Using advanced modelling tools to understand the hazards associated with liquid hydrogen in the aviation industry

Today, the aviation industry accounts for about 3% of global carbon emissions annually, with the UK having one of the highest per capita aviation emissions in the world.

This alone is a strong incentive to decarbonise the aviation industry in order to meet net-zero emissions by 2050.

Several options that are currently being pursued include Sustainable Aviation Fuels (SAF), hydrogen fuel-cell electric planes, and planes using hydrogen gas turbines.

For long-haul flights, the hydrogen turbine propulsion system is considered the most promising option, with hydrogen being stored as a liquid to carry the amount of fuel required. However, due to the unique flammability characteristics of liquid hydrogen (LH₂), the use of such fuel in aviation presents several safety challenges, from the materials used through aircraft refuelling procedures to the storage of large amounts of LH₂ at or near the airport.

During the 3^rd International Hydrogen Aviation Conference, Dr Karina Almeida Leñero, UK Energy Transition Technical Lead, will present a paper entitled ‘’Can we fly safely on liquid hydrogen? Using advanced modelling tools to understand the hazards’’, which she prepared together with Dr Chris Coffey and Dr Shona Mackie.

In this presentation, Karina will discuss how advanced modelling using Computational Fluid Dynamics (CFD) can be used to understand the hazards from potential LH₂ release scenarios while refuelling an aircraft and demonstrate how Gexcon’s FLACS tool can be used to simulate liquid hydrogen spills and their subsequent consequences (gas dispersion, fire, explosion).

By conducting such studies, we are able to provide reasonable estimates for the size of potentially flammable clouds, hazard distances for thermal radiation and explosion overpressure should a release be ignited, as well as explore how the layout and geometry around the release could influence these hazards.

These results can then be used to answer questions and provide guidance on issues pertaining to the location and layout of hydrogen refuelling “hubs” at airports, exclusion zones while refuelling aircraft, procedures for refuelling, and appropriate emergency response in case of an accidental release of hydrogen.