The net energy balance for corn ethanol increased from 1.76 to 2.3 BTUs of required energy, the U.S. Department of Agriculture noted in a recent news release. That means that for every 1 BTU of energy put into corn ethanol (from growing the corn through making ethanol), you get 2.3 BTUs of energy in return.
In fact, USDA said, corn ethanol production has transitioned from "a moderate net energy gain in the 1990s, to a substantial net energy gain in the present. And there are still prospects for improvement."
It said 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 measured all conventional fossil fuel energy used in the production of 1 gallon of corn ethanol. USDA noted that the ratio is somewhat higher for companies that are partially substituting biomass energy in processing energy.
The report is based on a USDA survey of corn growers for the year 2005 and ethanol plants in 2008, which indicates the net energy gain from converting corn to ethanol is improving in efficiency. The survey asked ethanol producers to respond to questions about ethanol yield (undenatured) per bushel of corn and energy used in the plants. The 2008 updates presented in the report recorded the effects of current practices used by corn producers and ethanol processors.
Click here for the full study (.pdf).
This study comes after a recent University of Illinois report that showed ethanol plant energy use declined significantly from 2001 to 2008. During that time, thermal energy use (natural gas) declined 28 percent and electrical use declined 32 percent per gallon of ethanol produced. Ethanol per bushel of corn, meanwhile, increased 5.3 percent to 2.78 gallons per bushel. For more, click here.
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