UL Firefighter Safety Research Institute Unveils New Report Investigating Near-Miss Lithium-Ion Battery Energy Storage System Explosion

Report details recommendations to enhance the safety of fire service personnel responding to incidents at battery storage sites and improve fire prevention and suppression measures

Near-Miss Lithium-Ion Battery

 UL Firefighter Safety Research Institute (FSRI) today released a report detailing a deflagration incident at a 2.16 MWh lithium-ion battery energy storage system (ESS) facility in Surprise, Arizona. The report provides a detailed 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 UL FSRI Vice President of Research Steve Kerber. “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.”

This report is a first-of-its-kind research effort from UL FSRI to capture the experience of surviving firefighters to better understand a potentially devastating situation. Four career firefighters with specialized hazardous materials (hazmat) training were severely injured in the explosion. They 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 continued. “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.”

Lithium-ion battery ESS facilities have proliferated in recent years, presenting a new challenge for the fire protection community. Sourcing the experiences of the firefighters, UL FSRI’s report recommends new standards and codes for ESS sites, research programs, and curricula. Recommendations include fire service training with an emphasis on ESS safety, remotely accessible gas monitoring systems, explosion prevention protection, and full-scale testing research to understand the most effective and safest tactics for fire service response to lithium-ion battery ESS incidents.

To read the full report and all recommendations, please visit ulfirefightersafety.org.


The 16 Firefighter Life Safety Initiatives are a blueprint to save firefighters lives. Firefighter Life Safety Initiative 9 calls for thorough investigations of all firefighter fatalities, injuries, and near-misses. “UL is to be commended for their thorough review of an incident which resulted in the serious injury of four firefighters. As the one organization charged with caring for the families of our fallen brothers and sisters, we are grateful for their work,” said Chief Ron Siarnicki, Executive Director of the National Fallen Firefighters Foundation.