MICHIGAN STATE (US)—Using productive farmland to grow crops for food instead of fuel is more energy efficient, but the ideal scenario may be a combination of both.
“It comes down to what’s the most efficient use of the land,” says Phil Robertson, distinguished professor of crop and soil sciences at Michigan State University. “Given finite land resources, will it be more efficient to use productive farmland for food or fuel?
“One compromise would be to use productive farmland for both—to use the grain for food and the other parts of the plant for fuel where possible. Another would be to reserve productive farmland for food and to grow biofuel grasses—cellulosic biomass—on less productive land.”
Robertson is the lead author of a study analyzing 17 years’ worth of data looking at energy balances of an entire cropping system over many years. The results are published in the journal Environmental Science & Technology.
Robertson and colleagues analyzed data collected from 1989 to 2007 at the W.K. Kellogg Long-Term Ecological Research site, that studies ecology and environmental biology to better understand natural and managed systems.
“It’s 36 percent more efficient to grow grain for food than for fuel,” says postdoctoral researcher Ilya Gelfand. “The ideal is to grow corn for food, then leave half the leftover stalks and leaves on the field for soil conservation and produce cellulosic ethanol with the other half.”
Energy inputs were compared with outputs of producing corn, soybeans and wheat and energy balances for growing alfalfa, an important forage plant that can be used either for biofuel or for beef cattle feed.
The analysis showed that using non-tilling production to grow grain for food was the most energy-efficient system for food or fuel production, as it reduces tractor fuel use.
Robertson and Gelfand also are members of the Great Lakes Bioenergy Research Center, a partnership between Michigan State and the University of Wisconsin-Madison funded by the U.S. Department of Energy to conduct basic research aimed at solving some of the most complex problems in converting natural materials to energy.
“This research is aimed at policymakers who have to decide how and where biofuels should be grown and the best way to encourage farmers to follow those suggestions,” Robertson says.
“The promise of biofuels made from biomass is huge, from both climate mitigation and economic perspectives,” he says. “But the promise could come up short if we don’t pay attention to details such as the land on which they are grown.”
The research is funded by the GLBRC, the NSF and the Michigan Agricultural Experiment Station.
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