Paul Krugman in the NY Times:
Where the effects of bad policy are clearest, however, is in the rise of demon ethanol and other biofuels. The subsidized conversion of crops into fuel was supposed to promote energy independence and help limit global warming. But this promise was, as Time magazine bluntly put it, a "scam."
This is especially true of corn ethanol: even on optimistic estimates, producing a gallon of ethanol from corn uses most of the energy the gallon contains. But it turns out that even seemingly "good" biofuel policies, like Brazil's use of ethanol from sugar cane, accelerate the pace of climate change by promoting deforestation.
And meanwhile, land used to grow biofuel feedstock is land not available to grow food, so subsidies to biofuels are a major factor in the food crisis.