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The United States became the world's largest producer of ethanol fuel in 2005. The U.S. produced 13.2 billion U.S. liquid gallons (49.2 billion liters) of ethanol fuel in 2010, and together with Brazil, accounted for 88% of that year's global production. In the U.S, ethanol fuel is mainly used as an oxygenate in gasoline in the form of low-level blends up to 10 percent, and to an increasing extent, as E85 fuel for flex-fuel vehicles. In 2009, 99% was consumed in gasohol. Most is produced using corn as feedstock.
The ethanol market share in the U.S. gasoline supply grew by volume from just over 1 percent in 2000 to more than 3 percent in 2006 to 10 percent in 2011. Domestic production capacity increased fifteen times after 1990, from 900 million US gallons to 1.63 billion US gal in 2000, to 13.5 billion US gallons in 2010.
By 2011 most cars on U.S. roads could run on blends of up to 10% ethanol, and manufacturers had begun producing vehicles designed for much higher percentages. Flexible-fuel cars, trucks, and minivans use gasoline/ethanol blends ranging from pure gasoline up to 85% ethanol (E85). By December 2011 there were nearly 10 million E85-capable vehicles on U.S roads. Regular use of E85 was low but common in the Midwest.
The Renewable Fuels Association reported 204 ethanol distilleries in operation and another 9 under construction or expansion as of December 2010, that upon completion, would bring U.S. total installed capacity to 14.6 billion US gallons. Ethanol production was expected to continue to grow over the next several years, since the Energy Independence and Security Act of 2007 required 36 billion US gallons of renewable fuel use by 2022. The target for ethanol production from cellulosic feedstocks was 16 billion US gallons a year. The corn ethanol target was 15 billion US gallons by 2015. Ethanol industries provided jobs in agriculture, construction, operations and maintenance, mostly in rural communities.
In early 2009 the industry experienced financial stress due to the effects of the economic crisis of 2008. Motorists drove less, gasoline prices dropped sharply, capacity rose and less financing was available.
Historically most U.S. ethanol came from corn and the required electricity for many distilleries came mainly from coal. Debate ensued about ethanol's sustainability. The primary issues related to the large amount of arable land required for crops and ethanol production's impact on grain supply, indirect land use change (ILUC) effects, as well as issues regarding its energy balance and carbon intensity considering its full life cycle. Recent developments with cellulosic ethanol production and commercialization may allay some of these concerns.
In 1826 Samuel Morey experimented with an internal combustion chemical mixture that used ethanol (combined with turpentine and ambient air then vaporized) as fuel. At the time, his discovery was overlooked, mostly due to the success of steam power. Ethanol fuel received little attention until 1860 when Nicholas Otto began experimenting with internal combustion engines. In 1859, oil was found in Pennsylvania, which decades later provided a new kind of fuel. A popular fuel in the U.S. before petroleum was a blend of alcohol and turpentine called "camphene", also known as "burning fluid." The discovery of a ready supply of oil and unfavorable taxation on burning fluid made kerosene a more popular fuel.
In 1896, Henry Ford designed his first car, the "Quadricycle" to run on pure ethanol. In 1908, the revolutionary Ford Model T was capable of running on gasoline, ethanol or a combination. Ford continued to advocate for ethanol fuel even during the prohibition, but lower prices caused gasoline to prevail.
Gasoline containing up to 10% ethanol began a decades-long growth in the United States in the late 1970s. The demand for ethanol produced from field corn was spurred by the discovery that methyl tertiary butyl ether (MTBE) was contaminating groundwater. MTBE's use as an oxygenate additive was widespread due to mandates in the Clean Air Act amendments of 1992 to reduce carbon monoxide emissions. MTBE in gasoline had been banned in almost 20 states by 2006. Suppliers were concerned about potential litigation and a 2005 court decision denying legal protection for MTBE. MTBE's fall from grace opened a new market for ethanol, its primary substitute. Corn prices at the time were around US$2 a bushel. Farmers saw a new market and increased production. This demand shift took place at a time when oil prices were rising.
