What is Hydroelectric Power?

Detailing the story of this renewable energy source

Hydroelectric Power 1200

For thousands of years, people have harnessed the energy contained in running water and used it to perform useful work. Water wheels and water mills for processing grain were widely used over 2000 years ago through ancient Greece. They were also used during the Han Dynasty in China and in Imperial Rome.

Industrial Revolution Spurred Innovation

Major innovations began in the mid-18th century, during the early days of the Industrial Revolution.

In 1753, a French engineer named Bernard Forest de Belidor published his seminal work, Architecture Hydraulique1. This work described both vertical and horizontal-axis hydraulic machines, and laid the groundwork for future innovations in hydropower. As the Industrial Revolution progressed, water was a key power source for many new inventions, notably Richard Arkwright's water frame for spinning cotton fibers.

In 1878, the very first hydroelectric power setup was used to power a single arc lamp. By 1881, Shoelkopf Power Station Number One near Niagara Falls had begun to produce electricity on a mass scale. Throughout the 20th and early 21st centuries, continuing technological improvements have helped establish hydroelectric power as a core element of an ongoing movement toward renewable energy solutions.

How Hydroelectric Power Works

Hydroelectric power plants are an important source of electricity in the United States.

Today's water power plants come in many sizes, from the massive Hoover Dam to small-scale projects that harness water flows in drainage ditches or irrigation facilities.

In a hydroelectric plant, natural water flows provide a source of energy that can be converted into electricity. Drought conditions notwithstanding, where water flows continuously, hydropower is a renewable resource. There are a few different types of hydropower facilities, all of which are based on the kinetic energy of moving water:

  • Impoundment Facilities
    Impoundment facilities use a dam to store water from a river in an artificial reservoir. As water is released from this reservoir, it flows through and spins and turbine, which activates a generator that produces electricity.

  • Diversion Facilities
    This type of hydroelectric facility channels part of a flowing river through a canal, either with or without an accompanying dam.

  • Pumped Storage Hydropower
    Pumped storage facilities are designed to store electricity that is derived from other energy sources, such as nuclear power plants or wind farms. Water is pumped uphill from one reservoir into a second reservoir at a higher elevation.

When local demand for electricity is low, pumping from lower to higher stores energy. When demand is increased, water is released back into the lower reservoir, where its motion powers a turbine that generates electricity. Like a battery, pumped storage allows unused energy to be utilized at a later time.

Is Hydropower Clean?

Hydroelectric power is a source of renewable energy. As a way of generating electricity, hydropower has several key advantages that contribute to its widespread usage:

  • Hydroelectric power does not contribute to air pollution. Since it derives energy from flowing water, and does not require the combustion of any fossil fuels, it does not release greenhouse gases and other harmful air pollutants.

  • Hydroelectric power is highly local, reducing dependence on outside sources of fuel.

  • Hydroelectric power is renewable.

  • Impoundment hydroelectric plants, in particular, create recreation areas as a byproduct. The reservoirs created by these projects can be used by people for swimming, fishing, and boating.

  • Hydroelectric plants generate power to the grid immediately. This means that they can very quickly go from no output to maximum output. During electricity outages and shortages, they provide a crucial backup.

  • Hydropower facilities can be beneficial for flood control, irrigation, and maintaining the water supply.

Despite its many advantages, hydroelectric power is not without its drawbacks. One of the foremost concerns is that these facilities disturb natural water flows, and may disrupt local riparian ecosystems. In areas prone to drought, the ability to use hydropower facilities can be diminished when the water supply is low. Despite being an ultimately renewable resource, most of the suitable existing reservoirs for hydropower are already in use, meaning that it may become difficult, (and not environmentally prudent,) to construct new hydroelectric plants in the future.

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