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 in 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 witch 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 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