(EN) An energy extraction device and method for extracting energy from a fluctuatingenergy flow from a renewable energy source. A hydraulic pump is driven by arotating shaft, driven in turn by a renewable energy source. A hydraulic motor drivesa load and a high pressure manifold communicates between the pump, motor and anelastically deformable fluid retaining body. The hydraulic pump and hydraulic motorcomprise working chambers displacing a volume of working fluid selectable on eachcycle of working chamber volume by the control of electronic valves. The pressure inthe high pressure manifold is measured and the net rate of displacement of workingfluid by the hydraulic pump is selected responsive thereto to regulate the torgueapplied to the said rotating shaft. The net rate of displacement of working fluid by thehydraulic motor is selected to smooth the energy flow to the load. The net rate ofdisplacement of working fluid by the hydraulic motor is selected to cause the pressurewithin the high pressure manifold to tend towards an optimum. The optimum isvariable and can be selected to optimise the efficiency of power transmission fromthe rotating shaft to the load or to increase the longevity of the energy extractiondevice.