The steep growth in twenty-first century ethanol consumption was driven by federal legislation aimed to reduce oil consumption and enhance energy security. The Energy Policy Act of 2005 required use of 7.5×109 US gal (28×106 m3) of renewable fuel by 2012, and the Energy Independence and Security Act of 2007 raised the standard, to 36×109 US gal (140×106 m3) of annual renewable fuel use by 2022. Of this requirement, 16×109 US gal (61×106 m3) had to be advanced biofuels, defined as renewable fuels that reduce greenhouse gas emissions by at least 50%.
|U.S. fuel ethanol|
production and imports
(Millions of U.S. liquid gallons)
|Note: Demand figures includes stocks change|
and small exports in 2005
The world's top ethanol fuel producer in 2010 was the United States with 13.2×109 US gal (50×106 m3) representing 57.5 percent of global production, followed by Brazil (6.92×109 US gal (26.2×106 m3)), and together both countries accounted for 88 percent of world production of 22.95×109 US gal (86.9×106 m3). By December 2010 the U.S. ethanol production industry consisted of 204 plants operating in 29 states, and 9 plants under construction or expansion, adding 560×106 US gal (2.1×106 m3) of new capacity and bringing total U.S. installed capacity to 14.6×109 US gal (55,000,000 m3). At the end of 2010 over 90 percent of all gasoline sold in the U.S. was blended with ethanol.
Beginning in late 2008 and early 2009, the industry came under financial stress due to that year's economic crisis. Motorists drove less and gasoline prices dropped sharply, while bank financing shrank. As a result, some plants operated below capacity, several firms closed plants, others laid off staff, some firms went bankrupt, plant projects were suspended and market prices declined. The Energy Information Administration raised concerns that the industry would not meet the legislated targets.
As of 2011, most of the U.S. car fleet was able to run on blends of up to 10% ethanol, and motor vehicle manufacturers produced vehicles designed to run on more concentrated blends. As of January 2008, three states – Missouri, Minnesota, and Hawaii – required ethanol to be blended with gasoline in motor fuels. These states, particularly Minnesota, had more ethanol usage and accumulated substantial environmental and economic benefits as a result. Florida required ethanol blends as of the end of 2010. Many cities had separate ethanol requirements due to non-attainment of federal air quality standards. In 2007, Portland, Oregon, became the first U.S. city to require all gasoline sold within city limits to contain at least 10% ethanol.
Expanding ethanol (and biodiesel) industries provided jobs in plant construction, operations, and maintenance, mostly in rural communities. According to RFA the ethanol industry created almost 154,000 U.S. jobs in 2005, boosting household income by $5.7 billion. It also contributed about $3.5 billion in federal, state and local tax revenues.
Ford, Chrysler, and GM are among many automobile companies that sell flexible-fuel vehicles that can run blends ranging from pure gasoline to 85% ethanol (E85), and beginning in 2008 almost any type of automobile and light duty vehicle was available with the flex-fuel option, including sedans, vans, SUVs and pick-up trucks. By December 2009 an estimated 9.3 million E85-compatible domestic vehicles had been produced, though actual use of E85 fuel was limited, because the ethanol fueling infrastructure was limited.
As of 2005, 68% of American flex-fuel car owners were not aware they owned an E85 flex. Flex and non-flex vehicles looked the same. There was no price difference. American automakers did not label these vehicles. In contrast, all Brazilian automakers clearly labeled FFVs with text that was some variant of the word Flex. Beginning in 2007 many new FFV models in the US featured a yellow gas cap to remind drivers of the E85 capabilities. As of 2008, GM badged its vehicles with the text "Flexfuel/E85 Ethanol". Nevertheless, the U.S. Department of Energy (DOE) estimated that in 2009 only 504,297 flex-fuel vehicles were regularly fueled with E85, and these were primarily fleet-operated vehicles. As a result, only 712×106 US gal (2.70×106 m3) were used for E85, representing just 1% of that year's ethanol consumption.
Fueling infrastructure was a major restriction hampering E85 sales. As of May 2011 only 2,749 fueling stations sold E85 in the U.S. Most stations were in the Corn Belt states. As of 2008 the leading state was Minnesota with 353 stations, followed by Illinois with 181, and Wisconsin with 114. About another 200 stations that dispensed ethanol were restricted to city, state and federal government vehicles.
The Energy Independence and Security Act of 2007, directed DOE to assess the feasibility of using intermediate ethanol blends in the existing vehicle fleet. The National Renewable Energy Laboratory (NREL) evaluated the potential impacts on legacy vehicles and other engines. In a preliminary report released in October 2008, NREL described the effects of E10, E15 and E20 on tailpipe and evaporative emissions, catalyst and engine durability, vehicle driveability, engine operability, and vehicle and engine materials. This preliminary report found that none of the vehicles displayed a malfunction indicator light; no fuel filter plugging symptoms were observed; no cold start problems were observed at 24 °C (75 °F) and 10 °C (50 °F) under laboratory conditions; and all test vehicles exhibited a loss in fuel economy proportional to ethanol's lower energy density. For example, E20 reduced average fuel economy by 7.7% when compared to gas-only (E0) test vehicles.
