Author(s): Casey Grant. Published on July 1, 2019.

Wake-Up Call

The explosion of an energy storage system in Arizona prompts a renewed urgency for research into this rapidly emerging technology


The battery explosion in April that injured eight firefighters in Surprise, Arizona, illustrates how far we still have to go to address the safety of electrical energy storage systems (ESS) as the technology continues to spread across the globe. For researchers everywhere, the incident should serve as a wake-up call.
Like many batteries being installed, the large lithium-ion ESS unit in Surprise was used to provide extra storage to the electrical power grid for use during times of high demand. By all indications, the battery was state of the art; it was designed, installed, and operated according to the best available science. When the fire department was called after smoke began rising from the unit, those on scene seemed to take appropriate measures. The unit was isolated from the electrical grid, and a hazardous materials team began monitoring the site from the exterior in coordination with the facility operators.

After waiting several hours, onsite readings suggested that the hazard was not subsiding, and so the fire department positioned a hose line and opened an access door to the battery in hopes that the vapors and smoke would dissipate. They never entered. Minutes after opening the door, with little warning, a violent explosion occurred, sending eight firefighters to the hospital, some with life-threatening injuries.

With so much at stake, significant efforts are now being made to understand what happened in Arizona and why. Many unresolved questions remain, including what caused the explosion and whether it could have been handled more effectively.

From a research perspective, the answers are crucial so that we can guard against similar incidents. Fire protection professionals are still looking for built-in fire protection features for ESS that will realistically protect against fire, explosion, electrical, and contamination hazards. We also need reliable mechanisms to monitor and understand what is happening inside these batteries, as well as clear firefighting tactics and strategies.

NFPA and the Fire Protection Research Foundation (FPRF) have multiple activities underway to begin addressing these needs. These include the development of ESS training material for the fire service, as well as a new standard, NFPA 855, Standard for the Installation of Stationary Energy Storage Systems, due out this year.

Several important research efforts are ongoing. This spring, the FPRF published the results of full-scale fire testing conducted to validate the effectiveness of ESS sprinkler protection. We have shared the results of a study on safe post-incident handling of batteries that still contain stranded electrical energy. In 2020, we and our partners will share the results of a comprehensive study on ESS hazards, including a focus on over-pressure explosion events like the one in Arizona.

So much activity is underway because these systems are coming online very quickly. ESS adoption has surged worldwide to support the proliferation of renewable energy sources and to help utilities balance out the challenging peaks and valleys inherent in electrical grids. In some jurisdictions, there is significant political pressure to get these systems installed as soon as possible. Increasingly, individuals and businesses are also eyeing battery storage as part of their energy strategies. As such, ESS of all sizes, types, and uses are popping up everywhere, including dense city centers and even in mechanical areas on the upper floors of high-rise buildings. These developments have safety experts rightly concerned about the outcome if something goes wrong. What if an explosion like the one in Arizona had occurred, not in the desert, but in a densely settled urban location?

Working with manufacturers, installers, responders, and others, it’s our responsibility to ensure that we never have to find out. 

Casey Grant is executive director of the Fire Protection Research Foundation. Illustration: Michael Hoeweler