Emergency Response Information: Complex Hydrides (19.7)
Criticality: High
Progress: Addressed, Not Adequately
Score: 20
DOT Relevance: §172 Subpart G
Description of Key Area
This key area pertains to the availability of appropriate
information resources needed by first responders to potential emergencies
(e.g., accidents) involving the refueling material transportation
infrastructure that might be used for hydrogen vehicles with complex hydride
fuel storage systems.
“Complex hydrides,” as used here, refers to hydrides that are not
readily reversible so that they are not regenerated while packaged in the
vehicle fuel tank by being exposed to hydrogen gas. Instead, they are usually
processed as a solution or slurry, which is often called a carrier. The
hydrogen-releasing reaction usually involves mixing the carrier with water with
the aid of a catalyst. The vehicle is refueled by removing the spent carrier and
replacing it with freshly regenerated (hydrided) carrier. The spent carrier is
then regenerated at a central processing plant, and the cycle repeats. Sodium
borohydride is the most frequently cited example of this type.
DOE is sponsoring a large team jointly headed by LANL and PNNL to
research and develop chemical hydrogen storage technologies of this type for
low-cost on-vehicle systems with high gravimetric and volumetric energy
density. Sodium borohydride systems have been field tested to a limited extent,
e.g., in the Chrysler Natrium fuel cell vehicle.
Here we are concerned with the material packaging and
transportation system that would be needed to support the refueling
infrastructure for hydrogen vehicles with hydrogen storage systems that require
defueling of a spent material, refueling with a regenerated material, and
material regeneration at a central plant.
Discussion of Criticality
This key area will be critical if commercial hydrogen vehicles
employ fuel storage systems containing hydrides such as sodium borohydride,
which must be recharged at a central processing plant. This is because, even
though some partially applicable emergency response information resources
currently exist (e.g., the DOT ERG2004, as discussed below), these resources
may not be ideally applicable to the specific chemicals and transportation
systems that support the refueling infrastructure, and they will probably not
be applicable to operations in an open-public-access environment such as a
public fueling station.
The important but unanswered question pertains to the likelihood
that hydrogen vehicles of this type will be commercialized, and the associated
spent/regenerated slurry exchange type of refueling infrastructure will
develop. In this regard, it should be recognized vehicle fueling infrastructure
will in fact develop but complex hydride based systems may not play a
significant role relative to distributed production (i.e., at the fueling
station) or delivery via pipeline
Discussion of Progress
Progress toward providing emergency response information
resources appropriate to the refueling transportation infrastructure that might
be used to support hydrogen vehicles with chemical hydride slurry fuel storage
systems is rated as “Addressed, Not Adequately.” This is because, while some
resources currently exist, they may not be applicable to the specific hazardous
materials that might be used in commercialized chemical hydride slurry fuel
storage systems, and they may not be adequate to cover operations at
public-access fueling stations.
For example, the DOT ERG2004 lists Sodium Borohydride (ID Number
1426, with reference to Guide Number 138). Guide Number 138 is for “Substances—Water
Reactive (Emitting Flammable Gases).” Other listings in the Guidebook address
other candidate chemical hydrides such as Magnesium Hydride (ID Number 2010,
which also references Guide Number 138). It remains to be determined if all
materials that might be used in a commercialized chemical hydride slurry
refueling infrastructure are in fact covered in the Guidebook, and if these
emergency response information resources are adequate for operations (i.e.,
tank truck loading of spent carriers, unloading of freshly regenerated carrier)
at public-access fueling stations.
In 2005, the NASFM and DOT’s RITA established the Hydrogen
Executive Leadership Panel (HELP). HELP’s mission is “…to bring together
emergency responders, government regulators, scientists, consumers and experts
from the automotive and energy industries to facilitate a safe and orderly transition
to hydrogen and other alternative fuel sources.” HELP will focus on issues
involved in training, educating, and mobilizing emergency responders to work
with government, industry, and community groups to facilitate and ensure
hydrogen transport, storage and distribution, and the safety of vehicles and
environs.
Recommendations
It is recommended that research to develop chemical hydride
hydrogen storage technologies (that are regenerated at a central plant and not
in the vehicle fuel tank) should be monitored. Emphasis should be placed on
characterizing the infrastructure required to “refuel” these systems—specifically,
the processes envisioned for transporting spent carrier from fueling stations
to central plants and for transporting regenerated (hydrided) carrier from
central plants to fueling stations. Potential hazards associated with this
transportation, including loading/unloading operations at public-access fueling
stations, should be identified and the applicability of existing emergency
response information resources should be assessed.
If R&D succeeds in developing this type of hydrogen storage
and refueling infrastructure technology, and it appears that this technology
may be used to support hydrogen vehicle commercialization, then work to develop
appropriate emergency response information resources should be accelerated.
|