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http://www.klikdokter.com/tumbuhkembanganak/read/2010/07/05/81/panduan-makanan-bayi

Sources of Renewable Energy

Hydropower:

Water's usability to generate electricity is tremendous since the kinetic energy of flowing water is amply used to produce hydroelectricity such as to rotate turbines. It's a form of renewable energy where it contributes to less pollution of environment and consumption of fossil fuels. In the United States there are approximately more than 5,000 dams that are used to produce hydroelectricity contributing to 9% of the nation's electricity.

Hydropower doesn't require a large dam to produce electricity but a small canal is enough is channel the river water to rotate the turbine. However, only large projects are able to produce on-demand electricity which unfortunately is the limitation for small projects. Dams producing hydroelectricity also offer other forms of recreation such as habitat for aquatic animals and destructive flooding downstream.

• Tidal Energy:

Tidal energy also called Tidal power is a renewable source of energy and a form of hydropower used to generate electricity using the energy of the tides. Though not widely used to generate electricity, it can be called as the energy resource of the future with the current rate of depletion of non-renewable resources. High costs and limited availability have kept tidal energy from being utilized to its full potential. Tidal power is generated through Tidal stream generator, Tidal barrage and Dynamic tidal power.

• Wave Power:

Wave power is the transport of energy on ocean wave to carry out multiple jobs like electricity generation, water desalination and pumping of water into reservoirs. Wave power is not currently used on a commercial scale though the first wave farm was opened in Portugal in 2008.

Geothermal Energy:

Geothermal energy is the thermal energy generated and stored in the earth that verifies the temperature of the matter. This clean and sustainable type of energy is found in shallow hot ground water, hot rocks a few miles beneath the earth's surface and in the molten magma if we go deeper. Geothermal energy produces few emissions and is consistently available for use. Technologies that make geothermal energy usable include geothermal heat pumps which take advantage of the warm ground temperature and use it to cool or heat buildings. Another use is for bathing as medium of hot water as it provides heat directly and also contains medicinal skin properties. Geothermal power plants convert hydrothermal fluids like hot water or steam accessed from deep wells to drive a turbine which then produces electricity.

Wind Energy:

Particularly in seabed, hilly areas and seashores, wind is easily available and hence it is less expensive source of energy. By utilizing the momentum and transferring it to rotor blades, energy can be produced from wind. The process of producing energy from this source does not create any type of pollution but the maintenance can produce negligible amount of water or air pollution. The usage of windmills or wind turbines to produce energy is constrained to installing them in windy areas where wind flows with high speed as otherwise wind cannot be utilized to produce energy. To generate energy, humans have been harnessing the wind since ages. But today's modern wind turbines continue to become more productive and powerful as they supply energy to hundreds of homes than the windmills used in old days which were good enough to produce energy only for small jobs like fetching water from sea or grinding grains.

Solar Energy:

The sun is the most important source of energy. The sun rays can be used as a mean of producing the energy. Photovoltaic cells possessing the characteristic of converting heat to energy are used to generate electricity. When sun rays strike the surface of these photovoltaic cells, electric current is produced. This device is also less expensive as it is made up of silicon which is one of the most abundant elements on earth. The only limitation of using solar energy or solar panels or photovoltaic cells is that they can produce electric current only in the day, when bright sunlight is available in abundance. Installing photovoltaic cells or solar panels hence cannot produce energy in rainy or snowy seasons.

Biomass Energy:

Biomass power is the electricity generated from biomass and is obtained from wood, crops, harvest residues, urban refuse and industrial wastes known as biomass. It is one of the important sources of renewable energy and serves as an essential part of waste management process. Pulp and paper industries in United States are prominent generators of biomass. Obtaining power from biomass substances is more cost-effective than that of obtaining it from wind using wind turbines or windmills or any other source as it requires less investment. Crops, woody plants, grass absorb carbon dioxide during their growth and emit same amount of carbon dioxide when processed to generate electricity. This recycling of atmospheric carbon may reduce global warming.

From: www.renewablaenergy.com