The Renewable Fuel Standard, passed in 2005, may sound like a high-minded environmental program. But pressing U.S. farmers to grow corn for ethanol fuel use is not good green policy. This past year, 40 percent of domestic corn crops have gone into gas tanks, even as a rise in global food prices has hurt the poorest families. And while the idea of growing fuel is a solid one, many scientists argue that turning corn into fuel has proved to be as water- and energy-intensive as drilling for oil. "It is time to take a hard look at the carbon benefits of corn ethanol and its impacts on food prices around the world," says Jonathan Foley, the director of the Institute on the Environment at the University of Minnesota.