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Biofuels are fuels made from organic matter. They include liquid fuels such as ethanol, biodiesel, and methanol; gaseous fuels such as methane and carbon monoxide; and solid fuels such as biochar and the more traditional charcoal. Biofuels may have some environmental advantages over gasoline and diesel fuels, but they are more expensive to produce and cannot supply more than a small part of the world’s total transportation energy needs. And because they compete with food crops and nature for land, water, and nutrients, expanding the use of biofuels could negatively affect human health and natural ecosystems.

The 2009 NIPCC report (Idso and Singer, 2009) addressed the likely adverse consequences of expanding the use of biofuels as reported by several scientists in the peer-reviewed literature. Here we document additional studies that raise similar concerns but were published after those discussed in the 2009 report.

We begin with the study of Delucchi (2010), who is associated with the Institute of Transportation Studies at the University of California, Davis (USA). Delucchi writes, “governments worldwide are promoting the development of biofuels, such as ethanol from corn, biodiesel from soybeans, and ethanol from wood or grass, in order to reduce dependency on oil imported from politically unstable regions of the world, spur agricultural development, and reduce the climate impact of fossil fuel combustion.” In light of the magnitude of this endeavor, Delucchi reviews what has been learned by many other students of the subject, after which he discusses “the impacts of biofuels on climate change, water use, and land use.”

Delucchi’s analysis leads him to state, “it is likely that biofuels produced from crops using conventional agricultural practices will not mitigate the impacts of climate change.” They will instead “exacerbate stresses on water supplies, water quality, and land use, compared with petroleum fuels.” He quotes Phalan (2009) as stating, “if risks and uncertainties are inadequately assessed and managed, even the best biofuels have the potential to damage the poor, the climate and biodiversity.”

“To avoid these problems,” in Delucchi’s words, “biofuel feedstocks will have to be grown on land that has no alternative commercial use and no potential alternative ecological benefits, in areas with ample rainfall or groundwater, and with little or no inputs of fertilizers, chemicals, and fossil fuels.” He adds, “it is not clear that it can be done economically and sustainably at large scales.”

In a paper focusing on economics, Bryan et al. (2010) “assessed the potential benefits, costs, and trade-offs associated with biofuels agriculture to inform bioenergy policy.” Specifically, they “assessed different climate change and carbon subsidy scenarios in an 11.9 million hectare region in southern Australia,” where they “modeled the spatial distribution of agricultural production, full life-cycle net greenhouse gas (GHG) emissions and net energy, and economic profitability for both food agriculture (wheat, legumes, sheep rotation) and biofuels agriculture (wheat, canola rotation for ethanol/biodiesel production).”

Results indicated “biofuels agriculture was more profitable over an extensive area of the most productive arable land,” producing “large quantities of biofuels” that “substantially increased economic profit.” The end result, however, was “only a modest net GHG abatement” that had “a negligible effect on net energy production.” In addition, they indicate the economic profit was largely due to “farm subsidies for GHG mitigation” and that whatever benefits were accrued came “at the cost of substantially reduced food and fiber production.”

Examining the issue from a different angle, Erisman et al. (2010) state, “there is much discussion on the availability of different biomass sources for bioenergy application and on the reduction of greenhouse gas emissions compared to [emissions from] conventional fossil fuels,” but “there is much less discussion on the other effects of biomass, such as the acceleration of the nitrogen cycle through increased fertilizer use resulting in losses to the environment and additional emissions of oxidized nitrogen.” Erisman et al. thus provide “an overview of the state of knowledge on nitrogen and biofuels,” particularly as pertaining to several sustainability issues.

According to the five researchers, “the contribution of N2O emissions from fertilizer production and application make the greenhouse gas balance for certain biofuels small positive or even negative for some crops compared to fossil fuels” because “N2O is a 300 times more effective greenhouse gas than CO2” and N2O emissions in the course of biofuel production “might be a factor 2–3 [times] higher than estimated up until now from many field trials.” In addition, they mention several other nitrogen-related environmental impacts of biofuel production, including modification of land for the growing of biofuels, wastes associated with biomass processing, and the “pollution entailed in constructing and maintaining equipment, transportation and storage facilities,” as well as “the higher levels of eutrophication, acidification and ozone depletion” associated with biofuels due to the nitrogenous compounds released to the atmosphere during their agricultural production.

In a contemporaneous article published in Ecological Applications, Bouwman et al. (2010) assessed the global consequences of implementing first- and second-generation bioenergy production in the coming five decades. They focused on the nitrogen cycle and used “a climate mitigation scenario from the Organization for Economic Cooperation and Development’s (OECD’s) Environmental Outlook, in which a carbon tax is introduced to stimulate production of biofuels from energy crops.” They calculated “the area of energy crops will increase from 8 Mha in the year 2000 to 270 Mha (14% of total cropland), producing 5.6 Pg dry matter per year (12% of energy use) in 2050.” They also found “this production requires an additional annual 19 Tg of N fertilizer in 2050 (15% of total), and this causes a global emission of 0.7 Tg of N2O-N (8% of agricultural emissions), 0.2 Tg NO-N (6%), and 2.2 Tg of NH3--N (5%).” In addition, they observed, “2.6 Tg of NO3--N will leach from fields under energy crops.”

