What Is The Model Of Hydroelectric Power Generation?
Hydroelectric power is the generation of electricity by harnessing the power of flowing or falling water. The energy from moving water is captured and converted into electricity using turbines and generators.[1]
The history of hydroelectric power dates back to the late 19th century, when the first small hydroelectric power plants began operating. In 1878, a hydroelectric plant opened in Wisconsin, United States that powered a single sawmill. In the 1880s, early hydroelectric plants began operating in the United States and Europe. The development of hydroelectric dams and larger power plants accelerated in the early 20th century. The Hoover Dam, completed in 1936, was an early large hydroelectric project that helped spur development and adoption of hydropower globally.[2]
Today, hydroelectricity is one of the largest and most widely used renewable energy sources. As of 2022, hydropower accounted for around 16% of total electricity generation globally.[3]
How Hydroelectric Power Plants Work
Hydroelectric power plants convert the energy from flowing water into electricity. Here are the main components and how they work together in the generation process:
Dam – The dam is constructed to create a reservoir by stopping and collecting water from a river or stream. The reservoir stores potential energy in the form of water held at an elevation.
Intake – The intake structure controls water flow into the penstocks from the reservoir.
Penstock – Penstocks are pipes that carry water from the reservoir to the turbines inside the powerhouse. The water gains kinetic energy as it flows through the penstock.
Turbine – The force of the moving water spins the turbine blades which rotates a shaft connected to the generator. Hydro turbines convert the kinetic energy of falling water into mechanical energy.
Generator – The generator converts the mechanical energy from the turbine into electrical energy. The spinning shaft inside the generator rotates magnets around a set of coils to generate electricity.
The electricity is then transmitted via cables to a local grid for distribution to homes, businesses, and industries. Dams assist in controlling water flow through the system and optimizing power generation.
Most hydroelectric plants rely on a large dammed reservoir for energy production. Some systems called run-of-river plants channel a portion of a river through a penstock while allowing the rest to flow naturally downstream.
Types of Hydropower Plants
There are three main types of hydropower plants: run-of-river, impoundment, and pumped storage. Each type utilizes flowing water in a different way to generate electricity.
Run-of-river hydropower plants channel a portion of a river’s water through a canal or penstock to spin turbines and generate electricity. These plants do not require large dams or water storage reservoirs. According to the International Hydropower Association, run-of-river projects account for over half of hydropower capacity additions today.
Impoundment hydropower facilities use dams to store river water in a reservoir. The water is released through the station’s turbines to generate electricity as needed. Impoundment plants provide a consistent supply of electricity by regulating water flow. Major dam projects like the Hoover Dam and Three Gorges Dam are impoundment facilities.
Pumped storage hydropower plants pump water uphill to a reservoir at higher elevation during times of low electricity demand. The stored water is later released to spin turbines and generate power when demand is high. Pumped storage allows energy from intermittent sources like wind and solar to be stored as potential hydro energy.
Advantages of Hydroelectric Power
Hydroelectric power offers several key advantages that make it an important source of renewable energy. Three of the main benefits are:
Renewable
Hydroelectric power is considered a renewable energy source because it relies on the water cycle. Rain and snow regenerate the water in hydroelectric dams and reservoirs, allowing generation to continue indefinitely as long as there is adequate water supply [1].
Reliable
Hydropower plants provide consistent and reliable electricity since generation can be quickly adjusted to meet demand. The flow of water driving turbines can be rapidly controlled. Hydropower has one of the highest capacities of any renewable energy technology [2].
Low Operating Costs
After a hydropower plant is constructed, electricity generation involves relatively low operating and maintenance costs. Water to drive turbines is free and renewable. Facility maintenance costs are also low compared to fossil fuel plants. This makes hydropower very cost effective over the long-term.
Disadvantages of Hydroelectric Power
While hydroelectric power has advantages, it also has some drawbacks. Two major disadvantages are the high upfront costs and impacts on aquatic ecosystems.
Constructing hydroelectric dams and power plants requires very large initial investments. Significant funds are needed for feasibility studies, obtaining permits, and carrying out engineering, procurement and construction. The costs can easily run into the billions of dollars for a single large hydroelectric project.[1]
The size of the dams and reservoirs can also drastically impact river ecosystems and disrupt fish migration patterns. As water levels rise, land needs to be flooded to create the reservoir. This can destroy forests and wildlife habitats in the area. Fish can also become injured and killed while passing through the turbines.[2] Protective screens and fish ladders can help mitigate the damage, but impacts on biodiversity still remain a major concern.
While hydroelectric power is renewable and cleaner than fossil fuels, these disadvantages need to be weighed when planning new projects. Proper siting, sizing and mitigation strategies are necessary to minimize the impacts on the environment and local communities.
