Mitsubishi Heavy Industries and SSE plc (formerly Scottish and Southern Energy) are soon to get under way with an energy storage system demonstration project installed in the power grid of the Orkney Islands (in the north of the United Kingdom) which has a high proportion of renewable energy generation in relation to demand.

The project aims at demonstrating power supply stabilisation in the islands by incorporating a cargo container-type large capacity energy storage system using a lithium-ion rechargeable battery, with a maximum power output capacity of 2 MW. The storage system is scheduled to be handed over for operational use in early 2013.

The demonstration project will be conducted with the support of New Energy and Industrial Technology Development Organisation (NEDO) of Japan, under the programme of “Development of Technology for Safe, Low-cost, Large-size Battery System.” In the project, Mitsubishi Power Systems Europe, the business base for MHI’s power system operations in Europe, and SSE Generation, the power generation unit of SSE group, will jointly provide the energy storage services to Scottish Hydro Electric Power Distribution plc (SHEPD), the SSE group company that handles power distribution in Scotland.

The system, which can store approximately 800 kWh nominal, 500 kWh on normal usage, consists of two 40ft-long container units for the batteries and a 40ft-long container unit for the power conditioning system. Each battery container houses more than 2000 units of lithium-ion rechargeable batteries. The power conditioning system container houses a converter and the associated input/output controls.

The storage system will be installed at SHEPD’s Kirkwall power station. In cases of slight power shortage or power surplus, power is transmitted from/to the mainland through a submarine cable. When there is too much renewable energy, exceeding the export capacity of the cable to the mainland, the energy storage system will import some of that excess energy, reducing the need to constrain renewable generation at that time.

In July 2010, MHI agreed with SSE to collaborate in the development of low-carbon energy. The two companies have been studying a broad range of collaboration, including offshore wind turbine power generation system, carbon sequestration and storage (CCS) and high-efficiency power generation system. The energy storage demonstration project using rechargeable lithium-ion batteries is a part of that initiative. The two companies intend to further strengthen their collaborative relationship.