The ranking of geological structures in deep aquifers of the Polish Lowlands for underground hydrogen storage.

Selection of the proper underground hydrogen storage (UHS) site is an essential issue for zero-emission systems based on renewables. The article presents the method for assessing storage traps in saline aquifers and the ranking of storage traps in saline aquifers from the Polish Lowlands for UHS. The ranking was based on the multi-criteria approach of the hierarchical analysis of the decision-making process. The best UHS site was determined based on geological and reservoir criteria. The criteria weights were evaluated using two methods for comparative purposes. The parameters of individual storage traps came from the database developed in the Hystories project. The highest positions in the ranking were obtained by storage traps characterized by the best sealing parameters of caprock, lack of faults within the traps, and good permeability of the reservoir layers. The presented ranking approach can support the decision-making process for selecting UHS sites in other countries. • Multi-criteria decision analysis was used to develop the ranking of storage traps. • The method was applied for pre-selection of UHS sites in deep aquifers in Poland. • The workflow was developed for the ranking of storage traps in deep aquifers. • The role of criteria weights in the ranking of storage traps was presented. • The method can be used for pre-selection of storage traps in aquifers worldwide. [ABSTRACT FROM AUTHOR]