Energy storage technologies include utility battery storage, flywheel storage, superconducting magnetic energy storage, compressed air energy storage, pumped hydropower, and supercapacitors. Existing UBS systems use lead-acid batteries. Flywheel Storage A flywheel spinning at very high speeds can be used to store energy by combining it with a device that operates either as an electric motor that accelerates the flywheel to store energy or as a generator that produces electricity from the energy stored in the flywheel.
Modern flywheels use composite rotors made with carbon-fiber materials.
The use of superconducting electromagnetic bearings can virtually eliminate energy losses through friction. When the air is released from storage, it expands through a combustion turbine to create electricity. Pumped Hydropower Pumped hydro facilities use off-peak electricity to pump water from a lower reservoir into one at a higher elevation. When the water stored in the upper reservoir is released, it is passed through hydraulic turbines to generate electricity.