Why Use Hydropower? History of Hydropower. Hydropower Glossary. Hydropower , or hydroelectric power, is a renewable source of energy that generates power by using a dam or diversion structure to alter the natural flow of a river or other body of water. Because hydroelectricity generation ultimately depends on precipitation, and precipitation levels vary seasonally and annually, the ranking of each state in annual hydroelectricity generation may be different from its ranking in generation capacity.
Pumped-storage hydroelectric systems generally use more electricity to pump water to upper water storage reservoirs than they produce with stored water. Therefore, pumped-storage facilities have net negative electricity generation balances. The U. Energy Information Administration publishes electricty generation from pumped storage hydroelectric power plants as negative generation. Only a small percentage of the dams in the United States produce electricity.
Most dams were constructed for irrigation and flood control and do not have hydroelectricity generators. Department of Energy estimated that in , non-powered dams in the United States had a total of 12, MW of potential hydropower capacity. Hydropower explained Where hydropower is generated.
What is energy? Units and calculators. Use of energy. Energy and the environment. China is the largest producer of hydroelectricity. Approximately 71 percent of all of the renewable electricity generated on Earth is from hydropower. The Three Gorges Dam in China, which holds back the Yangtze River, is the largest hydroelectric dam in the world, in terms of electricity production. The dam is 2, meters 7, feet long and meters feet tall, and has enough generators to produce 22, megawatts of power.
Also called hydroelectric energy or hydroelectric power. The audio, illustrations, photos, and videos are credited beneath the media asset, except for promotional images, which generally link to another page that contains the media credit.
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Text on this page is printable and can be used according to our Terms of Service. The Three Gorges Dam, for example, displaced an estimated 1. Dams also prevent fish such as salmon from swimming upstream to spawn. While equipment such as fish ladders are designed to help salmon go up and over dams and enter upstream spawning areas, such measures aren't always effective.
In some cases, fish are collected and trucked around the obstacles. Still, the presence of hydroelectric dams can often change migration patterns and hurt fish populations. In the Columbia River Basin in the Pacific Northwest, for example, salmon and steelhead have lost access to about 40 percent of their historic habitat because of dams.
Hydropower plants can also cause low dissolved oxygen levels in the water, which is harmful to river habitats. Other wildlife can be affected as well: In Indonesia, a hydroelectric project threatens rare Tapanuli orangutans because it stands to fragment their habitat. Climate change and the increased risk of drought are also having an impact on the world's hydropower plants. In the western U. Even the promise of carbon-free electricity from hydropower has been undermined by revelations that decaying organic material in reservoirs releases methane , a potent greenhouse gas that contributes to global warming.
However, some argue that the environmental impacts of hydroelectric power can be mitigated and remain low compared with burning fossil fuels. In some places, small hydro projects can take advantage of existing water flows or infrastructure.
Special water intakes and turbines can help make sure water released from a dam is better aerated to address the problem of low dissolved oxygen. Dams can be planned more strategically to allow fish passages, for example, while water flows at existing dams can be calibrated to give ecosystems more recovery time from flooding cycles. And research continues on ways to make hydropower projects more friendly to the ecosystems around them.
A growing movement is also working to tear down dams that are no longer functioning or needed around the world, with the aim at restoring more natural rivers and the many benefits they provide to wildlife and people, including recreation.
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