What Is Hydroelectric Power?

Hydroelectric power is sustainable energy generated by harnessing the flow of water and converting its motion into electricity using water turbines, generators, and other standard power generating equipment.

Hydroelectric power is sustainable energy generated by harnessing the flow of water and converting its motion into electricity using water turbines, generators, and other standard power generating equipment. Hydroelectric power is widely promoted as a cost-effective and environmentally responsible alternative to energy produced by burning fossil fuels such as petroleum and coal and accounts for approximately 6.6% of all energy consumed in the United States.

A Short History Of Hydroelectric Power

Hydropower was originally used in ancient times to grind flour and for other mechanical uses previously requiring horse-power. In 1878, William Armstrong created the first hydroelectric power generator based upon a simple waterwheel at Cragside, England, that was used to power a single light in his home. Three years later, in 1881, the Shoelkopf Power Station began producing the first hydroelectric power for commercial use, generating 1.3 kW to power 16 carbon arc lights on the streets of Niagara Falls, New York.

What Is Hydropower?

Hydropower Water Cycle Diagram
Hydropower Water Cycle Diagram

Hydropower is the energy derived from moving water. Hydropower is generated by the Earth’s natural water cycle:

  • Solar energy heats the surface water on oceans and lakes, causing water to evaporate.
  • Water vapor condenses into clouds and falls back to Earth as precipitation.
  • Rain and snow collect in rivers and streams that empty into oceans and lakes, and the cycle begins again.

As hydropower occurs naturally and is continuously being created by the Earth’s atmospheric processes, it is considered a carbon neutral renewable energy source.

How Is Hydropower Harnessed?

Hydropower is harnessed directly by using various methods such as watermills to channel the mechanical power of moving water. A watermill uses a running stream or river to turn a water wheel driving processes such as grinding, hammering, or sawing. Also, hydropower is used in trompe applications where falling water is funneled to produce compressed air for use in mining and metal forging furnaces.

How Is Hydropower Converted Into Electricity?

Hydroelectric Turbine
Hydroelectric Turbine

Hydropower is converted into electricity by using a hydroelectric power station. There are four types of hydroelectric power stations, dams, pumped-storage, running-river, and tidal, with conventional dams by far producing the most electricity. A hydroelectric dam operates by building a dam across a large fast-moving river and using the stored potential energy of the dammed water to spin an electricity generating water turbine. Hydroelectric power stations work similarly to geothermal power stations except they are open systems, the water is not recycled internally but by the Earth’s natural water cycle on a much grander scale.

How Much Hydroelectric Power Is Being Generated?

In 2019, hydroelectric power accounted for 6.6% of all energy used in the United States, generating approximately 102GW. World-wide, 16.6% of all electricity consumed is hydroelectric, with China being the largest producer at 311GW.

Who Generates Hydroelectric Power?

The following is a list of the 10 largest hydroelectric power stations:

Three Georges DamChina22.5GW
Itaipu DamBrazil/Paraguay14GW
Belo MonteBrazil11.2GW
Grand CouleeUnited States6.8GW
Longtan DamChina6.4GW

What Is The Future Of Hydroelectric Power?

Less than 20% of the world’s potential hydroelectric power capacity has been harnessed, with less developed nations in Africa and the Middle East realizing less than 5%. Scientists estimate that approximately 25% of the remaining exploitable potential will be realized within the next 25 years, achieved mostly in developing Asia-Pacific nations.

Hydroelectric Power In The News


Hydroelectric Power Producers: Bath County PSP, Chief Joseph Dam Project, Grand Coulee Dam, Hoover Dam, John Day Dam, Niagra Power Project

Jill is the Renewable Energy editor at Electric Guide and writes about the world-wide transition from fossil fuels to sustainability.  With a B.S. in Environmental Engineering from the Samueli School at UCI and having campaigned extensively for federal subsidization of affordable green housing, Jill is uniquely qualified to discuss the rapidly evolving renewables industry. Send tips and story ideas to Jill at: jill@electric.guide