In March 2009 Growth Energy, a lobbying group for the ethanol industry, formally requested the U.S. Environmental Protection Agency (EPA) to allow the ethanol content in gasoline to be increased to 15 percent, from 10 percent. In October 2010, the EPA granted a waiver to allow up to 15% blends to be sold for cars and trucks with a model year of 2007 or later, representing about 15% of vehicles. In January 2011 the waiver was expanded to authorize use of E15 to include model year 2001 through 2006 passenger vehicles. The EPA also decided not to grant any waiver for E15 use in any motorcycles, heavy-duty vehicles, or non-road engines because current testing data does not support such a waiver. According to the Renewable Fuels Association the E15 waivers now cover 62% of vehicles on the road in the country. In December 2010 several groups, including the Alliance of Automobile Manufacturers, the American Petroleum Institute, the Association of International Automobile Manufacturers, the National Marine Manufacturers Association, the Outdoor Power Equipment Institute, and the Grocery Manufacturers Association, filed suit against the EPA in the United States Court of Appeals for the District of Columbia Circuit. In August 2012 the federal appeals court rejected the suit against the EPA ruling that the groups did not have legal standing to challenge EPA's decision to issue the waiver for E15.
Despite EPA's waiver, there is a practical barrier to the commercialization of the higher blend due to the lack of infrastructure, similar to the limitations suffered by sales of E85, as most fuel stations do not have enough pumps to offer the new blend, few existing pumps are certified to dispense E15, and there are no dedicated tanks readily available to store E15. In July 2012 a fueling station in Lawrence, Kansas became the first in the U.S. to sell the E15 blend. The fuel is sold through a blender pump that allows customers to choose between E10, E15, E30 or E85, with the latter blends sold only to flexible-fuel vehicles.
The Obama Administration set the goal of installing 10,000 blender pumps nationwide by 2015. These pumps can dispense multiple blends including E85, E50, E30 and E20 that can be used by E85 vehicles. The US Department of Agriculture (USDA) issued a rule in May 2011 to include flexible fuel pumps in the Rural Energy for America Program (REAP). This ruling provided financial assistance, via grants and loan guarantees, to fuel station owners to install E85 and blender pumps.
In May 2011 the Open Fuel Standard Act (OFS) was introduced to Congress with bipartisan support. The bill required that 50 percent of automobiles made in 2014, 80 percent in 2016, and 95 percent in 2017, be manufactured and warrantied to operate on non-petroleum-based fuels, which included existing technologies such as flex-fuel, natural gas, hydrogen, biodiesel, plug-in electric and fuel cell. Considering the rapid adoption of flexible-fuel vehicles in Brazil and the fact that the cost of making flex-fuel vehicles was approximately $100 per car, the bill's primary objective was to promote a massive adoption of flex-fuel vehicles capable of running on ethanol or methanol fuel.
One rationale for ethanol production in the U.S. is increased energy security, from shifting supply from oil imports to domestic sources. Ethanol production requires significant energy, and current U.S. production derives most of that energy from domestic coal, natural gas and other non-oil sources. Because in 2006, 66% of U.S. oil consumption was imported, compared to a net surplus of coal and just 16% of natural gas (2006 figures), the displacement of oil-based fuels to ethanol produced a net shift from foreign to domestic U.S. energy sources.
According to a 2008 analysis by Iowa State University, the growth in U.S. ethanol fuel production caused retail gasoline prices to be 29–40 cents per gallon lower than would otherwise have been the case. The U.S. consumed 138.2×109 US gal (523×106 m3) of gasoline in 2008, blended with about 9.6×109 US gal (36×106 m3) of ethanol, representing a market share of almost 7% of supply by volume. Given its lower energy content, ethanol fuel displaced about 6.4×109 US gal (24×106 m3) of gasoline, representing 4.6 percent in equivalent energy units.
Since the 1980s until 2011, domestic ethanol producers were protected by a 54-cent per gallon import tariff, mainly intended to curb Brazilian sugarcane ethanol imports. Beginning in 2004 blenders of transportation fuel received a tax credit for each gallon of ethanol they mix with gasoline. Historically, the tariff was intended to offset the federal tax credit that applied to ethanol regardless of country of origin. Several countries in the Caribbean Basin imported and reprocessed Brazilian ethanol, usually converting hydrated ethanol into anhydrous ethanol, for re-export to the United States. They avoided the 2.5% duty and the tariff, thanks to the Caribbean Basin Initiative (CBI) and free trade agreements. This process was limited to 7% of U.S. ethanol consumption.
