What is Renewable Energy?
The United States currently relies heavily on coal, oil, and natural gas for its energy. Fossil fuels are nonrenewable, that is, they draw on finite resources that will eventually dwindle, becoming too expensive or too environmentally damaging to retrieve.
In contrast, renewable energy resources such as wind and solar energy are constantly replenished and will never run out. Most renewable energy comes either directly or indirectly from the sun. To learn more about renewable energy, why it's important, and what benefits it holds, visit the National Renewable Energy Laboratory (NREL) website.
The following are common renewable energy resources:
Most renewable energy comes either directly or indirectly from the sun. Sunlight, or solar energy, can be used directly for heating and lighting homes and other buildings, for generating electricity, and for hot water heating, solar cooling, and a variety of commercial and industrial uses.
The sun's heat also drives the winds, whose energy is captured with wind turbines. Then, the winds and the sun's heat cause water to evaporate. When this water vapor turns into rain or snow and flows downhill into rivers or streams, its energy can be captured using hydropower.
Along with the rain and snow, sunlight causes plants to grow. The organic matter that makes up those plants is known as biomass. Biomass can be used to produce electricity, transportation fuels, or chemicals. The use of biomass for any of these purposes is called biomass energy.
Not all renewable energy resources come from the sun. Geothermal energy taps the Earth's internal heat for a variety of uses, including electric power production, and the heating and cooling of buildings. And the energy of the ocean's tides comes from the gravitational pull of the moon and the sun upon the Earth.
Flowing water creates energy that can be captured and turned into electricity. This is called hydroelectric power or hydropower. NREL doesn't perform any research in hydroelectric power technologies. For more information on hydroelectric power, see the Hydropower Basics from the U.S. Department of Energy's Wind and Hydropower Technologies Program.
See also the Glossary of Renewable Energy and Electrical Terms.