Hydropower

Energy Mix

6% of world 🌎
2% of US 🇺🇸

Electricity Generation

15% of world 🌎
6% of US 🇺🇸

Hydroelectric Capacity by Type

Conventional Storage and Run-of-River Systems
(Electricity Generation)
90%

Pumped Storage Systems
(Energy Storage)
10%

Global Electricity Generation from Hydropower

Increase:
⬆6%
(2017-2022)

Most Installed Capacity

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

Most Generation

China 32% 🇨🇳
of global hydroelectricity generation

Highest Penetration

Paraguay >99% 🇵🇾
of country’s electricity generation comes from hydroelectricity

Most Installed Capacity

Washington 27%
of US hydroelectric generation installed capacity

Most Generation

Washington 27%
of US hydroelectricity generation

Highest Penetration

Washington 55%
of state’s electricity generation comes from hydroelectricity

Most Installed Capacity

China 22% 🇨🇳
of global pumped storage installed capacity

Share of Global Energy Storage Capacity

Pumped Storage Hydropower: 92%
Lithium-Ion Batteries: 5%
Other: 3%

Pumped Storage “Roundtrip” Efficiency

70-85%
of the energy used to pump water uphill can be converted back into electricity

Global Pumped Storage Capacity

Increase:
⬆10%
(2016-2021)

Drivers

• Abundant
• Co-benefits: flood control, water storage for agricultural, residential, commercial, recreational purposes
• Can be used to “black start” the electricity grid after major outages*
• The lowest-cost source of electricity globally based on LCOE**
• 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
• Pumped Storage alleviates intermittency when integrating other 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
• 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
• Seasonal changes in reservoir levels can affect soil quality and crop yields
• 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
**LCOE (levelized cost of electricity) - price for which a unit of electricity must be sold for system to break even
***NIMBY - not in my backyard; BANANA - build absolutely nothing anywhere near anything}

Climate Impact: Low to Medium

• Near-zero carbon emissions during operation
• However, reservoirs created by dams can flood ecosystems upstream in some climates, releasing significant amounts of methane (a potent GHG) as vegetation decomposes, which potentially negates climate benefits

Environmental Impact: Medium to High

• No local 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 October 2023