San Diego Gas & Electric partners with Sumitomo Electric on VRF battery microgrid

San Diego Gas & Electric (SDG&E), along with Sumitomo Electric (SEI), completed a zero-emissions microgrid pilot project using a vanadium redox flow (VRF) battery.

Microgrids are mini power grids that can operate independently of the larger grid and keep critical facilities powered during emergencies and Public Safety Power Shutoff (PSPS) events, like storms and wildfires. In one of the test runs for this pilot project, the 2MW/8MWh VRF battery – functioning as part of a microgrid – powered 66 residential and commercial customers for close to five hours.

“Climate conditions increasingly threaten the continuity of essential services that our customers expect and deserve from us, which is one of the many reasons we are so focused on innovation and technology,” SDG&E CEO Caroline Winn said. “There is a critical need to develop breakthrough solutions like zero-emissions microgrids to not only minimize disruptions but to also support the transition to a cleaner, safer and more reliable energy grid of the future.”

VRF batteries are different from more prevalent stacked lithium-ion battery cells as they consist of tanks of liquid electrolytes and pumps that charge and discharge electrons to the grid. During the pilot, the batteries charged when solar energy was abundant and discharged during peak hours to meet demand.

“We are honored that the Sumitomo flow battery has contributed to the successful demonstration of this large-scale microgrid,“ Hideo Hato, senior managing director of Sumitomo Electric, said. “Sumitomo’s cutting-edge non-flammable and reusable flow battery system can help support California’s climate goals and improve resiliency for the state’s electric infrastructure.”

The flow battery was installed at SDG&E’s substation in Bonita, Calif., in 2017 as part of a collaboration between SDG&E and SEI with project funding provided by Japan’s New Energy and Industrial Technology Development Organization (NEDO). NEDO collaborated with the California Governor’s Office of Business and Economic Development (GO-Biz) on this project.

“While climate change presents many challenges, it also spurs innovations that can lead to new industries and good, family-supporting jobs,” GO-Biz Director Dee Dee Myers said. “We are proud to be part of this international collaboration, which is a great example of Japan’s continued position as the top source of foreign investment in California and a demonstration of how that investment brings new opportunities both here at home and abroad.”