Renewable alternative energy is power that can be used repeatedly without depleting any natural resources. Sometimes referred to as sustainable energy, the alternatives available are derived from natural sources and include energy powered by the sun, water, wind, and earth. These renewable alternative energy sources are known respectively as solar, hydroelectric, wind, and geothermal power.
Solar energy can be captured by two basic methods, known as passive and active. Passive solar doesn’t use any kind of devices, such as solar panels, to collect the energy. South-facing windows that help illuminate and heat a dwelling are a good example of passive solar energy. Designing a home with brick walls and tile floors to absorb heat, enabling one to lower the cost of heating, is another way to use passive solar energy.
Active solar energy is harnessed using solar collectors to absorb energy. Photovoltaic arrays, commonly known as solar panels, are generally used to collect the solar energy, which is converted into electricity. This energy can be stored in batteries for later use. A drawback of solar energy is its dependence on the sun, since solar energy cannot be collected at night.
Hydroelectric power uses the energy from falling water to generate electricity. In order to use water as a renewable alternative energy, dams are constructed to build up pressure in the body of water, called a reservoir, behind them. When water is released from the reservoir, it falls onto the blades of a giant turbine, causing the turbine to spin.
A generator connected to the turbine transforms the kinetic energy created by the water pressure and spinning turbine into electricity. The drawback to hydroelectric power is that it requires flooding a large amount of land to build the dam. This can displace human communities and wildlife living in the area upstream.
Wind power is another form of renewable alternative energy that uses turbines, as hydroelectric power does, with the kinetic energy generated by the turbines and transformed into electricity created by wind. These turbines resemble windmills and work on the same principle. The drawback is that the wind has to be blowing in order for a wind power system to generate electricity.
Geothermal energy systems use the heat or thermal energy generated from the earth’s center. A geothermal heat pump is installed several feet under the earth’s surface and transforms the heat into electricity. A disadvantage of this form of renewable alternative energy is that some areas don’t have large enough reserves of thermal energy beneath the surface that can be accessed using heat pump technology, so geothermal energy isn’t available everywhere.