NFPA Journal - Spring 2024 - 59

While the fundamental
hazards of a single
lithium-ion battery and a
LIB-powered ESS are the
same, the size and energy
capacity of an ESS have
a significant influence on
its hazard profile.
Energy storage system batteries made by Tesla at a substation in California.
A recent Fire Protection Research Foundation project examined safety issues around
the marine transport of such batteries.
analysis, specifically focused on ESS in enclosed
spaces for marine transport.
The study concluded that marine vessels
and protective systems are often not
designed to manage explosion hazards or
substantial firefighting requirements for lithium-ion
battery or ESS incidents. Additionally,
crews often lack proper training and may
be further hindered by inadequate means of
early detection and suppression limitations.
Consequently, vessel operators are beginning
to implement practices and safety measures
that are more stringent than current
regulations for transporting LIB or ESS cargo.
The analysis identified five possible steps
to improve the safe marine transport of energy
storage systems.
Establish a state of charge threshold
State of charge, or SOC, is an important risk
factor for batteries or ESS, as it correlates
to the severity and intensity of a battery incident
under abnormal conditions. SOC refers
to the current level of energy stored
within the battery or ESS at a specific point
in time, expressed as a percentage of the
battery's maximum capacity. Although the
SOC is not currently regulated for transport
in the IMDG Code, setting an SOC threshold,
such as 30 percent of the battery's
maximum capacity-as practiced in air
transport-or some other threshold determined
by stakeholders was recommended.
Keep ESS stowed on deck
It is increasingly understood that lithium-ion
batteries and ESS, in the case of abnormal
events, have the potential to release large
quantities of flammable vent gases, including
hydrogen and methane, during thermal
runaway. If allowed to accumulate in an enclosed
space, these gases can present an
explosion hazard. This risk has called the
long-standing allowance for below-deck
stowage of large quantities of lithium-ion
batteries and ESS into question. Constraints
on crew response capabilities below deck
and the uncertain effectiveness of a " oneshot "
mitigation strategy for battery fires,
such as commonly used carbon-dioxide
suppression systems, have generated additional
support for on-deck stowage of
lithium-ion ESS cargo. This allows for regular
inspections and facilitates manual water-based
firefighting efforts.
Explore additional detection and
firefighting tools
The analysis supported the contention that
current detection and firefighting response
capabilities for handling this hazard on marine
vessels are inadequate. Enhanced capabilities
such as gas detection systems
and improved firefighting tools have been
requested by vessel operators and should
be explored as possible means of improving
ESS transport safety.
Clarify the requirements for ESS
outer housings
Ship operators have highlighted a concern
regarding the differences between the
purpose-built protective enclosures (outer
housings) for ESS and standard freight
containers. These outer housings, designed
specifically to ensure the safety, functionality,
and longevity of components such
as batteries, control systems, and cooling
mechanisms, diverge from the characteristics
typically found in standard freight containers.
While containers prioritize providing
a standardized, durable, and secure
enclosure for transporting goods across
various modes of transportation, including
ships, trains, and trucks, the outer housings
of ESS prioritize the unique needs
of energy storage. Additionally, ESS
housings are not marked with the appropriate
Convention for Safe Containers
(CSC) plate if they have not been
tested to that standard.
As a result, ESS enclosed in purpose-built
housings can only be transported
in specific locations, such as
the top tier of a container stack or other
positions where no containers can
be stacked on top of them. As the demand
for this cargo continues to increase,
these limitations on ESS storage
may become less feasible and may necessitate
a clarification of the current
ambiguity surrounding the outer-housing
requirements for marine transport of
large-format lithium-ion ESS.
Develop a basis for
classifying the health of used
or recycled batteries
Concerns arise when transporting these
batteries without verifying their stability
and state of health (SOH), which is an
indicator of the battery's health and performance
over time. Specifically, SOH
refers to a battery's overall capacity or
ability to store and deliver energy compared
to its capability when new.
If the SOH is unknown, it has become
common practice to implement additional
safety measures. The FPRF analysis
suggested the development of an investigation
into the basis for classifying
and ensuring the SOH of used or recycled
batteries, potentially incorporating
it into regulations or establishing robust
packing and stowage requirements.
-
These are just some of the areas that
will need to be examined for the safe
marine transport of ESS. Since these
cargoes are viewed as posing a high degree
of risk when balanced against current
regulatory provisions, vessel operators
often adopt a more restrictive
approach toward LIB ESS cargo than
that required by current regulations,
special provisions, and packaging requirements.
As a result of these discussions,
regulatory bodies and industry
stakeholders are collaboratively making
strides in improving the safe marine
transport of battery systems and cargo.
The results of the FPRF analysis
will be released soon. To learn more,
visit nfpa.org/foundation. -V.H.
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NFPA Journal - Spring 2024

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