Fire and Explosion Safety in Hydrogen Containing Processes : State of the Art and Outstanding Questions

International audienceThis paper is intended to be a brief survey of the state of the art about the safety aspects of industrial application using hydrogen. Although hydrogen has been used in the industry for a long time in chemistry, in metallurgy and more recently in the space industry and in electronics, new fields of application emerged at the turn of the century in the energy sector, broadening considerably both the technologies spectrum concerned but also the public exposed to the risks. Experts of the domain admit that the extent of the spreading of hydrogen technologies depends very much on the safety demonstration rendering the implementation acceptable to the public. Considerable effort was done along the two last decades both to develop risk assessment methods specific to hydrogen technologies and to understand better the key physical phenomena: material embrittlement, formation of explosive atmospheres, ignition, high pressure jet fires, unstable combustion, venting, etc. Major outcomes are recalled. But still much has to be done in research and technology development to achieve a massive development of “hydrogen energy applications”. For instance, the question of “spontaneous” ignition is not yet sufficiently resolved, flame front acceleration in congested environments (like in containers) is to be studied so as the efficiency of several mitigation techniques like venting and inerting