The use of native prairie grasses is meant to avoid some of the other risks associated with biofuels such as reduced diversity of local animal life and displacing food crops with fuel crops. "This is an energy crop that can be grown on marginal land," Vogel argues, such as the more than 35 million acres (14.2 million hectares) of marginal land that farmers are currently paid not to plant under the terms of USDA's Conservation Reserve Program.
His post is a very nice explanation, with a numbered list, of why ethanol is a bad idea.
Oh, by the way? The leftover stuff from the fermentation? If I read this right, it might be usable as cattle feed. (Plus foraging after harvest.)