Biomass is plant matter such as trees, grasses, agricultural crops, and other material derived from living matter. These materials are renewable and sustainable, and can be used as a solid fuel or converted into liquid or gaseous fuels to supply the electricity, heating, transportation, and other energy markets.
With more than 7,000 MW of installed capacity, biomass is the second-most utilized renewable power generation resource in the U.S. The 37 billion KWH of electricity produced each year from biomass is more than the entire state of Colorado uses annually. Generating this amount of electricity requires around 60 million tons of biomass per year.
Regardless of the specific technology used, the primary means of obtaining electricity from biomass are similar. A biomass fuel is converted to heat energy in a highly controlled reactor (boiler or gasifier). The heat is converted to mechanical energy in either a steam or gas turbine, or an internal combustion engine, and the mechanical device turns a generator that produces electricity. The majority of today’s Bio-Power generation comes from direct-fired facilities, but the most economical near-term option for introducing new biomass power generation is co-firing. Co-firing involves substituting biomass for a portion of coal in an existing power plant furnace. In the future, the use of biomass gasifiers will increase.
Residues are the most economical biomass fuels for generating electricity. These are the organic byproducts of food, fiber, and forest production such as sawdust, rice husks, and bagasse (the residue remaining after juice has been extracted from sugar cane). Low cost sources of biomass such as pallets and woody yard trimmings are common near population and manufacturing centers. In the future, much larger quantities of biomass power could come from fast-growing trees and crops (called "energy crops"), forest debris and thinnings, agricultural wastes, animal manures, and non-hazardous wood debris diverted from landfills.
The cost to generate electricity from biomass varies depending on the type of technology used, the size of the power plant, and the cost of the biomass fuel supply. Biomass power systems range in size from a few KW (enough for an average U.S. home) for on-site generation units, up to 80 MW for power plants. Each MW of Bio-Power capacity generates enough electricity in a year to power about 525 average U.S. homes. When low cost biomass fuels are used, co-firing systems can result in payback periods as low as 2 years. In today’s direct-fired biomass power plants, generation costs are about 9 ¢/kWh. In the future, advanced technologies such as gasification-based systems could generate power for as little as 5 ¢/kWh.
With an estimated 14,000 MW of annual worldwide installed generation capacity, biomass power is the largest source of non-hydro renewable electricity in the world. The U.S. is the largest single Bio-Power generator, representing a $15 billion investment and 66,000 jobs. In the future, the continued need for on-site industrial power, waste reduction, stricter environmental regulations, and rising consumer demand for renewable energy, will provide the main impetus for the industry's growth.
Worldwide Bio-Power generation is expected to grow to more than 30,000 MW by 2020. Developing countries are the top markets because of rapid economic growth, burgeoning demand for electricity, mounting environmental problems, and the need for rural electrification and reliable electricity. Most of them also have significant quantities of agricultural or forestry residues.
Recent studies indicate that additional (presently unused) quantities of economically available biomass may exceed 39 million tons per year in the U.S.-enough to supply about 7,500 MW of new Bio-Power, or a doubling of the existing U.S. Bio-Power capacity.