Enlarge Image Future food? Cellulose from switchgrass and other nonfood plants might be converted into edible starch to feed the hungry. Credit: Peggy Greb/ARS/USDA The main ingredient of wood, cellulose, is one of the most abundant organic compounds on Earth and a dream source of renewable fuel. Now, bioengineers suggest that it could feed the hungry as well. In a new study, researchers have found a way to turn cellulose into starch, the most common carbohydrate in the human diet. Ethanol is today's most common biofuel used to power vehicles. It's typically made using sugars from crop plants such...