"The Renewable Fuel Standard also requires more use of so-called advanced biofuels. Nearly all the ethanol produced in the U.S. today comes from corn â€” roughly 40 percent of the nation's largest cash crop gets burned up in gas tanks. Congress approved the RFS mostly to encourage commercial production of ethanol from inedible ingredients such as grass or wood chips.
That idea has flopped. Very little of this next-generation ethanol is available commercially. The outlook is bleak for ramping up production. Yet under the law, refiners and blenders are required to boost their use of this scarce fuel, which adds more unnecessary costs."