What might be some of the unfavorable impacts of these consequences of carbon-tax-supported biofuel production? For starters, the three employees of the Netherlands Environmental Assessment Agency note the greenhouse gas emissions that are supposed to be reduced by using biofuels instead of fossil fuels “are offset by 20% in 2030 and 15% in 2050 if N2O emission from the cultivation of energy crops is accounted for.” And even this blowback is but a fraction – 30–60 percent for maize and sugar cane, according to Bouwman et al. – “of total emissions from the cultivation, processing, and transportation of biofuels.” In addition, they write, “on a regional scale, increased N leaching, groundwater pollution, eutrophication of aquatic and terrestrial ecosystems, N2O and NH3 emissions from energy crop production, and NOX emissions from combustion of biofuels may cause relevant loss of human and ecosystem health.” With respect to the availability of land for the growing of biofuels, Bouwman et al. write, “the OECD-GC scenario shows a rapid expansion of agricultural land, mainly in Africa and the former Soviet Union,” and “this expansion will lead to a further loss of biodiversity.” The authors conclude by saying “bioenergy is economically feasible,” but only “because of the climate change policies” that are “implemented through carbon taxes.”

In an article published in the Journal of Plant Nutrition and Soil Science, Rattan Lal (Lal, 2010) of the Carbon Management and Sequestration Center of Ohio State University (USA) introduces the subject of his concern by writing, “the world is faced with the trilemma of climate change, food insecurity, and energy demand.” He states, (1) “there still are more than one billion food-insecure people in the world (FAO, 2009a,b),” (2) “the world food supply will have to be doubled between 2005 and 2050 (Borlaug, 2009) because of the increase in population and change in dietary preferences,” and (3) “the world energy demand is also increasing rapidly and is projected to increase by 84% by 2050 compared with 2005.” What makes the problem even worse, he observes, is that in an attempt to meet the anticipated increase in the global demand for energy, “the emphasis on biofuels is strongly impacting the availability of grains for food and soil resources for grain production.”

In response to this latter problem, Lal notes, crop residues are being “widely considered as a source of lignocellulosic biomass.” However, he states that removal of crop residues for this purpose “is not an option (Lal, 2007) because of the negative impacts of removal on soil quality, and increase in soil erosion (Lal, 1995)” and the loss of the residue’s “positive impacts” on “numerous ecosystem services.” Therefore, observing yet another shift in tactics, Lal reports that degraded soils are being considered as possible sites for establishing energy plantations. However, Lal (2010) notes, the extremely low capacity for biomass production from these soils means the amount of biofuel produced on globally abandoned agricultural land cannot even meet 10 percent of the energy needs of North America, Europe, and Asia, citing the work of Campbell et al. (2009) in this regard. Yet even these considerations are only half the problem.

In addition to the need for a considerable amount of land, the “successful establishment of energy plantations also needs plant nutrients” and an “adequate supply of water,” Lal notes. An adequate supply of water is on the order of 1,000 to 3,500 liters per liter of biofuel produced, which is, as Lal puts it, “an important factor.” And he notes this strategy also will “increase competition for limited land and water resources thereby increasing food crop and livestock prices (Wise et al., 2009).”

In closing, Lal writes society should not take its precious resource base for granted, stating, “if soils are not restored, crops will fail even if rains do not; hunger will perpetuate even with emphasis on biotechnology and genetically modified crops; civil strife and political instability will plague the developing world even with sermons on human rights and democratic ideals; and humanity will suffer even with great scientific strides.”

Additional concerns over the use of biofuels have been expressed by other authors. In a paper published in the Journal of Agricultural and Environmental Ethics, Gomiero et al. (2010) examine the wisdom of appropriating much of the planet’s land and water resources to support large-scale production of biofuels as replacements for fossil fuels. They come to several damning conclusions about the enterprise.

They report there is not enough readily available land to produce much fuel from biomass without causing a severe impact on global food production, while adding, “even allocating the entire USA cropland and grassland to biofuels production, the energy supply will account for only a few percentage points of the USA energy consumption,” which suggests “there is no hope for biomass covering an important share of USA energy demand.” Noting “the same is true for the European Union,” the researchers go on to observe that “biofuel production cannot, in any significant degree, improve the energy security of developed countries,” for to do so “would require so vast an allocation of land that it would be impossible for a multitude of reasons.”

Another problem Gomiero et al. observe is that biofuel production, including cellulosic ethanol from crop residues and grasslands, “does not appear to be energetically very efficient.” In fact, they note, fierce debates have arisen over whether the energy output/input ratio of various biofuel production enterprises is 0.2 of a unit above or below 1.0, which seems rather small in light of another item they report, that “our industrial society is fueled by fossil fuels that have an output/input ratio 15–20 times higher.” Indeed, they write that recent assessments demonstrate extensive biofuels production may actually tend to “exacerbate greenhouse gas emissions and in turn global warming.” They also state biofuels “may greatly accelerate” the destruction of natural ecosystems and their biodiversity by “the appropriation of far too large a fraction of net primary production,” thus resulting in a threat to their “health, soil fertility, and those key services needed by human society.”