As of 2011, blenders received a US$0.45 per gallon tax credit, regardless of feedstock; small producers received an additional US$0.10 on the first 15 million US gallons; and producers of cellulosic ethanol received credits up to US$1.01. Tax credits to promote the production and consumption of biofuels date to the 1970s. For 2011, credits were based on the Energy Policy Act of 2005, the Food, Conservation, and Energy Act of 2008, and the Energy Improvement and Extension Act of 2008.
A 2010 study by the Congressional Budget Office (CBO) found that in fiscal year 2009, biofuel tax credits reduced federal revenues by around US$6 billion, of which corn and cellulosic ethanol accounted for US$5.16 billion and US$50 million, respectively. A 2010 study by the Environmental Working Group estimated that the cumulative ethanol subsidies between 2005 and 2009 were US$17 billion. The same study estimated the future cost to taxpayers at US$53.59 billion if these tax credits were extended until 2015, yielding 15 billion US gallons (56.8 billion liters).
In 2010, CBO estimated that taxpayer costs to reduce gasoline consumption by one gallon were $1.78 for corn ethanol and $3.00 for cellulosic ethanol. In a similar way, and without considering potential indirect land use effects, the costs to taxpayers of reducing greenhouse gas emissions through tax credits were about $750 per metric ton of CO2-equivalent for ethanol and around $275 per metric ton for cellulosic ethanol.
On June 16, 2011, the U.S. Congress approved an amendment to an economic development bill to repeal both the tax credit and the tariff, but this bill did not move forward. Nevertheless, the U.S. Congress did not extend the tariff and the tax credit, allowing both to end on December 31, 2011. Since 1980 the ethanol industry was awarded an estimated US$45 billion in subsidies.
Taxpayers paid part of the cost of producing ethanol. Each gallon was subsidized by a 51-cent/gallon federal tax credit paid to U.S. producers. These subsidies, along with state incentive programs, cost the nation over $2 billion a year, leading legislators to pledge to invest in cellulosic ethanol.
Another issue was the loss of income to American crude oil refiners, who earn as much as $30 or more per barrel. Exxon Mobil Corp. earned $1.3 billion in its refining arm in the second quarter, up 11% from a year before. The expectation, over the long run, is that the U.S. economy would more than earn its share back if our primary source of energy were manufactured and processed in the United States, but individual companies could be adversely affected.
Corn is the main feedstock used for producing ethanol fuel in the United States. Most of the controversies surrounding U.S. ethanol fuel production and use is related to corn ethanol's energy balance and its social and environmental impacts.
Cellulosic sources have the potential to produce a renewable, cleaner-burning, and carbon-neutral alternative to gasoline. In his State of the Union Address on January 31, 2006, President George W. Bush stated, “We'll also fund additional research in cutting-edge methods of producing ethanol, not just from corn, but from wood chips and stalks or switchgrass. Our goal is to make this new kind of ethanol practical and competitive within six years.”
On July 7, 2006, DOE announced a new research agenda for cellulosic ethanol. The 200-page scientific roadmap cited recent advances in biotechnology that could aid use of cellulosic sources. The report outlined a detailed research plan for additional technologies to improve production efficiency. The roadmap acknowledged the need for substantial federal loan guarantees for biorefineries.
The 2007 federal budget earmarked $150 million for the research effort – more than doubling the 2006 budget. DOE invested in enzymatic, thermochemical, acid hydrolysis, hybrid hydrolysis/enzymatic, and other research approaches targeting more efficient and lower–cost conversion of cellulose to ethanol.
The first materials considered for cellulosic biofuel included plant matter from agricultural waste, yard waste, sawdust and paper. Professors R. Malcolm Brown Jr. and David Nobles, Jr. of the University of Texas at Austin developed cyanobacteria that had the potential to produce cellulose, glucose and sucrose, the latter two easily converted into ethanol. This offers the potential to create ethanol without plant matter.
Another source of ingredients for ethanol conversion is human waste. The company "Applied Clean Tech" recycles sludge from sewage treatment plants into "recyllose" pellets. Massachusetts biofuels company "Qtero" uses microbes to convert these pellets into ethanol on an approximately 2.5:1 ratio by weight. In other words, one ton of recyllose pellets can provide the volume equivalent to 123–133 US gallons (470–500 L) or 800 lb (360 kg) of ethanol. Nationwide, enough sludge exists to produce several billion gallons of ethanol per year.
