04 Sep 2009:
Revisiting the Question
Of Corn Ethanol’s Carbon Footprint
Do biofuels made from corn emit significantly less carbon dioxide than gasoline? That debate flared up last year as global commodity prices soared and biofuel critics argued that planting corn and converting it to liquid fuel not only produced nearly as many greenhouse gases per gallon as combusting gasoline, but also drove up world food prices. The Journal of Industrial Ecology
is taking another look at the question and concludes that corn ethanol probably produces about 35 to 40 percent fewer greenhouse gases than burning gasoline.
The journal features several articles
that debate the complicated issue of so-called life-cycle carbon intensity, which looks at all stages of fuel production to determine the quantity of greenhouse gases produced by different fuels. Scientists at the University of Nebraska argue in the journal that recent advances in refining efficiency, crop production, and utilization of by-products from corn ethanol production mean that corn ethanol generates roughly half as many greenhouse gases as gasoline. A researcher from the University of California, Berkeley, disputed that finding, saying that corn ethanol produces only about a third fewer greenhouse gases. The editors of the journal agree more with the Berkeley figures, and note that the debate is not merely academic: Accurately determining how many greenhouse gases corn ethanol generates will influence regulatory decisions on biofuel by both the U.S. Environmental Protection Agency and states such as California.
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Photographer Peter Essick documents the swift changes wrought by global warming in Antarctica, Greenland, and other far-flung places. View the gallery.
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The Warriors of Qiugang
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In a Yale Environment 360
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