NFPA Journal - Fall 2021 - 42

Guidance
needed
By the time Surprise firefighters arrived, white smoke they
described as " acrid " and " nasty " hung low to the ground in a
radius of about 30 feet surrounding the ESS structure. They
called for backup, and Clare and his HAZMAT team arrived
soon after.
Clare had experience with ESS fires. In 2017, he had
responded to a fire at an electric vehicle repair facility
involving lithium-ion batteries, and later attended HAZMAT
classes focused on lithium-ion battery fires. He had attended
an NFPA ESS awareness training focused on solar panels, as
well as similar local trainings. He knew to be extremely cautious
with battery fires. At the Peoria department, Ruiz said,
" It's always been our philosophy that, when it comes to batteries,
if it's burning, let it burn because it'll consume itself
faster than putting water on it. " Thanks to the Novec gas, the
McMicken battery wasn't burning, but smoke continued to
ooze from the container.
Available research at the time had revealed that the gases
released during thermal runaway are a highly flammable
mix of hydrogen, ethylene, methane, and carbon monoxide,
among others. However, few understood just how much of
this flammable gas can be produced by a relatively small
number of cells. Subsequent tests have shown that " it's just
a tremendous amount of cubic feet of off-gassing, lots of
flammable and toxic gases from just a few cells, " said Ruiz,
who participated in research at the University of Texas after
the Surprise incident. During small-scale tests, so much gas
was produced in a container that the atmosphere was too
rich to explode; researchers had to use fans to blow much of
it away to achieve a blast similar to the one that occurred in
Surprise, Ruiz said.
Over the course of two hours at McMicken, the firefighters
made three journeys inside the fence that surrounded the
ESS structure to take gas and temperature readings of the
container and the vapor spilling out. On each occasion, they
detected hazardous levels of carbon monoxide and hydrogen
cyanide gases-but concentrations of the gases were decreasing.
The HAZMAT team's instincts and training told them
As more money
is spent on
to be cautious, but they were running out of options. " The
concern was that if we turned the structure back over to the
utility, we'd leave and they'd go into a highly toxic environment
and drop like canaries, " Ruiz said.
The team decided to open the door of the structure to
vent it and see what was happening inside. A shaky video
taken during the entry shows Clare and Lopez under a
black night sky in full turnout gear as they approach a side
door. Lopez turns a key and pulls the door open; a dense
cloud of white gas can be seen streaming from the doorway
as the men turn and peer inside. Clare holds up a thermal
imaging camera to take a temperature reading, then turns
to grab a gas meter and radios back to his crew to report
there is no active fire or electrical arcing visible inside the
structure. A few seconds later, the video abruptly ends just
before the explosion.
Investigators later concluded that the open door allowed
oxygen to enter and some of the trapped flammable gases
to exit. In the three minutes the door was ajar, the gases
reached just the right mix and concentration to enter the
explosive range. One of several potential ignition sources
inside the container-such as the hot battery cells-did the
rest, triggering a massive deflagration.
Following the blast, Lopez and Clare endured lengthy
hospital stays, multiple surgeries, and a grueling regimen
of physical therapy. The two other injured firefighters, Matt
Cottini and Jake Ciulla, suffered burns and headaches,
among other lingering issues. All four have been back at
work for about a year, according to Ruiz. " They're all doing
fairly well-as well as could be expected, " he said.
According to Kerber, the decision to enter the structure
was consistent with training guidance at the time. " It
recommended ventilating the structure and going in and
taking samples, which seems like an okay approach, but
clearly the outcome we had here was unfortunate, " he said.
" I think obviously what that says is there are big knowledge
gaps that we need to fill and recommendations and tactical
considerations that still need to be developed. "
energy storage...
$5.4 billion
Amount spent globally on
new energy storage projects in 2020*
$86 billion
Estimated amount to be spent
globally on new ESS projects
by 2025*
. . . Energy storage
capacity will continue
to grow...
23.2 Gigawatt hours (GWh)
Energy storage capacity in
the US in 2020**
173.6 GWh
Global energy storage capacity
in 2020**
365 GWh
Forecasted energy storage
capacity in US in 2030*
741 GWh
Forecasted global energy storage
capacity in 2030*
42 | NFPA JOURNAL * FALL 2021
...With the US
leading the way
1,355
Energy storage projects
that were operational globally
in 2020-40% of which
are in the US. California
leads the US in energy
storage with 215
operational projects,
followed by Hawaii, New
York, and Texas**
Sources:
* Wood Mackenzie
** US Department of Energy
NFPA Journal - Fall 2021

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