Bioenergy is a renewable energy produced from natural sources -energy crops, biomass, wastes and by-products, macro algae, microalgae, seaweeds and aquatic plants- capable of replacing fossil energy.
Mirjam Röder, Andrew Welfle, in Managing Global Warming, 2019
Bioenergy can offer renewable, low-carbon energy systems, sequestering atmospheric carbon as well as offer numerous environmental and socioeconomic benefits and therefore supporting global climate change targets and wider environmental, social, economic, and sustainable targets. There is scientific evidence of the benefits of bioenergy, but results are often subject to variation and uncertainty. Additionally, it is important to consider various sustainable aspects of bioenergy systems beyond carbon. Treating bioenergy only as part of the energy sector will fail to ensure: sustainable biomass production and sourcing, clean applications with low health impacts, and fair and affordable energy vectors. Ensuring that bioenergy offers the required holistic emission reduction, context, specific and long-term approaches are necessary to understand synergies and tradeoff of the bioenergy and related agricultural and forestry systems. Assessing the environmental and wider sustainable impacts of bioenergy, full supply chains as well as direct and indirect stakeholders, their drivers, benefits and challenges needs to be considered. With these, we have to assess and evaluate bioenergy and its impacts in the context of the specific system it is part off and its direct and wider impacts on environment, economy, and society.
Nicolae Scarlat, Jean-Francois Dallemand, in The Role of Bioenergy in the Bioeconomy, 2019
10.1.6.1 Bioenergy markets and trade
Bioenergy provides about 56 EJ representing almost 10% of world primary energy supply, out of which traditional bioenergy still makes up more than 60% (IEA, 2017a). Traditional use of biomass has played a significant role for heating and cooking for long time. Traditional bioenergy relies on the use of agricultural by-products (animal dung and crop residues), fuelwood, and charcoal that are mostly used locally. Modern use of biomass for electricity and heat generation and provision of high temperature heat for industry and for biofuels production has started recently as a more efficient option of providing energy. Modern bioenergy relies on energy carriers such as bioethanol, biodiesel, wood pellets, and wood chips, through a range of modern technologies (Sharmina et al., 2017). Bioenergy markets, despite significant development over the last decade, are still immature and face complex interactions between agriculture, forestry, and energy sectors. The development of bioenergy and the increasing demand for biomass have been key drivers for international trade to exploit available biomass resources and local market potentials, which are currently underutilized in many world regions. International trade flows in bioenergy markets are still relatively low compared to fossil fuel markets and have intricate connections with food and wood commodities trade flows that make them difficult to estimate (Popp et al., 2014).
Annette L. Cowie, … Sampo Soimakallio, in Managing Global Warming, 2019
Bioenergy is a key strategy for climate change mitigation in many national and international climate change and renewable energy policies. However, over recent years, claims have been made that forest-based bioenergy can lead to losses in forest carbon (sometimes referred to as “carbon debt”) and, thus, their effectiveness at mitigating climate change has been questioned. Climate impacts of forest bioenergy are dependent on a range of case-specific factors, including biophysical features of the biomass-production system and GHG intensity of the energy source it displaces, which are largely determined by the location of the bioenergy project. Estimates of climate impacts are also strongly affected by methodological choices and assumptions, related to reference land use, spatial and temporal system boundary, allocation procedures, time horizon of assessment, metrics applied, and climate forces considered. In this chapter, these key issues are discussed and recommendations are provided for carrying out appropriate and comprehensive assessments of climate impacts of forest bioenergy systems.
Francisco José Domínguez Pérez, … Siwa Msangi, in The Role of Bioenergy in the Bioeconomy, 2019
Bioenergy can significantly contribute to rural development. And indeed bioenergy is commonly considered as a core element in most international, national, and regional strategies and plans for rural development.
A key characteristic of rural areas is the limited access to energy, in particular in developing countries. The lack of infrastructure in those remote regions hampers in many cases a reliable and affordable energy supply for rural residents who often face difficulties to cover basic needs (lighting, space heating) and to develop economic activities (agriculture, which requires energy in all steps, industry, or retail businesses).
Bioenergy has some comparative advantages over other options for energy provision in rural areas. Biomass resources are widely available. In addition, biomass fuels can be stored and used whenever needed and all energy carriers required (electricity, heat, gas, or liquid fuels for transport) can be produced from biomass.
