Three Japanese energy companies have been commissioned by the Japanese Ministry of Economy, Trade and Industry (METI) to design, build and test energy storage systems of a combined 80MWh across two projects.

Two storage systems will be tested, the first utilising 20MWh lithium-ion batteries, designed to address the problem of frequency variation in electricity supply from renewable sources. The second, a 60MWh redox flow battery system, also deals with frequency variation, but will also be used to research measures for adjusting the electricity supply-demand balance and to research technology to optimally control and manage the battery system.

The three companies include Tohoku Electric Power Co, Hokkaido Electric Company (Hepco) and Sumitomo Electric Company. Tohoku Electric will build the 20MWh storage system, with the 60MWh system to be built by Hokkaido Electric Company and Sumitomo Electric Industries. The New Energy Promotion Council organised the project and accepted submissions from applicants in April 2013, with a committee of experts and METI selecting the successful applicants.

The 20MWh lithium-ion battery project that Tohoku Electric has been commissioned to build will be situated at Nishisendai (west Sendai) substation in Sendai, Miyagi prefecture, around 50 miles north of Fukushima. The batteries will be evaluated on how readily electricity supply can be adjusted for frequency variations owing to wind and solar power generation.

The batteries will be centrally controlled by an automated system at the substation, regulating rates of charge and discharge of the batteries. It is hoped that if successful, such a system can go a long way toward stabilising the grid for use with renewable energy. The lithium-ion battery testing system is scheduled to be operational in 2015. It is hoped that supply-demand adjustment can be improved by up to 10%.

The 60MWh redox flow battery storage system was also commissioned with the aim of measuring the ability of storage systems to cope with frequency variations in electricity supply from renewable sources such as solar and wind, despite output levels that fluctuate due to climate conditions.

It will also be used to research control and optimisation of battery systems. A redox flow battery can be used to adjust electricity supply-demand balance in case of demand decreases, as well as frequency variations. The Hokkaido Electric-Sumitomo system will be situated at Minamihayakita substation on the island of Hokkaido, north of mainland Japan. The 60MWh facility will utilise the largest storage batteries in the world and will function as apart of a bulk grid power system. As with the 20MWh system, targets for improvements to efficiency are set at 10%.

The METI announcement regarding the storage system was issued on 31 July.

The original version of this article contained a reference to a company that was incorrect. We have since updated the text to rectify this inaccuracy.

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