Corn-based ethanol may be more emission-intensive than previously thought and is likely contributing to more emissions than gasoline, a new study finds. The study, published in Proceedings of the National Academy of Sciences, suggests that the environmental benefits of the U.S. renewable fuel standard (RFS) remain unclear. Under the Renewable Fuel Standard, oil refiners are required to blend growing amounts of renewable fuels into gasoline and diesel. The RFS raised corn prices, which in turn expanded the land used for corn crops. This increases emissions from the conversion of land to corn crops, and raises fertilizer and water usage, says...