some studies show that biofuels using switch grass produce 540 percent more energy than needed to grow, process and refine it. this is a very high "net energy yield," much better than corn ethanol. currently, the technology used to convert swith grass into ethanol is not as advanced as that for turning corn into ethanol. fortunately, switch grass is the one biofuel that does not adversely affect food prices. both of these biofuels are promising for the future.