Capacity and Generation Statistics
According to the 2019 Hydropower Status Report from the International Hydropower Association[1], global installed hydropower capacity was 1,308 gigawatts (GW) at the end of 2018. This accounted for over 16% of global electricity generation capacity. The top countries for installed hydroelectric capacity in 2018 were:
- China – 352 GW
- Brazil – 109 GW
- Canada – 81 GW
- United States – 80 GW
- Russia – 48 GW
The top regions for hydroelectricity generation in 2022 were Asia Pacific and South America, which accounted for over 50% of global generation[2]. The countries with the largest share of electricity generated from hydroelectric dams include:
- Norway – 95%
- Venezuela – 65%
- Brazil – 64%
- Canada – 59%
- Switzerland – 56%
Many countries still have significant potential to expand their hydroelectric capacity. The countries with the largest projected growth in hydro capacity between 2019-2029 are China, Brazil, India, Turkey and Vietnam[1].
Major Hydroelectric Projects
Some of the largest and most notable hydroelectric projects in the world include:
The Three Gorges Dam in China is the world’s largest hydroelectric dam by installed capacity at 22,500 MW. Completed in 2012, it spans the Yangtze River and also helps control flooding.
The Itaipu Dam on the Paraná River bordering Brazil and Paraguay is the second largest hydroelectric power station in the world with an installed capacity of 14,000 MW. Construction was completed in 1991.
The Grand Coulee Dam in Washington state, USA is the largest hydroelectric power station in the United States. With a capacity of 6,809 MW, it was completed in 1942 and provides irrigation water and flood control.
The Sayano–Shushenskaya Dam in Russia (6,400 MW) was the largest power plant in Russia and ranked in the top 10 globally when it opened in 1978.
The Xiluodu Dam (13,860 MW) and Xiangjiaba Dam (6,448 MW) in China both rank among the largest dams in the world and began operation in the last decade.
Small Scale and Micro Hydropower
Small scale hydropower projects generate up to 10 megawatts of electricity and can provide clean, renewable energy to local communities and industry. Small hydro plants are often built on existing dams or utilize natural water features like canal drops or mill races. Some key benefits of small hydro projects include:
- Low cost electricity generation – Small hydro requires relatively low capital investment compared to large hydro or other energy sources.
- Minimal environmental impact – Small hydro projects have little to no associated emissions and do not typically require dams or reservoirs, reducing disruption to surrounding ecosystems.
- Distributed generation – Small hydro can provide off-grid electricity to rural communities and supplement power grids locally.
- Low maintenance – Small hydro plants are automated, have few moving parts, and require minimal maintenance compared to diesel generators.
With advances in turbine technology, small hydro projects can be tailored to suit a wide variety of sites and power needs, from remote villages requiring just a few kilowatts to industrial facilities generating up to 10 megawatts. There is significant potential worldwide for growth in small scale hydropower as an affordable and sustainable energy solution.
Future Outlook
Hydropower has significant potential for future growth globally. According to the International Energy Agency (IEA), global hydropower capacity is forecast to increase by 17%, or 230 gigawatts, between 2021 and 2030.[1] This continued growth is driven by the increasing demand for clean renewable energy and hydropower’s ability to provide flexible and reliable electricity.
The United States also has substantial potential for new hydropower development. A 2016 Department of Energy report, Hydropower Vision, found that U.S. hydropower capacity could nearly double by 2050 under a high growth scenario.[2] Upgrades and improvements to existing facilities could add over 34 gigawatts of capacity, while new stream-reach development could add over 49 gigawatts.
Key future growth areas for hydropower include:
- Upgrading and modernizing existing hydropower infrastructure
- Developing new pumped storage capacity to support grid flexibility
- New stream-reach and conduit hydropower at existing dams, canals, and pipelines
- Small-scale and micro hydropower projects
Advancements in hydropower technology, such as advanced turbines, generators, and control systems, can also help increase generation and grid services. Overall, hydropower is poised for continued expansion as countries seek to increase renewable energy and meet climate goals.
Conclusion
Hydroelectric power generation involves using the energy from flowing water to produce electricity. At hydroelectric plants, water flows through turbines that spin generators to create electricity. There are several types of hydropower facilities, including impoundment, diversion, pumped-storage, and run-of-river plants. Each has different designs and methods to harness the kinetic energy in water.
The key advantages of hydroelectricity are its renewable, sustainable nature and ability to quickly adjust output to meet demand. It does not directly produce air pollution or greenhouse gases. However, building large dams can impact local ecosystems and communities. Most suitable sites in developed countries have already been utilized, so growth is slowing. But hydro remains a major electricity source globally, accounting for around 16% of production. With its unique benefits and ability to complement other renewables, hydropower will continue playing an important role in the world’s energy mix.
In summary, harnessing the natural movement of water is an essential way of generating carbon-free renewable electricity. While not without some drawbacks, hydroelectric power plants produce low-cost, flexible, reliable energy once built. With the growing shift towards clean energy worldwide, hydroelectricity will remain a key part of delivering stable power supplies and reducing dependence on fossil fuels.
