Energy storage and recovery.

摘要

Underground storage of energy, wherein a low-density fluid is pumped from an upper cavern to a lower cavern filled with a high-density fluid by means of an overground pump/turbine apparatus, as result of which high-density fluid is displaced out of the lower cavern to the upper cavern, and wherein subsequently, in order to retrieve the stored energy, the high-density fluid is allowed to return to the lower cavern displacing the low-density fluid to the upper cavern, which displaced low-density fluid drives the overground pump/turbine apparatus.