Oki Islands, Shimane, Japan

NAS Battery used to absorb fluctuation


Maximization of Renewable Energy Installations on the Oki Islands

Photo: The Chugoku Electric Power Co., Inc.
(supplied through Mitsubishi Electric Corporation)

Owner The Chugoku Electric Power Co., Inc.
System Size NAS battery: 4.2MW (25.2MWh)
(+ Lithium-ion battery: 2.0MW (0.7MWh))
Commissioning Operation Date September, 2015
Location Oki Islands, Shimane, Japan


  • This demonstration project was selected under the "2014 Storage Battery Demonstration Project to Promote the Introduction of Renewable Energy on Isolated Islands" of the Ministry of Environment. The Chugoku Electric Power Company, the operator of this project, is further expanding the introduction of renewable energy on the Oki Islands. Since renewable energy is highly sensitive to the effect of weather conditions, a solution was needed to deal with fluctuations in renewable output.


  • Through the "Oki Hybrid Project", a hybrid storage battery system was introduced, composing of NAS battery and lithium-ion battery. The NAS battery stabilizes large, slow fluctuations, while the lithium-ion battery absorbs rapid, small fluctuations due to passing clouds or sudden changes in wind speed.

Additional Benefits

  • Through the operation of the hybrid storage battery system, The Chugoku Electric Power Company expects to introduce renewables over 10MW, the minimum demand of the Oki Islands, by adding up approximately 8MW of new installations on the existing 3MW, in the entire Oki Archipelago.

NAS and the NAS logo are trademarks of NGK INSULATORS, LTD., registered in the U.S. and other countries.