UL Report Examines 2019 Energy Storage System Blast

Firefighters are not receiving sufficient training regarding the explosive potential of lithium-ion batteries, according to a report released by the UL Firefighter Safety Research Institute.

As a case in point, the report reviews an April 2019 emergency in which four Peoria, Arizona, firefighters were seriously injured responding to a suspected fire involving the McMicken Battery Energy Storage System in Surprise, Arizona.

“The ability to study lithium-ion battery-related fires on this scale with first person accounts from the responding firefighters is critically important to protecting the lives of first responders in similar situation,”  UL FSRI vice president of research Steve Kerber said. “We’re dealing with new technology, which brings about new fire-related hazards. We have an opportunity to learn from this incident and improve future outcomes by sharing resources and enhancing training and safety protocols,”

In the Surprise, Arizona, incident, a cascading thermal runaway within a 2.16 MWh lithium-ion battery energy storage system led to an explosion.

A smoke detector at the facility signaled a fire and immediately discharged a total flooding clean agent. Four members of the Peoria Fire-Medical Hazardous Response team arrived at the scene to find low-lying white clouds of a gas/vapor mixture issuing from the MBESS building.

“Despite all responding firefighters being current with HAZMAT competencies from First Responder to Technician level, core HAZMAT training curricula for these competencies do not yet cover basic ESS hazards,” the report states.

The team detected dangerously elevated levels of hydrogen cyanide and carbon monoxide during repeated entries. HCN and CO concentrations near the ESS were particularly concerning. Within three minutes of opening the ESS the team member suffered serious injuries from a powerful explosion.

“At the moment of the deflagration event, the firefighters outside the hot zone described hearing a loud noise and seeing a jet of flame that extended at least 75 feet outward and an estimated 20 feet vertically from the southeast-facing door,” the report states.

One firefighter came to rest 73 feet from the open door beneath a bush ignited by the blast. Another firefighter was thrown nearly 30 feet from the open door. All four firefighters lost their helmets and face shields in the explosion.

Among the contributing factors the report cites a fire and smoke detection system that did not allow firefighters to monitor toxic or explosive gas levels from a secure location. Also, the design of the ESS did not include deflagration venting or adequate mechanical ventilation to prevent the accumulation of flammable gases.

The report also notes that the HAZMAT team was not provided with an emergency response plan for the facility until arriving at the scene.

Recommendations contained in the report include requirements in the appropriate standards, codes, research programs, and curricula to ensure the safety of the fire service and maintenance personnel who work with lithium-ion battery ESS.