In concluding, Gomiero et al. warn “biofuels cannot be either our energy panacea, nor supply even a minimal share of energy supply for our society without causing major social and environmental problems.” Therefore, they suggest we use our “hard earned money,” as they put it, to “help farmers, both in developed and developing countries, to adopt energy saving-environmentally friendly agricultural practices, that can really help to cut greenhouse gas emissions, prevent soil erosion, reduce water consumption, relieve the environment from toxic pollutants, preserve wild and domesticated biodiversity and supply many other services.” And as the three scientists advise in their concluding sentence, “we should be careful not to let our ‘energetic despair’ (or vested interest) lead us to worsen the very same environmental and social problems we wish and need to solve.”

Introducing their contribution to the subject, Gelfand et al. (2010) write, “recently, the prospect of biofuel production on a large scale has focused attention on energy efficiencies associated with different agricultural systems and production goals,” but “few empirical studies comparing whole-system multiyear energy balances are available.” In fact, they state that as far as they are aware, “there are no studies that directly compare food vs. fuel production efficiencies in long-term, well-equilibrated cropping systems with detailed descriptions of fossil energy use.”

To begin filling this data void, Gelfand et al., as they describe it, “used 17 years of detailed data on agricultural practices and yields to calculate an energy balance for different cropping systems under both food and fuel scenarios.” They examined one forage and four grain systems in the U.S. Midwest that included “corn-soybean-wheat rotations managed with (1) conventional tillage, (2) no till, (3) low chemical input, and (4) biologically based (organic) practices, and (5) continuous alfalfa,” and “compared energy balances under two scenarios: all harvestable biomass used for food versus all harvestable biomass used for biofuel production.”

The three researchers report “energy efficiencies ranged from output:input ratios of 10 to 16 for conventional and no-till food production and from 7 to 11 for conventional and no-till fuel production, respectively.” Such a result, Gelfand et al. write, “points to a more energetically efficient use of cropland for food than for fuel production,” and the large differences in efficiencies attributable to the different management techniques they evaluated suggest there are “multiple opportunities for improvement.”

Exploring a different aspect of the debate, Witt (2010) notes “several studies in the last five years have warned against the potential impact of promoting biofuel crops that are known to be invasive or to have potentially invasive characteristics,” citing the studies of Raghu et al. (2006), Barney and DiTomaso (2008), Howard and Ziller (2008), and Buddenhagen et al. (2009). Witt notes “a large number of proposed biofuel crops share the same traits as known invasive plant species,” and many of them “are already present in Africa.” In light of these observations, Witt assesses the impacts of several species of the invasive Prosopis genus in Kenya and South Africa, where the spiny trees and shrubs have invaded more than four million hectares of crop and pasture land.

Witt writes, “communities in Kenya and elsewhere are becoming increasingly concerned about the displacement of other species important for local livelihoods, especially fodder species for livestock.” They are also concerned, he continues, about the invasive species’ encroachment onto “paths, dwellings, water sources, farms and pastureland” and their “negative impacts on animal and human health with injuries due to thorns resulting in some human fatalities,” citing Mwangi and Swallow (2005) and Maundu et al. (2009). In addition, he notes the plants’ tendency to invade riparian zones, dry river beds, and lowlands, where they “tap into underground water sources,” means they “interfere with drainage, blocking watercourses and exacerbating the effects of flooding.” Witt states the displacement of native plants by Prosopis species is especially serious, noting “the World Health Organization estimates that up to 80% of the world’s rural populations depend on [native] plants for their primary health care.”

Witt concludes that nonnative species that are known to be invasive elsewhere and have been deemed to be a high-risk species “should not be introduced and cultivated,” because “the costs associated with invasive species, even those that are deemed to be beneficial, in most cases, outweigh the benefits that accrue from their use.” He ends with the warning that “no widespread invasive plant species has been controlled through utilization alone in any part of the world.”

Lastly, in a paper published in AMBIO: A Journal of the Human Environment, Mulder et al. (2010) assess the connection between water and energy production by conducting a comparative analysis for estimating the energy return on water invested (EROWI) for several renewable and nonrenewable energy technologies using various life cycle analyses. This approach mirrors the energy return on energy investment (EROEI) technique used to determine the desirability of different forms of alternative energy, with the technique’s most recent application being adjusted to consider also the global warming potentials of the different forms of non-fossil-fuel energy and the greenhouse gases emitted to the atmosphere in the process of producing and bringing them to the marketplace.

The reason for bringing water into the equation derives from the facts, as noted by Mulder et al., that (1) “water withdrawals are ubiquitous in most energy production technologies,” (2) “several assessments suggest that up to two-thirds of the global population could experience water scarcity by 2050 (Vorosmarty et al., 2000; Rijsberman, 2006),” (3) “human demand for water will greatly outstrip any climate-induced quantity gains in freshwater availability (Vorosmarty et al., 2000; Alcamo et al., 2005),” and (4) the increased need for more fresh water “will be driven by the agricultural demand for water which is currently responsible for 90% of global freshwater consumption (Renault and Wallender, 2006).”

