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Hydroelectric Dams

Hydroelectric Dams


 

 

Dams are barriers that divide and retain water for a number of purposes. They provide water for irrigation and industrial applications, they improve navigation, generate electricity, control flood and provide recreational areas or habitat for fish and other wildlife. The world’s tallest dam at 300 meters high is found in Tajikistan. 

 


Origin of Hydroelectric Dams

Dams date back to the olden days with most of them found in Mesopotamia and the Middle East. The earliest known dam dated around 3000 B.C. is in Jawa, Jordan. For the record, the oldest dam in the world that still stands is the Quatinah barrage in Syria. The dam is believed to have been constructed during the time of Egyptian pharaoh Sethi and was expanded during the Roman period. 

Types of Hydroelectric Dams



Dams are categorized based on their size, purpose and structure. Large dams, according to international standards, are those with a height of more than 15 meters while major dams are more than 150 meters tall. Based on material and structure, they are either timber dams, arch-gravity dams or masonry dams each of which has further subtypes. 

By purpose, dams are of four types – the overflow, check, dry and diversionary. An overflow dam is used to measure the flow of water. A check dam is small in size and is aimed at reducing the flow velocity as well as control soil erosion. For flood control, a dry dam is used while a diversionary dam, as its name suggests, is aimed at diverting all or a part of a river flow from its natural course. 

Power generation

A major application of dams is in producing hydroelectric energy to generate electricity. Hydroelectric power supplies 63 percent of the earth’s 
renewable energy and an estimated 19 percent of the world’s electricity, according to 2005 statistics. 

As fossil fuels have been found to cause harm to the environment through their emissions and as their prices go up, the use of renewable energy is getting greater attention. And with many countries having large rivers, water has been tapped as a potential source of clean energy for generating electricity. 

Dammed water is responsible for producing hydroelectric power. The potential energy produced by the dam is what drives the water turbine and 
generator that creates electricity. One type of dam makes use of pumped storage hydroelectricity through reservoirs at different elevations. When demand for electricity is low, excess generation capacity is used to pump water into the higher reservoir. As demand peaks again, water is released back into the lower reservoir via a turbine. 

Dams are best built in a narrow part of a deep river valley. At this location, the valley sides can even serve as the dam’s natural walls. The main function of a dam is to fill the gap in the natural reservoir line left by the stream channel. 

As an alternative source of energy, hydroelectric power is considered less costly than wind energy and nuclear power. Compared to wind, it is easier to store water when necessary and generate electricity at high levels on demand. Additionally, well-designed hydroelectric dams that are maintained properly are cheaper in the long run and more reliable. 


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