Energy provision by means of bioenergy contributes to economic development in rural regions, where the income level is usually lower than in cities (most of the world’s poor population live in rural areas). Since feedstocks for bioenergy production are obtained from agricultural and forestry activities, the implementation of bioenergy projects in rural areas has a direct economic effect at local level because farmers have access to a new market for their products. Improvements in productivity as a consequence of energy provision and the income increase dynamize local economy and foster job creation which leads to a better quality of life of rural dwellers thus contributing to reduce the exodus from rural to urban areas.
Integrated systems for food, feed, and energy production allow the management and use of farm waste, which implies relevant environmental benefits as well. The experience of “Bioenergy villages” shows that this kind of systems can be used to cover the energy needs in rural communities while social cohesion is reinforced due to the participatory approach adopted in most cases for the project implementation.
In less developed countries, bioenergy may have even more significant impacts since it can greatly contribute to poverty alleviation and to improve healthcare services, education, as well as to provide new development opportunities for women, who in developing countries usually find it difficult to get jobs and to earn their own income.
The implementation of bioenergy projects can lead to a wide range of benefits but it should be done in a sustainable manner to prevent potential environmental and social risks. In this sense, the engagement of communities throughout the whole process is a crucial requirement for a successful deployment of bioenergy in rural areas.
A.M. Paz, in Reference Module in Earth Systems and Environmental Sciences, 2013
Bioenergy, or energy from biological resources, is renewable and carbon neutral. The carbon released during combustion is uptaken during renovation of the biological resources, which happens over a time span enough to make the resources continuously available. Although, the carbon emissions from a bioenergy system can be greater than zero, when considering the life cycle emissions, which include emissions from cradle to grave (Cherubini, 2010a). In bioenergy systems, emissions can arise from resources used during biomass production such as herbicides and pesticides, water, soil, biomass pre-treatments, collection, and transportation. Direct and indirect Emissions from land use changes should also be accounted for in life cycle analysis. Changes in the land cover can greatly affect the carbon stored in soil and plants. For instance, there is carbon emission when forest land is converted to pasture or agricultural land. Indirect land use changes occur when an agricultural land starts to be used for growing energy crops, if the demand for food and feed remains, a piece of land in another place has to be converted to agriculture, creating carbon emissions (Melillo et al., 2009). Life cycle analysis has shown that some bioenergy systems based on resource intensive energy crops can have higher carbon emissions than the fossil fuel they intend to replace, which shows the importance of accurate analysis upon choice of these systems (Gnansounou et al., 2009; Lapola et al., 2010). Bioenergy systems can also lead to socio-economical impacts on issues such as landscape, water and food security and price, employment generation, among others (German and Schoneveld, 2012; Ribeiro, 2013).
Uwe R. Fritsche, … Aurelie Perrin, in The Role of Bioenergy in the Bioeconomy, 2019
6.4.1 Methodological Background
Bioenergy production interacts with a host of environmental and ecological issues, ranging from human health to biodiversity, water, air, and soil quality through the eutrophication of ecosystems (see Section 6.1). Its impacts may be either negative or positive, depending on the systems and counterfactual situations considered. Bioenergy crops may increase or decrease biodiversity, as well as deplete or replenish soil organic matter stocks (Chum et al., 2011). To guide the implementation of bioenergy projects and optimize their environmental costs and benefits, a wealth of methods were developed over the last decades to provide relevant quantitative indicators of environmental impacts. Their main objective lies in the comparison with fossil-based alternatives, but they also seek to capture effects specific to bioenergy and feedstock production, in particular in relation to the use of natural resources such as land and water. These assessments of environmental sustainability have been high on the policy agenda for bioenergy, assigning for instance mandatory performance targets for the climate mitigation potential of biofuels (Gnansounou and Pandey, 2017).