The three U.S. researchers state their results suggest “the most water-efficient, fossil-based technologies have an EROWI one to two orders of magnitude greater than the most water-efficient biomass technologies, implying that the development of biomass energy technologies in scale sufficient to be a significant source of energy may produce or exacerbate water shortages around the globe and be limited by the availability of fresh water.”

In considering the policy ramifications, these findings will not be welcomed by those who promote biofuel production as a means of combating what they call “the threats posed by ‘climate refugees’ and ‘climate conflict’ to international security,” as discussed by Hartmann (2010) in the Journal of International Development, where she identifies some of the principals in the spreading of what she calls this “alarmist rhetoric” to various United Nations agencies, NGOs, national governments, security pundits, the popular media, and, specifically, the Norwegian Nobel Committee of 2007, which, as she describes it, “warned that climate-induced migration and resource scarcity could cause violent conflict and war within and between states when it awarded the Nobel Peace Prize to Al Gore, Jr. and the Intergovernmental Panel on Climate Change.”

Hartmann goes on to suggest “this beating of the climate conflict drums has to be viewed in the context of larger orchestrations in U.S. national security policy.” And in this regard it is clear that the promotion of biofuels to help resolve these concerns will only exacerbate them in one of the worst ways imaginable, providing a “cure” that is worse than the disease.

Hartmann notes, “in the United States, members of Congress eager to pass climate legislation” – which will likely mandate the use of more biofuels – “have resorted to the security threat argument as a way to win support on Capitol Hill.” She answers this by remarking that “according to the New York Times (2009), ‘many politicians will do anything for the Pentagon.’”

Clearly, there are various motives involved in the debate over possible CO2-induced climate change and what to do about it. Yet, it is equally clear that there simply is not enough land or fresh water on the face of the Earth to make the production of biofuels a viable and significant alternative to the mining and usage of fossil fuels.

From Climate Change Reconsidered, a work of the Nongovernmental International Panel on Climate Change

Biofuels are liquid and gaseous fuels made from organic matter. They include ethanol, biodiesel, and methanol. Biofuels may have some advantages over gasoline and diesel fuels, but they are more expensive to produce and can supply only a small part of the world’s total transportation energy needs. Because they compete with food crops and nature for land and nutrients, expanding the use of biofuels could negatively affect human health and natural ecosystems.

The IPCC does not discuss biofuels in the contributions of Group I (Science) or Group II (Impacts, Adaptation and Vulnerability) to the Fourth Assessment Report. When it finally does discuss them, in two sections of the contribution of Group III (Mitigation), it fails to address the likely adverse consequences of increased use of biofuels on human health and the natural environment. We discuss those consequences in this section.


About Biofuels

Biofuels are not new—Henry Ford’s first vehicle was fueled by ethanol—and conversion technologies exist or are in development for converting biomass into a wide range of biofuels suitable for heating, electric production, and transportation. For example, residues from agriculture and forestry long have been used by the lumber and papermaking industries to generate heat and power. Methane from animal waste and composting is captured and used locally or sold in commercial markets.

Of particular interest, and the focus of this section, is the biochemical conversion using enzymes of corn, soybeans, sugarcane, and other food crops into ethanol, biodiesel, and other biofuels used mainly for transportation. The country with the most aggressive biofuels program in the world is Brazil. After the country launched its National Alcohol Program in 1975, ethanol production in Brazil rose dramatically and now accounts for approximately 40 percent of total fuel consumption in the country’s passenger vehicles (EIA, 2008).

Ethanol became popular as a gasoline supplement in the U.S. during the 1990s, when Congress mandated that oil refiners add oxygenates to their product to reduce some emissions. Congress did not provide liability protection for the makers of methyl tertiary butyl ether (MTBE), ethanol’s main competitor in the oxygenate business, so most companies quickly switched from MTBE to ethanol (Lehr, 2006). Some states also began to mandate ethanol use for reasons discussed below.

Most ethanol made in the U.S. comes from corn. Its production consumed 13 percent of the U.S. corn crop (1.43 billion bushels of corn grain) in 2005 and an estimated 20 percent of the 2006 crop. E10 (a blend of 10 percent ethanol and 90 percent gasoline) is widely available. E85 is an alternative fuel (85 percent ethanol and 15 percent gasoline) available mainly in corn-producing states; vehicles must be modified to use this fuel.

The Energy Policy Act of 2005 mandated the use of 4 billion gallons of ethanol in 2006. The 2007 Energy Independence and Security Act (EISA) subsequently mandated the use of 36 billion gallons of renewable fuels by 2022—16 billion gallons of cellulosic ethanol, 15 billion gallons of corn ethanol, and 5 billion gallons of biodiesel and other advanced biofuels (U.S. Congress, 2007).

Federal subsidies to ethanol producers in the U.S. cost taxpayers about $2 billion a year (Dircksen, 2006). Congress protects domestic ethanol producers by imposing a 2.5 percent tariff and 54 cents per gallon duty on imports. Ethanol producers with plants of up to 60 million gallons annual production capacity are eligible to receive a production incentive of 10 cents per gallon on the first 15 million gallons of ethanol produced each year. Ethanol is also subsidized by scores of other countries and by at least 19 U.S. states (Doornbosch and Steenblick, 2007, Annex 1, pp. 45-47).

