“It’s 36 percent more efficient to grow grain for food than for fuel,” said the lead author of a paper that looked at 17 years worth of data to help settle the food versus fuel debate.
“The ideal is to grow corn for food,” said Ilya Gelfand , a Michigan State University postdoctoral researcher, “then leave the leftover stalks and leaves on the field for soil conservation and produce cellulosic ethanol with the other half.”
“It comes down to what’s the most efficient use of the land,” said Phil Robertson, University Distinguished Professor of crop and soil sciences and one of the paper’s authors. “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.”
Gelfand and Robertson along with Sieglinde Snapp, the third co-author and an MSU associate professor of crop and soil sciences, analysed data collected between 1989 and 2007 gathered from the W.K. Kellog Long Term Ecological Research site, a National Science Foundation-funded project.
The scientists compared the energy inputs and outputs of producing corn, soybeans and wheat grown in four distinct systems: conventional tillage, no-till, low chemical input and organic. They then compared the results for using all harvested plant material for either food or biofuel production. They also looked at the energy balance – the difference between the energy produced by 1 kilogram of fuel and the energy needed to produce the 1 kilogram – for growing alfalfa, which itself is an important forage plant that can be used either as a biofuel or as feed for beef cattle.
They found that the least efficient method was conventional tillage, which is currently the process used to grow and harvest 60% of these crops today and ends up requiring 40% more energy than no-tillage (which came out as the most efficient method of growing grains). This is almost a no-brainer as it reduces the tractor fuel used during production.
The most efficient plant as a biofuel was alfalfa, which turned out to be 60% more efficient than using it for cattle feed. The study also found that growing grasses on less productive land to feed beef cattle is 60% less efficient than using those same grasses to produce biofuels. “We found that it’s not energy-efficient to produce ethanol from grain crops that can serve as food,” says Gelfand. “It’s more efficient to produce ethanol from cellulosic feedstocks such as grasses.”
Neville Millar, a colleague of Ilya Gelfand at the W.K. Kellog Biological Station, described the study as “important,” saying that “it shows that from an energy efficient standpoint, the best agricultural systems may be those that can produce both food and fuel.”
The study comes at a time when America is pushing to make 22% of the U.S. Transportation fuel mix biofuels by 2022. Subsequently the debate rages as to whether land should be used to produce biofuels or food. With 40% of America’s 350 million tonnes of corn grain going to cattle, and the remaining 60% split between people for food, ethanol and industrial products, this study could help drastically increase energy efficiency for the next decade and beyond.
“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 said.
“Our research suggests that this is an energy-efficient strategy as well, so long as the grain is used for food,” Robertson said. “But there are not enough corn stalks to meet expected energy needs and federal policy also may decide to offer incentives to grow crops that offer more environmental benefits than corn, including incentives to grow grasses on less productive land. The promise of biofuels made from biomass is huge, from both climate mitigation and economic perspectives,” he continued. “But the promise could come up short if we don’t pay attention to details such as the land on which they are grown.”