07 July 2023

Ex-post Evaluation of Redox Flow Battery Demonstration Project in California and Public Event to Present the Results of Demonstration Project in San Diego

In 2015, Sumitomo Electric Industries, Ltd. was selected by the New Energy and Industrial Technology Development Organization (hereinafter “NEDO”) as a contractor for the International Demonstration Project to Prove Japanese Technology for Improved Energy Consumption Efficiency/Demonstration Project Testing Storage Battery Operation for Both Electricity Transmission and Distribution in California, USA. For seven years from FY2015 to FY2021, the Company conducted the demonstration project in San Diego, California, using its redox flow batteries, which are long-life stationary storage batteries suitable for large capacity applications.

Following the completion of the demonstration, an ex-post evaluation by external experts was conducted on December 7, 2022, and the evaluation results were announced by NEDO. Those external experts gave high marks on four evaluation items with many positive comments.

In addition, as a follow-up activity for the demonstration project, on February 6, 2023 in San Diego, California, a debriefing meeting was held under the theme of “The Future of Long-Duration Energy Storage.” At the meeting, which was held by NEDO and the Governor’s Office of Business and Economic Development (GO-Biz), presentations on the details and results of the demonstration by Sumitomo Electric and San Diego Gas & Electric (SDG&E), a panel discussion on promising long-duration energy storage (LDES) technologies, and a tour to the redox flow battery installation site at SDG&E’s facility were conducted. People involved in the electric power industry from around the world, mainly from North America, attended the event and had a lively question-and-answer session, showing their high interest in and expectations for redox flow batteries.

Utilizing the knowledge gained from the demonstration project and reviewing the suggestions for improvement obtained at the ex-post evaluation by external experts, Sumitomo Electric will continue to develop its redox flow battery business to meet the growing needs in North America and other countries and help create decarbonized society.

[Evaluation comments from external experts]
· The demonstration project is evaluated as having achieved significant results in that it comprehensively demonstrated in practice  the business feasibility of electric power market bidding using storage battery technologies that have been cultivated in Japan over many years, as well as the basic functions of redox flow batteries as core supply equipment for microgrids.

· This large-scale redox flow battery demonstration project in California, one of the most prominent proving grounds for innovative clean technologies in the world, included a world-first achievement (black start). As the need for long-duration energy storage technology is rapidly increasing worldwide, this project will have a very large ripple effect in promoting the spread of redox flow batteries.

· The knowledge obtained through this demonstration project will be particularly useful in forming an electricity market in Japan and creating a system for its operation, and it will serve as a basis for promoting and achieving decarbonization in Japan. Technically, it is extremely significant that the storage battery system showed a high operating rate (99% in the final year of the project) and durability (a capacity retention rate of 90% or more for 20years) in the actual electricity market.

[Rating result]

Evaluation item Average score Raw score*
1. Positioning and necessity of project 2.8 A A B A A
2. Project management 3.0 A A A A A
3. Project results 2.6 B A A A B
4. Possibility of dissemination of project results 3.0 A A A A A
* The raw scores are the ratings given by each external expert. The average scores were calculated by converting the raw scores into numerical values with the conversion rates: A=3, B=2, C=1, and D=0

“The Future of Long-Duration Energy Storage” Redox Flow Battery Demonstration Project in California
Tour to the redox flow battery installation site at SDG&E’s facility


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