For all the green fantasies about endless solar panels and sprawling wind farms, the only alternative energy truly to achieve scale in the U.S. has been humble corn ethanol. Thanks chiefly to generous federal corn subsidies, ethanol has become a $32 billion industry, with scores of refining plants scattered throughout the Midwest and a quarter of the nation's corn crop turned into fuel. But in 2008, several new scientific studies undercut ethanol's green credentials, while the poor around the world came to blame record high food prices on the biofuel boom. Inevitably, the bubble burst — overinvestment led to a collapse in ethanol prices, even as fuel costs rapidly declined from their summer highs. Respected investors like Bill Gates who had sunk money into ethanol plants lost millions. Although government subsidies ensure that ethanol isn't going anywhere, the dream that the U.S. would replace oil fields with cornfields is surely dead.