The first hydropower facility to supply electricity to commercial and residential customers went online in 1882 in Appleton, Wisconsin. In the first decades of the 20th century hydropower capacity expanded in the United States, Canada, and Europe. After World War II hydropower expanded to other regions including India, Brazil, Japan, Russia, and Egypt. Beginning in the 1990s, China launched a massive drive to expand hydropower capacity that continued through the 2010s.
Hydropower currently supplies about 17% of global electricity generation. It has been called the “forgotten giant of low carbon electricity” because it provides 55% more power than nuclear, and more than wind, solar PV, bioenergy, and geothermal power combined.1 All these sources have substantially lower greenhouse gas emissions compared to electricity generation from fossil fuels.
This visualization illustrates the importance of geography to the location of hydropower. Large river systems support the construction of massive reservoirs. Examples here include the Yangtze (China), the Nile (northeastern Africa), the Columbia (Pacific Northwest of North America), and the Amazon (South America). Large, rapid elevation change is also conducive to hydropower. Examples here include the deployment of hydropower beginning in the 1940s in the river systems that drain out of the Sierra Nevada mountains in northern California, and India’s use of rivers in the Himalayas beginning in the 1970s.
Large hydropower projects can cause significant environmental degradation. Reservoirs dramatically alter the landscape and rivers they are built on. Dams and reservoirs can reduce river flows, raise water temperature, degrade water quality, and cause sediment to accumulate. Such changes have negative impacts on fish, birds, and other biodiversity that rely on riparian ecosystems.2
The construction of dams and reservoirs has collectively displaced 80 million people around the world.3 Many of the people impacted by dams live in marginalized, vulnerable communities. Social conflict over dams is characterized by the repression, criminalization, and violent targeting of activists, especially when indigenous people are involved.4
1 International Energy Association, “Hydropower Special Market Report,” 2021, https://www.iea.org/reports/hydropower-special-market-report
2 Why aren’t we looking at more hydropower?, MIT Climate Portal, March 2, 2021,https://climate.mit.edu/ask-mit/why-arent-we-looking-more-hydropower
3 Blaine, Tegan, “How to Balance Hydropower and Local Conflict Risks,” United States Institute of Peace, October 27, 2022, Link
4 Del Bene, Daniela, Arnim Scheidel, and Leah Temper. “More Dams, More Violence? A Global Analysis on Resistances and Repression around Conflictive Dams through Co-Produced Knowledge.” Sustainability Science 13, no. 3 (May 1, 2018): 617–33. https://doi.org/10.1007/s11625-018-0558-1.