Farm fields landscape

Is ethanol energy-efficient?


[Editor's note: This is an excellent annotated bibliography, but a bit dated. I have tested all the links and noted their current validity, or done a search and updated them. - CS]

One of the most controversial issues relating to ethanol (and more recently to biodiesel as well, see below) is what environmentalists call the "net energy" of ethanol production: is more energy used to grow and process the raw material into ethanol than is contained in the ethanol itself?

It's especially controversial in the US. In the US most ethanol is made from corn (maize), which is far from the best energy crop (Brazil uses sugar cane). Nonetheless, a US Department of Agriculture study concludes that ethanol contains 34% more energy than is used to grow and harvest the corn and distill it into ethanol. "Estimating the Net Energy Balance of Corn Ethanol", by Hosein Shapouri et al., US Department of Agriculture, Economic Research Service, Office of Energy and New Uses, Agricultural Economic Report No. 721, July 1995 -- "Studies conducted since the late 1970s have estimated the net energy value of corn ethanol. However, variations in data and assumptions used among the studies have resulted in a wide range of estimates. This study identifies the factors causing this wide variation and develops a more consistent estimate... We show that corn ethanol is energy efficient as indicated by an energy ratio of 1.24."  [Link updated 3/29/14]

"The Energy Balance of Corn Ethanol: An Update", by Hosein Shapouri and James A. Duffield, U.S. Department of Agriculture, Office of Energy Policy and New Uses, and Michael Wang of the Center for Transportation Research, Energy Systems Division, Argonne National Laboratory. Agricultural Economic Report No. 813, 2002: "Corn ethanol is energy efficient... For every BTU dedicated to producing ethanol there is a 34% energy gain... Only about 17% of the energy used to produce ethanol comes from liquid fuels, such as gasoline and diesel fuel. For every 1 BTU of liquid fuel used to produce ethanol, there is a 6.34 BTU gain." Full report (Acrobat file, 176 kb):  [Link updated 3/29/14]

In "How Much Energy Does It Take to Make a Gallon of Ethanol?", David Lorenz and David Morris of the Institute for Local-Self Reliance (ILSR) state: "Using the best farming and production methods, the amount of energy contained in a gallon of ethanol is more than twice the energy used to grow the corn and convert it to ethanol." A 1992 ILSR study, based on actual energy consumption data from farmers and ethanol plant operators, found that the production of ethanol from corn is a positive net energy generator. In this updated paper the numbers look even more attractive: more energy is contained in the ethanol and the other by-products of corn processing than is used to grow the corn and convert it into ethanol and by-products.  [Link updated 3/29/14]

New study confronts old thinking on ethanol's net energy value, 3/28/2005 -- Ethanol generates 35% more energy than it takes to produce, according to a recent study by Argonne National Laboratory conducted by Michael Wang. The new findings support earlier research that determined ethanol has a positive net energy balance, according to the National Corn Growers Association. That research was conducted by USDA, Michigan State University, the Colorado School of Mines, the Institute for Local Self-Reliance and other public and private entities. Argonne is one of the US Department of Energy's largest research centers. [Link not currently valid]

Report on the new study : [Link not currently valid]

A USDA study released in 2004 found that ethanol may net as much as 67% more energy than it takes to produce. [Link not currently valid]

Ethanol under fire: David Pimentel et al

Actually it's Big Ethanol and Big Corn that are under fire by Big Oil, though Big Corn and Big Agriculture are a major client of Big Oil. We tend to think they might all deserve each other. Small is beautiful, especially with food and biofuels, and we don't support Big Ethanol producers like Archer Daniels Midland, Cargill or Monsanto any more than we support ExxonMobil or Shell.

But we don't like disinformation either. The Biofuel mailing list [Link not currently valid] has been outing Cornell University Prof. David Pimentel for five years – see: [Link not currently valid]
    biofuel - Search results for 'pimentel'

    And more recently his new ally Tad Patzek of Berkeley: [Link not currently valid]
    biofuel - Search results for 'Patzek'

In August 2001 Pimentel attacked the economics of corn-to-ethanol production in an article published in the Encyclopedia of Physical Sciences and Technology. Pimentel asserted that ethanol production is uneconomic: "The growers and processors can't afford to burn ethanol to make ethanol. US drivers couldn't afford it, either, if it weren't for government subsidies to artificially lower the price."

