Last updated on: 2/25/2009 7:52:00 AM PST
Does Ethanol Generate More Energy Than the Amount Needed to Produce It?
General Reference (not clearly pro or con)
The Congressional Research Service wrote in its Mar. 16, 2007 report "Ethanol and Biofuels: Agriculture, Infrastructure, and Market Constraints Related to Expanded Production," available at its website:
"A frequent argument for the use of ethanol as a motor fuel is that it reduces U.S. reliance on oil imports, making the U.S. less vulnerable to a fuel embargo of the sort that occurred in the 1970s. However, while corn ethanol use displaces petroleum, its overall effect on total energy consumption is less clear. To analyze the net energy consumption of ethanol, the entire fuel cycle must be considered. The fuel cycle consists of all inputs and processes involved in the development, delivery and final use of the fuel. For corn-based ethanol, these inputs include the energy needed to produce fertilizers, operate farm equipment, transport corn, convert corn to ethanol, and distribute the final product. Some studies find a significant positive energy balance of 1.5 or greater — in other words, the energy contained in a gallon of corn ethanol is 50% higher than the amount of energy needed to produce and distribute it. However, other studies suggest that the amount of energy needed to produce ethanol is roughly equal to the amount of energy obtained from its combustion."
Mar. 16, 2007 - Congressional Research Service (CRS)
"Ethanol and Biofuels: Agriculture, Infrastructure, and Market Constraints Related to Production" (116KB)
The Renewable Fuels Association wrote the following in its fact sheet "Ethanol Facts: Environment," published on its website (accessed Oct. 6, 2008):
"Whether produced from corn or other biomass feedstocks, ethanol generates more energy than used during production. Plants used in ethanol production harness the power of the sun to grow. By releasing the energy stored in corn and other feedstocks, ethanol production utilizes solar energy, replacing fossil energy use. A life cycle analysis of ethanol production - from the field to the vehicle - found that ethanol has a large and growing positive fossil energy balance. According to a 2004 U.S. Department of Agriculture Study, ethanol yields 67% more fossil energy than is used to grow and harvest the grain and process it into ethanol."
Oct. 6, 2008 - Renewable Fuels Association
C. Matthew Rendleman, PhD, Associate Professor in the Department of Agribusiness Economics at Southern Illinois University at Carbondale, and Housein Shapouri, PhD, Economist at the Office of Energy Policy and New Uses at of the United States Department of Agriculture (USDA), wrote the following in their Feb. 2007 report "New Technologies in Ethanol Production," published on www.usda.gov:
"In 2002, Shapouri et al. surveyed energy values and reported that fuel ethanol from corn produced about 34 percent more energy than it took to produce it...This value was revised in 2004 ["The 2001 Net Energy Balance of Corn-Ethanol"] by updating energy estimates for corn production and yield, improving estimates of energy required to produce nitrogen fertilizer and energy estimates for seed corn, and using better methodologies for allocating energy for producing coproducts. With these revisions, the energy gain is 57 percent for wet milling and 77 percent for dry milling, yielding a new weighted average of 67 percent."
Feb. 2007 - C. Matthew Rendleman, PhD
Hosein Shapouri, PhD
David Morris, PhD, Vice President of the Institute for Local Self-Reliance, wrote the following in his Aug. 2005 article "The Carbohydrate Economy, Biofuels and the Net Energy Debate," available at the New Rules Project website:
"It often seems that every article, every interview, every public discussion about our most used and visible biofuel, ethanol, starts, and sometimes ends, with the question, 'Doesn't it take more energy to make ethanol than is contained in the ethanol?' In 1980, the short and empirical answer to this question was yes. In 1990, because of improved efficiencies by both farmer and ethanol manufacturer, the answer was, probably not. In 2005 the answer is clearly no...
Several ethanol facilities are today beginning to use wood waste or, in the near future, corn stover, to replace natural gas to meet their thermal energy needs. The net energy ratio in that situation should be well over 2 to 1!"
Aug. 2005 - David Morris, PhD
The Office of Energy Efficiency and Renewable Energy of the US Department of Energy wrote the following in its 2007 paper "Ethanol Myths: Under the Microscope," published on its website:
"Each gallon of corn ethanol today delivers as much as 67% more energy than is used to produce the ethanol.
Over the last two decades, the amount of energy needed to produce corn ethanol has decreased because of improved farming techniques, more efficient use of fertilizers and pesticides, higher-yielding crops, and advances in conversion technology.
Today, ethanol has a positive energy balance. That is, the energy content of corn ethanol is greater than the energy used to produce it."
2007 - Office of Energy Efficiency and Renewable Energy (EERE)
Jason Hill, PhD, Research Associate in the Department of Applied Economics at the University of Minnesota at St. Paul, Erick Nelson, PhD, Postdoctoral Economist at the Stanford University Natural Capital Project, and David Tilman, PhD, Regent's Professor and McKnight Presidential Chair in Ecology at the University of Minnesota at St. Paul, et al., wrote in their June 2, 2006 study "Environmental, Economic, and Energetic Costs and Benefits of Biodiesel and Ethanol Biofuels," published in the Proceedings of the National Academy of Sciences:
"To be a viable substitute for a fossil fuel, an alternative fuel should...provide a net energy gain over the energy sources used to produce it.
