Natural reservoirs: Economics
Free water, costly dams, and rising value from price swings
What this tab covers Economics and financial structure: capital versus operating cost, levelised cost of storage, and how the asset earns money.Natural stores are not bought as storage. Their value is captured inside hydropower prices and in the flexibility reservoirs give to grids with much wind and solar.
Capex versus opex
MixedThe relevant capex is the hydro plant: a global average of USD 2,267 per kW in 2024, up from USD 1,494 in 2010, mostly civil works. The water itself is free and running costs are low. Snowpack, glaciers and ocean heat need no investment to exist but cannot be expanded.2
Hydropower installed cost, 2010 / 2024 USD 1,494 / 2,267 per kW2Levelised cost of storage
FavourableDoes not apply directly; there is no charging cost. The nearest measure is the cost of the electricity a reservoir plant delivers: USD 57 per MWh in 2024, up from 44 in 2010. Compared with a 4-hour lithium battery at USD 210 to 292 per MWh (Lazard 2026), reservoir hydro supplies flexible energy more cheaply, but only where sites exist.29
Hydropower LCOE, 2010 / 2024 USD 44 / 57 per MWh2 Lithium-ion 4-hour LCOS comparator (2026) USD 210-292 per MWh9Revenue stack and market participation
FavourableReservoir operators earn by holding water for high-price hours and seasons, and from capacity payments, reserves and frequency services. Value rises as solar and wind create price swings: at least six European countries had more than 500 hours of negative prices in 2025. Hydrology is the main revenue risk.1
European countries with over 500 negative-price hours, 2025 at least 61Sources
- Year of the water battery: global pumped storage capacity surpasses 200 GW (2026 World Hydropower Outlook) International Hydropower Association, 2026
- Renewable Power Generation Costs in 2024: Summary (Table S1) IRENA, 2025
- Lazard's Levelized Cost of Energy+ (LCOE+), July 2026 (LCOS) Lazard, 2026