While this section focuses on life cycle assessment (LCA), currently the most commonly used framework to assess bioenergy chains (Cherubini, 2010; Hellweg and Mila i Canals, 2014), other methods are worth mentioning here insofar as they complement this approach. From the point of view of the use of natural resources, “Emergy assessment” provides a “donor’s” perspective (as opposed to user’s with LCA) to the efficiency of a bioenergy chain. It computes its capacity to convert incoming solar radiation into utilizable energy, accounting for the same life cycle stages as LCA (Perrin et al., 2017). The ecological footprint pursues a similar objective via a single metric, the use of global hectares of biosphere that supply both feedstock and sinks for the pollutants emitted by the system (de Oliveira et al., 2005). Lastly, the ecosystem services framework appears particularly relevant to bioenergy since it can account for the implications of developing nonfood biomass on ecosystems in general (Koh and Ghazoul, 2010), and their capacity to regulate climate and biogeochemical cycles, to provide food, feed, fiber, and fuel, along with cultural services. However, this framework focuses on feedstock production and does not consider the whole life cycle of bioenergy systems. Growing bioenergy feedstock or extracting it from ecosystems is likely to impact biodiversity, either positively or negatively depending on the former use of land (Chum et al., 2011). However, a recent review of literature studies addressing this issue underlined an overall negative trend in relation to bioenergy development, but also a lack of consensus on the methodology used to estimate its effects, with metrics ranging from species richness to proxies such as habitat quality change (Gaba, 2018). On-going work under the auspices of the International Programme on Biodiversity and Ecosystem Services is likely to shed light on this particular matter.
Among the diversity of environmental assessment methods, LCA is predominanty used for policy purposes, eco-design of products, or the information of consumers. It aims to estimate the impacts resulting from the use of a particular product through its entire life cycle “from cradle to grave” (i.e., from the extraction of raw materials to the recycling or disposal of the product considered). The results are expressed relative to a measure reflecting the usefulness of the product system, called “functional unit.” For bioenergy systems, functional units usually involve final usages (e.g., 1 km traveled in a passenger car) or the supply of energy carriers (e.g., 1 kWh of electricity delivered to the grid). These choices are directly related to the goals of the assessment, which may be diverse: benchmarking a given product against an alternative or reference product (e.g., bio-based versus fossil-derived, or first-versus second-generation biofuels), identifying “hotspots” in the life cycle of a product to improve its environmental performance or reporting the environmental footprint of a product or a portfolio of products to consumers or regulation authorities.
LCA is an ISO-standardized (ISO 14044, 2006) method consisting of four stages:
goals and scope of the study, including the definition of system boundaries and the functional unit(s);
the inventory of resource consumption (e.g., fossil energy) and environmental emissions (e.g., greenhouse gases (GHGs)) occurring throughout the product’s life cycle;
the characterization of the potential impacts associated with the emissions of pollutants, which are grouped into broad impact categories such as global warming or human toxicity; and
interpretation of impact results and system optimization.
The implementation of LCA will be illustrated in Section 6.4.3 in the context of miscanthus production in Eastern France, while the following section introduces key issues in its application to bioenergy systems.
Ranadhir Mukhopadhyay, … Julie Mukhopadhyay, in Climate Change, 2018
Bioenergy can be obtained from biological and renewable sources. And, South Asia offers a conducive environment for accelerating the use of bioenergy technologies. Nearly 25% of its primary energy comes from biomass resources, and close to 70% of rural population depend on biomass to meet their daily energy needs. Bioenergy is of two types—traditional and modern. The traditional type appears in solid form that includes fuel-wood, charcoal, wood pellets, animal-dung, briquettes and so forth. The modern bioenergy, in contrast, comes in liquid form that includes bioethanol and biodiesel (Gumartini, 2009).
Traditional Bioenergy: The burning of biomass is still prevalent widely in South Asia for energy needs, despite the fact that biomass burning for cooking causes severe indoor air pollution impacting health, particularly of women and children. Hence, any critical technological improvement in the form of a cheap efficient oven that involves low-cost biomass burning with the least GHG emission could bring about a socioeconomic-health revolution in South Asia. The children, who were supposed to study, are being engaged in collecting wood-biomass, refusing in the process long-term HR development in the country. Although lately, respective governments in South Asia are gearing up to supply LPG stoves to rural households for cooking. The unsustainable use of forest biomass by industries and increasing demand for land has led to deforestation and change in land use that contribute about 40% of carbon emissions from anthropogenic sources (WRI, 1996).
