USDA report shows improving corn-ethanol energy efficiency

Sep 21, 2010 by Brenda Chapin
USDA Report highlights Increased Energy Efficiency for Corn-based Ethanol

Harry Baumes, Acting Director of USDA's Office of Energy Policy and New Uses, says a report that surveyed corn growers in 2005 and ethanol plants in 2008 indicates the net energy gain from converting corn to ethanol is improving in efficiency.

Titled “2008 for the Corn-Ethanol Industry,” the report surveyed producers about ethanol yield (undenatured) per bushel of corn and energy used in ethanol plants.

This report measured all conventional fossil fuel energy, 53,785 BTU used in the production of 1 gallon of corn ethanol. For every British Thermal Unit (BTU) (unit of heat equal to the amount of heat required to raise one pound of water one degree Fahrenheit at one atmosphere) of energy required to make ethanol, 2.3 BTUs of energy are produced (energy output/energy input). The ratio is somewhat higher for some firms that are partially substituting biomass energy in processing energy (thermal and electrical energy required in the plant to convert corn to one gallon of ethanol). Since the last study in 2004, the net energy balance of has increased from 1.76 BTUs to 2.3 BTUs of required energy.

According to the report, overall, ethanol has made the transition from an energy sink (more energy used than energy produced), to a moderate net energy gain in the 1990s, to a substantial net gain in the present. And there are still prospects for improvement. Ethanol yields have increased by about 10 percent in the last 20 years, so proportionately less corn is required. In addition to refinements in ethanol technology, corn yields have increased by 39 percent over the last 20 years, requiring less land to produce ethanol. The report can be found here.

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Provided by USDA Agricultural Research Service

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Biodiversivist
1 / 5 (1) Sep 23, 2010
Robert Rapier took a close look at this latest analysis. Google the term " rapier fun with numbers "

Refineries have not been getting more efficient this fast, instead, in an attempt to show corn ethanol in a positive light, they have been biasing the way they do their energy accounting.

For example, a bushel of corn contains a set amount of calories. The 2.77 gallons of ethanol you get from it contains a set amount of calories. Subtract one from the other and you find corn ethanol has a negative return on energy before you begin accounting for the energy used to make it. Giving an energy credit to refinery byproducts still shows a net loss from the calories in that bushel you started with.