How A Century-Old Technology Could Save The World - ThinkProgress - 08/15
Future of Energy
Renewable Energy Sources
Renewable energy is energy generated from natural resources—such as sunlight, wind, rain, tides, and geothermal heat—which are renewable (naturally replenished). Most renewable energy comes either directly or indirectly from the sun. Solar energy can be used directly for heating and lighting, for generating electricity and a variety of commercial and industrial uses.
The sun's heat also drives the winds, whose energy is captured with wind turbines. Rain or snow flowing downhill into rivers or streams can be captured using hydropower.
The organic matter that makes up 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.
Hydrogen also can be found in many organic compounds, as well as water. It's the most abundant element on the Earth. But it doesn't occur naturally as a gas. It's always combined with other elements, such as with oxygen to make water. Once separated from another element, hydrogen can be burned as a fuel or converted into electricity.
Geothermal energy taps the Earth's internal heat for a variety of uses. And the energy of the ocean's tides comes from the gravitational pull of the moon and the sun upon the Earth.
In fact, ocean energy comes from a number of sources. In addition to tidal energy, there's the energy of the ocean's waves, which are driven by both the tides and the winds. The sun also warms the surface of the ocean more than the ocean depths, creating a temperature difference that can be used as an energy source. All these forms of ocean energy can be used to produce electricity.
More Information on Renewable Energy Sources