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 hydrogen’s 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 industries—including metals, glass and semiconductors—and 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 in upgrades.

Hydrogen safety has evolved to a very high level in today’s 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 today’s 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.
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