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الأربعاء، 22 سبتمبر 2010

Why is hydropower a green energy source?

Why is hydropower a green energy source?

Why is hydropower a green energy source? Hydropower or hydro-electric energy, is obtained when electricity is produced by converting hydraulic energy from moving water in lakes or rivers. It is a renewable source of energy, and it is also a clean energy but it is not always considered a green energy by everyone as some critics point out to the damages caused to lakes by release of methane gas.
More than 2000 years ago  the Ancient Greek used waterwheels in rapidly flowing rivers to turn millstones and other equipment. During the middle ages Europe had several thousands hydraulic installations that provided mainly mechanical energy for mills. And we can even say that for over 2000 years the hydraulic wheel did not see much evolution. It must noted that the power generated by a water wheel is limited to the size of the wheel that can be built and to the mass of water that can be displaced, which depend on the width of the water fall and the height of the wheel itself.
The US Corps of Engineers that regulates rivers and lakes waterways was created in 1775.  By 1881 Nigara Falls were powering city lights. By 1886 the US and Canada had about 45 water powered electric plants.
Today’s hydroelectric plants still use the same basic principles as the historical waterwheel with some variations. The hydraulic turbines of today are essentially, like the ancient wheels, a motor.
At this time, hydroelectricity represents roughly 19% of all electricity produced in the world.
To produce electricity, large quantities of water and steady flow are needed. Many countries invested in construction of dams during the 50′s, to provide the water needed to supply the plants that made electricity. Water was stopped and released at will or according to needs. To ensure a constant water supply, some dams have installed recovery and pumping systems so the water released can be used again.
As already stated some take issue with the use of hydroelectricity, they claim that the release of methane gas poses a problem for fish and aquatic plants on both sides of the dam. Oftentimes the construction of a dam cause the natural flow of water to be diverted, the nutrient rich silt which helps crops grow could be affected. This alteration of the eco-system is what happened when the Aswan Dam was completed in Egypt.
Given the bigger picture, it is possible to repair or counteract the negative effects of building dams, and it important to remember that power produced from hydroelectric plants do not generate any emissions or waste. And no matter how we look at it, it is a cleaner source of energy than burning fossil fuels.
Sea water is another option to produce hydroelectric power. Known as wave power or wave energy it uses changes in air levels of sealed chambers to power turbines. When a wave rises into a chamber, the rising water pushes the air out which then causes a generator to turn. Once the wave goes down, air flows into the turbine and back into the chamber.
These chambers are kept afloat on the ocean and produce electricity in varied quantities. They are found on the western coasts of Scotland, in northern Canada, southern Africa, Australia, and the northwestern coasts of the United States. Often times these are smaller systems that do not produce large quantities of power and serve to provide enough electricity to aliment a warning buoy or a small light house.
Tidal energy can also be used. When a tide approaches, water is trapped in reservoirs behind dams. When the tide drops, the water behind the dam is released to produce power similar to a hydroelectric power plant. This is limited as tides need to be at least 16 feet, and only a few places on the planet can do that.
Lastly, we must talk about ocean thermal energy. A system where power is based on the different temperatures in the water. There must a difference of at least 38 degrees Fahrenheit between the warmer surface water and the colder deep ocean water. This technology is still in trial stages, in place like Japan and Hawaii.

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