The LA Times has a terrific article outlining the problems with ethanol, whether from corn or cellulosic from plants like switchgrass.
"Alcohol is best taken in moderation, and that applies to cars as much as people. Ethanol isn't all hype -- it's a promising alternative fuel that could stretch gasoline supplies and cut emissions. But as politicians try to outdo one another by approving ever-bigger ethanol subsidies, production mandates and research grants, few are considering the environmental and economic effects of a massive, rapid rise in ethanol production. These are so severe that unless the mania ends soon, they could far outweigh any gains."::LA Times
photograph by Robert Wellman Campbell