Council study session examines proposed moratorium on large battery-energy storage systems after national incidents

Planning staff presented a study-session briefing on April 28 proposing a six-month moratorium on new commercial and grid-scale battery energy storage systems (BESS) while the city drafts siting, construction and operational code standards.

Gabriel Clark, Planner II, told council that energy storage systems — particularly grid-scale lithium-ion battery installations — serve useful roles in load-leveling, renewable-energy smoothing and emergency backup but pose specific public-safety and environmental risks that warrant detailed local standards. He said residential and smaller on-site commercial batteries would not be covered by the moratorium because their scale and risk profile are substantially lower.

Clark described the principal hazard as thermal runaway, a cell-level failure process that can cause intense heat, venting of gases and, in some cases, multi-hour fires. He referenced incidents elsewhere (including the Moss Landing event in Monterey County) as evidence that a large-scale BESS fire can require prolonged multi-agency firefighting responses and may prompt localized evacuations. “Thermal runaway … is a phenomenon in which lithium ion cell enters an uncontrollable self heating state,” Clark said, summarizing industry safety guidance.

Valley Regional Fire Authority (VRFA) and other first responders discussed firefighting tactics; staff said VRFA concluded that prolonged cooling with water is often the primary operational tactic to limit heat propagation, but that approach raises questions about where firefighting runoff would go and whether storm or groundwater contamination could occur. Councilmembers also asked about floodplain siting, rail-corridor proximity and other local constraints; Clark said those are among the issues staff will study.

Staff recommended a six-month moratorium on Tier 2 (larger commercial integrated with a customer site) and Tier 3 (front-of-meter, grid-scale) installations to allow development of a new Title 18 zoning chapter and associated engineering, fire protection and environmental containment standards. The draft timeline calls for coordination with fire, public works, Ecology and other stakeholders in June–July, Planning Commission review and a council hearing in the fall; staff said the moratorium would expire when the revised code is adopted but not later than November unless council extends it.

Council members asked several technical questions, including whether rail operators (BNSF) and other critical-infrastructure owners would be engaged; staff said outreach to rail and other stakeholders is expected during the standards-development phase. Council also asked about water-supply needs for firefighting, HVAC redundancy and flood risk; staff said they will incorporate those considerations in the draft code and agreed to consult external engineering and environmental resources.

Ending: Council did not act on the moratorium at the study session; staff said a moratorium ordinance will be presented for council action on May 5, and that staff will return with draft siting and operational standards for public review and Planning Commission recommendation.