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The economics of ethanol. (Alternative Fuels).

The conversion of corn into ethanol to produce gasohol (a gasoline-ethanol mixture) is touted by some scientists as an economical and environmentally cleaner alternative to fossil fuels. However, ethanol production is neither economical nor environmentally sound, concludes David Pimentel, a professor of insect ecology and agricultural science at Cornell University in Ithaca, New York. According to a study by Pimentel that appears in the third edition of the Encyclopedia of Physical Science and Technology, published in October 2001, 1.7 times more energy is required to grow and process corn and then distill the ethanol than is obtained from burning it. "The myth is that ethanol frees us from dependence on oil, yet we actually import oil to run ethanol plants and grow corn," Pimentel says.

In addition, most other economic calculations of ethanol production have ignored the costs of environmental damage associated with corn production. "Corn uses more herbicides and pesticides than any other U.S. crop," says Pimentel. In addition, he says, corn production erodes soil about 12 times faster than the soil can be naturally reformed, and irrigating corn depletes groundwater 25% faster than the natural recharge rate. Pimentel calculates that if the average automobile in the United States, traveling 10,000 miles a year, were to be fueled by ethanol, seven times more cropland would be required for fuel than is currently devoted to feeding one American citizen. He further contends that if the current $1 billion in federal and state subsidies were dropped, ethanol production "could not float on its own."

In contrast, Estimating the Net Energy Balance of Corn Ethanol: An Economic Research Service Report, a 1995 report by Hosein Shapouri, James A. Duffield, and Michael S. Graboski of the U.S. Department of Agriculture, claims that the net energy content of ethanol runs 1.2 times more than the fossil energy needed to produce it. Experts agree that differences in corn yields, credit for the energy content of nonethanol by-products such as distillers and grains, varied technologies used at different processing plants, and the regional costs of machinery, fertilizer, irrigation, and transportation contribute to the discrepancy between the two studies' findings. "The analysis is difficult because there's a wide range of processing plants operating at different efficiencies using different equipment and technology," says chemical engineer George Robertson of the Agricultural Research Service Western Regional Research Center in Albany, California.

Robertson sees changes pointing toward economic feasibility. For instance, his laboratory has developed enzyme variants that convert cornstarch into sugars (for fermentation into ethanol) over 50 times faster and at lower temperatures than the original enzymes, making production more energy-efficient. At the biotechnology company Genencor International in Palo Alto, California, researchers are designing enzymes to make ethanol from the cellulose in cornstalks. (Cornstalks are a cheaper raw material than kernels, and using cellulose avoids competion with food markets for kernels.) In addition, new ethanol plants are built near feedlots, and corn by-products are sold as cattle feed to offset processing costs.

As for subsidies, "they got the ethanol industry on its feet," Robertson says. As ethanol processing evolves and the world's finite oil supply dwindles, he predicts that subsidies for ethanol will disappear and the ethanol industry will be able to support itself. Moreover, he says, the oil industry is subsidized indirectly by military and diplomatic activities abroad to ensure a continuous oil supply. Yet, Robertson points out, "There's no need for a military force in our Midwest to ensure a continuous supply of corn to produce ethanol."
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Author:Potera, Carol
Publication:Environmental Health Perspectives
Date:Jan 1, 2002
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