Ethanol and other "bio-fuels" require extensive amounts of land for the cultivation of crops or other source material. So much so, that the environmental costs of such fuels can be substantial. Even from a carbon-emission standpoint, bio-fuels appear to be a bad investment. New research documents that forest conservation is a more effectie way of reducing atmospheric carbon dioxide concentrations than conversion to bio-fuels. Indeed, in some cases it is better to use gasoline and plant some trees than to convert land to ethanol. More from Ron Bailey and the New Scientist.