There's a tide of approval out there for switchgrass as a biofuels source following an article which appeared in Science Now and reported briefly here on the basis that switchgrass is energetically sustainable
Typical is James Hudnall in his official site in a post no corn for oil, he says:
The idea of using food crops for energy is a bad one to begin with. There are plenty of alternatives. As I’ve said before, switchgrass is the answer. It’s cheaper to grow, takes less energy and less pesticides and fertilizer and it can grow on land unsuitable for farming.
Over on Ecoworld we had a little reality check in switching to switchgrass
According to the BBC report, “One acre (0.4 hectares) of the grassland could, on average, deliver 320 barrels of bioethanol.” That suggests (320 x 640) that 204,800 barrels per year per square mile would come from this switchgrass - an improbable amount. So we called one of the study’s authors, Dr. Ken Vogel at the University of Nebraska, to ask him to clarify this number. It turned out the BBC reporter had mixed up barrels and gallons. The researchers had actually estimated switchgrass can yield 4,896 barrels per square mile per year.
and there's a pretty straight report on Green Car Congress.