Biofuel production requires energy to grow crops and convert them to biofuels. We estimate farm energy use...including energy use for growing the hybrid or varietal seed planted to produce the crop, powering farm machinery, producing farm machinery and buildings, producing fertilizers and pesticides, and sustaining farmers and their households. We also estimate the energy used in converting crops to biofuels, including energy use in transporting the crops to biofuel production facilities, building and operating biofuel production facilities, and sustaining production facility workers and their households...
In short, we find no support for the assertion that either biofuel [corn ethanol or soy biodiesel] requires more energy to make than it yields. However, the NEB [net energy balance] for corn grain ethanol is small, providing ~25% more energy than required for its production. Almost all of this NEB is attributable to the energy credit for its DDGS [distillers' dry grain with solubles] coproduct, which is animal feed, rather than to the ethanol itself containing more energy than used in its production. Corn grain ethanol has a low NEB because of the high energy input required to produce corn and to convert it into ethanol."
June 2, 2006 - Jason Hill, PhD
Erik Nelson, PhD
David Tilman, PhD
Walter Youngquist, PhD, Emeritus Chair of the Department of Geology at the University of Oregon at Portland, wrote in his Spring 2005 article "Spending Our Great Inheritance; Then What?," published in The Social Contract:
"Ethanol is a net energy loss – it takes 70 percent more energy to produce than is obtained from the product itself."
Spring 2005 - Walter Youngquist, PhD
David Pimentel, PhD, Professor Emeritus of Ecology and Evolutionary Biology at Cornell University, et al., wrote the following in their Sep. 2008 article titled "Biofuel Impacts on World Food Supply: Use of Fossil Fuel, Land and Water Resources," published in Energies:
"Manufacture of a liter of 99.5% ethanol uses 46% more fossil energy than it produces and costs $1.05 per liter ($3.97 per gallon). The corn feedstock alone requires more than 33% of the total energy input.
The largest energy inputs in corn-ethanol production are for producing the corn feedstock plus the steam energy and electricity used in the fermentation/distillation process. The total energy input to produce a liter of ethanol is 7,474 kcal. However, a liter of ethanol has an energy value of only 5,130 kcal. Based on a net energy loss of 2,344 kcal of ethanol produced, 46% more fossil energy is expended than is produced as ethanol...
In 2006, nearly 19 billion liters of ethanol were produced on 20% of U.S. corn acreage. These 19 billion liters represents only 1% of total U.S. petroleum use. However, even if we completely ignore corn ethanol's negative energy balance and high economic cost, we still find that it is absolutely not feasible to use ethanol as a replacement for U.S. oil consumption. If all 341 billion kg of corn produced in the U.S. were converted into ethanol at a rate of 2.69 kg per liters of ethanol, then 129 billion liters of ethanol could be produced. This would provide only 7% of total oil consumption in the U.S."
Sep. 2008 - David Pimentel, PhD
Alan Reynolds, Senior Fellow at the CATO Institute, wrote in his July 3, 2005 article "Energy Piracy," published in the Washington Times:
"Ethanol cannot be produced from corn without wasting huge amounts of petroleum. Petroleum is needed to fuel farm machinery, to produce fertilizer and insecticide, and to transport the corn and ethanol by diesel truck or train...
Ethanol already gets an indefensible tax break at the pump of 51 to 71 cents a gallon, but Congress now wants to compel everyone to add it to their tanks. But doing so would leave us with less fuel at higher prices. Why? Because there is much less energy in eight gallons of ethanol than in the seven gallons of gasoline it takes to produce it."
July 3, 2005 - Alan Reynolds
Tad W. Patzek, PhD, Chair of the Petroleum and Geosystems Engineering Department at the University of Texas at Austin, et al., wrote the following in their Sep. 2005 article "Ethanol from Corn: Clean Renewable Fuel for the Future, or Drain on our Resources and Pockets," published in Environment, Development and Sustainability:
"It takes a lot of energy from methane, oil, and coal to produce corn, and even more fossil energy to convert the corn feedstock into ethanol...
When one analyzes the energy inputs to corn production in the U.S., such as fertilizer, pesticides and herbicides, machinery, fuel, irrigation, drying, and transportation, only 3.65 times more energy can be gained from corn than was used to produce it. In other words, to produce from corn the amount of energy equivalent to 3.65 gallons of gasoline, one has to burn 1 gallon of gasoline equivalent in fossil fuels. Conversion of corn to ethanol by fermentation and distillation requires even more fossil energy. In the end, about 2.66 gallons of ethanol are obtained from one bushel of corn. During the corn conversion process, more fossil energy is used, and additional environmental pollution from the waste streams, water, gases and solids, is generated...
[I]n the process of converting industrial corn grain into ethanol, we have lost 65% of the energy inputs. More ominously, we have burned at least as much fossil fuel energy to obtain ethanol, as we may gain by burning it.
In our opinion, at this time the U.S. does not need ethanol from corn or any other plant. If, for example, the unnecessary corn were not planted, and the corn ethanol not produced, the large quantities, nine million gallons of gasoline equivalent per day, of methane, gasoline, diesel fuel and coal would be saved."
Sep. 2005 - Tad W. Patzek, PhD