U.S. ethanol output rose from 3.4 billion gallons from 81 facilities in 2004 to 9 billion gallons from 170 facilities in 2008 (RFA, 2009). According to a forecast by the Energy Information Administration (EIA), “total U.S. biofuel consumption rises from 0.3 quadrillion Btu (3.7 billion gallons) in 2005 to 2.8 quadrillion Btu (29.7 billion gallons) in 2030, when it represents about 11.3 percent of total U.S. motor vehicle fuel on a Btu basis” (EIA, 2008). In 2005 ethanol represented about 2 percent of total gasoline consumption, and biodiesel less than 0.2 percent of diesel consumption, in the U.S.

Doornbosch and Steenblick (2007), in a report produced for the Organization for Economic Cooperation and Development (OECD), reported that “global production of biofuels amounted to 0.8 EJ [exajoule] in 2005, or roughly 1% of total road transport fuel consumption. Technically, up to 20 EJ from conventional ethanol and biodiesel, or 11% of total demand for liquid fuels in the transport sector, has been judged possible by 2050.” Also for the world as a whole, EIA predicts “alternative fuels [will] account for only 9 percent of total world liquids use in 2030, despite an average annual increase of 5.6 percent per year, from 2.5 million barrels per day in 2005 to 9.7 million barrels per day in 2030” (EIA, 2008).

Costs and Benefits

Proponents of biofuels say their increased production will increase the supply of transportation fuels and therefore lead to lower prices. Critics of biofuels point out that ethanol often costs more, not less, than gasoline, either because of production costs or supplies that can’t keep pace with government mandates, and therefore leads to higher prices at least in the short run.

Ethanol has only two-thirds the energy content of gasoline, which makes it a poor value for most consumers. The production cost of ethanol (which is only one component in determining its price) has fallen as a result of technological innovation and economies of scale, but some properties of ethanol continue to make it expensive compared to gasoline. Transportation costs for ethanol, for example, are high because it picks up water if it travels through existing pipelines, diluting the ethanol and corroding the pipelines. Therefore, it is being trucked to the Northeast and along the Gulf Coast. Ethanol must be kept in a different container at the terminal and is blended into the gasoline in the truck on its way to the retailer from the terminal. This has caused regional shortages, further increasing the retail prices in these areas (Dircksen, 2006).

Ethanol also has been promoted as a fuel additive to reduce emissions. It reduces carbon monoxide in older vehicles and dilutes the concentration of aromatics in gasoline, reducing emissions of toxins such as benzene. Because ethanol has only two-thirds the energy content per volume as gasoline, it increases volumetric fuel use (with small increases in energy efficiency.) Ethanol increases air emissions such as aldehydes. In some areas, the use of 10 percent ethanol blends may increase ozone due to local atmospheric conditions (Niven, 2004).

Ethanol also is promoted as a “homegrown” and renewable energy source, so using more of it could help reduce a country’s dependency on foreign oil, which in turn might benefit national security and international relations. But ethanol used in the U.S. mostly supplants oil from domestic suppliers, which is more expensive than foreign oil, and leaves the country’s dependency on foreign oil the same or even makes it higher (Yacobucci, 2006). Rural communities benefit from the economic boost that comes from higher prices for corn and the jobs created by ethanol plants, but those economic benefits come at a high price in terms of higher food prices and tax breaks financed by government debt or higher taxes on other goods and services.

Finally, biofuels are renewable resources, which advocates say makes them environmentally friendlier than fossil fuels. But the energy consumed to make biofuels—to plant, fertilize, irrigate, and harvest corn and other feedstocks as well as to generate the heat used during the fermentation process and to transport biofuels to markets by train or trucks—is considerable. Fossil fuels (natural gas or coal) are typically the source of that energy. This environmental impact is the focus of the rest of this section.

Net Emissions

The US 2007 Energy Independence and Security Act (EISA) mandates that life-cycle greenhouse gas emissions of corn ethanol, cellulosic ethanol, and advanced biofuels achieve 20 percent, 60 percent, and 50 percent greenhouse gas (GHG) emission reductions relative to gasoline, respectively. But there is considerable controversy over whether these fuels do in fact reduce GHG emissions.

Numerous studies of GHG emissions produced during the life-cycle of ethanol (from the planting of crops to consumption as a fuel) have found them to be less than those of gasoline, with most estimates around 20 percent (Hill et al., 2006; Wang et al., 2007; CBO, 2009). Emissions vary considerably based on the choice of feedstock, production process, type of fossil fuels used, location, and other factors (ICSU, 2009). Liska et al. (2009), in their study of life-cycle emissions of corn ethanol systems, found the direct-effect GHG emissions of ethanol (without any offset due to changes in land use) to be “equivalent to a 48% to 59% reduction compared to gasoline, a twofold to threefold greater reduction than reported in previous studies,” largely because they incorporate a credit for the commercial use of dry distilled grain (DDG). They report that “in response to the large increase in availability of distillers grains coproduct from ethanol production and the rise in soybean prices, cattle diets now largely exclude soybean meal and include a larger proportion of distillers grains coproduct (Klopfenstein et al., 2008). Thus, the energy and GHG credits attributable to feeding distillers grains must be based on current practices for formulating cattle diets.” They give corn ethanol systems DDG credits ranging from 19% to 38% depending on region and type of fossil fuels used.

