Scientists at Purdue University have developed a portable generator that uses trash as its primary fuel source. Called a tactical biorefinery, the device was designed at the behest of the U.S. Army. But researchers say the generators could also be used in civilian situations, such as emergencies that require portable generators. About the size of a small moving van, the diesel generator can process several types of refuse, including paper, plastic, Styrofoam, cardboard, woodchips and food waste.