Abstract: A hydraulic-pneumatic energy storage and recovery system, which comprises first and second sealed containers within each of which a volume of liquid is introducible and from which the introduced liquid is pneumatically propellable; a turbine interposed between the first and second containers and coupled with a generator, to produce power when caused to be rotated by the pneumatically propelled liquid; and collection-delivery apparatus located externally to the first and second containers, for collecting energy-depleted liquid gravitating from the turbine and for delivering the collected liquid to one of the first and second containers, to be used in subsequent energy recovery cycles.

Abstract: A hydrostatically based energy conversion unit, which comprises a vertically oriented cylinder; a piston sealingly engaged with and vertically displaceable within the cylinder; a horizontal shaft rotatably mounted to a surface located above the cylinder and mechanically connected to the piston; a motor for driving the shaft in a first rotational direction; and a generator coupled to the shaft for producing electrical power when the shaft rotates in a second rotational direction opposite to the first rotational direction. The piston is vertically displaceable in a first vertical direction during a charging mode following operation of the motor, and is vertically displaceable in a second vertical direction opposite to the first vertical direction during a power generating mode after being hydrostatically driven to produce electrical power in conjunction with the generator.