Pumped hydro storage
Pumping water uphill when power is spare and running it back through turbines when needed; the largest grid store in the world.
Storage · Mechanical · No. 78
- Storage
- Duration: Hours to days
Over 90% of the world's stored energy sits as water in hilltop lakes, in plants that can run for a century.
Chart: Illustration: Pumped hydro storage
Where it comes from
Chart: Map of where it comes from
Reversible machines pump water uphill when power is cheap and let it run back to generate; China's Tiantai plant uses a 724 m drop.
Three things to know
- About 80% of the electricity used to pump water uphill comes back when it falls through the turbines.
- Adding hours is cheap: a 24-hour plant costs USD 143/kWh against USD 263/kWh for a 10-hour one (2021 data).
- Each plant is a 6 to 8 year civil project, and the hardest part is finding hills, water and land.
The journey
- 1 Spare powerCheap midday solar or night wind
- 2 PumpingWater lifted to the upper reservoir
- 3 HoldingStored as height, for hours to days
- 4 ReleaseWater falls back through pump-turbines
- 5 GridEvening peaks, reserves and multi-day lulls