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 hydroelectric power.
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 bioenergy.
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.
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 come 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.
Why is renewable energy important?
- Renewable energy technologies are clean sources of energy that have a much lower environmental impact than conventional energy technologies.
- Protects our environment and public health by avoiding or reducing emissions that contribute to smog, acid rain, and global warming; and by reducing water consumption, thermal pollution, waste, noise, and adverse land use
- Increases economic development and create new family-wage jobs
- Creates new competition to help restrain fossil fuel price increases
- Improves our national security
- Diversifies our fuel mix and enhance the reliability of fuel supplies
- Insulates our economy from fossil fuel price spikes and supply shortages or disruptions
- Reduces a growing reliance on imported fuel and electricity
- Reduces the cost of complying with present and future environmental regulations
- Conserves our natural resources for future generations