Soybean Tops Corn in Fuel Study, But It’s No Gas

For alternative fuel, soybeans beat corn, but neither can do much to satisfy the fuel needs of the U.S., according to a study published Tuesday.

The report is the first to examine comprehensively the life cycles of soybean-oil biodiesel and corn-grain ethanol and to determine their costs and benefits.

The calculations by a team of ecologists and economists led by ecologist Jason Hill of the University of Minnesota at Twin Cities showed that soybean-derived biodiesel gives more bang for the buck, yielding a 93% return on the energy investment used in its production, compared with a 25% return for ethanol.

According to the report, which was published in the Proceedings of the National Academy of Sciences, soybean biodiesel releases less nitrogen, phosphorus and pesticide into the environment than ethanol from corn.

Biodiesel, a type of diesel made from a biological source like plants, could reduce emissions by 41% compared with regular diesel fuel. Ethanol replacement of gasoline could reduce greenhouse gas emissions by 12%, the study found.

Neither of these alternative fuels, however, could relieve the nation’s reliance on petroleum.

The report said that if all U.S. corn and soybean crops were used for fuel instead of food, they would produce only enough fuel to replace 8.7% of diesel demand and 11% of gasoline demand.

“The next step is a biofuel crop that requires low chemical and energy inputs and can give us much greater energy and environmental returns,” said ecologist G. David Tilman, a study coauthor.

Woody plants, like switch grass, are good candidates because they can be grown on land unsuitable for crops without large inputs of energy, fertilizers or pesticides, the report said.