As the lithium-ion battery energy storage system (ESS) industry grows and demand for renewable energy increases, ESS facilities will likely continue to proliferate in communities and urban areas around the world, providing multiple benefits, along with some risks.
Lithium-ion batteries are generally very safe, but they have been linked to fire, explosion and hazardous material exposure under certain conditions. The April 2019 explosion at a 2.16 MWh lithium-ion battery ESS site in Surprise, Arizona, left four firefighters severely injured and spurred the energy industry and first responders to grapple with new safety considerations.
Given this is a fairly new technology, most first responders have limited experience with lithium-ion battery fires, which behave differently than typical fires.
“Lithium-ion batteries have flammable chemical electrolytes and are susceptible to thermal runaway if the battery has faults, contaminants or experiences physical or operational stress,” said Ken Boyce, principal engineer director, UL Energy and Power Technologies division. “Additionally, lithium-ion batteries can spontaneously reignite hours or even days later after a fire event if cells go into thermal runaway, making decommissioning, deconstructing and storing more complicated. Adding to that complexity, safety requirements for ESS sites are still evolving as more information about the technology becomes available,” he said.
Research and curricula for first responders on lithium-ion battery fires on this scale is inadequate, leading to situations where the fire service must piece together limited information to suppress fires and keep themselves and surrounding communities safe. This was the case in Surprise. Firefighters did everything in accordance with the most recent training and information available to them and an extremely dangerous – potentially avoidable – explosion still occurred.
Learning from the APS storage explosion
Typically, these kinds of near miss events are examined only when a fatality occurs, but UL Firefighter Safety Research Institute (FSRI) had the unique opportunity to interview the firefighters and learn from their experiences. This is the first time UL FSRI took the approach of capturing the experience of surviving firefighters to inform an investigation and incorporate their firsthand experience into fire safety recommendations.