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UL FSRI releases report on battery facility explosion that injured 8 Ariz. FFs

Researchers used first-person accounts from responders to inform recommendations for firefighter safety at ESS sites


Scattered debris and the door to the ESS can be seen after the deflagration incident.

Photo/Peoria Fire-Medical Department

By Janelle Foskett

COLUMBIA, Md. — The UL Firefighter Safety Research Institute (FSRI) today released a report investigating a 2019 explosion that injured eight firefighters at a battery energy storage system (ESS) facility.

The deflagration incident occurred at a 2.16-MWh lithium-ion battery ESS facility in Surprise, Ariz. Eight firefighters were injured in the blast and transported to the hospital. Four firefighters suffered serious injuries, including one who was in critical condition; the others suffered non-life-threatening injuries.

The UL FSRI report provides a technical account of the explosion and fire service response, along with recommendations on how to improve codes, standards, and emergency response training to better protect first responders, maintenance personnel and nearby communities.

“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 situations,” said Steve Kerber, UL FSRI vice president of research. “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.”

UL FSRI notes that this report is a first-of-its-kind research effort from the institute to capture the experience of surviving firefighters to better understand a potentially devastating situation. Four of the career firefighters injured – all of whom had specialized hazmat training – recounted their experience to help inform the report, the investigation team’s understanding of how the fire and gases behaved, and subsequent recommendations for ESS safety training.

“Typically, these kinds of events are examined when a fatality occurs,” Kerber said. “But with this report, we’re trying to make sure the firefighter experiences are taken into account, providing valuable context to the findings so that they can be channeled into actionable insights for other fire service personnel to prevent future close calls and potential fatalities We’re incredibly grateful for Peoria and Surprise Fire-Medical teams and Arizona Public Service for providing information to support learning from this incident.”

Note: Read the Arizona Public Service report on the event here.

Lithium-ion battery ESS facilities have proliferated in recent years, presenting a new challenge for the fire protection community.

Report recommendations include the following:

  • Fire service training with an emphasis on ESS safety
  • Remotely accessible gas monitoring systems
  • Explosion prevention protection
  • Full-scale testing research to understand the most effective and safest tactics for fire service response to lithium-ion battery ESS incidents.

The full report and recommendations can be found at the UL FSRI website.