Wind Power

• Wind turbines use the mechanical energy produced from wind to rotate the turbines blades and produce electricity. Historically, windmills were used to power the blades of turbines to pump water or crush grain. Now, wind turbines are typically built on wind farms and harness the wind's power to provide electrical currents for national electric grids. Wind turbines operate when the wind is blowing at speeds between 2.5 and 25 miles per second. This means that wind power is subject to seasonal and wind speed variations.
  
  

Solar Power

• According to the U.S. Department of Energy, a typical American household uses 920kWh of electricity per month. Appliances account for almost 65 percent of electricity consumption. Every hour enough sunlight reaches the Earth to meet the world's energy demand for a whole year. And yet we only use a fraction of that for our energy consumption.
  
  Solar power uses photovoltaic cells to convert the light from the sun into electrical energy. The amount of energy produced depends on how directly the rays of sunlight are hitting the PV cells. This means that, while the optimum time is for PV cells to gather light is during the summer when the sun is most intense, PV cells can also produce electricity in the winter and when it is cloudy, but at a reduced rate. Solar cells can be easily made at home for powering some or all of a house's electricity.
  
  

Geothermal Energy

• According to The Solar Guide, geothermal energy in the United States accounts for five times more total energy production than solar energy and three times more than wind energy. Geothermal energy is energy produced by heat emitted from within the Earth, usually in the form of steam or hot water.
  
  Geothermal energy is an inexhaustible energy source, since the Earth's core is constantly emitting heat toward the surface and the crust has only cooled by about 2 percent over the Earth's lifetime, according to the Department of Energy. There are two sources for geothermal heat. The first is heat produced by radioactive decay of isotopes and the second is the original heat that is produced from the earth's gravitational collapse.
  
  

Hydropower

• Hydropower is a renewable source of energy that is derived from the force of moving water. In the United States, hydropower accounts for up to 10 percent of the nation's electricity supply, and 90 percent of all electricity from renewable resources is from hydropower.
  
  There are two main types of hydropower plants for creating hydropower: run-of-river plants and dams. Both pump water to conduct electricity. In homes, it is possible to harness the power of moving water if you have an on-site river or lake.
  
  Hydropower plants are the main energy carrier for storing electricity on a large scale. Water naturally accumulates in water reservoirs from rain and snow runoff, and storage facilities pump the water to produce energy.