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A University of Minnesota study finds Midwestern U.S. ethanol plants use much less water than do plants located in areas in which water is not as plentiful.
The study's lead author, Assistant Professor Sangwon Suh, said Iowa uses six gallons of water to make one gallon of ethanol, while California's ethanol plants use 2,100 gallons.
The researchers said the study is the first to compare water use in corn-ethanol production on a state-by-state basis. Minnesota, which in 2007 produced about a third as much ethanol as Iowa, used approximately 19 gallons of water per ethanol gallon. South Dakota, with total production roughly equal to Minnesota's, uses about 96 gallons of water to produce one gallon of ethanol.
The scientists said their study highlights the need to strategically promote ethanol development in states with lower irrigation rates and less groundwater use.
"Both energy security and water security are too important; improvement of one of them should not be made at the expense of another," said Suh. "Understanding the dependence of biofuel on water and its spatial disparity will be critical in implementing the biofuel policy in the United States."
The research appears in the journal Environmental Science and Technology.
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