Four Firefighters Injured in Lithium-Ion Battery Energy Storage System Explosion -- Arizona

Abstract

On April 19, 2019, one male career Fire Captain, one male career Fire Engineer, and two male career Firefighters received serious injuries as a result of cascading thermal runaway within a 2.16 MWh lithium-ion battery energy storage system (ESS) that led to a deflagration event. The smoke detector in the ESS signaled an alarm condition at approximately 16:55 hours and discharged a total flooding clean agent suppressant (Novec 1230). The injured firefighters were members of a hazardous materials (HAZMAT) team that arrived on the scene at approximately 18:28 hours. The HAZMAT team noted low-lying white clouds of a gas/vapor mixture issuing from the structure and nearby components and drifting through the desert. The team defined a hot zone and made several entries into the hot zone to conduct 360-degree size-ups around the ESS using multi-gas meters, colorimetric tubes, and thermal imaging cameras (TICs). The team detected dangerously elevated levels of hydrogen cyanide (HCN) and carbon monoxide (CO) during each entry. The team continued to monitor the ESS and noted the white gas/vapor mixture stopped flowing out of the container at approximately 19:50 hours. The HAZMAT leadership developed an incident action plan with input from a group of senior fire officers and information about the ESS provided by representatives from the companies that owned, designed, and maintained the ESS. The HAZMAT team made a final entry into the hot zone and found that HCN and CO concentrations in the vicinity of the ESS were below an acceptable threshold. In following with the incident action plan, the team opened the door to the ESS at approximately 20:01 hours. A deflagration event was observed by the firefighters outside the hot zone at approximately 20:04 hours. All HAZMAT team members received serious injuries in the deflagration and were quickly transported to nearby hospitals. Note: The lithium-ion battery ESS involved in this incident was commissioned prior to release of a first draft of the current consensus standard on ESS installations, NFPA 855 [1]; the design of the ESS complied with the pertinent codes and standards active at the time of its commissioning.