Study: Ethanol production more efficient in Minnesota

Producing ethanol in Minnesota and other Midwestern states uses far less water during processing than western states where more irrigation is needed, according to a University of Minnesota study released Wednesday.

The study, which appeared in the April 15 edition of Environmental Science and Technology, found in Minnesota, where 2.2 billion liters of ethanol were produced in 2007, it takes 19 liters of water to grow and harvest corn and then process it into ethanol.

California, the nation’s 13th largest ethanol producer, needed 2,100 liters of water to produce one gallon of ethanol — making it the worst state in water efficiency.

By comparison, Iowa, the nation’s largest corn ethanol producer, uses about six liters of water to make one liter of ethanol.

With the results of this study, lead author and bioproducts and biosystems engineering professor Sangwon Suh said policy makers can consider the water costs of producing ethanol in different areas of the U.S. as they look to expand the industry.

Even though water is a cheap commodity in the United States, Suh said “the perception that water is everywhere is a problem.”

There is a risk of humans depleting water supplies faster than they are refilled by rainfall, he said, so it’s important that water not be used inefficiently to grow corn for fuel.

“Water security is too important to sacrifice for energy security,” he said.

Suh said water is used inefficiently for corn irrigation because if the crop was grown in a part of the country with better rainfall, irrigation wouldn’t be necessary and water could be saved. Irrigation is used to grow only 11 percent of the corn in the United States, he said, but that 11 percent accounts for 98 percent of the total water used in ethanol production.

“If that 11 percent can be produced in the regions that do not need irrigation, we can reduce 98 percent of the water used to produce ethanol,” Suh said.

Cornell University ecology and agricultural sciences professor David Pimentel , who conducted similar research to Suh’s, questioned the value of Suh’s research results because they don’t include rainfall consumed during corn production in the total cost.

In the study Pimentel helped conduct, he said researchers found that 2,900 liters of water are required to make one liter of ethanol, regardless of whether the water came from irrigation or natural rainfall.

By only looking at the water input from irrigation, Suh’s study doesn’t take a broad enough view, Pimentel said.

For farmers and ethanol producers in states like Nebraska, water is “a precious resource,” Todd Sneller administrator of the Nebraska Ethanol Board, said.

Although Nebraska ranked lowest in efficiency for states producing more than 1 billion liters of ethanol, Sneller said farmers and producers are constantly working to conserve water because it is such an important resource.