The boom in cellulosic ethanol that was predicted four years ago never happened. Or hasn't happened yet. The idea of making ethanol from all manner of plant material other than corn still promises major net environmental benefits -- unline corn ethanol, which doesn't do much for the environment. But a lot depends on oil prices, electric car sales, financing, and the economies of scale.
"The Cellulosic Ethanol Boom That Never Happened"
Source: Stateline, 03/09/2011