Cyanobacteria, enzymes and microbes, combined with ingredients from plants and human waste and grasses offer the potential to replace all food ingredients now converted into ethanol at a fraction of the financial and economic cost.
| United States fuel ethanol|
imports by country (2002–2007)
(Millions of U.S. liquid gallons)
|Trinidad and Tobago||42.7||24.8||10.0||0||0|
Producing ethanol from sugar is simpler than converting corn into ethanol. Converting sugar requires only a yeast fermentation process. Converting corn requires additional cooking and the application of enzymes. The energy requirement for sugar conversion is about half that for corn. Sugarcane produces more than enough energy to do the conversion with energy left over. A 2006 U.S. Department of Agriculture (USDA) report found that at market prices for ethanol, converting sugarcane, sugar beets and molasses to ethanol would be profitable. As of 2008 researchers were attempting to breed new varieties adapted to U.S. soil and weather conditions, as well as to take advantage of cellulosic ethanol technologies to also convert sugarcane bagasse.
U.S. sugarcane production occurs in Florida, Louisiana, Hawaii, and Texas. The first three plants to produce sugarcane-based ethanol were expected to go online in Louisiana by mid 2009. Sugar mills in Lacassine, St. James and Bunkie were converted to sugarcane ethanol production using Colombian technology to enable profitable ethanol production. These three plants planned to produce 100×106 US gal (380×103 m3) of ethanol per year within five years.
By 2009 two other sugarcane ethanol production projects were being developed in Kauai, Hawaii and Imperial Valley, California. The Hawaiian plant was projected to have a capacity of between 12–15 million US gallons (45×103–57×103 m3) a year and to supply local markets only, as shipping costs made competing in the continental US impractical. This plant was expected to go on line by 2010. The California plant was expected to produce 60×106 US gal (230×103 m3) a year and it was expected in 2011.
In March 2007, "ethanol diplomacy" was the focus of President George W. Bush's Latin American tour, in which he and Brazil's president, Luiz Inacio Lula da Silva, promoted the production and use of sugarcane ethanol throughout the Caribbean Basin. The two countries agreed to share technology and set international biofuel standards. Brazilian sugarcane technology transfer was intended to permit various Central American, such as Honduras, El Salvador, Nicaragua, Costa Rica and Panama, several Caribbean countries, and various Andean Countries tariff-free trade with the U.S., thanks to existing trade agreements. The expectation was that such countries would export to the United States in the short-term using Brazilian technology.
In 2007, combined exports from Jamaica, El Salvador, Trinidad & Tobago and Costa Rica to the U.S. reached a total of 230.5×106 US gal (873×103 m3) of sugarcane ethanol, representing 54.1% of imports. Brazil began exporting ethanol to the U.S. in 2004 and exported 188.8×106 US gal (715×103 m3) representing 44.3% of U.S. ethanol imports in 2007. The remaining imports that year came from Canada and China.
Cheese whey, barley, potato waste, beverage waste, and brewery and beer waste have been used as feedstocks for ethanol fuel, but at a far smaller scale than corn and sugarcane ethanol, as plants using these feedstocks have the capacity to produce only 3 to 5 million US gallons (11×103 to 19×103 m3) per year.
Sugarcane ethanol has an energy balance 7 times greater than corn ethanol. As of 2007, Brazilian distiller production costs were 22 cents per liter, compared with 30 cents per liter for corn-based ethanol. Corn-derived ethanol costs 30% more because the corn starch must first be converted to sugar before distillation into alcohol. However, corn-derived ethanol offers the ability to return 1/3 of the feedstock to the market as a replacement for the corn used in the form of Distillers Dried Grain. Sugarcane ethanol production is seasonal: unlike corn, sugarcane must be processed into ethanol almost immediately after harvest.
