Grass grows without tending and can be harvested repeatedly without disturbing the roots making it an efficient renewable source. These qualities have made grass a reliable source of fuel (and building material) for centuries in Europe where it was first cut (the "auld sod" of Ireland), then burned in little stoves or fireplaces for heat. Dr. Jerry Cherney, a member of the agriculture faculty at Cornell University, advocates harnessing this energy source in the U.S. by drying and compressing ("pelletizing") grass into chunks and burning it like coal. Grass pellets, according to Dr. Cherney, would create 90 percent fewer greenhouse gases than fossil fuels. As anyone who's turned a compost heap knows, grass and other decomposing plants generate a lot of heat as their glucose breaks down the fibers of the plants. By pelletizing the grass in local processing facilities, that energy could be concentrated for use in combustion furnaces, providing a clean fuel.