H2Tech - Q3 2021 - 42

SAFETY AND SUSTAINABILITY
On August 10, 2008, a boiling liquid
expanding vapor explosion (BLEVE)
at the Sunrise Propane facility rocked
Toronto. This explosion was the result
of the illegal practice of swapping propane
loads between trucks, which was
faster than unloading to and loading from
storage tanks. The event forced 12,000
residents to evacuate and resulted in two
deaths and dozens of injuries. Houses
and businesses near the blast site were
destroyed, and the total cleanup bill was
approximately C$1.8 MM, with an additional
multimillion-dollar class-action
lawsuit settlement.9
The Sunrise Propane
event caused a significant reaction from
regulators and the public, ultimately resulting
in new regulations (FIG. 5).
The Technical Standards and Safety
Authority (TSSA) for the Ontario Province
responded to the incident with
Ontario Regulation 211/01: Propane
Storage and Handling, which requires
propane facilities to have risk and safety
management plans (RSMPs) in place
to ensure public safety.11
The Propane
RSMP requires strict risk criteria to be
met for offsite impacts as part of a detailed
site risk assessment. Unfortunately,
because this standard was reactive instead
of proactive, it meant that a portion of the
propane autofilling infrastructure was not
compliant and either had to be taken out
of the network (shut down) or brought
into compliance, with heavy investment,
to make stations safety compliant.
Practices for assessing risk. Regardless
of location, safety requirements tend
to incorporate one or more of the following
approaches to siting: spacing distances,
HAZOP/LOPA and/or select
detailed modeling. With regard to spacing
distances, a number of international
standards exist for various parts of the H2
technology process. These standards are
often supplemented by local regulatory
requirements for minimum design spacing
for facility layouts. The problem with
spacing distances is that they are not site
specific and tend to focus on minimizing
equipment damage and business interruption
due to small, more likely accidental
releases, and they fail to address more
severe accidents that could occur with impacts
to nearby populations.
Countries with specific regulatory and
permitting requirements tend to also require
a qualitative hazard review process,
such as a hazard and operability study
(HAZOP) or layers of protection analysis
(LOPA). Using these methodologies to
apply order of magnitude consequences
and frequency to hazardous events can be
challenging with emerging technology in
potentially densely populated areas, such
as H2
fueling stations. This often involves
defining one or more " maximum credible
events " (MCEs) and has the unintended
consequence of missing low-frequency,
catastrophic events as well as high-frequency,
low-impact events. As a result,
safeguards are identified and selected
based on MCEs rather than a thorough
range of potential events and the associated
risk profile. This is especially troubling
for a technology with a lack of historical
data on the likelihood of human errors
associated with filling activities-a traditionally
applied HAZOP/LOPA methodology
may struggle to account for these
risks in a meaningful way.
In rare instances, detailed modeling is
FIG. 4. Petrol station fire in St. Louis.8
FIG. 5. Sunrise Propane BLEVE.10
42 Q3 2021 | H2-Tech.com
conducted to quantitatively address the
hazard and/or risk impacts of a facility.
Many of the up-and-coming fueling station
owner-operators are utilizing free,
open-source software codes with inherent
simplifications to conduct risk assessments.
While these may be good for a
quick answer in some situations, companies
should be wary of using any code that
they do not fully understand when making
important safety and infrastructure
decisions. A good rule of thumb is that
if it is not readily apparent what calculations
are being done and what the model
limitations are, then expensive and lifeimpacting
decisions should not be based
on those answers.
Key takeaways for safe rollout of H2
infrastructure. To date, the availability
of publicly accepted and mandated hazard
and risk criteria is limited; therefore,
risk assessments are compared to company
guidelines or applicable best practices
rather than reviewed critically against a
given standard. Due to the unique properties
of H2
with respect to ignition and
explosion characteristics, care must be
shown when undertaking detailed hazard
and risk modeling to ensure that results
are representative of current knowledge
and technology. Be wary of falling into the
trap of using readily available tools without
understanding their basis and limitations.
Pitfalls to watch out for include:
* Spacing distances that consider
only small hole sizes or are
focused on fire events and are
generally intended to limit
property damage or minimize the
likelihood of fire propagation
* Qualitative, experience-based
reviews have inherent bias and may
lack sufficient knowledge when
dealing with new technology and
applications without verifying
with quantitative analysis
* Assuming that safety
shutdown or isolation systems
ensure safe operations:
° History has shown us that
these systems have limitations
and limited reliability
° High-pressure H2
a dangerous flammable vapor
cloud, or could lead to a jet
fire with lethal impacts faster
than the release could feasibly
be detected and isolated
* Using models without
understanding the basis and
limitations of those models
(i.e., lack of flexibility to
model site-specific conditions,
buildings and scenarios)
* Models that do not take into
account the surroundings; if the
results are the same regardless
of the location and neighboring
properties, then the answers may
not reflect the actual environment
and should be investigated further
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