"The International Institute for Sustainable Development was not so diplomatic, and estimates that the CO2 and climate benefits from replacing petroleum fuels with biofuels like ethanol are basically zero (IISD). They claim that it would be almost 100 times more effective, and much less costly, to significantly reduce vehicle emissions through more stringent standards, and to increase CAFE standards on all cars and light trucks to over 40 miles per gallon as was done in Japan just a few years ago.
With more than 60 nations having biofuel mandates, the competition between ethanol and food has become a moral issue. Groups like Oxfam and the Environmental Working Group oppose biofuels because they push up food prices and disproportionately affect the poor.
Most importantly, the new IPCC report is a complete about-face for the UN’s Panel. Its 2007 report was broadly condemned by some environmentalists for giving the green light to large-scale biofuel production, resulting in environmental and food supply problems.
The general discussion on biofuels has changed over the last few years. In December, Senators Feinstein (D-CA) and Coburn (R-OK) introduced a bill that would eliminate the corn ethanol mandate within the Federal Renewable Fuel Standard (Oil&Gas Journal) that requires blending ethanol into gasoline at increasing levels over the next decade. It was met with stiff opposition from heavily agricultural states, but had strong support from the petroleum industry.