Bioenergy, or biomass power, is renewable energy made available from materials derived from biological sources.  Biomass is any organic material which has stored sunlight in the form of chemical energy.  As a fuel it may include manure, ethanol, landfill gas, wood, and many other byproducts from a variety of agricultural processes.  There are six major types of biopower systems: direct-fired, cofiring, gasification, anaerobic digestion, pyrolysis, and small, modular.