|Comparison of key characteristics between|
the ethanol industries in the United States and Brazil
|Main feedstock||Sugar cane||Maize||Main cash crop for ethanol production, the US has less than 2% from other crops.|
|Total ethanol fuel production (2010)||Million U.S. liquid gallons|
|Total arable land||355||270||Million hectares. Only contiguous U.S., excludes Alaska.|
|Total area used for ethanol crop (2006)||3.6|
|Million hectares (% total arable)|
|Productivity||6,800–8,000||3,800–4,000||Ethanol yield (liter/hectare). Brazil is 727 to 870 gal/acre (2006), US is 321 to 424 gal/acre (2003–05)|
|Energy balance (input energy productivity)||8.3 to 10.2||1.3 to 1.6||Ratio of the energy obtained from ethanol/energy expended in its production|
|Estimated greenhouse gas emission reduction||86–90%(1)||10–30%(1)||% GHGs avoided by using ethanol instead of gasoline, using existing crop land, without ILUC effects.|
|EPA's estimated 2022 GHG reduction for RFS2.||61%(2)||21%||Average % GHGs change as compared to gasoline and considering direct and indirect land use change effects.|
|CARB's full life-cycle carbon intensity||73.40||105.10(3)||Grams of CO2 equivalent released per MJ of energy produced, includes indirect land use changes.|
|Estimated payback time for greenhouse gas emission||17 years(4)||93 years(4)||Brazilian cerrado for sugar cane and US grassland for corn. Land use change scenarios by Fargione et al.|
|Flexible-fuel vehicles produced/sold|
(includes autos, light trucks and motorcycles)
|16.3 million||10 million||All fleets as of December 2011. The Brazilian fleet includes 1.5 million flex fuel motorcycles.|
USDOE estimates that in 2009 only 504,297 flex-fuel vehicles were regularly fueled with E85 in the US.
|Ethanol fueling stations in the country||35,017|
|As % of total gas stations in the country. Brazil by December 2007, U.S. by May 2011. (170,000 total.)|
|Ethanol's share within the gasoline market||50%(5)||10%||As % of total consumption on a volumetric basis. Brazil as of April 2008. U.S. as of December 2010.|
|Cost of production (USD/US gallon)||0.83||1.14||2006/2007 for Brazil (22¢/liter), 2004 for U.S. (35¢/liter)|
|Notes: (1) Assuming no land use change. (2) Estimate is for U.S. consumption and sugarcane ethanol is imported from Brazil. Emissions from sea transport are included. Both estimates include land transport within the U.S. (3) CARB estimate for Midwest corn ethanol. California's gasoline carbon intensity is 95.86 blended with 10% ethanol. (4) Assuming direct land use change. (5) If diesel-powered vehicles are included and due to ethanol's lower energy content by volume, bioethanol represented 16.9% of the road sector energy consumption in 2007.|
Until 2008, several full life cycle ("Well to Wheels" or WTW) studies had found that corn ethanol reduces greenhouse gas emissions as compared to gasoline. In 2007 a team led by Farrel from the University of California, Berkeley evaluated six previous studies and concluded corn ethanol reduces greenhouse gas emissions by only 13 percent. However, a more commonly cited figure is 20 to 30 percent, and an 85 to 85 percent reduction for cellulosic ethanol. Both figures were estimated by Wang from Argonne National Laboratory, based on a comprehensive review of 22 studies conducted between 1979 and 2005, and simulations with Argonne's GREET model. All of these studies included direct land use changes.
The reduction estimates on carbon intensity for a given biofuel depend on the assumptions regarding several variables, including crop productivity, agricultural practices, and distillery power source and energy efficiency. None of these studies considered the effects of indirect land-use changes, and though their impact was recognized, its estimation was considered too complex and more difficult to model than direct land use changes.
|Summary of Searchinger et al.|
comparison of corn ethanol and gasoline GHG emissions
with and without land use change
(CO2 release rate (g/MJ))
|Notes: Calculated using default assumptions for 2015 scenario for ethanol in E85.|
Gasoline is a combination of conventional and reformulated gasoline.
Two 2008 studies, both published in the same issue of Scienceexpress, questioned the previous assessments. A team led by Searchinger from Princeton University concluded that once direct and indirect effect of land use changes (ILUC) are considered, both corn and cellulosic ethanol increased carbon emissions as compared to gasoline by 93 and 50 percent respectively. The study limited the analysis to a 30 year time horizon, assuming that land conversion emitted 25 percent of the carbon stored in soils and all carbon in plants cleared for cultivation. Brazil, China and India were considered among the overseas locations where land use change would occur as a result of diverting U.S. corn cropland, and it was assumed that new cropland in each of these regions correspond to different types of forest, savanna or grassland based on the historical proportion of each natural land converted to cultivation in these countries during the 1990s.
A team led by Fargione from The Nature Conservancy found that clearing natural lands for use as agricultural land to produce biofuel feedstock creates a carbon debt. Therefore this carbon debt applies to both direct and indirect land use changes. The study examined six scenarios of wilderness conversion, Brazilian Amazon to soybean biodiesel, BrazilianCerrado to soybean biodiesel, Brazilian Cerrado to sugarcane ethanol, Indonesian or Malaysian lowland tropical rainforest to palm biodiesel, Indonesian or Malaysian peatland tropical rainforest to oil palm forest, and U.S. Central grassland to corn ethanol.