Modern Bioenergy: The modern type of bioenergy is produced through anaerobic digestion—a type of biological process—and is also known as biofuel/biodiesel. This ester-based fuel-oxygenate is derived from renewable bioresources such as jatropha, soybean, mustard, rapeseed, peanuts, palm oil, other vegetable oils, and animal waste like beef tallow (Raju, 2006). Biofuel takes a short period of time (days, weeks, or months) to prepare, compared to millions of years taken by fossil fuel. Biofuels can also be made through chemical reactions, carried out in a laboratory or industrial setting to use organic matter (i.e., biomass) to make fuel. Biofuel is cheap, environment friendly, and does not necessarily depend on vagaries of nature (Raju, 2006). Countries spending huge sums on oil imports would naturally be interested to introduce biofuels aggressively by cutting down the cost of production.
In South Asia, India is promoting bioethanol and biodiesel through phased mandates, fixed prices, and tax incentives, with production picking up since 2006. This includes production of ethanol from sweet sorghum, sugar beet, cassava, and tapioca, and production of biodiesel from nonedible seed bearing trees/shrubs like jatropha. To avoid any conflict between food and biofuel (as they compete for the same land to grow), planting biofuel crops only on wastelands throughout the country is recommended. In addition, integrating such a production with rural development programs is being worked out (Institute for Global Environmental Strategies White Paper), to encourage further research and development on cultivation, processing and production of biofuels. Moreover a blending mandate of 20% ethanol and biodiesel by 2017 is being explored.
Besides India and Pakistan, Bangladesh is also gearing up and has allowed private companies to explore manufacturing fuel alcohol in the country. An investment of US$4.5 million will be made for a 12,000 L/day ethanol plant in Bangladesh, which would use molasses as a feedstock. This modern group of bioenergy uses highly efficient combustion technology under tight regulations on emissions (Lali, 2016).
Carmen Lago, … Yolanda Lechón, in The Role of Bioenergy in the Bioeconomy, 2019
1.1 Nexus Bioenergy–BE
Bioenergy is defined as a renewable energy produced from natural sources capable of replacing fossil energy. There exist a wide range of biological resources that can be used to produce bioenergy such as energy crops, biomass residues from forest and crops, wastes and by-products from agro-industries and pulp and paper industries, wet organic wastes and the organic fraction of municipal solid wastes. Macro algae, microalgae, seaweeds, and aquatic plants are also considered very attractive future biological resources (OECD/IEA, 2017). Regardless of the resource, bioenergy can be used as a sustainable source of power providing heat, gas, and fuel to produce heat, electricity, and cogeneration and transportation fuels. More recently, biomass can also be used for the production of biomaterials and bioproducts.
Projections by the International Energy Agency (IEA) provide a clear vision of the importance of bioenergy expansion. According to the same source, bioenergy will provide nearly 17% of the final energy demand by 2060. At the same time, bioenergy can reach 20% of cumulative greenhouse gas (GHG) emission savings (OECD/IEA, 2017; Scatlat et al., 2015). These remarkable figures must be obtained in a sustainable way contributing to decarbonize the energy systems. Modern bioenergy is obtained by mature technologies currently available in the biomethane market from wastes and residues, district heating networks, agricultural residues to generate electricity, and different transportation fuels, while other technologies, mostly related to transportation fuels are close to market (biomass gasification, pyrolysis and ethanol from lignocellulosic feedstock) and require additional support.
The BE concept is still under development. According to the OECD, BE refers to the set of economic activities relating to the invention, development, production, and use of biological products and processes. According to the same source, BE could bring major future benefits related to improvements in people’s health, agriculture, and industrial productivity boosts while enhancing environmental sustainability (OECD, 2009). Other authors such as McCormick and Kautto understand BE as an economy where the basic components for the production of materials, chemicals, and energy are derived from renewable biological resources (McCormick and Kautto, 2013). The European Commission first defined BE as an economy where production of food, feed, fiber, bio-based products, and bioenergy is efficient and sustainably obtained from renewable resources from land, fisheries, and aquaculture environments including the related public goods (EC, 2012). Later, in 2014, the concept was modified to include that efficient and sustainable primary production and processing meet industry demand, consumer’s needs, and at the same time address environmental challenges such as climate change (van de Pas, 2015). Other authors stated that BE uses renewable biological biomass (trees, shrubs, crops, plantations, algae and aquatic plants, waste and primary agricultural residues, waste and secondary agricultural residues, and successive generations of waste and residues) in its production processes obtaining different types of outputs (thermal energy, liquid fuels, chemicals, bioproducts, food and fodder, as well as cosmetics and medicines; Adamowicz, 2017). More recently, BE has gone from being perceived as a promise to become a tangible reality that will play a remarkable role when it comes to achieving global sustainability (Maciejczak, 2017). On the same line, the revised Bioeconomy Strategy and Action Plan broadens the definition of the BE, which must to make connections with other industrial sectors (construction, engineering, manufacturing, information and communication technology, and urban planning) to make human activity more environmentally friendly, more circular, more bio-based, more nature-inspired, more inclusive, and more competitive, and ultimately more sustainable (Rauschen and Esch, 2017).
