Renewable energy is the future and hydropower plants are its biggest global suppliers. Hydropower, in the right locations, is a sustainable way to cut our reliance on fossil fuels. This source now accounts for 54% of the world’s renewable energy supply.
In certain parts of the developed world, there has been a major shift away from large-scale hydro towards wind, solar, and other forms of renewable energy. This is in part because, although hydropower is renewable, it comes at a cost to the environment.
Big dams have taken a huge toll and can continue to take a huge toll, on people and the planet. They have flooded areas of our precious ecosystems, degraded landscapes downstream, and displaced people from their homes. The best environmental results from hydropower come from the small scale plants2.
Regardless, hydropower continues to dominate in many parts of the globe. Whereas the US and parts of Europe have decommissioned several dams, hydro still dominates the industry. Particularly in China, South America, and Africa, where hydro is likely to continue to be an important part of the renewable energy mix for many years to come.
Let's take a close look at the 10 biggest hydropower plants in the world, along with a few plants that are under construction, and may well soon knock some of these other examples off the list.
China dominates when it comes to hydroelectricity, generating more power than any other nation in the world. The largest hydropower plant in the world is the Three Gorges Dam, in Yichang, Hubei province. It dams the Yangtze River and resulted in the flooding of a staggering 1,084 km2.
Developers installed this power station with a capacity of 22,500 MW and completed the project between 2008 and 2012. Though it generates a huge amount of renewable power, this dam is controversial – to say the least. Some of the environmental impacts of this project are often questioned as well as displacing over a million people.
The Baihetan dam on the Jinsha River is currently under construction. Work commenced on this project in 2008. The developers expect to complete this project between 2021-2022, and they expect that it will have a capacity of 16,000 MW.
The Jinsha River is a tributary of the Yangtze River in Sichuan and Yunnan provinces. Once finished, this will be the second-largest hydropower plant in the world. (check this site out for some pics of this monster dam under construction)
The Itaipu dam is currently the second-largest hydropower plant in the world by installed capacity. The countries created this plant between 1984 and 1991 and installed two additional units in 2003.
Though the installed capacity of this dam is far lower than the Three Gorges Dam, with 14,000 MW installed capacity, the annual production of this dam is higher. This is because the Parana River that feeds this dam has much less seasonal variance inflow. So the energy output here is more stable.
China completed another massive dam on the Jinshu River, Xiluodu in 2014. This is one completed section of the massive dam project on the river. It is one of four dams on the downstream that is part of phase one of the project.
In the future, there are plans for eight dams on the middle section of the river and eight more on the upper stream. This dam has an installed capacity only slightly lower than the Itaipu Dam, 13,860 MW, yet does have a significantly lower energy generation figure.
Brazil built Belo Monte between 2016 and 2019 on the Xingu River. It has an installed capacity of 11,223 MW. Like other mega hydropower plants, this project is mired in controversy. Indigenous people and other groups have strongly criticized it, including environmental organizations in Brazil, and organizations and individuals around the world.
Damming the Caroni River, Venezuela completed this project in 1978 and 1986. It has an installed capacity of 10,235 MW. The creation of this enormous project involved the flooding of 4,250 km2. Although the dam is key to Venezuela's economy, it has had profound negative effects.
Flooding from the dam created a lake that destroyed huge areas of the ecosystem and resulted in the loss of countless wildlife species. And the problems did not end with construction. Since its construction, many have criticized this plant for its several generating failures and blackouts, most recently in 2019.
The second-largest hydropower plant currently under construction, the Wudongde project is, like the Baihetan project and the Xiluodu Dam mentioned above, on the Jinsha River. Developers expect this plant to have a capacity of 10,200 upon completion. They also expect to complete this project between 2020 and 2021.
We can find the Tucurui hydropower plant on the Tocantins river in Brazil. Developers completed the first phase of the project in 1984, then made additions in 2007. This site has an installed capacity of 8,370 MW.
This project in Amazonia is archetypical of non-environmentally-conscious development. Like other large dams, this project has had significant negative environmental effects1.
The Grand Coulee hydropower plant is the largest in the United States. It dams the Columbia River. Constructed between 1942 and 1991, in phases, this dam has an installed capacity of 6,809 MW.
Since the US completed this project, the Grand Coulee Dam has provided many long-term jobs, and annual irrigation to more than 2,000 Washington farmers. It is one of the top producers of hydroelectric power in the United States.
Slated for completion in the next couple of years, developers expect this grand hydropower project on the Blue Nile River to have an installed capacity of 6,450 MW. It has been under construction since 2011 and, once completed, will be the largest hydroelectric power plant in Africa.
The reservoir could take between 5 and 15 years to fill with water after completion. The country expects this project to have immense benefits for Ethiopia, and serve as the backstop of the national grid. However, there are concerns over the environment and the health of regions downstream. Experts have also raised concerns that the dam is oversized.
This is another part of the hydropower generation scheme in China's Jinshu River. It was, like the Xiluodu Dam, completed in 2014 long after work commenced in 2006. This hydropower plant has an installed capacity of 6,448 MW and is currently the third-largest hydropower station in the country.
Completed between 2001-2009, the Longtan Dam is another of China's biggest hydropower projects. Located on the Hongshui River, a tributary of the Xi and Pearl Rivers, this hydropower plant has an installed capacity of 6,426 MW. Many have raised concerns, not only surrounding environmental issues but also surrounding the safety of this dam.
This is the largest hydropower plant in Russia. Construction took place in phases between 1985 and 2014 on the Yenisei River. It has an installed capacity of 6,400 MW.
This dam has been problematic in a range of ways over the years. There have been some accidents here, including a catastrophic one in 2009 which killed 75 people and caused environmental damage through a large oil spill.
From these largest hydropower plants in the world, we can see both the immense benefits and negatives that large-scale hydropower can bring. Hydropower generates large amounts of needed power. But that power can come at a cost, just like every other renewable energy source.
Hydropower will inevitably play an important role in increasing the amount of renewable energy, required to power the green energy transition. But it is important to look at all factors when determining whether or not a scheme should go ahead. And it is also clear that we must not be blind to the toll these massive engineering projects can take on the planet and people.
|Fearnside PM. Environmental impacts of Brazil's Tucuruí Dam: unlearned lessons for hydroelectric development in Amazonia. Environ Manage. 2001;27(3):377‐396. doi:10.1007/s002670010156|
|Leonard B Lerer, Thayer Scudder, Health impacts of large dams, Environmental Impact Assessment Review, Volume 19, Issue 2, 1999, Pages 113-123, ISSN 0195-9255, https://doi.org/10.1016/S0195-9255(98)00041-9|