Aternative Sources of Energy

• Renewable energy sources generate electricity without the use of fossil fuels. Lauren Burke/Photodisc/Getty Images

  Renewable energy sources are an eco-friendly way to reduce the need for fossil fuels to produce electricity and heat for indoor spaces, offices and industrial factories. Although the use of renewable energy sources is expected to grow in popularity, they are often expensive and are not always as readily available as fossil fuel sources.

Solar

• Solar power from the sun converts into thermal energy to heat water and indoor spaces. Harnessed by photovoltaic devices, these devices consist of individual cells grouped into panels. Cells range in size from small cells on watch and calculator batteries, to large power plants that cover several acres of land. Solar energy, harnessed by solar power plants that use the thermal energy from the sun to heat fluids, produces steam that powers the generators.

Geothermal

• Geothermal energy is an energy source found in the core of the earth. When magma comes to the crust of the earth, surrounding rocks and water absorb the heat from the magma. Tapping into geothermal energy includes digging deep wells and pumping heated groundwater and steam to the surface, creating heat for homes and electricity generation. Most geothermal energy sources are found near plate boundaries on the crust of the earth, such as the areas bordered by the Pacific Ocean. Geothermal energy can also be generated from electricity generation power plants near the Pacific Ocean and hot water from natural hot springs near the surface.

Hydropower

• Hydropower accounts for 67 percent of electricity generated from renewable sources in 2008, according to the Energy Information Administration. Moving water also provides electricity. The water flows through a pipe where it turns blades in a turbine that spins a generator. The spinning generator produces electricity. Water movement can be found along rivers, or collected in a reservoir where water is released as needed to generate electricity. Although hydropower produces clean energy, dams and reservoirs can obstruct migration of fish and change natural water temperatures, chemistry and silt loads. Such changes can alter the ecology of the water source significantly.