Part of corn ethanol's claim to fame has been that, when burned, it decreases greenhouse emissions by 10-20% as compared to gasoline, according to the U.S. Department of Energy (DOE).

But cellulosic ethanol, if it comes to be, could cut emissions by 90%, DOE officials say.

Cellulosic ethanol also will use less energy to produce than gasoline, which has a negative net energy balance, and corn ethanol, which has a slight positive energy balance, says Matt Digman, ag engineer at the U.S. Dairy Forage Research Center at Madison, WI.

DOE estimates that cellulosic's energy balance is five times greater than that of corn ethanol.

Cellulosic material is also a diverse, abundant feedstock, Digman says, and doesn't, like corn, compete in the human food arena. Yet transportation and storage costs, conversion technology and other questions need answering, he adds. ?