Production efficiency continues to improve

By Holly Jessen | July 15, 2010
When battling outdated data on efficiency, ethanol producers can now point to two studies on ethanol's increased energy efficiency that came out in June, one conducted by the USDA and the other by researchers at the University of Illinois at Chicago. Both tell a positive story about today's corn-to-ethanol production.

The USDA report by the Office of Energy Policy and New Uses indicates there's now a net energy gain from converting corn to ethanol. "Overall then, ethanol has made the transition from an energy sink, to a moderate net energy gain in the 1990s, to a substantial net energy gain in the present," states the report. "And there are still prospects for improvement."

The University of Illinois study was released right before the International Fuel Ethanol Workshop & Expo, held June 14-17 in St. Louis, where researcher Steffen Mueller spoke about the findings at the conference. The research shows that today's U.S. dry mill ethanol plants are using less thermal energy, electricity and water while producing more ethanol.

For the USDA report, ethanol producers in Iowa, Minnesota, Nebraska and eastern South Dakota were surveyed in the fall of 2008 and winter of 2009. The plants surveyed were dry grind plants that produce and sell dry distillers grains and use fossil fuel power for thermal energy and electricity. The study measured the conventional fossil fuel energy used to produce a gallon of ethanol. The conclusion was that for every Btu of energy required to make one gallon of ethanol, 2.3 Btus of energy are produced. For those companies that use up to 50 percent biomass power, the study said, the ratio of Btus used to produce a gallon of ethanol is a conservative 1: 2.8 Btus of energy produced. In the future, if more biomass is utilized for power, the energy ratio could reach 1: 26. The numbers are an improvement from the last study conducted in 2004 that concluded 2.3 Btus of energy were required to create 1.76 Btus of energy in a gallon of ethanol. In the past 20 years, ethanol yields have improved by 10 percent, which means less corn is needed to produce ethanol, the report said. Besides that, less land is needed to produce corn because corn yields have increased by 39 percent in the same two decades.

For the University of Illinois study, surveys were sent to dry mill plants across the U.S. with 90 out of 150 plants operating in 2008 responding. That represents a 66 percent response rate, making it the most comprehensive data on energy use to date, according to the Renewable Fuels Association. The last comprehensive study was done in 2001 by BBI International.

Compared to the 2001 data, 2008 ethanol yields increased 5.3 percent while thermal energy use decreased by 28 percent, electricity use went down 32 percent and water use was down to 2.72 gallons per gallon of ethanol produced. 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 coproductsbeyond 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.

Ethanol plants source corn from an average distance of 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, 25 percent by truck and 3 percent by ship or barge.

A third study released in April came to some interesting conclusions on plant profitability. Over the past two years, ethanol plants smaller than 60 MMgy were slightly more profitable than large plants, according to "Biofuels Benchmarking," an annual report released by Christianson & Associates. That might be surprising news for an industry that has been, in recent years, constructing larger plants, reaching for lower capital cost per gallon and operating efficiencies. "We haven't found through the data so far that the economies of scale are there that are assumed for larger plants," Paula Emberland, business analyst for the company told EPM.

That study showed a 2 percent increase in ethanol yield from the previous year's results. Of the more than 50 plants participating, the average capacity was 63 MMgy, according to the report's overall industry analysis. Of those plants, 20 percent are producing primarily wet distillers grains, 50 percent primarily dry distillers grains and 30 percent modified wet distillers grains. Corn oil was a popular technology upgrade, going from 30 percent in 2008 to 70 percent among participating plants in 2009. In total, the plants' annual production of corn oil was about 6.6 million pounds. About 17 percent of the plants capture CO2 and sell an average of 70,000 tons of it annually.