Hydropower

Energy Mix

3% of world 🌎
1% of U.S. 🇺🇸

Electricity Generation

14% of world 🌎
6% of U.S. 🇺🇸

Hydroelectric Capacity by Type

Storage (Dams) and Run-of-River Systems
(Electricity Generation)
87%

Pumped Storage Systems
(Energy Storage)
13%

Global Electricity Generation from Hydropower

Increase:
⬆5%
(2019-2024)

Most Installed Capacity

China 30% 🇨🇳
of global hydroelectric generation installed capacity (excluding pumped storage)

Most Generation

China 30% 🇨🇳
of global hydroelectricity generation

Highest Penetration

Bhutan, Paraguay, Albania, Ethiopia >95%
of country’s electricity generation comes from hydroelectricity

Most Installed Capacity

Washington 27%
of U.S. hydroelectric generation installed capacity

Most Generation

Washington 26%
of U.S. hydroelectricity generation

Highest Penetration

Washington 63%
of state’s electricity generation comes from hydroelectricity

Most Installed Capacity

China 31% 🇨🇳
of global pumped storage installed capacity

Share of Global Energy Storage Capacity

Pumped Storage Hydropower: 54%
Lithium-ion Batteries: 43%

Pumped Storage “Roundtrip” Efficiency

~80%
of the energy used to pump water uphill can be converted back into electricity

Global Pumped Storage Capacity

Increase:
⬆18%
(2019-2024)

Drivers

• Abundant hydro resource
• Electricity generation can be a co-benefit to dams built for flood control, water storage for agricultural, residential, commercial, recreational purposes
• Energy security
• Mature, reliable technology
• Can be used to "black start" the electricity grid after major outages*
• Qualifies under some nations' renewable energy targets (although large hydro may not count in some jurisdictions due to environmental impacts)
• Financial incentives such as production tax credits (PTC) and feed-in tariffs
• Supports integration of intermittent renewables

Barriers

• Site-specific resource, only available in some geographies
• Droughts and climate change can impact water cycle, changing long-term resource availability
• Competing downstream uses for water can limit its use for electricity generation
• Downstream fish passage through or around the powerhouse can injure or kill fish
• Battery storage is gaining market share relative to pumped storage due to falling costs and other advantages

Dams and reservoirs**

• Destruction of cultural heritage sites and human settlements, forcing mass relocation and compensation
• Flooding of terrestrial habitat, disrupting ecosystems that rely on lakes and rivers
• Impacts on aquatic species (e.g., fish mortality and barriers to migration); may also be culturally and economically important to Indigenous communities
• Disruption of ecosystems that are culturally and economically important to Indigenous and local communities
• Impacts on water quality, temperature, and nutrient flux
• Seismic impacts from large reservoirs
• Expensive initial capital costs to build dams
• Lengthy planning, permitting, and construction process
• Local opposition to dam construction (NIMBY/BANANA***)
• Inconsistent policy support
• Movement to remove dams due to environmental harms

_{*Black start - recovering from a blackout by individually restarting power systems and gradually reconnecting them to form an interconnected grid
**Some of these barriers are relevant to run-of-river systems as well
***NIMBY - not in my backyard; BANANA - build absolutely nothing anywhere near anything}

Climate Impact: Low to Medium

• Relatively low GHG emissions on average
• Reservoirs created by dams can flood ecosystems upstream, releasing significant amounts of methane (a potent GHG) as vegetation decomposes

Environmental Impact: Low to Medium

• No air pollution
• Dams can submerge natural habitat, cultural heritage sites, and human settlements, potentially displacing tens of thousands
• Impacts to aquatic ecosystems can disrupt life cycles by blocking or injuring migratory species
• Some run-of-river systems can avoid major environmental impacts

^{Updated April 2026}