Study: Midwestern Ethanol Plants Use Less Water than Western Counterparts

April 13, 2009 07:00 PM

via a special arrangement with Informa Economics, Inc.

Another Univ. of Minnesota study brings different analysis from ethanol industry watchers

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Ethanol production in Minnesota and Iowa uses far less water overall than similar processes in states where water is less plentiful, according to a new University of Minnesota study.

The study, to be published in the April 15 edition of the journal Environmental Science and Technology, is the first to compare water use in corn-ethanol production on a state-by-state basis. The authors used agricultural and geologic data from 2006-2008 to develop a ratio showing how much irrigated water was used to grow and harvest the corn and to process it at ethanol plants.

Among the major ethanol-producing states, Iowa uses the least water, with about six gallons of water used for each gallon of ethanol. Minnesota, which in 2007 produced roughly a third as much ethanol as Iowa, uses about 19 gallons of water per ethanol gallon.

States where irrigation is needed to grow corn fared far worse than those where almost no corn is irrigated. California, which produces only a tiny fraction of the nation's ethanol but irrigates most of its corn, is the largest water consumer, at about 2,100 gallons of water per gallon of ethanol. South Dakota, with total production roughly equal to Minnesota's, uses about 96 gallons of water to produce one gallon of ethanol.
Water usage could be an important factor in policy decisions about where ethanol plants are built. The study "highlights the need to strategically promote ethanol development in states with lower irrigation rates and less groundwater use,” the authors wrote. All the states with high water usage ratios are classified by the federal government as likely to experience water shortages in coming years.

"Both energy security and water security are too important; improvement of one of them should not be made at the expense of another,” said Sangwon Suh, an assistant professor in the university's department of bioproducts and biosystems engineering and the study's lead author. "Understanding the dependence of biofuel on water and its spatial disparity will be critical in implementing the biofuel policy in the United States."

The study was funded in part by the U.S. Department of Energy and by the Legislative Citizens Commission on Minnesota Resources.

Responding to the conclusions of the Minnesota study, Tom Buis, CEO for Growth Energy, cited technology improvements that he said are allowing ethanol producers to "continuously decrease water usage in their plants -- from a high of eight gallons of water per gallon of ethanol 20 years ago to around 3.5 gallons today."

Buis said the water use study misses several points, one being that only four percent of the corn used to produce ethanol in the U.S. is on irrigated land, with 86 percent being rain-fed. In addition, he said, seed companies are developing new hybrids that will "drastically decrease the amount of water needed to grow crops."

An article in the MIT Technology Review noted that the study showed that ethanol derived from corn consumes up to three times more water than previously thought. It added that as corn-based ethanol production has approximately doubled nationwide between 2005 and 2008, related water use has more than tripled.

"Ethanol consumes more water over time as corn production extends to regions that need extensive irrigation," said Sangwon Suh. "That means more water is needed to produce a given unit of ethanol over time."

Geoff Cooper, vice president of research at the Renewable Fuels Association in Washington D.C., questioned the researchers' claim that water use has tripled as ethanol production has doubled. "The bulk of expansion from '05 to '08 occurred in the central corn belt--places that don't irrigate corn," according to the Technology Review article. "There is a finite limit to how much ethanol you can put in water-constrained areas. We are not putting ethanol plants into areas where water is severely limited."

Suh is also optimistic that water use can be reduced while ethanol production continues to grow. He said that agricultural land that has been set aside for conservation in regions that do not require irrigation could be brought back into production, and genetically engineered corn could maintain high yields with lower water requirements. "I'm very optimistic we can achieve the ethanol production mandate without sacrificing water security in the U.S.," he said.

Comments: Still another study and still more widely different conclusions from industry proponents, opponents and hopefully unbiased observers.


NOTE: This column is copyrighted material, therefore reproduction or retransmission is prohibited under U.S. copyright laws.


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