Sources for Alternative Energy

Sun

• Every day, energy from the sun reaches our planet. Solar technologies can harness this energy, converting it directly into electricity or focusing the rays for use in heating systems and steam generators. Photovoltaic cells, commonly known as solar panels, convert the sun's rays directly into electricity. Solar power plants use vast solar arrays to generate electricity for towns and cities. Smaller cells can power individual homes as well as smaller items, such as calculators and portable radios. Solar technologies are expensive, but the energy produced is renewable and clean. Solar power provides less than 1 percent of U.S. energy needs, according to the National Atlas website. This percentage is likely to increase as solar technology becomes more efficient and cheaper to produce.
  
  

Wind

• Modern wind turbines harness the power of moving air in much the same way as traditional windmills. The power of the wind forces large blades, not unlike those of a propeller, to rotate around an axis. The blades then turn an electrical turbine, generating electricity. Wind turbines cause no pollution, but they do disrupt the natural environment. Large-scale wind farms require a lot of space in order to generate viable amounts of energy. Despite being renewable and clean, wind energy is limited in terms of overall energy production potential.
  
  

Water

• Energy is stored within any body of flowing or falling water. Hydroelectric power plants use this energy, known as hydropower, to generate electricity using water turbines. Turbines can be placed directly into rivers or within dams across rivers. Once in place, a hydroelectric plant produces cheap and renewable electricity. However, they do disrupt the natural environment, particularly when large dams radically alter a river's flow. Tidal movements of the ocean provide another source of renewable energy. Turbines placed in coastal waters generate electricity by harnessing the ebb and flow of the tide. According to the U.S. Energy Information Administration's Energy Kids website, hydropower accounted for 7 percent of total U.S. electricity generation and 35 percent of generation from renewables in 2009.
  
  

Geothermal

• Geothermal power plants generate electricity by tapping into natural heat reserves stored within the Earth's crust. Power plants use this heat to create steam, which is then used to drive turbines at the Earth's surface. Geothermal energy provides a constant source of electricity. The energy produced also is environmentally friendly with harmless steam being the only significant byproduct released into the atmosphere. The one great disadvantage of geothermal energy is the need for a suitable geographic location. Power plants are only viable in areas with naturally occurring heat reserves close to the Earth's surface.
  
  

Bioenergy

• Power plants create bioenergy by converting the energy stored within organic materials into usable fuel or electricity. Sources of bioenergy include agricultural and forestry residues, municipal and industrial wastes, and terrestrial and aquatic crops grown solely for energy purposes, according to the U.S. Department of Energy website. A bioenergy plant produces electricity by burning these organic materials, using the heat to produce steam to drive turbines. Alternatively, biomass can be used to produce biofuels, such as ethanol and biodiesel. Biofuels offer a renewable alternative to traditional vehicle fuels.