Hydrogen Odorant and Leak Detection: Part 1, Hydrogen Odorant - Project Closure Report

This work programme was focused on identifying a suitable odorant for use in a 100% hydrogen gas grid (domestic use such as boilers and cookers). The research involved a review of existing odorants (used primarily for natural gas), and the selection of five suitable odorants based on available literature. One odorant was selected based on possible suitability with a Polymer Electrolyte Membrane (PEM) based fuel cell vehicle, which could in future be a possible end-user of grid hydrogen. NPL prepared Primary Reference Materials containing the five odorants in hydrogen at the relevant amount fraction levels (as would be found in the grid) including ones provided by Robinson Brothers (the supplier of odorants for natural gas in the UK). These mixtures were used by NPL to perform tests to understand the effects of the mixtures on pipeline (metal and plastic), appliances (a hydrogen boiler provided by Worcester Bosch) and PEM fuel cells. HSE investigated the health and environmental impact of these odorants in hydrogen. Olfactory testing was performed by Air Spectrum to characterise the ‘smell’ of each odorant. Finally, an economic analysis was performed by E4tech. The results confirm that Odorant NB would be a suitable odorant for use in a 100% hydrogen gas grid for combustion applications, but further research would be required if the intention is to supply grid hydrogen to stationery fuel cells or fuel cell vehicles. In this case, further testing would need to be performed to measure the extent of fuel cell degradation caused by the non-sulphur odorant obtained as part of this work programme, and also other UK projects such as the Hydrogen Grid to Vehicle (HG2V) project would provide important information about whether a purification step would be required regardless of the odorant before the hydrogen purity would be suitable for a PEM fuel cell vehicle. If purification was required, it would be fine to use Odorant NB as this would be removed during the purification step.
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