(organic matter) can be used to provide heat, make fuels, chemicals
and other products, and generate electricity. Wood, the largest
source of bioenergy, has been used to provide heat for thousands of
years. But there are many other types of biomass—such as wood,
plants, residue from agriculture or forestry, and the organic
component of municipal and industrial wastes— can now be used to
produce fuels, chemicals and power. In the future, biomass resources
may be replenished through the cultivation of energy crops, such as
fast-growing trees and grasses, called biomass 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, like corn, through a process similar to
brewing beer. It is mostly used 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 greases. It can be used as a diesel
additive to reduce vehicle emissions or in its pure form to fuel a
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 use high
temperatures 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 under development, the potential
benefit of these products is great.