Switch grass is one of the most efficient biofuels yet developed. It is a perennial crop, meaning that it grows all year long. Normally, switch grass grows on the prairies and can reach 2.2 meters tall. Through a refining process, switch grass is turned into cellulosic ethanol which can be used in car engines. Some studies show that biofuels using switch grass produce 54 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 switch grass into ethanol as advanced as that for turning corn into ethanol Fortunately, is not switch grass is the one biofuel that does not adversely affect food prices. Both of these biofuels are promising for the future