Switch Grass the most efficient biofuels yet developed. It is a perennial itch grass is one of crop, meaning that it grows all year long. Normall Witch grass grows on the prairies and can reach 2.2 meters t 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 5 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 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