Renewable energy sources are those provided directly or indirectly
by the either the Sun or the Earth's processes. They include:
solar energy, wind energy, bioenergy, geothermal energy, hydropower
and ocean energy. They are constantly replenished and will always
be available for our use.
Sunlight, or solar energy, can be used directly for heating and lighting homes, captured in solar cells to generate electricity, and used to heat residential hot water. Solar energy is also the cause of wind, which can be harnessed through windmills to pump water, grind grain, or produce electricity. The energy provided by the Sun also makes plants grow, and the organic matter that makes up those plants (biomass) can be used to produce electricity directly, or become stored in fuel or chemicals.
Geothermal energy uses the Earth's internal heat to make steam, which can produce electric power or heat buildings. Rivers and streams were once used as a direct energy source for industry and some have been blocked with large dams to provide falling water to produce electricity. The energy of the ocean's tides is another renewable source. In the future we might even use waves or the differences in the ocean temperature to extract energy for our use or decompose water to produce hydrogen as a clean burning fuel.
Find out more about energy efficiency and renewable energy at:
There are a lot of intermediate stages in the transfer of energy from a root source such as the Sun into the various forms of energy that people use. Try the tracing the path activity on this site to explore this topic further.