Improving quantification and understanding of the global H2 soil sink through field and lab based flux measurements

An improved quantification of the soil sink of Hydrogen (H₂) gas is required to understand the environmental implications of a future Hydrogen economy and global atmospheric models. Typically, soil microbes utilise H₂ as an energy source, but we also have evidence that emission of H₂ from soils is also possible via microbial processes. We present new H₂ flux data from several field sites and lab studies in which a variety of soils from around the world have been measured from. These sites include agricultural and forest soils from the UK where we have preliminary data of a longer-term measurement campaign. We have developed flux chamber methodology to establish a best practice for measuring H₂ flux in soils, which is radically different from typical greenhouse gas protocols. We present our work so far on the development of H₂ measurement methodology and on the characterisation of the H₂ soil sink in relation to soil physical & chemical properties, vegetation and climate under controlled environment conditions. We also present observations of spatial and temporal soil H₂ uptake rates from sites across the UK. We highlight the importance of soil aeration and the physical barriers that strongly interfere with H₂ uptake in soils, particularly the influence of high water-filled pore space which should be accounted for in future modelling efforts.