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HYDROELECTRIC DAMS: How They Work

 Hydroelectric dams are very high-tech but simple machines. A dam holds back water, creating a reservoir of potential power. On the upper side of the dam, a water gate is opened to let water surge through a tunnel leading to turbines. The water turns the turbines which in turn spin generators to generate electricity. The electricity is carried through cables to wherever it's needed.

HYDROELECTRIC DAMS: History

 Hydroelectric power has been around for a very long time. Antipater, the Greek poet, mentioned the use of falling water to create energy in 4th century B.C. writings. The Romans used the waterwheel, but later saw no need to use it, and it wasn't used until centuries later. Then, after war and famine diminished great numbers of Europe's population, labor-saving mills came into higher use.

 On September 30th, 1882, in Appleton, Wisconsin, falling water produced electricity for the first time. Since this contribution to modern science, hydroelectric power production has risen to an astonishing 2,044 billion kilowatt hours worldwide.

 The largest hydroelectric complex in the world is on the Parana River, between Paraguay and Brazil. Called the Itaipu Dam, its 18 turbines produce 12,600 megawatts of electricity! That is enough to light 120 million 100 watt light bulbs at once. Now that is a lot of power.

HYDROELECTRIC DAMS: Design Issues and Problems

 The main reasons that hydroelectric dams are not popping up everywhere are that they are costly and require large bodies of water relatively close to civilization. According to the World Bank, "developing countries will need to raise an estimated $100 billion by the year 2000 for hydroelectric plants currently in the planning stage." Large bodies of water are needed for these kinds of dams because large scale dams can pay off construction costs quicker than smaller dams.

 Another arising problem is the effect of dams on river ecosystems. Many rivers, before dams, used to have spring floods that washed out river backwaters and deposited silt to form sandbars. Dams put an end to those spring floods and allow vegetation to clog up river backwaters. This kills many different kinds of fish that live in those areas. Also, if chemicals or oils mix with the water running through the turbines, animals downstream will die. Another problem exists in the planning of large dams. Large dams require large discharge areas. Many people have to be evacuated to make room for these discharge areas. In many places, almost 80,000 people have to be evacuated within a period of only a few weeks.

PICTURES FOR:

Grand Coulee Dam, located on the Columbia River in Washington

Itaipu Dam, largest dam in the world. Located between Brazil and Paraguay

Yellowtail Dam, on the Bighorn River in eastern Montana