Over the next few years, the concept of BE will probably continue to evolve until a more precise and consensual definition is achieved.
O. Olsson, B. Hillring, in Comprehensive Renewable Energy, 2012
5.06.2 Biofuels, Biomass, and Bioenergy: Definitions
Bioenergy markets are still a relatively new phenomenon. One symptom of this is the lack of terminological consensus in the literature on bioenergy markets. A typical example of this is the term ‘biofuel’, which according to the European standard is “any fuel produced directly or indirectly from biomass”  and according to Encyclopedia Britannica is “any fuel that is derived from biomass” . However, in both research literature and mainstream media, the term biofuel is to a large degree synonymous with ‘liquid biofuel’ . In the same vein, solid biofuels such as wood chips or wood pellets are often referred to as ‘biomass’. As we do not wish to encourage this rather illogical terminology, we will use the term ‘biofuels’ for all forms of biomass used for energy purposes. This means that bioethanol and biodiesel are referred to as ‘liquid biofuels’, and wood pellets, firewood, and wood chips are referred to as ‘solid biofuels’, and biomethane as a ‘gaseous biofuel’. An overview of different biomass resources and how they may be utilized for energy purposes can be found in Figure 1 .
Figure 1. Means of conversion from biomass to biofuels.
Modified from Hammarlund C, Ericsson K, Johansson H, et al. (2010) Bränsle för ett Bättre Klimat: Marknad och Politik för Biobränslen (Fuel for a Better Climate: Biofuel Market and Policies). Lund, Sweden: Agrifood Economics Centre.
Douglas Arent, … Alison Wise, in Energy, Sustainability and the Environment, 2011
3.5 Growth of Bioenergy
Bioenergy remains one of the world’s most used energy sources globally. However, most of this use is categorized as “traditional biomass” in developing countries. Modern bioenergy has two primary subuses: biopower and biofuel.
For biofuels, the United States has become the dominant ethanol producer (corn-based for blending gasoline), producing 18 billion liters in 2006, 24 billion liters in 2007 (RFA, 2009), and 34 billion liters in 2008 (REN21, 2009). However, ethanol production in Brazil increased to almost 19 billion liters in 2007 and 25 billion liters in 2008. Biodiesel production has increased in recent years at 20%–100% the annual rates, particularly in Germany, France, Brazil, Argentina, and the United States. Meanwhile, the impact of the production and consumption of biofuels on food prices, biodiversity, water consumption, and the mitigation of greenhouse gases (GHGs) is strongly debated, especially in Europe and the United States. Global biofuel production has more than quadrupled from 4.8 billion gallons2 in 2000 to about 24 billion in 2009, but still accounts for less than 3% of the global transportation fuel supply (Figure 16). About 90% of production is concentrated in the United States, Brazil, and the EU (Figure 17). Production could become more dispersed if development programs in other countries, such as Malaysia and China, are successful. The leading feedstocks for producing biofuels include corn, sugar, and vegetable oils.
Figure 16. Global Production of Liquid Biofuels between 2000 and 2008.
Source: RFA 2010, REN21 2010
Figure 17. Global Biofuel Production by Country in 2009.
Source: RFA 2010, REN21 2010
The installed capacity of biopower (biomass used to generate electricity) grew at a rate of about 4% a year between 2000 and 2008; the capacity increased from about 37 GW in 2000 to 52 GW in 2008 (Figure 18). The worldwide biopower sector is expected to increase by another 21 GW in the next five years to reach a cumulative installed capacity of 71 GW by 2012, suggesting a growth rate of about 9% a year (NEF, 2008a). The growth in the worldwide biopower energy market is particularly driven by the United States, Brazil, and Germany. However, by 2012, Spain and India are expected to surpass the leading nations in annual installed capacity—Spain is expected to add 8 GW and India is expected to add 4 GW annually, becoming the fastest-growing biopower nations in the world (NEF, 2008a).
