Renewable energy is energy derived from naturally-occurring sources that can be constantly replenished such as solar, wind and hydroelectric power. This contrasts with energy sources like oil and coal, which rely on burning a material which must be found extracted and is not recreated. Renewable energy is often associated with environmentally-friendly, or green energy, since it largely involves the use of clean natural resources, though certain types of renewable energy do produce pollution, and some even argue nuclear power is a renewable energy source. As the global demand for energy increases, renewable energy has become an increasingly important focus around the world, as relying on non renewable energy sources is an unsustainable practice in the long run.
Sources of Renewable Energy
The largest source of renewable energy currently used is hydroelectric power. Hydroelectric power involves harnessing the kinetic energy of flowing water to turn turbines in order to produce electricity. A similar form of renewable energy is wind power, which involves harnessing the kinetic energy of wind currents to turn large fan-like turbines. Solar power, involves using the light and heat produced by the sun as an energy source. The oldest, and perhaps the most common type of renewable energy is the burning of biomass--such as burning wood in a fireplace to heat a home. Plants have more recently been used to create bio fuels (such as ethanol as an alternative to gasoline) and bio gases as an alternative to natural gas. Geothermal energy is another type of renewable energy that involves harnessing the natural heat of the earth's core to produce power.
Potential of Renewable Energy
Given the increasing population of the human race, the importance of renewable energy is likely to continue to increase in the future, as well as a shift toward more cost efficient energy sources. Currently most of the world's vehicles operate on gasoline or diesel fuel derived from crude oil, and renewable substitutes to these fuels, such as ethanol, are not terribly energy efficient. Other clean technologies, such as electric power, hydrogen power cells, compressed air, or new biofuels present possible sources of renewable and efficient fuels for vehicles. From the standpoint of electrical power, solar energy has a huge potential, considering the amount of energy the sun produces is thousands of times greater than the needs of earth.