See Energy Balance of Corn Ethanol Resultssix charts that show the picture at a glance [link good 3/24/14]

"Ethanol fuel from corn faulted as 'unsustainable subsidized food burning' in analysis by Cornell scientist", August 6, 2001 -- "Neither increases in government subsidies to corn-based ethanol fuel nor hikes in the price of petroleum can overcome what one Cornell University agricultural scientist calls a fundamental input-yield problem: It takes more energy to make ethanol from grain than the combustion of ethanol produces."  [link good 3/24/14]

In a detailed analysis of Pimentel's research, Dr. Michael S. Graboski of the Colorado School of Mines says Pimentel's findings are based on out-of-date statistics (22 year-old data) and are contradicted by a recent US Department of Agriculture (USDA) study.

"Comparison of USDA and Pimentel Net Energy Balances" -- "The USDA analysis clearly shows, contrary to the Pimentel paper, that US farming and ethanol manufacture are very energy efficient, and that the energy content of ethanol delivered to the consumer is significantly larger than the total fossil energy inputs required to produce it. USDA estimates that ethanol facilities produce at least 1.23 units of energy as ethanol for every fossil BTU included considering all energy inputs related to corn farming, corn transport, ethanol production, and distribution and transport of finished ethanol." Full report: [Link not currently valid] 

"Pimentel clearly does not understand the economics of ethanol manufacture" -- a full rebuttal, from the US National Corn Growers Association. [Link not currently valid]

Another rebuttal: "Industry Argues That Ethanol Delivers" [link good 3/24/14]

In fact this isn't the first time Pimentel had published misinformation about ethanol, nor the first time critics had poked his analyses full of holes. He knows he's using outdated data, but that doesn't stop him. In 1998 he published this report:

"Energy and Dollar Costs of Ethanol Production with Corn" by David Pimentel, April 1998 -- "Ethanol does not provide energy security for the future. It is not a renewable energy source, is costly in terms of production and subsidies, and its production causes serious environmental degradation." [Link updated 3/29/14]

This report was debunked by, among others, Michael Wang and Dan Santini of the Center for Transportation Research, Argonne National Laboratory, who conducted a series of detailed analyses on energy and emission impacts of corn ethanol from 1997 through 1999:

"Corn-Based Ethanol Does Indeed Achieve Energy Benefits" -- "Prof. David Pimentel's 1998 assessment of corn ethanol concluded that corn ethanol achieved a negative energy balance (which is usually defined as the energy in a product minus energy used to produce the product). Unfortunately, his assessment lacked timeliness in that it relied on data appropriate to conditions of the 1970s and early 1980s, but clearly not the 1990s... With up-to-date information on corn farming and ethanol production and treating ethanol co-products fairly, we have concluded that corn-based ethanol now has a positive energy balance of about 20,000 Btu per gallon." [Link updated 3/29/14]

Wang and Santini found that Pimentel had been recycling his already-ancient data for at least 10 years.

In August 2002 a new report from the USDA found that not only is ethanol energy-efficient, it's efficiency is steadily improving.

"Only Dr. Pimentel disagrees with this analysis. But his outdated work has been refuted by experts from entities as diverse as the USDA, DOE, Argonne National Laboratory, Michigan State University, and the Colorado School of Mines. While the opponents of ethanol will no doubt continue to peddle Pimentel's baseless charges, they are absolutely without credibility," the Renewable Fuels Association commented.

"From stalk to fuel tank, ethanol a net energy gain" -- Washington, August 7, 2002, Reuters: Measured from cornfield to the fuel tank, ethanol provides more energy than is consumed in producing it, researchers said in a new report that could figure in congressional debate over U.S. energy policy. [Link good, 3/29/14]
The Renewable Fuels Association report on the study: [link not currently valid]
Full report (Acrobat file, 176 kb): [link not currently valid]

Biofuels: Energy Balance, Environmental and Energy Study Institute, October, 2003 -- ... A 2002 study by the US Department of Agriculture that accounts for gasoline and diesel fuel use, fertilizers and a variety of other energy inputs in the production, concluded that the energy balance of ethanol is 1.34:1. This means that ethanol "yields 34% more energy than it takes to produce it, including growing the corn, harvesting it, transporting it and distilling it into ethanol." These data are consistent with a study by Dr. Bruce Dale, Michigan State University (2002), and a study by Argonne National Laboratory (1999). [link not currently valid]