On April 23, 2009, the California Air Resources Board approved specific rules and carbon intensity reference values for the California Low-Carbon Fuel Standard (LCFS) that was to go into effect on January 1, 2011. The consultation process produced controversy regarding the inclusion and modeling of indirect land use change effects. After the CARB's ruling, among other criticisms, representatives of the ethanol industry complained that the standard overstated the negative environmental effects of corn ethanol, and also criticized the inclusion of indirect effects of land-use changes as an unfair penalty to home-made corn ethanol because deforestation in the developing world had been tied to US ethanol production. The emissions standard for 2011 for LCFS meant that Midwest corn ethanol would not meet the California standard unless current carbon intensity is reduced.
A similar controversy arose after the U.S. Environmental Protection Agency (EPA) published on May 5, 2009 its notice of proposed rulemaking for the new Renewable Fuel Standard (RFS). EPA's proposal included the carbon footprint from indirect land-use changes. On the same day, President Barack Obama signed a Presidential Directive with the aim to advance biofuel research and commercialization. The Directive asked a new Biofuels Interagency Working Group comprising the Department of Agriculture, EPA, and DOE, to develop a plan to increase flexible fuel vehicle use, assist in retail marketing and to coordinate infrastructure policies.
In December 2009 two lobbying groups, the Renewable Fuels Association (RFA) and Growth Energy, filed a lawsuit challenging LCFS' constitutionality. The two organizations argued that LCFS violates both the Supremacy Clause and the Commerce Clause of the US Constitution, and "jeopardizes the nationwide market for ethanol." In a press release the associations announced that “If the United States is going to have a low carbon fuel standard, it must be based on sound science and it must be consistent with the U.S. Constitution..."
On February 3, 2010, EPA finalized the Renewable Fuel Standard Program (RFS2) for 2010 and beyond. EPA incorporated direct emissions and significant indirect emissions such as emissions from land use changes along with comments and data from new studies. Adopting a 30 year time horizon and a 0% discount rate EPA declared that ethanol produced from corn starch at a new (or expanded capacity from an existing) natural gas-fired facility using approved technologies would be considered to comply with the 20% GHG emission reduction threshold. Given average production conditions it expected for 2022, EPA estimated that corn ethanol would reduce GHGs an average of 21% compared to the 2005 gasoline baseline. A 95% confidence interval spans a 7-32% range reflecting uncertainty in the land use change assumptions.
The following table summarizes the mean GHG emissions for ethanol using different feedstocks estimated by EPA modelling and the range of variations considering that the main source of uncertainty in the life cycle analysis is the GHG emissions related to international land use change.
|U.S. Environmental Protection Agency|
Life cycle year 2022 GHG emissions reduction results for RFS2 final rule
(includes direct and indirect land use change effects and a 30 year pay back period at a 0% discount rate)
|Renewable fuel pathway|
(for U.S. consumption)
|Corn ethanol||New or expanded natural gas fired dry mill plant, 37% wet and 63% dry DGS it produces, and employing corn oil fractionation technology.|
|Corn biobutanol||Natural gas fired dry mill plant, 37% wet and 63% dry DGS it produces, and employing corn oil fractionation technology.|
|Cellulosic ethanol from switchgrass||Ethanol produced using the biochemical process.|
|Cellulosic ethanol from corn stover||Ethanol produced using the biochemical process. Ethanol produced from agricultural residues does not have any indirect land use emissions.|
|Notes: (1) Percent reduction in lifecycle GHG emissions compared to the average lifecycle GHG for gasoline or diesel sold or distributed as transportation fuel in 2005.|
(2) Confidence range accounts for uncertainty in the types of land use change assumptions and the magnitude of resulting GHG emissions.
Several studies concluded that increased ethanol production was likely to result in a substantial increase in water pollution by fertilizers and pesticides, with the potential to exacerbate eutrophication and hypoxia, particularly in the Chesapeake Bay and the Gulf of Mexico.
Growing feedstocks consumes most of the water associated with ethanol production. Corn consumes from 500–2,000 litres (110–440 imp gal; 130–530 US gal) of water per liter of ethanol, mostly for evapotranspiration. In general terms, both corn and switchgrass require less irrigation than other fuel crops. Corn is grown mainly in regions with adequate rainfall. However, corn usually needs to be irrigated in the drier climates of Nebraska and eastern Colorado. Further, corn production for ethanol is increasingly taking place in areas requiring irrigation. A 2008 study by the National Research Council concluded that "in the longer term, the likely expansion of cellulosic biofuel production has the potential to further increase the demand for water resources in many parts of the United States. Biofuels expansion beyond current irrigated agriculture, especially in dry western areas, has the potential to greatly increase pressure on water resources in some areas."