Figure 18. Global Growth of Biomass Based Electricity Generation Capacity.
Source: DOE (2009).
3.5.1 Bioenergy Market Development
Bioenergy is poised to create a growing impact on the global energy infrastructure, provided that technology innovation and distribution issues continue to be addressed. Observers have predicted that the biofuels industry has a 10-year window of opportunity to evolve into a global, interdependent energy system (Accenture, 2008). The growth of this industry will depend on the fluctuation of traditional fuel prices, potential instability of existing fossil fuel resources and distribution, and the technological innovation needed to adapt the worldwide vehicle and transport fleet to new fuels. Future trends could include the use of first-generation biofuels and “next-generation” biofuels side by side in the energy market, with fuels sourced from the more challenging cellulosic feedstocks entering after several years.
Market data on biomass power capacity and generation is sparse: The European Commission (EC, 2008a; 2008b) does not distinguish between electricity generation from biomass and heat production from biomass in its statistics. Germany has the most extensive data collected on biomass electricity generation and capacity of any country. Germany provides differentiated tariffs for each type of biomass electricity generation, which has led to market development in all areas. At the end of 2008, the globally installed biopower capacity was estimated at 52 GW, mostly in developing countries (25 GW) and EU-27 (15 GW) (REN21, 2009) (Figure 19).
Figure 19. Total Global Investment in Biomass Electricity.
Source: UNEP (2009).
New investments in biofuels reached $16.9 billion in 2008 (UNEP, 2009) (Figure 20). For 2008, investors announced more than $6 billion for ethanol production facilities in Brazil, Canada, France, Spain, and the United States. In 2007, about 50 billion liters of ethanol fuel were produced globally (RFA, 2008), and in 2008 about 67 billion liters (REN21, 2009).
Figure 20. Venture Capital/Private Equity Cumulative Biofuel Investment.
Source: NEF (2009a).
Figure 20 highlights investment trends for technologies that appear to hold the most market promise for “next-generation” applications. From October 2006 to December 2008, there was $915 million privately invested in this new generation of biofuels (NEF, 2009). Approximately $220 million of this has gone to researching algae as a potential feedstock, as companies look to alternative feedstocks to address controversy regarding energy versus food markets. In this period, investments were made in biobutanol companies totaling $154 million; biobutanol can be used in the existing vehicle fleet and can be distributed in the existing pipeline infrastructure (NEF, 2009a). Finally, $539 million was invested in enzymatic hydrolysis; this technology is attractive because of its compatibility with “first-generation” starch and sugar hydrolysis and fermentation.
The term “next generation” in bioenergy is widely accepted for a technology that uses nonfood feedstocks and new ways of converting the power stored in plant-based carbohydrates to usable energy. Figure 21 captures the essence of this by categorizing three primary nonfood feedstocks, with six conversion technology pathways, and multiple fuel and product outputs. A fourth important fuel output category is “fungible” fuels, which are fully compatible with existing petroleum refining, distribution, and use value chains. These advances could widen the market for biofuels considerably. New feedstocks could also dramatically reduce the cost of fuel production and reduce land-use requirements and environmental emissions.
Figure 21. Pathways to Biofuels.
3.5.4 Bioenergy and Food versus Fuel Debate
The perception that land and feedstocks for bioenergy may be competing with their potential use for food can have negative ramifications on continued government support for the technology. Renewable energy RE production continues to rely on public policy support; as of late 2008, subsidies for renewables globally are greater than $20 billion per year, a majority of which are allocated for biofuels. While perception is key, analyses conducted by New Energy Finance, the Department of Energy (DOE), and the Food and Agriculture Organization (FAO) (NEF, 2008a; Karsner, 2008; Glauber 2008) note that biofuel production has not been the dominant factor in the steady increase in food prices from 2004 to 2008. The authors conclude that, while biofuel production has been one driver of food-price inflation, more significant drivers are the increase of input costs, changes in consumption habits, and increase in global population.3 The decrease of food prices after mid-2008 supports this finding. Figure 22 shows the estimated fraction that biofuels contribute to the supply and demand price drivers for grains, food oils, and sugar.
Figure 22. Contribution of Biofuels to Food Supply/Demand Price Drivers between 2004 and April 2008.
Source: NEF (2008a) and UDOP (2008).