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.