What Is Renewable Energy

Renewable energy refers to energy resources that are not depleted as they are consumed or converted to other forms of energy. Renewables include solar energy used directly or converted to electricity; wind power; hydroelectric power; geothermal energy; ocean and tidal energy; biomass fuels; and – depending on how it's produced –; hydrogen. Renewables complement fossil fuels and other sources in meeting the world's energy requirements. In the year 2000, for example, coal fueled 39 percent of worldwide electricity generation, followed by renewables (mostly hydroelectric) at 19 percent, natural gas (17 percent), nuclear (17 percent), and oil (8 percent). (Source: International Energy Agency, Renewables for Power Generation 2003.)

Environmental and energy security concerns and, in some situations, favorable economics, are promoting public interest, R&D, and investment in renewable energy. Although the amount of energy produced from renewables will increase in coming years, informed projections show that renewables will be just one part of the overall energy picture.

What is renewable energy?   Renewable energy is the term used to describe energy flows that occur naturally and continuously in the environment, such as energy from the wind, waves or tides. The origin of the majority of these sources can be traced back to either the sun (energy from the sun helps to drive the earth’s weather patterns) or the gravitational effects of the sun and the moon. This means that these sources are essentially inexhaustible.

The key issue is how to extract this energy as effectively as possible and convert it into more useful forms of energy. This can range from directly using the energy from the sun to heat water to using mechanical devices, such as wind turbines, to convert the kinetic energy in the wind into electrical energy.

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