Firefighters Battle Batteries

Firefighters from the 48th Civil Engineer Squadron extinguish a battery fire during training.

Three Arizona cities have adopted fire codes with specific provisions for battery energy storage systems at both residential and commercial sites following a fire and explosion at an Arizona Public Service battery facility in April that remains under investigation.

The new rules outline permitting for battery installations and new requirements for ventilation, signage, fire suppression, explosion control, hazardous-materials containment, thermal runaway prevention and other specifications. They are the first of their kind in the nation.

"We were looking at creating something to address batteries as they increased in popularity," Brian Scholl, deputy fire marshal for the Phoenix Fire Department, said in a telephone interview. The McMicken Substation incident in the Phoenix suburb of Surprise accelerated that effort. Phoenix, Surprise and Peoria, which had firefighters injured when the battery facility unexpectedly exploded, all adopted the code over the summer.

There has been some question as to who has jurisdiction over the rules, APS spokeswoman Jill Hanks said in a phone interview. At this point it seems local regulations will supersede others, though Hanks didn't rule out the possibility that the Arizona Corporation Commission could initiate a rulemaking on the matter.

Chapter 12 of the new International Fire Code that is still in development and the National Fire Protection Association's newly adopted Standard 855. The 2018 IFC base code, the first to include specific requirements for lithium-ion batteries, did not adequately cover existing battery technology, Scholl said.

"It's always been a problem that codes are on a three-year cycle" while technology is moving much faster, Scholl said. The Arizona fire departments wrote Chapter 12 of the Phoenix code with the expectation that it would work to regulate new technologies in the future, particularly with the influx of rooftop solar and home battery storage in Phoenix, Scholl said. He heads a special hazards unit that will review hazard analyses that will accompany permit applications for battery system installations at both residential and commercial sites.

Fire Chief Tom Abbott of Surprise in a telephone interview agreed that the code is designed with flexibility in mind. He said he is already considering amendments that would require home batteries to be installed outdoors and not in utility closets and garages. Abbott pointed out that hazardous conditions in garages lead to numerous fires independent of battery systems. The presence of a battery inside the garage could cause the system to go into thermal runaway even if the root cause of the fire was unrelated to the battery, he said. This could lead to the release of electrolytes comprised of combustible oils, lithium salts, methane and other toxic and environmentally hazardous materials that would literally add fuel to the fire, he said.

The same is true for an electric car parked inside a garage, Scholl said, adding that firefighters need to know such risks are or could be present before they respond to calls. The central dispatch system of the Phoenix-area fire departments coupled with the permitting requirements in the new code will enable dispatchers to include that information with the touch of a button so that responders are prepared before they arrive, Scholl said.

Abbott said at the time of the McMicken incident the departments were operating under the 2012 IFC code, which does not cover battery energy storage systems. A fence and a concrete pad were the only requirements for that installation to be code-compliant, Abbott said. "To be perfectly frank, we didn't know the facility was out there," he said.

APS on Sept. 25 issued an update on the McMicken investigation indicating that the final battery rack had been removed and disassembled for shipment to a forensics lab in Michigan. "The majority of the battery cells in these modules have melted together, but the other electrical components are largely intact," the report says. The components will be evaluated to determine if any shorting or other issues might have occurred around them. Third-party experts are working on modeling the explosion, and that modeling will be correlated with lab findings to reconstruct the incident. APS said the investigation team hopes to have more specific information by year's end and to be able to recommend precautions or modifications to other batteries on the APS system before returning them to service.

"We want to ensure that best practices are followed throughout the energy storage supply chain," Kelly Speakes-Backman, CEO of the Energy Storage Association, said in an emailed statement. The ESA launched a Corporate Responsibility Initiative earlier this year, which now has 48 members and just published an emergency response plan that storage businesses can use as a playbook for risk and safety issue management.

"We believe it's important for regulators, utilities and developers to work together to ensure fire and other risks are addressed and mitigated as a part of any standard grid operations," the statement says. Speakes-Backman pointed state and local jurisdictions to current standards in NFPA 855 and the UL 9540 Standard for Energy Storage Systems and Equipment "as a baseline to ensure that rules are consistent across jurisdictions."

"At the end of the day, everyone has safety top of mind," Hanks said. "We'll work with all parties to comply with these rules and go beyond them when it's warranted."