Renewable Energy Resources
Renewable energy comes from sources that have an ability to be
replenished continually. Energy from the sun, from moving water, from
wind, and from the Earth's geothermal heat are examples.
The conventional energy resources on which our economy is built are
not renewable; these are nuclear power and the fossil fuels, such as
coal, natural gas, and oil. Because it takes millions of years for
natural processes to create the fossil fuels, they are considered to be
a finite source of energy. These fuels are consumed faster than they are
The sun's heat can be used directly for heating homes and water,
through passive solar techniques; it can also be used for cooking in a
solar cooker. The technology currently exists to convert the energy of
the sun directly into electricity by using photovoltaic (PV) cells, or
indirectly, by generating steam that runs an electricity generating
The sun's energy also drives the wind; energy from the wind is
captured by sails to move boats, and by wind mills or wind turbines to
generate electricity or to run a pump. The sun's energy also drives the
hydrologic cycle, moving water in an endless cycle; energy from moving
water is captured by dams that drive turbines, generating electricity.
Geothermal heat is energy stored in the ground; it is considered to
be renewable because it is such a vast resource. This energy can be used
to heat and cool buildings through geothermal heat pumps.
Bioenergy comes from using rapidly renewable plant or plant-derived
material such as trees, crops, agricultural or forestry residues, and
waste materials to generate energy. They can be burned directly, or
converted to fuel such as alcohol or methane. Bioenergy can be used to
generate electricity in a turbine through steam or by running a gas
turbine; they can provide fuels for running automobiles.
Renewable forms of energy play a critical role in our economy and in
our future. To learn more about them, visit the U.S. Department of
Energy Energy Efficiency and Renewable Energy web site: