Innogy Technology Ventures Limited, a subsidiary of Innogy plc, has developed a new energy storage technology that is based on a regenerative fuel cell. This differs from conventional battery systems in that the electrochemical species are not part of the electrodes and thus can be stored external to the electrochemical cell. The power (MW) and storage energy (MWh) are therefore separated, which results in significant cost reductions for long storage times. The technology has been proven on a laboratory scale and a full-scale production module (0.7 m2electrode area) has been designed and a number of units are currently under test at a purpose built pilot plant. The module is manufactured from HDPE and carbon, all the components are manufactured by mass production methods, i.e. injection moulding and extrusion and are designed for automated assembly. Subcontractors or alliance partners manufacture the components, while the assembly process is carried out at Innogy plc's premises. The design stage of a 120 MWh plant has been completed and it is envisaged that it will be built, commissioned and operational by spring 2002 at Little Barford Power Station in the UK.