Underground compressed air
Adiabatic storage power plants
Adiabatic storage power plants (AA-CAES) store not only the compressed air but also the heat that is released upon compression of the air. For generating the electricity, the heat is returned to the compressed air flowing to the turbine. This renders the use of natural gas unnecessary. AA-CAES plants should therefore achieve efficiencies of up to 70 per cent. However, the development of such plants is still in its infancy. Almost all components must be newly developed.