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 or prairies and can reach 2.2 meters tall. Through a refining process, switch grass turned into cellulosic ethanol which can be used in car engines. Some studies show that biofuels using switch grass produce 540 percent more energy needed to grow, process and refine it. This is a very high"net energy yield, better than corn ethanol. Currently, the technology used to convert switch 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. these biofuels are promising for the future.