Renewable Energy Sources: Biomass Energy

Biomass (organic matter) can be used as a fuel, and to generate electricity, both called forms of bioenergy. Wood, the largest source of bioenergy, has been used to provide heat for thousands of years. However, there are many other sources of biomass such as plants, residue from agriculture or forestry, and the organic component of municipal and industrial waste that are used today as sources of energy. Today, many bioenergy resources are replenished through the cultivation of energy crops, such as fast-growing trees and grasses, called bioenergy feedstocks.

Unlike other renewable energy sources, biomass can be converted directly into liquid fuels for our transportation needs. The two most common biofuels are ethanol and biodiesel. Ethanol, an alcohol, is made by fermenting any biomass high in carbohydrates such as corn, through a process similar to that used in brewing beer. It is used mostly as a fuel additive to cut down a vehicle's carbon monoxide and other smog-causing emissions. Biodiesel, an ester, is made using vegetable oils, animal fats, algae, or even recycled cooking grease. It can be used as a diesel additive to reduce vehicular emissions or in its pure form to fuel a vehicle.

Heat can be used to chemically convert biomass into a fuel oil, which can be burned like petroleum to generate electricity. Biomass can also be burned directly to produce steam for electricity production or manufacturing processes. In a power plant, a turbine usually captures the steam, and a generator then converts it into electricity. In the lumber and paper industries, wood scraps are sometimes directly fed into boilers to produce steam for their manufacturing processes or to heat their buildings. Some coal-fired power plants use biomass as a supplementary energy source in high-efficiency boilers to significantly reduce emissions.

Even gas can be produced from biomass for generating electricity. Gasification systems at high temperatures are used to convert biomass into a gas (a mixture of hydrogen, carbon monoxide, and methane). The gas fuels a turbine, which is very much like a jet engine, only it turns an electric generator instead of propelling a jet. The decay of biomass in landfills also produces a gas-methane-that can be burned in a boiler to produce steam for electricity generation or for industrial processes.
New technology could lead to using biobased chemicals and materials to make products such as anti-freeze, plastics, and personal care items that are now made from petroleum. In some cases these products may be completely biodegradable. While technology to bring biobased chemicals and materials to market is still being developed, the potential benefit of these products is great.