A Safe, Long-Lasting, Large-Capacity Energy Storage Battery Transforming the Future of Energy: Sumitomo Electric's Vanadium Redox Flow Battery

Renewable energy is gaining increasing attention in efforts to achieve a decarbonized society. However, because renewable energy depends on natural phenomena for power generation, it is difficult to control power output in accordance with demand. This results in rapid fluctuations between power surpluses and shortages, making it difficult to maintain a stable power supply. Large-scale energy storage batteries are attracting significant attention as a promising solution to this challenge.
Sumitomo Electric has been engaged in the development of large-capacity energy storage batteries for approximately 40 years. As the adoption of renewable energy continues to expand worldwide, Sumitomo Electric is promoting the development of large-capacity Vanadium Redox Flow Batteries (VRFBs) to contribute to the stabilization of power grids. Sumitomo Electric has supplied VRFBs to companies and municipalities both in Japan and overseas, including the start of full-scale operation at Hokkaido Electric Power Network, Inc. in April 2022 and the expansion of its business in the United States in February 2023.

Key Features and Benefits of the VRFB

	High Level of Safety (Minimal Fire Risk) The electrolyte is non-flammable and all components are made of flame-retardant materials.
	Long Life Due to its fundamental charge/discharge mechanism, there is no degradation of electrolyte, and the number of charge-discharge cycles does not accelerate degradation. The system can be operated for long periods, regardless of the operating method.
	Environmentally Friendly The electrolyte can be reused, a practice already proven in the field. Additionally, with proper material separation, up to 99% of system components can be recycled. (Sumitomo Electric also participates in the Green Transformation (GX) League, an initiative led by the Ministry of Economy, Trade and Industry of Japan; and has obtained wide-area certification for industrial waste treatment from Japan’s Ministry of the Environment.)

Global Installations

As illustrated below, Sumitomo Electric's VRFBs have been deployed across multiple countries and regions worldwide.

Case Studies / Press Releases

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  Enabling Grid Decarbonization through Long-Duration Energy Storage — SDG&E VRFB Project, San Diego

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  Integrating Renewable Energy through Long-Duration Storage — Kashiwazaki VRFB Deployment

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  Firming Wind Power for Grid Decarbonization — Hokkaido Electric Power Network Project

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  Enabling Renewable Integration through Frequency Regulation? Large-Scale Grid Storage with Hokkaido Electric Power Network

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  Launching a Long-Life Redox Flow Battery Project in Oki-island to Support Renewable Integration (Press Release)

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  Contributing to the Green Transformation of Boggabri Coal Mine with Solar Power and Long-Duration VRFB Storage (Press Release)

Group GX Practice / Net-Zero Initiative

Achieving Net-Zero Operations Using Vanadium Redox Flow Batteries — Sumitomo Electric Group Factory in Japan

In August 2025, the Sumitomo Electric Group launched its first Net Zero Factory at the Matsuzaka Plant of SWS West Japan, Ltd.
This project combines renewable energy sources—including rooftop solar power and off-site power purchase agreements (PPA)—with Sumitomo Electric’s own vanadium redox flow battery (VRFB) for energy storage.
By wheeling surplus renewable electricity to another group facility, the project achieves net-zero greenhouse gas emissions across operations.
This initiative represents a concrete step toward the Group’s 2030 Vision and Go for Green™ 2025 goals, demonstrating how our technologies are applied internally to advance decarbonization and operational resilience.

Press Release:
https://sumitomoelectric.com/jp/press/2025/08/prs110（Japanese Only）