A 2009 study estimated that irrigated corn ethanol implied water consumption at between 50 US gal/mi (120 L/km) and 100 US gal/mi (240 L/km) for U.S. vehicles. This figure increased to 90 US gal/mi (210 L/km) for sorghum ethanol from Nebraska, and 115 US gal/mi (270 L/km) for Texas sorghum. By contrast, an average U.S. car effectively consumes between 0.2 US gal/mi (0.47 L/km) to 0.5 US gal/mi (1.2 L/km) running on gasoline, including extraction and refining.
In 2010 RFA argued that more efficient water technologies and pre-treated water could reduce consumption. It further claimed that non-conventional oil "sources, such as tar sands and oil shale, require far more water than conventional petroleum extraction and refining."
Some part of these chemicals leaves the field. Nitrogen in forms such as nitrate (NO3) is highly soluble, and along with some pesticides infiltrates downwards toward the water table, where it can migrate to water wells, rivers and streams. A 2008 National Research Council study found that regionally the highest stream concentrations occur where the rates of application were highest, and that these rates were highest in the Corn Belt. These flows mainly stem from corn, which as of 2010 was the major source of total nitrogen loading to the Mississippi River.
Several studies found that corn ethanol production contributed to the worsening of the Gulf of Mexico dead zone. The nitrogen leached into the Mississippi River and out into the Gulf, where it fed giant algae blooms. As the algae died, it settled to the ocean floor and decayed, consuming oxygen and suffocating marine life, causing hypoxia. This oxygen depletion killed shrimp, crabs, worms and anything else that could not escape, and affected important shrimp fishing grounds.
Some environmentalists, such as George Monbiot, expressed fears that the marketplace would convert crops to fuel for the rich, while the poor starved and biofuels caused environmental problems. The food vs fuel debate grew in 2008 as a result of the international community's concerns regarding the steep increase in food prices. On April 2008, Jean Ziegler, back then United Nations Special Rapporteur on the Right to Food, repeated his claim that biofuels were a "crime against humanity", echoing his October 2007 call for a 5-year ban for the conversion of land for the production of biofuels. Also in April 2008, World Bank President Robert Zoellick stated that "While many worry about filling their gas tanks, many others around the world are struggling to fill their stomachs. And it's getting more and more difficult every day."
A July 2008 World Bank report found that from June 2002 to June 2008 "biofuels and the related consequences of low grain stocks, large land use shifts, speculative activity and export bans" accounted for 70–75% of total price rises. The study found that higher oil prices and a weak dollar explain 25–30% of total price rise. The study said that "...large increases in biofuels production in the United States and Europe are the main reason behind the steep rise in global food prices." The report argued that increased production of biofuels in these developed regions was supported by subsidies and tariffs, and claimed that without such policies, food price increases worldwide would have been smaller. It also concluded that Brazil's sugarcane ethanol had not raised sugar prices significantly, and recommended that both the U.S. and E.U. remove tariffs, including on many African countries.
An RFA rebuttal said that the World Bank analysis was highly subjective and that the author considered only "the impact of global food prices from the weak dollar and the direct and indirect effect of high petroleum prices and attribute[d] everything else to biofuels."
A 2010 World Bank study concluded that its previous study may have overestimated the impact, as "the effect of biofuels on food prices has not been as large as originally thought, but that the use of commodities by financial investors (the so-called ”financialization of commodities”) may have been partly responsible for the 2007/08 spike."
A July 2008 OECD economic assessment agreed about the negative effects of subsidies and trade restrictions, but found that the impact of biofuels on food prices was much smaller. The OECD study found that existing biofuel support policies would reduce greenhouse gas emissions by no more than 0.8 percent by 2015. It called for more open markets in biofuels and feedstocks to improve efficiency and lower costs. The OECD study concluded that "...current biofuel support measures alone are estimated to increase average wheat prices by about 5 percent, maize by around 7 percent and vegetable oil by about 19 percent over the next 10 years."
The 2008 financial crisis illustrated corn ethanol's limited impact on corn prices, which fell 50% from their July 2008 high by October 2008, in tandem with other commodities, including oil, while corn ethanol production continued unabated. "Analysts, including some in the ethanol sector, say ethanol demand adds about 75 cents to $1.00 per bushel to the price of corn, as a rule of thumb. Other analysts say it adds around 20 percent, or just under 80 cents per bushel at current prices. Those estimates hint that $4 per bushel corn might be priced at only $3 without demand for ethanol fuel.".