Natural reservoirs

Nature's own stores: snowpack, lakes, glaciers, ocean and ground heat, and the air's pressure differences.

Storage · Electrical and system · No. 95

• Storage
• Duration: Seasons and longer

Norway keeps over 87 TWh of energy as water in about 1,100 mountain reservoirs, about half of Europe's reservoir storage.

Chart: Illustration: Natural reservoirs

Where it comes from

Chart: Map of where it comes from

Nature charges these stores for free: evaporation lifts water onto mountains, and oceans and rock hold heat, but humans can only manage the release.

Three things to know

1. A cubic metre of water falling 100 m holds only about 0.28 kWh, so storing 1 GWh needs about 3.6 million m3.
2. Reservoirs emit about 0.8 Gt CO2e a year, mostly methane from rotting plants under water.
3. Only 37% of the world's long rivers still flow freely.

The journey

1. 1 SunEvaporates water and heats air and oceans
2. 2 Rain and snowLift water onto high ground
3. 3 Natural storeLakes, snowpack, glaciers, ground heat
4. 4 Managed releaseDams time when water flows
5. 5 TurbinesUp to 92% of water energy captured

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