Wind Power

• Capturing the energy produced by wind with large wind turbines is an environmentally sound alternative to nuclear power. A small wind turbine in your backyard can make a serious contribution to your power needs while a larger commercial model can produce enough power to supply hundreds of homes. Some argue that they are bad for the environment. To make wind power a reliable source of energy would require thousands of wind farms across the country. Wind turbines also are the subject of criticism for the number of birds they kill.
  
  

Solar Power

• The sun produces enough power in just one hour to meet the whole world's energy needs for an entire year. The problem is capturing and storing that energy in sufficient quantities. Although solar power is an almost inexhaustible source of clean energy, the equipment and technology required to harness it is currently expensive and, like wind power, requires a lot of land. Despite the drawbacks, use of solar energy has increased by 20 percent since the mid-1990s and could rise further as tax incentives and advances in technology make it a more attractive proposition.
  
  

Hydro Power

• Hydro power is the cheapest way to produce electricity and currently supplies almost one-fifth of the world's energy needs. Water flowing through a turbine in a man-made dam produces electricity. Hydro power is distinct from wave power, which provides considerably less energy. Wave technology is relatively young, and to date, scientists and engineers have been unable find a way to effectively harness the power of the sea.
  
  

Geothermal

• Geothermal energy comes from reservoirs of hot water and steam below the surface of the earth. Wells of up to one mile deep tap into the pockets of steam and water, which power a turbine linked to electricity generators. America is the world's largest producer of geothermal energy but countries close to the Arctic like Iceland are thought to have large untapped reserves.