None of these estimates, however, takes into account the emission increases likely to come about from land-use changes. Righelato and Spracklen (2007) wrote that using ethanol derived from crops as a substitute for gasoline, and vegetable oils in place of diesel fuel, “would require very large areas of land in order to make a significant contribution to mitigation of fossil fuel emissions and would, directly or indirectly, put further pressure on natural forests and grasslands.” The two British scientists calculated that a 10 percent substitution of biofuels for gasoline and diesel fuel would require “43% and 38% of current cropland area in the United States and Europe, respectively,” and that “even this low substitution level cannot be met from existing arable land.”

Righelato and Spracklen add that “forests and grasslands would need to be cleared to enable production of the energy crops,” resulting in “the rapid oxidation of carbon stores in the vegetation and soil, creating a large up-front emissions cost that would, in all cases examined, out-weigh the avoided emissions.” They report further that individual life-cycle analyses of the conversion of sugar cane, sugar beet, wheat, and corn to ethanol, as well as the conversion of rapeseed and woody biomass to diesel, indicate that “forestation of an equivalent area of land would sequester two to nine times more carbon over a 30-year period than the emissions avoided by the use of the biofuel.” They conclude that “the emissions cost of liquid biofuels exceeds that of fossil fuels.”

Fargione et al. (2008), writing in Science, said “increasing energy use, climate change, and carbon dioxide (CO2) emissions from fossil fuels make switching to low-carbon fuels a high priority. Biofuels are a potential low-carbon energy source, but whether biofuels offer carbon savings depends on how they are produced.” They explain that “converting native habitats to cropland releases CO2 as a result of burning or microbial decomposition of organic carbon stored in plant biomass and soils. After a rapid release from fire used to clear land or from the decomposition of leaves and fine roots, there is a prolonged period of GHG release as coarse roots and branches decay and as wood products decay or burn. We call the amount of CO2 released during the first 50 years of this process the ‘carbon debt’ of land conversion. Over time, biofuels from converted land can repay this carbon debt if their production and combustion have net GHG emissions that are less than the life-cycle emissions of the fossil fuels they displace. Until the carbon debt is repaid, biofuels from converted lands have greater GHG impacts than those of the fossil fuels they displace.”

Fargione et al. calculate the number of years required to repay carbon debts for six areas: Brazilian Amazon (319 years), Brazilian Cerrado wooded (17 years), Brazilian Cerrado grassland (37 years), Indonesian or Malaysian lowland tropical rainforest (86 years), Indonesian or Malaysian peatland tropical rainforest (423 years), and U.S. central grassland (93 years). They observe that no carbon debt is incurred when abandoned cropland or marginal prairie in the U.S. is used without irrigation to produce ethanol. They conclude that “the net effect of biofuels production via clearing of carbon-rich habitats is to increase CO2 emissions for decades or centuries relative to the emissions caused by fossil fuel use,” and “at least for current or developing biofuels technologies, any strategy to reduce GHG emissions that causes land conversion from native ecosystems to cropland is likely to be counterproductive.”

In a companion essay in the same issue of Science, Searchinger et al. (2008) also describe the carbon debt due to land-use conversion, but measure it as the difference between biofuels and gasoline in GHG emissions measured in grams per MJ (megajoule) of energy. They begin by explaining that “to produce biofuels, farmers can directly plow up more forest or grassland, which releases to the atmosphere much of the carbon previously stored in plants and soils through decomposition or fire. … Alternatively, farmers can divert existing crops or croplands into biofuels, which causes similar emissions indirectly. The diversion triggers higher crop prices, and farmers around the world respond by clearing more forest and grassland to replace crops for feed and food.”

Searchinger et al. used the Greenhouse gases Regulated Emissions and Energy use in Transportation (GREET) computer program created by the Center for Transportation Research at Argonne National Laboratory to calculate the GHGs in grams of CO2 equivalent emissions per MJ of energy consumed over the production and use life-cycles of gasoline, corn ethanol, and biomass ethanol fuels. They observe that “emissions from corn and cellulosic ethanol emissions exceed or match those from fossil fuels, and therefore produce no greehouse benefits,” unless biofuels are given a “carbon uptake credit” for the amount of carbon dioxide removed from the air by the growing biofuels feedstocks. When that adjustment is made, they estimate that gasoline (which gets no carbon uptake credit) produces 92g/MJ; corn ethanol, 74g/MJ; and biomass ethanol, 27g/MJ.

Searchinger et al. then calculate the amount of land that would be converted from forest and grassland into cropland to support the biofuels and, like Fargione et al. (2008), apply the GHG emissions due to land-use change to each type of fuel. The result is that total net GHG emissions from both kinds of biofuel exceed those from gasoline, 177g vs. 92g in the case of corn ethanol and 138g vs. 92g in the case of biomass ethanol. They conclude that “corn-based ethanol, instead of producing a 20% savings, nearly doubles greenhouse emissions over 30 years and increases greenhouse gases for 167 years. Biofuels from switchgrass, if grown on U.S. corn lands, increase emissions by 50%. This result raises concerns about large biofuels mandates and highlights the value of using waste products.”

