San Diego Gas and Electric Co. (SDG&E) recently completed a four-year zero-emissions microgrid pilot project testing a vanadium redox flow battery (RFB) from Sumitomo Electric Industries Ltd. (SEI).
The microgrid project, completed late last year, tested the RFB’s ability to seamlessly transition from the larger grid to the microgrid without any power interruption. The RFB was also able to provide electricity after customers experienced a momentary outage before they were transitioned to the microgrid, which operated completely independent of the larger power grid.
“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,” said SDG&E CEO Caroline Winn. “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.”
As California utilities have ramped up their wildfire mitigation efforts, public safety power shutoffs (PSPS) have become more common, with the average outage lasting roughly two days.
Compared to stacked lithium-ion battery cells, RFBs consist of tanks of liquid electrolytes and pumps that charge and discharge electrons to the grid. The batteries charge when renewable generation is abundant, and discharge during peak hours to help meet demand.
“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,” said Sumitomo Electric’s Senior Managing Director Hideo Hato.
In 2015, the California Governor’s Office of Business and Economic Development signed a memorandum of understanding with Japan’s New Energy and Industrial Technology Development Organization (NEDO). Two years later, SDG&E and Osaka-based SEI installed the RFB at a substation in Bonita, CA as part of a collaboration project with funding from NEDO, making the battery the first of its kind to be connected to the California grid.
During testing, the RFB was capable of powering 66 residential and commercial customers for nearly five hours during pilot tests. The 2 MW battery is capable of storing 8 MWh, enough to power about 1,000 homes for four hours, according to SDG&E.
Tests were conducted during variable weather conditions, and SEI demonstrated that the microgrid could provide essential energy service despite lower solar power output on cloudy days.
“The microgrid project shows flow batteries are an innovative technology that can prevent blackouts caused by natural disasters, such as wildfires, improve grid resiliency and integrate large amounts of renewable energy,” said NEDO Executive Director Shuji Yumitori.
SDG&E brought America’s first utility-scale microgrid in Borrego Springs online in 2013, the utility said. SDG&E is currently upgrading it to run on 100% renewable energy, complete with a hydrogen-based energy storage system that is expected to come into service later this year.
Officials in Southern California and statewide have sought to accelerate the transition to low-carbon energy.
The Los Angeles City Council recently approved a motion to prohibit drilling new oil and gas wells, in addition to phasing out production from existing wells, echoing calls from Gov. Gavin Newsom in 2020 to phase out oil and gas extraction entirely by 2045.
Similarly, the California Energy Commission (CEC) recently approved a plan to provide $1.4 billion in funding to improve the state’s electric vehicle refueling infrastructure, in line with Newsom’s executive order to phase out new gasoline-powered passenger vehicle sales by 2035. During planning, the CEC also approved SDG&E’s plan to add four energy storage microgrid projects to provide up to 160 MWh of capacity to fill expected summer shortfalls in 2022 and/or 2023.
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