Corn-Ethanol Net Energy Balance Rising

9 June 2004

The net energy balance of any fuel is the difference between the amount of energy the fuel produces and the amount of energy it takes to generate that fuel. For several years, there has been a dispute raging over the energy balance of corn-ethanol. Some, notably Dr. David Pimentel at Cornell, insist that ethanol actually has a negative energy balance -- in other words, that it takes more energy to produce ethanol than the ethanol itself delivers. From a global energy point of view, of course, that’s bad.

Many, notably the USDA and the corn industry, have disputed that research. Now, the USDA is providing preliminary findings of a new study on the net energy balance of ethanol indicating ethanol now produces 67 percent more energy than it takes to generate. This represents a relative increase of more than 2.5 times in 10 years. (Chart at right. Click to enlarge.)

The study, “The 2001 Net Energy Balance of Corn-Ethanol,” was presented Tuesday at the Corn Utilization and Technology Conference (CUTC) by Hosein Shapouri, a U.S. Department of Agriculture economist.

Shapouri said his research proves ethanol undoubtedly has a positive energy balance, even before subtracting the energy allocated to coproducts. In a 1996 study, Shapouri calculated the net energy balance of ethanol at 36 percent, up from 24 percent in 1991. Technological advances in crop production and the ethanol plant have helped to reduce the amount of energy required to produce ethanol, he said.

“Corn yields per acre have increased, fertilizer is more energy efficient and ethanol plants are more efficient,” Shapouri said. “So the net energy value of corn-ethanol improves.”

And as technology continues to improve, so will the energy value of ethanol, Shapouri says. Higher yields, more energy efficient inputs and improved technologies in ethanol plants will drive the energy balance of ethanol even higher, he said.

We are starting to see some of that with the annoucements I posted earlier-- the Pioneer testing tool for ethanol yield, and the five new Mycogen strains, optimized for ethanol production.