Abstract: An energy storage method and system includes a collapsible bladder that is filled with water at depth. The bladder may be lowered to additional depths to increase the pressure experienced within the bladder and to increase the stored energy. In a preferred embodiment, over produced electricity is used to pump water into a bladder. During periods of high electricity demand, pressurized water within the bladder is directed through a conduit to turn turbines of generators and produce electricity. Two large all-thread screws are attached to the bladder and anchored to the seafloor or at or near a bottom of a body of water. Associated threaded mechanisms are connected to the exterior of the bladder such that when the all-thread screws are turned, the bladder is raised and lowered within the water to vary the internal pressure. In this manner, the bladder is lowered or anchored deeper as needed to produce additional pressure.