Releases of Unignited Liquid Hydrogen

If the hydrogen economy is to progress, more hydrogen fuelling stations are required. In the short term, in the absence of a hydrogen distribution network, these fuelling stations will have to be supplied by liquid hydrogen road tanker. Such a development will increase the number of tanker offloading operations significantly and these may need to be performed in close proximity to the general public.
The aim of this work is to identify and address hazards relating to the storage and transport of bulk liquid hydrogen (LH2) that are associated with hydrogen refuelling stations located in urban environments. Experimental results will inform the wider hydrogen community and contribute to the development of more robust modelling tools. The results will also help to update and develop guidance for codes and standards.
The first phase of the project was to develop an experimental and modelling strategy for the issues associated with liquid hydrogen spills; this was documented in HSL report XS/10/06[1].
The second phase of the project was to produce a position paper on the hazards of liquid hydrogen which was published in 2009, XS/09/72[2]. This was also published as a HSE research report RR769 in 2010[3].
This report details experiments performed to investigate spills of liquid hydrogen at a rate of 60 litres per minute. Measurements were made on unignited releases which included concentration of hydrogen in air, thermal gradient in the concrete substrate, liquid pool formation and temperatures within the pool. Computational modelling of the unignited releases has been undertaken at HSL and reported in MSU/12/01 [4]. Ignited releases of hydrogen have also been performed as part of this project; the results and findings from this work are reported in XS/11/77[5].