Coming to much the same conclusion, Laurance (2007) observed that “tropical forests, in particular, are crucial for combating global warming, because of their high capacity to store carbon and their ability to promote sunlight-reflecting clouds via large-scale evapotranspiration,” which led him to conclude that “such features are key reasons why preserving and restoring tropical forests could be a better strategy for mitigating the effects of carbon dioxide than dramatically expanding global biofuel production.”

Doornbosch and Steenblick (2007), while reporting that biofuels could provide up to 11 percent of the total world demand for road transport fuel by 2050, say “an expansion on this scale could not be achieved, however, without significant impacts on the wider global economy. In theory there might be enough land available around the globe to feed an ever increasing world population and produce sufficient biomass feedstock simultaneously, but it is more likely that land-use constraints will limit the amount of new land that can be brought into production leading to a ‘food-versus-fuel’ debate.”

Looking at a different environmental impact of expanded biofuel production, Crutzen and three collaborators calculated the amount of nitrous oxide (N2O) that would be released to the atmosphere as a result of using nitrogen fertilizer to produce the crops used for biofuels (Crutzen et al., 2007). Their work revealed that “all past studies have severely underestimated the release rates of N2O to the atmosphere, with great potential impact on climate warming” because, as they report, N2O “is a ‘greenhouse gas’ with a 100-year average global warming potential 296 times larger than an equal mass of CO2.” The consequence is that “when the extra N2O emission from biofuel production is calculated in ‘CO2-equivalent’ global warming terms, and compared with the quasi-cooling effect of ‘saving’ emissions of CO2 derived from fossil fuel, the outcome is that the production of commonly used biofuels, such as biodiesel from rapeseed and bioethanol from corn, can contribute as much or more to global warming by N2O emissions than cooling by fossil fuel savings.”

Crutzen et al. concluded that “on a globally averaged basis the use of agricultural crops for energy production … can readily be detrimental for climate due to the accompanying N2O emissions.” Their concerns were confirmed by a 2009 report from the International Council for Science (ICSU), which found “the increased N2O flux associated with producing ethanol from corn is likely to more than offset any positive advantage from reduced carbon dioxide fluxes (compared to burning fossil fuels). Even for ethanol from sugar cane or biodiesel from rapeseed, emissions of nitrous oxide probably make these fuels less effective as an approach for reducing global warming than has been previously believed” (ICSU, 2009).

Producing ethanol from crop residues, or stover, is often proposed as a way to avoid carbon emissions arising from land conversion. But as Lal (2007) points out, crop residues perform many vital functions. He reports that “there are severe adverse impacts of residue removal on soil and environmental degradation, and negative carbon sequestration as is documented by the dwindling soil organic carbon reserves.” He notes that “the severe and widespread problem of soil degradation, and the attendant agrarian stagnation/deceleration, are caused by indiscriminate removal of crop residues.” Lal concludes that “short-term economic gains from using crop residues for biofuel must be objectively assessed in relation to adverse changes in soil quality, negative nutrients and carbon budget, accelerated erosion, increase in non-point source pollution, reduction in agronomic production, and decline in biodiversity.”

Finally, while using abandoned or degraded lands to produce biomass, rather than converting existing cropland or forests, is often alleged to reduce carbon emissions (e.g., Fargione et al., 2008), the ICSU report notes that “of course, if the lands have the potential to revert to forests, conversion to biofuels represents a lost opportunity for carbon storage. The environmental consequences of inputs (irrigation water, fertilizer) required to make degraded and marginal lands productive must also be considered” (ICSU, 2009).

In conclusion, the production and use of biofuels frequently does not reduce net GHG emissions relative to gasoline, the fossil fuel they are intended to replace. Therefore, there is no basis from an environmental perspective for preferring them to fossil fuels.

Impact on Food Prices

Biofuel refineries compete with livestock growers and food processors for corn, soybeans, and other feedstocks usually used to produce biofuels in the United States, leading to higher animal feed and ingredient costs for farmers, ranchers, and food manufacturers. Some of that cost is eventually passed on to consumers. A study by the Congressional Budget Office (CBO) found “the demand for corn for ethanol production, along with other factors, exerted upward pressure on corn prices, which rose by more than 50 percent between April 2007 and April 2008. Rising demand for corn also increased the demand for cropland and the price of animal feed” (CBO, 2009). The CBO estimated that increased use of ethanol “contributed between 0.5 and 0.8 percentage points of the 5.1 percent increase in food prices measured by the consumer price index (CPI).”

Johansson and Azar (2007) analyzed what they called the “food-fuel competition for bio-productive land,” developing in the process “a long-term economic optimization model of the U.S. agricultural and energy system,” wherein they found that the competition for land to grow crops for both food and fuel production leads to a situation where “prices for all crops as well as animal products increase substantially.” Similarly, Doornbosch and Steenblick (2007) say “any diversion of land from food or feed production to production of energy biomass will influence food prices from the start, as both compete for the same inputs. The effects on farm commodity prices can already be seen today. The rapid growth of the biofuels industry is likely to keep these prices high and rising throughout at least the next decade (OECD/FAO, 2007).”

