How can moving water produce electricity

Because the source of hydroelectric power is water, hydroelectric power plants are usually located on or near a water source. The volume of the water flow and the change in elevation—or fall, and often referred to as head —from one point to another determine the amount of available energy in moving water.

In general, the greater the water flow and the higher the head, the more electricity a hydropower plant can produce. At hydropower plants water flows through a pipe, or penstock , then pushes against and turns blades in a turbine to spin a generator to produce electricity. Conventional hydroelectric facilities include Run-of-the-river systems , where the force of the river's current applies pressure on a turbine.

The facilities may have a weir in the water course to divert water flow to hydro turbines. Storage systems , where water accumulates in reservoirs created by dams on streams and rivers and is released through hydro turbines as needed to generate electricity. Most U. Pumped-storage hydropower facilities are a type of hydroelectric storage system where water is pumped from a water source up to a storage reservoir at a higher elevation and is released from the upper reservoir to power hydro turbines located below the upper reservoir.

The electricity for pumping may be supplied by hydro turbines or by other types of power plants including fossil fuel or nuclear power plants.

Pumped-storage hydroelectric systems generally use more electricity to pump water to the upper water storage reservoirs than they produce with the stored water. Therefore, pumped-storage facilities have net negative electricity generation balances. The U. Energy Information Administration publishes electricity generation from pumped storage hydroelectric power plants as negative generation. Click to enlarge. Hydropower is one of the oldest sources of energy for producing mechanical and electrical energy and up until , it was the largest source of total annual U.

Thousands of years ago, people used hydropower to turn paddle wheels on rivers to grind grain. Before steam power and electricity were available in the United States, grain and lumber mills were powered directly with hydropower.

The first industrial use of hydropower to generate electricity in the United States was in to power 16 brush-arc lamps at the Wolverine Chair Factory in Grand Rapids, Michigan.

The first U. There are about 1, conventional and 40 pumped-storage hydropower plants operating in the United States. The oldest operating U. The largest U. Generation capacity is net summer capacity. Hydropower explained. Using water as a source of energy is generally a safe environmental choice. Its not perfect, though. Hydroelectric power plants require a dam and a reservoir.

These man-made structures may be obstacle s for fish trying to swim upstream. Some dams, including the Bonneville Dam, have installed fish ladder s to help fish migrate. Fish ladders are a series of wide steps built on the side of the river and dam. The ladder allows fish to slowly swim upstream instead of being totally block ed by the dam. Dams flood river bank s, destroying wetland habitat for thousands of organism s.

Aquatic birds such as crane s and duck s are often at risk, as well as plants that depend on the marsh y habitat of a river bank. Operating the power plant may also raise the temperature of the water in the reservoir. Plants and animals near the dam have to adjust to this change or migrate elsewhere. Environmental coalitions opposed the dam, citing the destruction of the environment and the habitats it provided.

However, the power plant provided affordable hydroelectric energy to the booming urban area around San Francisco. The Hetch Hetchy Reservoir is still a controversial project. Many people believe the OShaughnessy Dam should be destroyed and the valley returned to its native habitat.

Others contend that destroying a source of energy for such a major urban area would reduce the quality of life for residents of the Bay Area. There are limits to the amount of hydroelectric energy a dam can provide. The most limiting factor is silt that builds up on the reservoirs bed. This silt is carried by the flowing river, but prevented from reaching its normal destination in a delta or river mouth by the dam. Hundreds of meters of silt build up on the bottom of the reservoir, reducing the amount of water in the facility.

Less water means less powerful energy to flow through the systems turbines. Most dams must spend a considerable amount of money to avoid silt build-up, a process called siltation. Some power plants can only provide electricity for 20 or 30 years because of siltation. Hydroelectric Energy and People Billions of people depend on hydroelectricity every day. It powers homes, offices, factories, hospitals, and schools. Hydroelectric energy is usually one of the first methods a developing country uses to bring affordable electricity to rural area s.

Hydroelectricity helps improve the hygiene , education, and employment opportunities available to a community. China and India, for instance, have built dozen s of dams over the past decade, as their development has quickly grown. The United States depended on hydroelectric energy to bring electricity to many rural or poor areas. Most of this construction took place during the s. Dams were a huge part of the New Deal , a series of government programs that put people to work and brought electricity to millions of Americans during the Great Depression.

Today, the TVA is the largest public power company in the U. However, hydroelectricity often comes at a human cost. The huge dams required for hydroelectric energy projects create reservoirs that flood entire valleys.

Homes, communities, and towns may be relocated as dam construction begins. Egypt began construction of the Aswan Dam complex on the Nile River in Engineers realized that ancient temple s of Abu Simbel were going to be flooded by the reservoir, called Lake Nasser.

These monuments were built directly into cliff s several stories tall. The Abu Simbel temples are a part of Egypts cultural heritage and a major tourist destination. Rather than have the monuments flooded, the government of Egypt relocate d the entire mountainside to an artificial hill nearby.

Today, Abu Simbel sits above the Aswan Dam. Chinas massive Three Gorges Dam project will bring safe, affordable electricity to millions of people. It will allow hospitals, schools, and factories to work longer, more reliable hours. It will also allow people to maintain healthier lifestyles by providing clean water.

Construction of the dam directly benefited workers, too. More than a quarter of a million people have found work with the project. However, the project has forced more than a million people to relocate. Lifestyles were disrupted. Many families were relocated from rural towns on the banks of the Yangtze River to Chongqing, a major urban area with 31 million residents. Other people were relocated out of the province entirely.

Hoover Dam The Hoover Dam was built during the Great Depression, a period when most people had little money and jobs were very scarce. Building the dam seemed like an impossible task.

Many people said it could not be built. Workers labored long, hard days for two years, building tunnels that are 15 meters 50 feet widebig enough to fit a commercial airplane without its wings. Building the dam gave hope and dignity to many victims of the Great Depression.

It gave people a job and a way to earn money. The Hoover Dam is still in use, providing power to 1. A hydroelectric dam converts the potential energy stored in a water reservoir behind a dam to mechanical energy—mechanical energy is also known as kinetic energy.

As the water flows down through the dam its kinetic energy is used to turn a turbine. Check out this video from the United States Department of Energy for more information on how hydroelectricity is generated:.

Curious about the energy terminology used in this piece? The U. Hydro: how hydro power is generated. Department of Energy: how hydropower works.