Where Are Hydroelectric Power Plants Usually Located?
Hydroelectric power plants generate electricity using the energy from flowing water. At hydroelectric plants, flowing water spins large turbines that are connected to generators that convert the mechanical energy into electrical energy.
The use of flowing water to generate power has a long history dating back thousands of years, with early uses like waterwheels for grinding grains. The first hydroelectric power plant was built at Niagara Falls in 1879. The importance of locating hydroelectric plants near flowing water sources with adequate elevation drop became clear early on. Situating plants near population centers reduced transmission losses.
Today hydropower generates around 16% of the world’s electricity. Large scale hydro plants continue to be built around the world, especially in developing countries, to provide renewable power for growing populations. However, suitable locations are limited by geography. There are also environmental concerns around large dams flooding habitat and altering ecosystems.
Flowing Water Source
Hydroelectric power plants require a reliable, fast-flowing source of water like a river or waterfall. The force of the flowing water spins a turbine connected to a generator to produce electricity. Dams are typically built on rivers to create reservoirs to provide a controlled source of water flow. For example, the Lahnasenkoski Hydropower Dam on the River Hiitolanjoki in Finland was built to create a reservoir to feed an existing hydropower plant downstream. The Kangaskoski Hydropower Dam on the same River Hiitolanjoki also created a reservoir for electricity generation.
To maximize energy production, hydroelectric dams are often built in places with existing waterfalls or locations where a river descends rapidly in elevation. The most powerful waterfall in the world, Niagara Falls on the border between the United States and Canada, has multiple massive hydroelectric plants taking advantage of the tremendous water flow. Other places ideal for hydroelectric dams include the steep rivers of mountainous regions and the powerful rapids of massive rivers like the Congo and Amazon Rivers.
Elevation Change
Hydroelectric plants require an elevation drop to allow gravity to give the water flow energy. Water is directed downhill and through turbines, which capture the kinetic energy of the moving water. The faster the water flows, the more energy can be generated. Greater elevation changes result in faster water flows, which allows hydroelectric plants to generate more electricity.
For example, there is a stream flowing from a mountain down 100 meters that can be directed through a pipe to generate hydropower from the elevation drop, as described here: Elevation generating hydropower example. The greater the elevation change from the water source to the turbines below, the more electricity the plant can produce from the force of gravity pulling the water downhill.
Proximity to Population Centers
Hydroelectric power plants are often strategically located near major population centers that have high electricity demands. This proximity minimizes transmission losses that would occur over long distances (Where hydropower is generated – U.S. Energy Information Administration). By generating electricity close to where it will be consumed, less energy is wasted heating up the transmission lines.
Many hydroelectric dams are built near or directly upstream of major cities and metropolitan areas that require large amounts of electricity. This location reduces the need for new transmission infrastructure and makes the generated power readily available to the end users. For example, the massive Three Gorges Dam in China provides electricity to the nearby megacity of Chongqing (Hydropower generation by country 2022 – Statista).
Strategic placement near population centers allows hydroelectricity to be a reliable and efficient energy solution for meeting the considerable demands of industry, businesses, and homes. With less distance to travel, the power gets to where it needs to go quickly.
Environmental Concerns
While hydropower is a renewable energy source, hydroelectric dams can have negative environmental impacts. The reservoirs created by dams flood large areas of land, which can destroy wildlife habitats and disrupt ecosystems. For example, the Three Gorges Dam in China flooded around 400 square miles of land, displacing over a million people and submerging entire cities, forests and farmlands. This flooding impacted endangered species like the Yangtze dolphin and Chinese sturgeon (https://environmentalevidencejournal.biomedcentral.com/articles/10.1186/s13750-021-00271-5). Dams also alter the natural flow of rivers, changing water temperatures and oxygen levels in ways that harm native fish populations (https://grist.org/article/why-some-hydropower-plants-are-worse-for-the-climate-than-coal/).
Efforts have been made to mitigate hydropower’s environmental damage. Fish ladders are sometimes installed to help migratory fish move past dams. Rivers can be mimicked with artificial spawning channels for fish breeding. Minimum water flow levels may be mandated to sustain downstream ecosystems. But these efforts don’t eliminate all impacts. The location, design and operation of hydroelectric dams requires balancing power generation with ecological concerns (https://www.sciencedirect.com/topics/social-sciences/hydroelectric-power).
