Discovery Guides Areas


What Place in Our Energy Future?

(Released April 2009)

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  by Ethan Goffman  


Key Citations




Corn, Corn, Fields of Corn


In the United States ethanol was first mandated in 1978, largely in response to the Arab oil embargo. Ethanol continued as a minor part of the energy picture until the Energy Policy Act of 2005 that "aimed to double the use of renewable fuel, mainly ethanol made from corn, by 2012" (Energy Information Administration). In 2007 this was expanded to "require that 36 billion gallons of ethanol and other fuels be blended into gasoline, diesel, and jet fuel by 2022" (Ibid). The impact of these laws is powerful. The United States Department of Agriculture projects that corn-ethanol production will have doubled from 5 billion gallons in 2006 to 10 billion gallons in 2009 (Morrow).

Corn from test plots near Rochelle, Illinois, 2007.

Currently, the minimum mandated ethanol blend in gasoline is 7.6%, or E7.6, with a maximum of 10%, or E10, the amount for which today's car engines are designed. Engines have been designed for E85, yet remain rare. Flex fuel vehicles that use variable amounts of ethanol would greatly ease infrastructure problems, and indeed are now common in Brazil. According to one expert, "Manufacturing flex fuel vehicles is a trivial change. It costs less than $200 per vehicle." (Greer). Still, ethanol provides about 30 percent fewer miles per gallon than gasoline, necessitating bigger engines or more frequent stops to fill up.

Numerous factors contribute to corn ethanol's overall environmental cost. One study explains that: "Direct-effect life cycle energy and GHG assessment of corn-ethanol considers the energy used for feedstock production and harvesting, including fossil fuels (primarily diesel) for field operations and electricity for grain drying and irrigation" (Liska et al). Yet a complete assessment requires examining even more factors, particularly energy inputs: "Energy expended in crop production also includes upstream costs for the production of fertilizer, pesticides, and seed; depreciable cost of manufacturing farm machinery; and the energy required in the production of fossil fuels and electricity" (Liska et al). While fossil fuels currently generate much of the energy input, in the long run more of it will come from renewable sources.

US ethanol production
Critics of corn ethanol cite several studies showing very little improvement in greenhouse gas emissions over gasoline, or even a loss. Dramatically, a Minnesota study shows that "about 25 percent more energy is squeezed out of the biofuel than is used to produce it" (Rotman). Yet a recent University of Nebraska study contradicts this, estimating direct effect GHG emissions as "equivalent to a 48% to 59% reduction compared to gasoline, a twofold to threefold greater reduction than reported in previous studies" (Liska et al). The discrepancy is largely because older studies "rely on estimates of energy efficiencies in older ethanol plants that were built before the recent investment boom in new ethanol biorefineries that initiated production on or after January 2005" (Liska et al). Improved corn yields make the picture brighter, as does better conservation tillage. With better technologies, newer biorefineries could lead to a far better corn ethanol GHG balance. Additionally, the Nebraska study, unlike many, accounts for the effect of distiller grains derived from ethanol production in animal feed, maintaining some of the food that would otherwise be displaced, explains renewable energy expert Nathaneal Greene. Still, the Nebraska study does not take indirect land use into account and therefore presents only part of the picture. Greene explains indirect land use as "the 800 pound gorilla, anywhere from relatively modest to very large impact."

The American ethanol industry is using the Nebraska study to argue for renewed commitment to corn ethanol. They also believe that the regulatory cap should be raised from a 10% ethanol blend (E10) to 15%, arguing that today's car engines are capable of handling this blend (Galbraith).

Increased agricultural efficiency is also decreasing greenhouse gas emissions from ethanol, a trend that is likely to continue. Much of this improvement is due to genetically modified crops grown on a large scale. Such practices, however, are anathema to environmentalists. "Where would we ever want to have huge fields of any crop just for biofuels production," asks Greene, who cites "bedrock issues of monoculture-biodiversity, water quality, and soil quality." Corn may create special environmental problems, since it "requires large doses of herbicide and nitrogen fertilizer and can cause more soil erosion than any other crop" (Bourne).

Ethanol backers also argue that corn ethanol will serve as a bridge to better ethanol, providing the basic infrastructure for a future of cellulose-based energy. Greene agrees, although adding "that argument has largely run its course. I don't think there's any need for the corn market to continue to grow to make cellulosic viable." Government subsidies of ethanol are also moving from corn to cellulose: A 2007 bill moves toward "43 percent of the standard going to corn and 57 percent to advanced biofuels, including cellulose" by 2015 (Tyner).

Corn ethanol is thus an industry created by and subsisting on government mandates. It has definite benefits in creating jobs in rural areas and improving local air quality. Yet two of its stated reasons for being subsidized, alleviating global warming and increasing energy security, are arguable.

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