yesterday's news drew attention to two new studies in Science on the problems of biofuels as a panacea for the damage wrought by reliance on fossil fuel energy. i don't find it that surprising that burning more biomass isn't a great way to reduce carbon emissions, even if the plants' growth is supposed to offest their greenhouse impact by absorbing CO2. by taking into account the effect of converting existing cropland to biofuel farming, one of the studies found that "corn-based ethanol, instead of producing a 20% savings, nearly doubles greenhouse emissions over 30 years and increases greenhouse gases for 167 years. Biofuels from switchgrass, if grown on U.S. corn lands, increase emissions by 50%." both studies suggest that to offset greenhouse gases (GHG), biofuels will have to come from waste products and abandoned agricultural land: "[i]n contrast, biofuels made from waste biomass or from biomass grown on abandoned agricultural lands planted with perennials incur little or no carbon debt and offer immediate and sustained GHG advantages" (Land Clearing and the Biofuel Carbon Debt, Fargione et al).
it's unfortunate that even a hardy cover crop like switchgrass might not be as promising a solution as it looks (though the studies do suggest that integrated properly, such perennials could provide efficient biofuel with low carbon impact), but i also take this as a reminder of the negative consequences of enormous federal corn subsidies. corn-based ethanol has been an attractive fuel alternative because it creates a potential new market for all that cheap corn grown in the midwest, which has long outpaced demand. ethanol offers American agribusiness a new market for their undervalued product, while promising the political expedience of claiming to reduce our "dependency on foreign oil." but unless biofuels can be shown actually to reduce carbon emissions, they only people they'll benefit are big corporations, at the expense of the rest of us.
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