Geographic Regions
Hydroelectric power plants are located around the world, but some regions have significantly more capacity than others. The continent with the most hydropower capacity is Asia, where massive dams in China and other countries generate substantial amounts of electricity. For example, the Three Gorges Dam in China has an installed capacity of 22,500 MW, making it the world’s largest hydroelectric facility 1.
South America also has enormous hydro capacity, especially in Brazil where facilities like the 14,000 MW Itaipu Dam provide clean energy. In North America, Canada and the United States have many large hydroelectric plants like the Robert-Bourassa generating station in Quebec with 5,616 MW of capacity. And in Europe, major facilities can be found in Norway, France and other countries.
Overall, hydropower plants are present on every inhabited continent due to the worldwide abundance of flowing water sources and elevation changes. But the density of large hydroelectric dams varies greatly depending on a region’s topography, demand for electricity, and environmental regulations.
Capacity and Generation
Hydroelectric power plants account for over 16% of the world’s electricity production and the largest facilities generate immense amounts of renewable power. The Three Gorges Dam in China is currently the world’s largest hydroelectric power station, with a massive capacity of 22,500 megawatts (MW). When operating at full capacity, Three Gorges alone can supply the electrical needs of over 50 million people. Other hydroelectric mega-projects like Brazil’s Itaipú Dam (14,000 MW) and Venezuela’s Guri Dam (10,200 MW) also rank among the biggest power stations in the world by capacity.
In terms of annual energy generation from hydroelectric sources, China leads the world by a significant margin. Chinese hydro plants produce over 1,100 terawatt-hours per year, accounting for nearly 30% of the country’s electricity. Canada, Brazil, and the United States rank next in hydro generation, each producing over 250 terawatt-hours annually. Norway and Venezuela also obtain the bulk of their electric power from hydro plants. Globally, hydroelectricity continues to expand as an emissions-free renewable energy source that provides reliable baseload power to electrical grids.
Sources:
https://www.worldatlas.com/articles/largest-hydroelectric-power-plants-in-the-world.html
Pumped Storage
Pumped storage hydropower (PSH) plants store energy in the form of water pumped from a lower elevation reservoir to a higher elevation reservoir. When the stored water is released, it flows downhill through a turbine to generate electricity[1]. PSH plants essentially act as a large battery, able to store power and generate electricity on demand.
The lower reservoir is typically a lake or river while the upper reservoir is often an artificial reservoir specifically constructed for the PSH plant. During periods of low electricity demand, excess generation capacity is used to pump water uphill into the upper reservoir. When electricity demand is high, the stored water can be released to produce power quickly[2].
PSH currently accounts for over 90% of utility-scale energy storage in the United States[3]. The ability to store large amounts of energy and provide grid reliability makes PSH an important renewable energy resource.
[1] https://www.energy.gov/eere/water/pumped-storage-hydropower
[2] https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricity
[3] https://www.energy.gov/eere/water/how-pumped-storage-hydropower-works
Small Scale Hydro
Small-scale and mini hydro systems that generate under 10 megawatts are often used to provide electricity for isolated rural areas and remote communities, as an alternative to costly extension of transmission lines from the main grid (Hydropower (Small-scale) – SSWM.info). These small plants can utilize natural streams, small rivers, man-made channels, or existing infrastructure like irrigation canals or pipes. Micro hydro systems generating under 100 kilowatts are especially suitable for off-grid rural electrification.
Small hydropower systems can also utilize run-of-river designs which harness the natural flow of rivers without requiring large dams or water storage reservoirs. These systems divert a portion of the river flow through channels or pipes to spin turbines and generate electricity, before returning the water back to the river further downstream. Run-of-river plants have a much lower environmental impact compared to conventional reservoir-based hydro dams (Small Hydropower – Drawdown). Their flexibility and low cost make small run-of-river systems an attractive option for remote and rural communities near suitable river sites.
Future Outlook
The future of hydropower looks promising globally, with growth projections showing continued expansion. According to the International Energy Agency (IEA), global hydropower capacity is forecast to increase by 17%, or 230 gigawatts (GW), between 2021 and 2030.IEA Driving this growth is rising electricity demand and the low operating costs of hydropower plants compared to fossil fuels.
There are also significant technology improvements underway, including new turbine designs, that will increase generating capacity at existing facilities. Additionally, new potential hydropower sites are being identified through advanced mapping and geological data. The Hydropower Vision Report by the U.S. Department of Energy highlights future pathways where U.S. hydropower capacity could double by 2050.DOE With greater investment and supportive policies, global hydropower looks positioned to expand as a renewable energy source.
