Packaging Instructions for Micro Metal Hydride Hydrogen Storage Systems (18.2)
Criticality: High
Progress: Not Addressed
Score: 40
DOT Relevance: §173 Subpart D
Description of Key Area
UN SCETDG has approved entry UN 3468, Hydrogen in a metal hydride storage system, to the Dangerous Goods
List in the UN Model Regulation for the Transport of Dangerous Goods. This
entry has been adopted by the US DOT and is included in the Hazardous Materials
table in 49 CFR 172.101. Packaging instructions for UN 3468 require approval by
the Associate Administrator prior to first shipment (49 CFR 173.214). The
Hazardous Materials table also includes entry NA 9279, Hydrogen absorbed in metal hydride, which includes no packaging
instructions and requires a special permit for transport. Without any guidance
on packaging, the OHMS must individually review and issue an approval or
special permit for each system design and manufacturer/offeror for all metal
hydride-based hydrogen storage systems.
This discussion applies to both entries, UN 3468 and NA 9279.
Systems which are appropriately identified by these entries can be divided into
two broad groups that really only differ in where and how they might be used
and transported. This section will discuss “Micro” systems and Item 18.3 will
discuss “Portable” systems. Micro systems are ones that are expected to be
transported both as stand-alone storage containers and as storage containers
connected to and in use with fuel cell systems. It is anticipated that Micro
systems will be approved for transport and use with all modes of transport
including the passenger cabin of aircraft. Portable systems are not expected to
be transported or used within the passenger cabin of aircraft. Micro systems will
likely have a maximum size limitation applied to them. Current proposed size
limitations have been arbitrarily chosen and will likely be revised as a
natural safety or application-based limit becomes apparent.
Today travelers expect to be allowed to carry and use a host of
electronic devices while traveling by road, rail, ship, and air. These devices
include laptop computers, cellular phones, PDAs, video games, DVD players,
cameras, video recorders, and others. Many devices combine several functions
into a single device. As the number of functions a device performs increases,
as their overall performance is enhanced and as customer expectations rise, the
power and energy requirements for the devices become greater. This has lead to
a widening gap between device power and energy demand and the ability of
current battery technology to meet demand. One technology that is expected to
be able to provide better power and energy capabilities in these applications
is hydrogen fuel cells. Fuel cells are similar to batteries in that they
convert chemical potential energy into electrical power and energy. However
unlike batteries, the fuel and oxidant are supplied from external sources and
the by-products exhausted. With hydrogen fuel cells, the fuel is hydrogen and the
by-product is water.
Currently there are a lot of development activities being carried
out by various companies and organizations around the world on these
technologies. Advanced prototypes and early entry products are starting to
leave the laboratory environments and enter the marketplace. The number of
products and designs available are expected to increase dramatically over the
next few years. Without packaging instructions being included in the hazardous
materials regulations and without at least a template or set of guidelines for
use by the OHMS for evaluating these systems, the effort required to review and
approve or issue special permits for each may be burdensome.
Micro systems have additional complexities in their review since
it will also need to consider the implications of when they are attached to or
detached from a fuel cell appliance. This becomes even more critical in light
of their expected transport and use within the passenger cabin of aircraft in
today’s environment of heightened concern of potential terrorism.
Discussion of Criticality
This item has been assigned a criticality of high. Without
packaging instructions being developed for metal hydride-based hydrogen storage
systems, there is no set of consistent minimum requirements to manufacturers
and offerors follow. The absence of packaging instructions requires that OHMS
personnel review and approve each system from each offeror and manufacturer.
This could present a burdensome work load on the OHMS if this technology is
found to be able to meet current expectations leading to many requests for
approval.
While it is considered critical that packaging instructions be
developed for systems identified by UN 3468 and NA 9279, it is also recommended
that the packaging instructions be designed so as to not prohibit new and
innovative designs. This technology is relatively new and is evolving. New
advanced materials and designs are expected. The packaging instructions should
therefore be performance-based and avoid being too prescriptive, while ensuring
a minimum level of safety.
Discussion of Progress
The hazardous materials table currently includes two listings: NA
9279, Hydrogen absorbed in metal hydride
and UN 3468, Hydrogen in a metal hydride
storage system. Currently these identifications can only be used with
approval from the OHMS after review and approval of the packaging. No packaging
instructions have been adopted in either the US
regulations or the UN Model Regulations. The OHMS has issued several special
permits for metal hydride hydrogen storage systems that are identified by
either one or both of these identifiers.
Progress on developing consensus standards that might be used as
packaging instructions include:
- The
ISO technical committee for hydrogen technologies (TC 197) has a working group
drafting a standard for transportable reversible metal hydride hydrogen storage
systems (ISO 16111). This document is currently in the approval stage as a
committee draft (“CD”) for advancement to the draft international standard
stage (“DIS”). In parallel to the CD approval, the document is being considered
for publication as a technical specification; with possible publication of the
TS much earlier than possible for the International Standard. Once the
international standard is approved, the technical specification will be
withdrawn. This document only considers stand-alone containers.
- IEC
TC 105 has drafted and is currently reviewing a draft publicly available
standard for Micro Fuel Cell Systems (IEC PAS 62282-6-1). This document
includes sections on fuel storage containers and complete integrated fuel cell
appliances with fuel containers. This standard is expected to reference ISO
16111 for metal hydride-based hydrogen storage container design and testing.
- UL
is developing a consensus standard (UL 2265) on micro fuel cell systems. An
effort is being made to keep UL 2265 consistent with IEC 62282 and its
development is therefore trailing that of IEC 62282.
- CGA
has also considered developing a standard for portable metal hydride hydrogen
storage systems. This effort is early in development and the expected
publication date is unknown.
Proposals have been submitted to ICAO and the UN SCETDG for
approval of metal hydride hydrogen storage systems of limited size being
transported aboard aircraft, both cargo and passenger, including within the
passenger cabin. ICAO has approved part of the request to allow transport
aboard cargo aircraft. These proposals have included introducing system level
tests of the systems and/or reference to ISO 16111 to approve packaging.
ASME's Boiler and Pressure Vessel project team on hydrogen tanks
is addressing metal hydride vessel design in a code case to Section VIII-1.
Recommendations
It is recommended that the OHMS develop a minimum set of design
and test criteria for packaging of systems that meet the UN 3468 and NA 9279
hazard descriptions and that meet the micro system definition used in this
report. These criteria should be provided to potential manufacturers and
offerors for use in their design and testing of the storage systems and would
help ensure consistency in application of rigor in determining the minimum
level of safety. It is preferred that these criteria be performance-based.
Ideally they would be based on the ISO and IEC standards underdevelopment by international
expert committees (ISO 16111 and IEC 62282-6-1).
To help ensure that the standards being developed for metal
hydride-based hydrogen storage systems meet the need of OHMS, it is recommended
that the OHMS assign personnel or contractors to actively participate on the
applicable development committees. These would include ISO TC 197 working group
10, IEC TC 105 working group 8, the CGA Hydrogen Fuel Technology committee and
UL’s 2265 technical committee.
From experience obtained from systems approved under these
guidelines, they could, at an appropriate future time, be refined and used as a
basis for a New Rule Making Proposal for conversion into regulations and
incorporated into 49 CFR 173.
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