Abstract: The invention relates to systems and methods for rapidly and isothermally expanding gas in a cylinder. The cylinder is used in a staged hydraulic-pneumatic energy conversion system and includes a gas chamber (pneumatic side) and a fluid chamber (hydraulic side) and a piston or other mechanism that separates the gas chamber and fluid chamber while allowing the transfer of force/pressure between each opposing chamber. The gas chamber of the cylinder includes ports that are coupled to a heat transfer subassembly that circulates gas from the pneumatic side and exchanges its heat with a counter flow of ambient temperature fluid from a reservoir or other source.

Abstract: In various embodiments, efficiency of energy storage and recovery systems compressing and expanding gas is improved via heat exchange between the gas and a heat-transfer fluid.

Abstract: The invention relates to systems and methods including an energy conversion system for storage and recovery of energy using compressed gas, a source of recovered thermal energy, and a heat-exchange subsystem in fluid communication with the energy conversion system and the source of recovered thermal energy.

Abstract: In various embodiments, systems for providing a constant electrical output from a compressed gas energy storage and recovery system include a hydraulic-pneumatic energy storage and recovery system configured to provide a varying pressure profile at least at one outlet, a hydraulic motor-pump in fluid communication with the outlet, and a control system for enabling the constant electrical output by controlling at least one of pressure, piston position, power, flow rate, torque, RPM, current, voltage, frequency, or displacement per revolution.

Abstract: The invention relates to systems and methods for rapidly and isothermally expanding and compressing gas in energy storage and recovery systems that use open-air hydraulic-pneumatic cylinder assemblies, such as an accumulator and an intensifier in communication with a high-pressure gas storage reservoir on a gas-side of the circuits and a combination fluid motor/pump, coupled to a combination electric generator/motor on the fluid side of the circuits. The systems use heat transfer subsystems in communication with at least one of the cylinder assemblies or reservoir to thermally condition the gas being expanded or compressed.

Abstract: The invention relates to methods and systems for the storage and recovery of energy using open-air hydraulic-pneumatic accumulator and intensifier arrangements that combine at least one accumulator and at least one intensifier in communication with a high-pressure gas storage reservoir on a gas-side of the circuits and a combination fluid motor/pump, coupled to a combination electric generator/motor on the fluid side of the circuits.

Abstract: In various embodiments, energy is stored or recovered via super-atmospheric compression and/or expansion of gas in conjunction with substantially adiabatic compression and/or expansion from or to atmospheric pressure.

Abstract: In various embodiments, cylinder assemblies are coupled in series pneumatically, thereby reducing a range of force produced by or acting on the cylinder assemblies during expansion or compression of a gas.

Abstract: In various embodiments, compressed-gas energy storage and recovery systems feature one or more valves, which may be disposed within end caps of cylinder assemblies in which gas is expanded and/or compressed, for admitting fluid to and/or exhausting fluid from the cylinder assembly.

Abstract: In various embodiments, energy storage and recovery features energy conversion to and from gravitational potential energy.

Abstract: In various embodiments, a pneumatic cylinder assembly is coupled to a mechanism that converts motion of a piston into electricity, and vice versa, during expansion or compression of a gas in the pneumatic cylinder assembly.

Abstract: In various embodiments, heat is exchanged with a gas being compressed or expanded within an energy storage and recovery system without the use of flexible hoses.

Abstract: In various embodiments, pneumatic cylinder assemblies are coupled in series pneumatically, thereby reducing a range of force produced by or acting on the pneumatic cylinder assemblies during expansion or compression of a gas.

Abstract: In various embodiments, energy is stored or recovered via super-atmospheric compression and/or expansion of gas in conjunction with substantially adiabatic compression and/or expansion from or to atmospheric pressure.

Abstract: In various embodiments, motor-pump efficiency is increased by limiting the fluid pressure communicated to the motor-pump to a range smaller than that communicated by other components of an energy storage and/or recovery system.

Abstract: In various embodiments, gas is compressed to store energy and/or expanded to recover energy to or from high pressures, and the gas is exchanges heat with a heat-exchange fluid that is thermally conditioned at low pressures.

Abstract: In various embodiments, efficiency of energy storage and recovery systems compressing and expanding gas is improved via heat exchange between the gas and a heat-transfer fluid.

Abstract: In various embodiments, energy-storage systems are based upon an open-air arrangement in which pressurized gas is expanded in small batches from a high pressure of, e.g., several hundred atmospheres to atmospheric pressure. The systems may be sized and operated at a rate that allows for near isothermal expansion and compression of the gas.

Abstract: In various embodiments, compressed-gas energy storage and recovery systems include a cylinder assembly for compression and/or expansion of gas, a reservoir for storage and/or supply of compressed gas, and a system for thermally conditioning gas within the reservoir.

Abstract: In various embodiments, a pneumatic cylinder assembly is coupled to a mechanism that converts motion of a piston into electricity, and vice versa, during expansion or compression of a gas in the pneumatic cylinder assembly.