NFPA Journal - January/February 2020 - 33

BEYOND EVs

SAN DIEGO GAS & ELECTRIC

STRANDED ENERGY IS A CONCERN ACROSS
ALL ENERGY STORAGE TECHNOLOGIES

ENERGY ARRAY
A San Diego Gas
& Electric energy
storage facility
in Escondido,
California.

STRANDED ENERGY AND problems like thermal
runaway are not exclusive to batteries in electric
vehicles (EVs). Both can occur in any battery, including stationary energy storage systems (ESS), which
are being installed around the world in residential
and office buildings, utility-owned industrial parks,
and even private homes.
The devices are in demand because they can store
energy created from renewable sources like wind
and solar for use later. Battery energy storage is also
becoming increasingly critical for utilities because
stored energy reduces the need to build additional
power plants to meet growing energy demands. The
recently released NFPA 855, Standard for the Installation of Stationary Energy Storage Systems, includes
detailed installation guidelines that take into account
the needs of emergency agencies during incidents
involving these systems.
The potential dangers posed by these large battery
systems were revealed last April when firefighters
were called to a utility-owned lithium-ion ESS in Surprise, Arizona, after heat and smoke were detected
inside the battery. Out of caution, firefighters opted
to monitor the situation for hours from outside of the
battery container when, without warning, the battery
exploded. Eight firefighters were injured, including
four with severe burns and one with life-threatening
injuries. The cause of the thermal runaway, and subsequent explosion, are still under investigation. In
the last six months, NFPA instructors have traveled
to Surprise, Phoenix, and 10 other locations across
the country to lead training events intended to help
responders understand how to handle ESS incidents
effectively. NFPA also has online ESS training for first
responders at NFPA.org/ess.

Although battery failures that lead to thermal
runaway grab headlines, battery manufacturers
and researchers are quick to point out that they
are exceedingly rare. Reports have estimated the
failure rate for lithium-ion batteries to be between
1 in 10 million on the high end, and 1 in 40 million
on the low end, depending on the quality of the
manufacturing. Bigger battery systems, however,
like utility-owned energy storage systems in containerized units, may have 100,000 battery cells or
more within the installation, making the failure rate
per container much higher than it seems-as many
as 1 in 100 containers on average could experience a
failure in one of its battery cells.
As with EV, when ESS experience a fire or thermal
runaway, response options are limited. Currently,
there are no good ways for responders to determine how much energy remains in a damaged
battery, and no effective means to drain energy
from a battery to reduce the threat. In addition, the
environmental impact of fighting fires in batteries
is also not well understood. According to the Fire
Protection Research Foundation, firefighters may
need in excess of 3,000 gallons of water and more
than an hour of constant spray to prevent the threat
of reignition.
That creates concerns over the runoff created
by these incidents, according to Cory Wilson, a
chief at the Fremont (California) Fire Department.
"Where does all that runoff water go? How bad is it
for the environment? How do you collect that? Do
you worry about collecting it?" Wilson said. "These
are all issues that I think we're going to have to start
working through as you see more and more of these
vehicles on the road." -J.R.

N F PA . O R G / J O U R N A L * NFPA JOURNAL

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NFPA Journal - January/February 2020

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