Improving our understanding of Hydrogen through testing and advanced modeling to avoid possible pitfalls and ensure its safe use

For the past 40 years, hydrogen has been mostly used as a rocket fuel, in oil refineries and in fertilizers. However, interest in hydrogen as a clean fuel and energy carrier of the future has grown in many countries which motivated comprehensive research and development activities with the ultimate goal being the transition from fossil fuels towards an energy source with lower CO₂ emissions. Given its high energy content and clean energy source to the end user, hydrogen has become an acceptable fuel for many energy applications and systems. Hydrogen can be stored and transported as a compressed gas, however, due to its comparatively small energy content per unit volume as a gas, it is necessary in some instances to liquefy hydrogen. Similar to liquefied natural gas (LNG), large amounts of hydrogen can be stored and transported as a liquid.

Given the complex conditions in which hydrogen can be used and stored, it is important to understand all the possible nuisances of this fuel in order to define basic safety specifications and avoid possible pitfalls. This is especially true given the very high reactivity of hydrogen, its extensive flammability range, extremely low ignition energy, and its ease of transitioning to detonations as compared to other traditional hydrocarbon fuel gases. Understanding important combustion phenomena, including fires and explosions, is critical to ensure the safe use of hydrogen regardless of whether it is used as a compressed gas or cryogenic liquid. This paper summarizes the critical combustion parameters associated with hydrogen and discusses its unique properties when it comes to evaluating unintentional releases. It also summarizes some of the latest research into accidental hydrogen releases and the associated deflagration explosion hazards. The work is intended to help ensure that hydrogen is used safely and that certain pitfalls associated with its use are avoided due to the unique properties of the fuel.