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to make ethanol, turning our entire corn crop to ethanol production would reduce our fossil fuel use by just 2.4 percent.
So why do governments subsidize corn-based ethanol production? "If the energy source is environmentally benign, especially compared to alternatives, then a subsidy can be justified," explains Stephen Polasky, University professor of applied economics and co-author of the study. "What we found for corn ethanol is there really isn't much basis to justify a subsidy on environmental grounds."
But what about ethanol's contribution to local economies? "I don't think ethanol is a job engine," says C. Ford Runge, professor of applied economics and law at the University. "It's not going to have an appreciable impact on rural employment opportunities."
Once a plant is built, its operation requires only a few people. And while corn farmers benefit from a better market, livestock producers worry that competition for corn from ethanol plants will drive up prices and make their products less competitive. "There's enormous anxiety in the surrounding countryside that the ethanol plant is going to suck all the corn out of the local economy," Runge says.
Meanwhile, the subsidies to support corn growing and ethanol production are funneled from a broad base of taxpayers and consumers to a small number of beneficiaries--mainly investors in ethanol plants. These include not only local farmer cooperatives, but also giant agriculture processors like Archer Daniels Midland.
If corn isn't the answer, what is?
Ethanol isn't the only biofuel in town. Minnesota--as does much of the rest of the nation--also produces biodiesel from soybeans. According to Hill's study, soy diesel trumps ethanol by almost any measure:
• Biodiesel yields 93 percent more energy than is required to produce it.
• Compared with corn, soy uses 1 percent of the nitrogen, 8 percent of the phosphorus, and 13 percent of the pesticides--and less toxic chemicals too.
Soy produces less air pollution. Whereas E85 over its life-cycle actually pollutes more than gasoline, biodiesel containing 20 percent soy burns cleaner than the diesel it replaces. Particulate matter is reduced by 31 percent, carbon monoxide by 21 percent, and total hydrocarbons by 47 percent. It produces 41 percent fewer greenhouse gases than diesel.
"Biodiesel provides sufficient environmental advantages to merit subsidy," states the report.
A second way to improve the efficiency of biofuels is to find alternative sources of heat to distill it. For example, says Tiffany, corn stalks and husks contain enough energy to distill ethanol. According to the National Renewable Energy Laboratory, part of the U.S. Department of Energy, 85 percent of the stalks and other plant material rots on the ground, releasing carbon dioxide. The rest is incorporated into the soil. By collecting and burning a portion, "we could certainly get some excellent energy balances," Tiffany says.
The third--and possibly the real hope--for making a viable biofuel lies in making ethanol and the energy to process it, not from cultivated crops, but from the cellulose in native perennials.
The prairie proposition
"We have a vision of restoring a lot of prairie throughout the Midwest, and having something that will be mowed every year for hay and then either pelletized and burned, or converted into ethanol," says Tilman, who has conducted prairie grass research at the U's Cedar Creek Natural History Area for 12 years.
According to a study by Tilman, Hill, and University research associate Clarence Lehman (B.A. '67, M.S. '92, Ph.D. '00), published in December 2006 in the journal Science, producing "cellulosic" ethanol from diverse plots of perennial grasses promises several advantages over corn-grain ethanol: greater yields, more ethanol, less pollution, and fewer greenhouse gases. And all that without diverting a food source.
According to Tilman's study:
• Perennial biomass such as native grasses would need little in the way of chemicals, energy, or even work--just mow it once a year. It wouldn't even need to be planted. "What we've seen is that we can get a lot of biomass produced in plots
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