Ethanol production gains efficiency

By Holly Jessen | May 21, 2010
Posted June 1, 2010

Research published in the scientific journal Biotechnology Letters shows that today's U.S. dry mill ethanol plants are using less thermal energy, electricity and water while producing more ethanol. Dr. Steffen Mueller at the University of Illinois at Chicago compared 2008 dry mill production statistics to statistics gathered in 2001—the last comprehensive survey of energy use by corn ethanol plants.

Mueller will speak on this topic at this year's International Fuel Ethanol Workshop & Expo (FEW), set for June 14-17 in St. Louis. His remarks will come during the first session held June 15, entitled Examining Corn Ethanol's Falling Carbon Score: A Review of the Data and Critical Process Evolution. For more information about FEW check out the website.

About 90 percent of U.S. ethanol production is at dry mill plants. In all, 90 out of 150 ethanol plants that were operating in 2008 responded to the survey. That represents about 66 percent response rate and makes it the most comprehensive data on energy use to date, according to the Renewable Fuels Association.

Compared to the 2001 data, the RFA said, ethanol yields increased 5.3 percent. Energy and water use, however, decreased.
• Thermal energy use decreased by 28 percent
• Electricity use went down 32 percent
• Water use was down, to 2.72 gallons per gallon of ethanol produced

In addition, the report shows that about a third of ethanol plants surveyed utilize back-end corn oil separation. The survey also revealed a trend of further diversification in coproducts—beyond dry distillers grains, wet distillers grains and corn oil. Other coproducts reported included syrup, modified distillers grains, CO2, bran, germ syrup and condensed distillers solubles.

The average distance that ethanol plants get their corn from is 75.6 miles, according to the study. However, that number was skewed by two plants from the southwest, which reported transportation distances in excess of 1,000 miles. Excluding the information from those two plants, the average transportation distance was 47.1 miles. A total of 72 percent of the ethanol produced at the plants surveyed is distributed via rail. The remainder is transported by truck, 25 percent; or ship/barge, 3 percent.

Mueller is a principal research economist and research assistant professor at the university's Energy Resources Center. He's also one of 30 people appointed by the California Air Resources Board expert workgroup that will look at, among other things, indirect land use change as included in the state's low carbon fuel standard.

For more information, see the full report.

UPDATED: Information added about Mueller's speaking engagement at this year's FEW.