Technology Status of Hydrogen Road Vehicles
Technology Status of Hydrogen Road Vehicles
Technology Status of Hydrogen Road Vehicles
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! The minimum ignition energy is indeed lower for hydrogen by an order <strong>of</strong> magnitude, but any real-life<br />
ignition source (electrostatic discharge, etc.) has an energy content higher than the minimum for the other<br />
fuels, so again fires can start just as easily with the other fuels.<br />
! Although the detonation limits and velocity are in general higher for hydrogen, the explosive energy <strong>of</strong><br />
the much less dense hydrogen in air is considerably less.<br />
Rather than continue this comparison <strong>of</strong> basic properties, it is much more instructive to proceed by illustrating<br />
hydrogen experience from more traditional industries, analyzing recent integral safety testing for hydrogen<br />
vehicles, and reviewing the findings from the investigation <strong>of</strong> the Challenger accident.<br />
A1.2 <strong>Hydrogen</strong> Safety Experience from Traditional Industries<br />
The most comprehensive treatment available to us 7 on this subject is the Safety Guide for <strong>Hydrogen</strong> published<br />
by the National Research Council Canada (Kalyanam and Moore 1987). It is required reading and reference<br />
for anyone in the field. The main chapters are highlighted here.<br />
A1.2.1 Classifying <strong>Hydrogen</strong> Hazards<br />
The known hazards associated with hydrogen can be classified under the following headings:<br />
! Leakage and spillage<br />
! Combustion<br />
! Detonation<br />
! Reactions with oxidants, halogens, and metals<br />
! Metal embrittlement<br />
! Asphyxiation<br />
! Cryogenic hazards<br />
A1.2.2 Methods for Reducing Risks<br />
The general industrial practices and guidelines for reducing risks in hydrogen systems are:<br />
! Comply with codes, standards, and guidelines.<br />
! Limit quantities for indoor storage.<br />
! Locate and separate process and storage equipment.<br />
! Control hydrogen accumulation within enclosures.<br />
! Exclude air.<br />
! Eliminate ignition sources.<br />
! Detect and control leakage.<br />
! Contain LH 2 spills.<br />
! Verify instrumentation.<br />
! Verify safety reliefs.<br />
! Vent and dispose safely.<br />
! Select proper construction materials.<br />
7 As already mentioned, the unpublished report EQHHPP Nov. 1993 would supersede this since<br />
it is in effect an updating <strong>of</strong> the available safety information and methodology, and includes a valuable survey <strong>of</strong><br />
the international regulations, as well as the national ones <strong>of</strong> 6 countries <strong>of</strong> Europe and North America; it also<br />
addresses the societal concerns regarding hydrogen safety.<br />
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