It turns out that a lot of corn is used to make the biofuel. in 2010, for the first time, farmers actually used more corn for ethanol than they did for animal feed. The difference was small (5 billion bushels for feed, 5.05 billion for ethanol) but the implications may be big. More corn is now being feed to our cars than to our animals.
That 40 percent of corn production headed for ethanol results in around 13 billion gallons of ethanol. Which in turn accounts about 10 percent of the gasoline consumed in the US. Because ethanol is so cheap, the U.S. actually exported 397 million gallons in 2010. Other methods for making ethanol are in use, and continue to be researched, but corn dominates this market at the moment. How long this lasts is not certain. In 2011, a combination of market conditions and bad weather has led to a decline in U.S. ethanol production and a proposal to end ethanol subsidies was passed by the Senate this summer.