Pumped hydro electricity storage

Electricity is stored by using it to pump water from a low-lying reservoir to a higher one. When wind or solar power falls short, the water flows back down, spinning turbines to generate power

1 Pumped storage: Output from solar panels and wind turbines used to pump water from lower to upper reservoir, several hundred metres higher

2 Underground pumps: Cavern contains reversible Francis turbines powerful enough to pump water up 10-metre-wide shaft at rate that would fill an Olympic pool in 6 seconds

3 Demand peaks: Water is released from 
upper reservoir under immerse pressure. Water spins turbines in reverse, generating electricity

Upper reservoir
Lower reservoir

1 2 3 

Francis turbines: Most widely used type of hydro turbine - exhibits efficiencies of between 80% and 95%

Pumped hydro: Lifespan in excess of 50 years, compared to batteries, which last 8 to 15 years 

Sources: Andritz, Arena, Science
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