Energy Balance/Life Cycle Inventory for Ethanol, Biodiesel and Petroleum Fuels, Minnesota Department of Agriculture -- ... "The finished liquid fuel energy yield for fossil fuel dedicated to the production of ethanol is 1.34 but only 0.74 for gasoline. In other words the energy yield of ethanol is (1.34/0.74) or 81 percent greater than the comparable yield for gasoline." [Currently available at 3/29/14] 

Pimentel's arguments

Under the heading "Food Versus Fuel Issues", Pimentel writes that "expanding ethanol production could entail diverting essential cropland from producing corn needed to sustain human life to producing corn for ethanol factories." He says corn is "a human-food resource" and adds: "Present food shortages throughout the world call attention to the importance of continuing US exports of corn and other grains for human food to reduce malnutrition and starvation. Increased corn exports... most importantly help feed people who need additional food for their survival."

But as Pimentel should surely know, most US corn is used for feeding animals, not hungry people -- 76% of the corn used in the US is used for animal feed. Twenty percent of the total US corn crop is exported; two-thirds of these exports go directly to the wealthy industrial OECD countries, mostly to feed animals.

Less than three-tenths of one percent of total US corn exports went to the 25 poorest countries in 1996. More US corn goes to make alcoholic beverages in the US than is exported to feed the hungry in the world's 25 most undernourished countries combined.

The Energetics of Ethanol: An Introduction and Link to Studies by David Morris, Institute for Local Self-Reliance -- Does it take more energy to make ethanol than is contained in ethanol? That question continues to haunt the ethanol industry even after 27 years of expanding production. Over the years more than 20 scientific studies have examined the question. This document contains links to the major studies of the subject completed during the last decade. [Link updated 3/29/14] 

MSU Ethanol Energy Balance Study, May 2002. Independent study by Michigan State University MSU shows that there is 56% more energy in a gallon of ethanol than it takes to produce it. "The available energy from ethanol is much higher than the input energy for producing ethanol. In other words, using ethanol as a liquid transportation fuel would significantly reduce domestic use of petroleum even in the worstcase scenario." 288kb Acrobat file:  [Link updated 3/29/14]

Ethanol Can Contribute to Energy and Environmental Goals, Alexander E. Farrell, Richard J. Plevin, Brian T. Turner, Andrew D. Jones, Michael O'Hare, Daniel M. Kammen, SCIENCE, Vol. 311, 27 Jan. 2006: "Studies that reported negative net energy incorrectly ignored coproducts and used some obsolete data. All studies indicated that current corn ethanol technologies are much less petroleum-intensive than gasoline but have greenhouse gas emissions similar to those of gasoline." 180kb Acrobat file:  [Link updated 3/29/14]

Pimentel published further reports attacking the ethanol energy balance in 2003 and again in 2005, this time accompanied by Tad Patzek of the University of California, Berkeley. This time they attacked biodiesel as well, which is firmly established as energy-efficient, even biodiesel from soybean monocrops grown by the usual fossil-fuel intensive industrial agriculture methods.

Ethanol Production Using Corn, Switchgrass, and Wood; Biodiesel Production Using Soybean and Sunflower, David Pimentel and Tad W. Patzek, Natural Resources Research, Vol. 14, No. 1, March 2005 (C 2005). 116kb Acrobat file. [Link confirmed 3/29/14]

News release from Cornell University, July 5, 2005: "Cornell ecologist's study finds that producing ethanol and biodiesel from corn and other crops is not worth the energy."  [Link confirmed 3/29/14]

Pimentel still used the antiquated data from his 1979 study. Some insight into Patzek's bias against ethanol can be found on his own website: [Link not currently valid]

Patzek worked for Shell Oil Company as a researcher, consultant, and expert witness. He founded and directs the UC Oil Consortium, which is mainly funded by the oil industry at the rate of US$60,000-120,000 per company per year.

