Underground Hydrogen Storage in the Bunter Sandstone Formation in the North German Basin: Capacity Assessment and Geochemical Modeling

With planned hydrogen import terminals and production sites along the North and Baltic Seas, the German coast is likely to become the center of the hydrogen economy. Underground hydrogen storage in the sedimentary reservoirs of the region, particularly in the Bunter Sandstone Formation, could provide the required storage capacity for the future hydrogen economy due to its widespread occurrence and proven sealing system. Herein, the storage capacity is assessed using a probabilistic volume approach and possible reactions between the Bunter Sandstone and hydrogen based on geochemical simulations with PHREEQC are determined. This assessment gives an effective storage capacity of 0.84-4.14 PWh in the saline aquifers of the Bunter Sandstone, of which 0.52-2.57 PWh could be stored onshore. If production from currently operating fields are to cease, additional capacities of between 89.43 and 285.53 TWh could be found in its hydrocarbon fields. Mineralogical reactions are shown to be restricted to redox reactions, which do not affect the formation integrity of siliciclastic reservoirs. As a result, pore storage facilities in the Bunter Sandstone could provide an important storage option for the hydrogen economy, but will require further investigations in the lab and in the field.