Patent ID: 8456031

Claim:
An underwater pumped-hydro energy storage device, comprising: at least one submersible tank that includes an inlet and an outlet; a pump disposed at the outlet of the at least one submersible tank to evacuate water from the submersible tank; a valve disposed at the inlet of the at least one submersible tank to control a flow of water into the at least one submersible tank from a surrounding body of water; and a turbine power unit to generate output electrical power from the flow of water into the at least one submersible tank, wherein the turbine is designed to operate at first hydrostatic pressure; and a gas vent attached to the at least one submersible tank, the gas vent to enable gas to flow into or out of the at least one submersible tank, wherein the gas vent includes a throttling gas valve which opens and closes automatically to regulate the flow of the gas into or out of the at least submersible tank to maintain a hydrostatic pressure between a first threshold which is less than the first hydrostatic pressure and a second threshold which is greater than the first hydrostatic pressure.