Pumped Storage

More electricity is needed during the day than in the middle of the night. Because power stations run all the time, there is a surplus of electricity at night. Pumped storage is a way of storing the energy from this surplus electricity.

At Dinorwig pumped storage power station in North Wales when there is a need for extra electricity, water from the upper lake can flow down to the lower lake and be used to drive turbines and generators. The electricity produced then goes to the National Grid.

At night, surplus electricity from the National Grid is used to pump the water back up to the upper lake. Pumped storage runs at between 70 and 80% efficiency - this means it uses 20% more electricity (when pumping the water back up to the upper lake) than it actually produces.

Pumped Storage fills an important need in the system as this type of power plant can respond very fast to sudden surges in electricity demand. It can be switched into full production in 16 seconds.

More information:

First Hydro Company