Runge and Senauer (2007), writing in Foreign Affairs, reported that the production of corn-based ethanol in the United States “takes so much supply to keep ethanol production going that the price of corn—and those of other food staples—is shooting up around the world.” The rising prices caused food riots to break out in Haiti, Bangladesh, Egypt, and Mozambique in April 2008, prompting Jean Ziegler, the United Nations’ “special rapporteur on the right to food,” to call using food crops to create ethanol “a crime against humanity” (CNN, 2008). Jeffrey Sachs, director of Columbia University’s Earth Institute, said at the time, “We’ve been putting our food into the gas tank—this corn-to-ethanol subsidy which our government is doing really makes little sense” (Ibid.). Former U.S. President Bill Clinton was quoted by the press as saying “corn is the single most inefficient way to produce ethanol because it uses a lot of energy and because it drives up the price of food” (Ibid.). Unfortunately, as the CBO report concluded a year later, corn is likely to remain the main source of ethanol for quite some time as “current technologies for producing cellulosic ethanol are not commercially viable” (CBO, 2009).

Use of Water

The third strategy proposed by Tilman et al. (2002) to address the conflict between growing food and preserving natural ecosystems is finding ways to conserve water. Biofuels, as the following studies demonstrate, fail to advance this objective.

Elcock (2008) projects that 12.9 billion gallons per day of water will be consumed in the manufacture of ethanol by 2030. This “increase accounts for roughly 60% of the total projected nationwide increase in water consumption over the 2005-2030 period, and it is more than double the amount of water projected to be consumed for industrial and commercial use in 2030 by the entire United States.”

A 2009 study by Argonne National Laboratory estimated life-cycle water consumption for one gallon of four types of fuel: ethanol, gasoline from domestic conventional crude oil, gasoline from Saudi conventional crude oil, and gasoline from Canadian oil sands (Wu et al., 2009). For ethanol, they estimated an average consumption of 3.0 gallon of water/gallon of corn ethanol during the production process in a corn dry mill, a yield of 2.7 gallons of ethanol per bushel of corn, and the average consumptive use of irrigation water for corn farming in three U.S. Department of Agriculture Regions (5, 6, and 7) representing the vast majority of corn production in the United States. They found “total groundwater and surface water use for corn growing vary significantly across the three regions, producing 1 gallon of corn-based ethanol consumes a net of 10 to 17 gallon of freshwater when the corn is grown in Regions 5 and 6, as compared with 324 gallon when the corn is grown in Region 7.” When these figures are adjusted to reflect the lower Btu/gallon of ethanol compared to gasoline (75,700 / 115,000, or .66), the amount of water consumed per gallon of gasoline equivalent ranges from 15.2 to 25.8 gallons in Regions 5 and 6 and 492 gallons in Region 7.

Wu et al. (2009) found the amount of water required to create a gallon of gasoline was dramatically less: 3.4-6.6 gallons of water to make one gallon of gasoline from U.S. conventional crude oil, 2.8-5.8 gallons to make one gallon of gasoline from Saudi conventional crude, and 2.6-6.2 gallons to make one gallon of gasoline from Canadian oil sands.

An even more recent review of the literature conducted by the International Council for Science (ICSU) found “the water requirements of biofuel-derived energy are 70 to 400 times larger than other energy sources such as fossil fuels, wind or solar. Roughly 45 billion cubic meters of irrigation water were used for biofuel production in the [sic] 2007, or some 6 times more water than people drink globally” (ICSU, 2009). The authors also point out that “severe water pollution can result from runoff from agricultural fields and from waste produced during the production of biofuels,” and that “the increase in corn [production] to support ethanol goals in the United States is predicted to increase nitrogen inputs to the Mississippi River by 37%.”

In light of this evidence, there can be little doubt that biofuels are a much less efficient use of scarce water resources than are fossil fuels. This means increased reliance on fossil fuels would make it more difficult to increase food production per unit of water in the future, one of Tilman et al.’s three strategies to solve the food vs. nature conflict.


The production and use of biofuels has increased dramatically in recent years, due largely to government mandates and taxpayer subsidies. But the alleged environmental benefits of these “renewable fuels” disappear upon close inspection. As Doornbosch and Steenblick (2007) say in their OECD report, “when such impacts as soil acidification, fertilizer use, biodiversity loss and toxicity of agricultural pesticides are taken into account, the overall environmental impacts of ethanol and biodiesel can very easily exceed those of petrol and mineral diesel. The conclusion must be that the potential of the current technologies of choice—ethanol and biodiesel—to deliver a major contribution to the energy demands of the transport sector without compromising food prices and the environment is very limited.”

The decision by the IPCC and many environmental groups to embrace ethanol pits energy production against food production, making even worse the conflict between the two that this section has addressed. There can be little doubt that ethanol mandates and subsidies have made both food and energy more, not less, expensive, and therefore less available to a growing population. The extensive damage to natural ecosystems already caused by this poor policy decision, and the much greater destruction yet to come, are a high price to pay for refusing to understand and utilize the true science of climate change.

Additional information on this topic, including reviews of newer publications as they become available, can be found at


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