Hydrogen Fuel: Managing its Safety
by James G. Hansel, Air Products and Chemicals, and
Karen Miller, National Hydrogen Association
Undetected leaks in outdoor hydrogen piping
and equipment is a risk within the industrial gas industry because of the
relatively high or even very high probability that a continuous leak will
eventually ignite. Outdoor hydrogen leaks are susceptible to static electricity
and other sources of ignition.
With a continuous outdoor leak, time is the
enemy. Recognizing the risk of ignition, the first question to ask is: What
will the flame impinge upon? A combustible material, a meltable gasket,
or even a passing employee? Herein is the risk. Ignition often occurs because
of hydrogens extremely low ignition energy in combination with the
very wide flammability range. The corresponding high probability of eventual
ignition with a continuous leak does not exist with natural gas. Hydrogen
piping outside of enclosures exists on vehicles as well as on fueling stations.
Interestingly, in many of these applications the risk is somewhat reduced
because the hydrogen flow, and thus a leak, is not continuous. Technologies
are being developed and tested to detect and manage these risks.
Hydrogen energy safety is based on three primary
elements: codes and standards, how well the regulated safety measures work,
and proper use of the equipment to minimize risks.
Industry currently implements many successful
proprietary methodologies for handling large amounts of hydrogen safely.
There are several codes and standards for hydrogen specifically that are
under construction at all levels of government. The National Hydrogen Association
(NHA) and the U.S. Department of Energy (DOE) are working on many of these
efforts. The National Aeronautics Space Administration (NASA), specifically,
has just published a comprehensive safety standard (NSS 1740.16) which is
considered by many a milestone in hydrogen safety. The International Standards
Organization work in hydrogen is proceeding vigorously and the World Hydrogen
Energy Conference in June 1998 should witness the progress of international
acceptance of hydrogen energy safety.
Safety technologies for hydrogen have progressed
in several areas. Gas detection and measurement capability has advanced
based on the extensive investment of the DOE in the last few years. Several
of these technologies are becoming available as commercial products. Hydrogen
flame detection has progressed mainly from the commercialization of NASA
technology. The safe production and storage of hydrogen is proven. The commercial
availability of hydrogen as a fuel will drive the applications and variety
of configurations of these technologies even further. The current initiative
of the nuclear industry in upgrading reactors with hydrogen monitoring and
safety signals the high confidence of a very conservative industry in regards
to the capabilities of hydrogen safety products.
The best way to reduce the likelihood of a hydrogen
leak igniting is to detect the leak prior to the gas reaching flammable
concentrations. This can be done today using hydrogen leak detectors. Currently,
hydrogen leak detectors are used in food processing for the safe hydrogenation
of foods, process industriesincluding metals, glass and semiconductorsand
the energy sector.
The NHA acts as an information source and facilitator
in the hydrogen safety discussion. A current example is the discussion of
the use of analogous odorants to detect hydrogen gas leaks. The natural
gas industry has accumulated over 60 years of safety experience in the use
of odorants yet the hydrogen community is not persuaded that this passive
technique is adequate or even effective and that active sensing might be
a preferable method.
Currently, DOE and NASA are supporting several
programs which apply new generation hydrogen detection and measurement technology
in order to qualify them for more expansive deployments. The
hydrogen safety community is evolving to service both transportation and
utility infrastructures by leveraging aerospace and power industry investments
Hydrogen safety has evolved to a very high level
in todays implementations throughout industry. The extension of this
experience to the evolution of a new broad infrastructure to replace certain
nonrenewable and polluting fuels is achievable and logical. There is no
fundamental new safety challenge which must be overcome, only the scaling
of todays successful new technologies and refined risk management
techniques applied in accordance with hydrogen specific codes and standards.
Industry is committed to the actions necessary to achieve the acceptance
of hydrogen as a commercial energy carrier.
©1998. All Rights Reserved. A Publication of
the National Hydrogen Association.
This material may not be reproduced in any form without permission.
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