One thing to note about switchgrass as a source of bio-fuel -- it requires a significant amount of rainfall to produce in economic quantities. Much of the "marginal" farmland in the U.S. that has been taken out of production and converted to CRP or other programs probably does not receive adequate rain.
Grass biofuels 'cut CO2 by 94%'
Producing biofuels from a fast-growing grass delivers vast savings of carbon dioxide emissions compared with petrol, a large-scale study has suggested.
A team of US researchers also found that switchgrass-derived ethanol produced 540% more energy than was required to manufacture the fuel.
One acre (0.4 hectares) of the grassland could, on average, deliver 320 barrels of bioethanol, they added.
Their paper appears in the Proceedings of the National Academy of Sciences.
The five-year study, involving 10 farms ranging in size from three to nine hectares, was...(complete article here).