogal et al., 2007. 22 THE STATE OF FOOD AND AGRICULTURE 2008

Key messages of the chapter • Even though liquid biofuels supply only a small share of global energy needs, • Bioenergy covers approximately they still have the potential to have a 10 percent of total world energy significant effect on global agriculture supply. Traditional unprocessed biomass and agricultural markets because of the accounts for most of this, but commercial volume of feedstocks and the relative bioenergy is assuming greater land areas needed for their importance. production. • Liquid biofuels for transport are • The contribution of different biofuels to generating the most attention and have reducing fossil-fuel consumption varies seen a rapid expansion in production. widely when the fossil energy used as an However, quantitatively their role is only input in their production is also taken marginal: they cover 1 percent of total into account. The fossil energy balance transport fuel consumption and 0.2– of a biofuel depends on factors such as 0.3 percent of total energy consumption feedstock characteristics, production worldwide. location, agricultural practices and the • The main liquid biofuels are ethanol and source of energy used for the conversion biodiesel. Both can be produced from a process. Different biofuels also perform wide range of different feedstocks. The very differently in terms of their most important producers are Brazil and contribution to reducing greenhouse gas the United States of America for ethanol emissions. and the EU for biodiesel. • Second-generation biofuels currently • Current technologies for liquid biofuels under development would use rely on agricultural commodities as lignocellulosic feedstocks such as feedstock. Ethanol is based on sugar wood, tall grasses, and forestry and or starchy crops, with sugar cane in crop residues. This would increase Brazil and maize in the United States of the quantitative potential for biofuel America being the most significant in generation per hectare of land and terms of volume. Biodiesel is produced could also improve the fossil energy and using a range of different oil crops. greenhouse gas balances of biofuels. • Large-scale production of biofuels However, it is not known when such implies large land requirements for technologies will enter production on a feedstock production. Liquid biofuels can significant commercial scale. therefore be expected to displace fossil fuels for transport to only a very limited extent.