DURHAM, N.C. -- To avoid creating greenhouse gases, it makes more sense using today's technology to leave land unfarmed in conservation reserves than to plow it up for corn to make biofuel, according to a comprehensive Duke University-led study.
"Converting set-asides to corn-ethanol production is an inefficient and expensive greenhouse gas mitigation policy that should not be encouraged until ethanol-production technologies improve," the study's authors reported in the March edition of the research journal Ecological Applications.
Nevertheless, farmers and producers are already receiving federal subsidies to grow more corn for ethanol under the Energy Independence and Security Act of 2007.
"One of our take-home messages is that conservation programs are currently a cheaper and more efficient greenhouse gas policy for taxpayers than corn-ethanol production," said biologist Robert Jackson, the Nicholas Professor of Global Environmental Change at Duke's Nicholas School of the Environment, who led the study.
Making ethanol from corn reduces atmospheric releases of the greenhouse gas carbon dioxide because the CO2 emitted when the ethanol burns is "canceled out" by the carbon dioxide taken in by the next crop of growing plants, which use it in photosynthesis. That means equivalent amounts of carbon dioxide are removed from the atmosphere and "fixed" into plant tissues.
But the study notes that some CO2 not counterbalanced by plant carbon uptake gets released when corn is grown and processed for ethanol. Furthermore, ethanol contains only about 70 percent of gasoline's energy.
"So we actually reduce greenhouse gas emissions only 20 percent when we substitute one liter of ethanol for one liter of gasoline," said Gervasio Pieiro, the study's first author, who is a Buenos Aires, Argentina-based scientist and postdoctoral research associate in Jackson's Duke laboratory.
Also, by the researchers' acc
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