See Energy Balance of Corn Ethanol Results -- six charts that show the picture at a glance (Acrobat file, 140 kb) [Link confirmed 3/29/14]

New study confronts old thinking on ethanol's net energy value, 3/28/2005 -- Ethanol generates 35% more energy than it takes to produce, according to a recent study by Argonne National Laboratory conducted by Michael Wang. The new findings support earlier research that determined ethanol has a positive net energy balance, according to the National Corn Growers Association. That research was conducted by USDA, Michigan State University, the Colorado School of Mines, the Institute for Local Self-Reliance and other public and private entities. Argonne is one of the US Department of Energy's largest research centers.
/ag/story/data/agNews_050328crETHANOL.xml&catref=ag1001[Link not currently valid]
Report on the new study : [Link updated 3/29/14]

A USDA study released in 2004 found that ethanol may net as much as 67% more energy than it takes to produce. [Link updated 3/29/14 – paper is 2001]

[Regarding the energy balance of biodiesel...[Snipped; see link at end]]

See also Food or Fuel?

What standard farm?

The energy in-energy out life-cycle studies use a standard farm as the production model. Such a thing as a standard farm may exist as a statistical average, but a "standard" farming procedure is a myth even on industrialised farms. Anyway, industrial farming has about as much future as the cheap fossil fuels it depends on so heavily, it's hardly a suitable model for sustainable biofuels production.

What would these models have to do with a homesteader who has a good supply of waste wood to burn and no better way of using it, plus a large supply of past-their-use-by-date cakes from a bread factory that he's rescuing from the waste stream? (An actual case.) The cakes could go to a pig farm instead, but they don't. There are many such niches -- spoiled fruit from farms that ought to have pigs but don't, and so on and on. Such factors never get calculated.

What would it have to do with this? "We are looking at a very interesting integrated distillery approach being developed by the Brazilians, where instead of going for the large 300,000 litres per day plants, a fully integrated approach is taken with a 1,500 ha area, farmed by small growers, and feeding sugarcane and sweet sorghum into a 20,000 litres per day plant, with cattle feedlots at the distillery, the manure going into [biogas] digesters with the stillage, producing enough energy for the distillery, leaving the bulk of the bagasse to be used for power generation to supply the surrounding areas." (Energy projects in Africa.)

See also Bio-regional energy -- India's Talukas

Once you start looking at the local level and at integrated approaches to crop production and wastes, and include energy production and use, a different picture emerges that leaves these broad generalisations without much meaning.

A sustainable mixed farm can produce all its own fuel, with much or possibly all of it coming from crop by-products and waste products without any dedicated land use, and with very low input levels.

Biofuels production only makes real sense when the fuel is used as close as possible to where the crop is grown. It makes no sense to waste energy trucking crops long distances to a centralised Big Biofuels plant and then wasting even more energy trucking it all the way back again. The Fuel Miles issue is the same as the Food Miles issue. [Link confirmed 3/29/14]

See also How much fuel can we grow? How much land will it take? [Link confirmed 3/29/14]

There's yet another way of looking at it. This is from Offgrid-Online, April 5, 2000 [Link no longer valid].
"Will we get out more energy than we put in? Does it matter? Generally a scheme that did not create more energy than it consumed would be useless, but in this case we might have a different view. Since we are after a portable fuel, we might be willing to spend more energy to get it, so long as we used a non-portable fuel to do so. For example, suppose we use wood-fired heat to make alcohol. Wood is a poor fuel as far as portability in general is concerned and is nearly useless for internal combustion engines. [But see Woodgas -- JtF - link confirmed] So what if we have to spend 2 BTUs of wood heat for each BTU of alcohol fuel produced? That might still be a good deal if we had lots of wood and gasoline was (that is, continues to be) highly priced."

Source: [Link no longer valid]

The Sierra Club, among other "green" organisations in the US, has a different objection to ethanol. They see the whole issue as clouded by the high levels of nitrogen fertilisers used to grow the maize, and the eco-damage the N-runoff causes.

But that's an objection to US factory farming, not to ethanol. In a more rational system there's no need [link confirmed] for nitrogen fertilisers, and no loss of yield through not using them.

One 15-year study found that organic farming is not only kinder to the environment than "conventional", intensive agriculture but has comparable yields of both products and profits. The study showed that yields of organic maize are identical to yields of maize grown with fertilisers and pesticides, while soil quality in the organic fields dramatically improves. (Drinkwater, L.E., Wagoner, P. & Sarrantonio, M. "Legume-based cropping systems have reduced carbon and nitrogen losses." Nature 396, 262–265.) These findings are widely corroborated. See, eg: The case for organics -- Scientific studies and reports [Link confirmed 3/29/14] 

It seems strange that an organisation like the Sierra Club doesn't know about organic farming, or pretends not to. But then they're still fighting diesels.