Can pumped storage increase our domestic electricity production?
Alas, no. Pumped storage is not a source of energy, but a process for storing electricity that results in a loss of energy of around 17-30%.
European countries regularly produce surplus electricity when the demand for electricity is relatively low. Pumped storage involves using this surplus electricity injected into the power grid to pump water from a low-lying lake to a storage lake higher up. Instead of being wasted, this surplus electricity is converted into so-called potential energy, or “uplift” energy. This water stored at high altitude can then be converted back into electricity by turning hydroelectric turbines to be used at a later date.
Pumped storage is currently the only economical storage option for large quantities of electricity. It absorbs surpluses from nuclear and coal-fired power plants (in Europe), whose generating capacity is not very flexible, as well as surpluses from intermittent renewable energies (solar and wind), whose production cannot be controlled [→ Q74].
Of course, pumping has an energy cost, in the order of 17-30% losses. For example, for every 100 GWh of electricity stored by pumping, turbines will return an average of only 70-83 GWh to the power grid, because neither pumping nor turbine systems can be 100% energy-efficient. The 17-30% lost in the process represents the price to pay for storing and using the remaining 70-83%. This process therefore makes it possible to use part of the surplus, preventing it from being entirely lost. However, pumped storage is not an energy source in itself. On the contrary, it consumes energy.
- Office fédéral de l'énergie (OFEN) (2008)
- Office fédéral de l'énergie (OFEN) (2008). Clarification sur la part du renouvelable dans le pompage-turbinage. [Online]. Available at: www.admin.ch/gov/fr/accueil/documentation/communiques.msg-id-17892.html.