28 March 2025

Sumitomo Electric Industries, Ltd. is pleased to announce that its redox flow battery (hereinafter “RF battery”) has been selected as a grid-scale battery for a power system stabilization project by SHIN-IDEMITSU Co., Ltd. (Headquarters: Hakata-ku, Fukuoka; President and Group CEO: Yasunori Idemitsu; hereinafter “IDEX”). Construction for this project has now commenced in Kumamoto.

The RF battery was adopted as part of IDEX’s efforts to enhance the supply of renewable energy. This project marks the first redox flow battery ever approved under Japan’s Ministry of Economy, Trade and Industry (METI) and the Agency for Natural Resources and Energy’s subsidy program for grid-scale energy storage batteries*. The RF battery will be installed at the Nagasu Energy Storage Facility where construction has already commenced in Tamana District, Kumamoto Prefecture, Kyushu. Completion is scheduled for October 2026, which features a capacity of 8,000 kWh (2,000 kW × 4 hours).

To achieve carbon neutrality by 2050, as outlined in Japan’s Basic Energy Plan, it is crucial to maximize the utilization of renewable energy over the long term. However, in regions such as Kyushu, high solar radiation levels have led to a significant expansion of solar power deployment. As a result, solar power supply has exceeded the surrounding areas’ electricity demand during the daytime, becoming a challenge. In response, IDEX has decided to construct an energy storage facility in Kumamoto Prefecture to help stabilize the supply of renewable energy. Sumitomo Electric’s redox flow battery was chosen for this project due to its long lifespan, excellent durability, and reduced risk of fire.

Sumitomo Electric aims to contribute to further grid stability, efficient utilization of renewable energy, and greenhouse gas reduction through the use of safe and long-lasting RF batteries.


Feature of Sumitomo Electric's RF Battery

	High Level of Safety (Extremely Low Fire Risk) The electrolyte is non-flammable, and all components use flame-retardant materials, meaning it is not classified as hazardous under fire safety regulations. No special permits for hazardous materials or on-site hazardous materials handlers are required.
	Long Life Due to the fundamental charge-discharge principle, the electrolyte and electrodes do not degrade, and the number of charge-discharge cycles does not contribute to degradation. The system can be operated for extended periods, regardless of the operating method.
	Eco-Friendly The electrolyte has been proven to be reusable, and up to 99% of system materials can be recycled through proper separation.

＊This subsidy is available under the "FY2024 Renewable Energy Expansion and Grid-Scale Energy Storage System Support Program (Grid-Scale Energy Storage & Water Electrolysis System Support Project)" administered by the Environmental Symbiosis Initiative.

(For Reference)
IDEX’s News Release
IDEX’s First Initiative: Commencement of Construction for the Nagasu Energy Storage Facility Using Redox Flow Batteries
https://www.idex.co.jp/news_release/detail.php?id=331  (Japanese version only)

About RF Battery
https://sumitomoelectric.com/products/flow-batteries

Sumitomo Electric Group Future Building Magazine "id" Vol.19
https://sumitomoelectric.com/id/project/v19/01