NFPA Journal - Fall 2021 - 43

NO HELP FOR FIREFIGHTERS
While it's uncertain what firefighters on the scene knew
about the explosion hazards posed by ESS, the reports
make it clear that they received little technical help from
subject-matter experts on-site. According to the UL report
and Ruiz, representatives from the utility and battery maker
had a limited response plan and offered little guidance to
the HAZMAT crews about possible courses of action. " There
were no safety material sheets on-site, " Ruiz said. " Representatives
from APS arrived, but they were electrical engineers
and didn't know much about the byproducts off-gassing
from the battery in thermal runaway. " Ruiz said one on-site
staffer told his firefighters that the white smoke oozing from
the battery was Halon, a gas formerly used in suppression
systems that had been banned for nearly two decades. " We
knew it certainly wasn't Halon, so that was kind of concerning, "
he said.
APS said that it, too, was not properly educated on the
battery's hazards, and it claims that the responsibility of that
oversight lies with the battery system designer, a firm called
AES, and the battery manufacturer, LG Chem. In its own
report on the incident, the utility said that " the emergency
response plan provided by AES to APS did not have instructions
on how to respond to a potential explosion or how to
enter the system after the fire suppression system had been
discharged. " Further, in that emergency response plan, neither
AES or LG Chem " had conveyed that a large flammable
gas hazard or cell-to-cell and module-to-module cascading
thermal runaway was possible. "
In a detailed paper responding to the APS report, LG
Chem claimed that all of " these hazards were widely known "
before the McMicken site was designed and constructed
and that the onus of crafting emergency response plans falls
jointly on the battery owner and system designer-in this
case, on APS and AES. According to LG Chem, " The time to
develop careful plans to protect first responders is during the
design and commissioning and operation of these projects-
not after an incident has started. "
Despite this apparent lack of understanding and planning
by the parties involved, the catastrophe could still have been
avoided if engineering systems and the proper tools were in
place to give firefighters a better sense of what was happening
inside the ESS, according to Mark McKinnon, a co-author
of the UL report.
" An up-to-date history of the measurements of gas composition
and potentially the percent LEL (lower explosive
limit) inside the structure would have been the best information
for the firefighters on scene, and undoubtedly would
have changed their response and would have prevented the
injuries, " McKinnon told NFPA Journal. No gas monitoring
capabilities were built into the McMicken battery, however,
and what diagnostic systems did exist were handled by the
battery management system, which failed minutes before
firefighters arrived.
To make matters worse, the basic tools that firefighters use
during responses are generally ineffective for ESS incidents.
In subsequent tests at the UL laboratories, McKinnon found
that, due to the sooty and rapidly changing conditions of a
thermal-runaway event, standard thermal cameras and gas
meters have difficulty providing reliable information about
whether a battery is on fire, which battery modules are
undergoing thermal runaway, or even what gases are being
emitted.
In effect, the Peoria firefighters had to make decisions in
the absence of any information whatsoever. Much of that
could have been mitigated if the department had been made
aware of the facility, had worked with the utility to develop
a preplan for the incident, and even trained on-site, Kerber
said. But none of that happened.
" What happens a lot with new technology is there's an
expectation that the fire department immediately becomes
an expert on how to mitigate a hazard that they respond
to, and I don't think that's a fair expectation, " Kerber said.
" There has to be research upfront, there have to be codes and
standards in place, and sometimes the technology gets ahead
of that. In this case, there was really no good guidance. There
was no good training. "
WOULD NFPA 855 HAVE HELPED?
According to after-incident reports, there were several design
flaws with the McMicken battery that contributed to the
eventual outcome. Part of that was likely because battery
design-and-installation standards were limited at the time
the battery was installed in 2017; one of the most cited standards,
NFPA 855, Standard for the Installation of Stationary
Energy Storage Systems, did not come out until late 2019.
Still, experts are divided over whether a strict adherence
to NFPA 855 would have made a significant difference in the
McMicken case. While the standard is comprehensive, as
with everything involving ESS, any attempt to impose hard
and fast rules quickly runs up against the realities of technical
capabilities, available knowledge, and politics.
For instance, had NFPA 855 existed before the installation
of the McMicken battery, it's doubtful the facility would have
even been subject to its requirements. For a variety of reasons,
batteries owned and operated by utilities are exempted
from most of NFPA 855, a fact that the UL report recommends
changing and which is still being debated (see " Power
Struggle, " previous spread). As a result, the McMicken facility
was not required to have-or to offer the fire department-an
emergency operations plan, something UL report authors say
would " have made a significant difference. "
Experts say that if McMicken had been subject to NFPA
855, several factors may have made a difference in the
outcome. For one, NFPA 855 requires most ESS to have
deflagration venting and explosion prevention, features the
McMicken battery lacked. To the contrary, the McMicken's
NOVEC 1230 suppression system featured dampers that were
" designed to seal when the suppression agent was discharged
to prevent venting that could decrease the effectiveness of
the clean-agent suppressant, " the UL report said. Rather than
vent flammable gases to keep them below the lower explosive
limit, the McMicken system held them in. Exacerbating the
problem, the NOVEC gas prevented a fire from ever starting
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NFPA Journal - Fall 2021

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