Static underground hydrogen storage capacities of oil and gas fields in the North Alpine Foreland Basin, SE Germany

Underground hydrogen storage (UHS) is a central aspect of Germany's national hydrogen strategy. Hereby, existing salt caverns in Northern Germany are considered for UHS, even though porous formations comprise approximately one third of Germany's in-place capacity for natural gas storage. In addition, first tests in the German and Austrian parts of the North Alpine Foreland Basin showed promising results for UHS in porous formations. The undeformed part of the North Alpine Foreland Basin in SE Germany hosts 58 oil and gas fields, with 5 still actively producing and another 5 converted to natural gas storage sites. The latter currently provide 30% of Germany's in-place natural gas storage capacity in porous formations.

We investigated the static hydrogen storage capacity of all 58 oil and gas fields on the basis of oil and gas production data. We considered ambient densities based on average hydrocarbon compositions and pure hydrogen, and calculated subsurface hydrogen and hydrocarbon densities as a function of temperature and pore pressure gradients, both of which are varying with depth and laterally. Finally, we assumed a range of working-gas-to-cushion-gas ratios which resemble the current natural gas storage sites in the area to estimate static hydrogen storage capacities for each field.

Our results show that the cumulative hydrogen storage capacity in the SE German part of the North Alpine Foreland Basin is close to the capacity of salt caverns in Northern Germany. Hereby, the 5 active natural gas storage sites comprise around 40% of the overall storage capacity, which - by building on the existing infrastructure - would allow for a fast and smooth implementation of additional and spatially diversified UHS capacities in Germany.