Abstract: The present invention is a power storage system for use in a body of water, including a cable strung between at least one lower pulley and an upper pulley. A tank arrangement includes an outer tank disposed in the body of water and having an open bottom end, the outer tank fixed with the cable and configured to move between a lowered position and a raised position. An inner tank is disposed within the outer tank and includes an air compressor configured to move air from the outer tank to the inner tank and a dump valve configured to release compressed air within the inner tank into the outer tank. A generator produces electricity as the air within the inner tank is released to cause the outer tank to rise. A second tank arrangement is fixed to an opposing side of the cable.