An Underground Hydrogen Storage Site Selection Ranking Matrix: Insight into the Friulian Plain, Italy

Net-zero emission targets for 2050 are pushing governments, energy industries, and the scientific community to explore the use of alternative energetic vectors. Among them, hydrogen has risen as a potentially extremely relevant technology, as testified by the establishment of several “hydrogen valleys” in the EU. One of the key aspects in the use of hydrogen as energy vector is its underground storage. The majority of studies focus on physical experiments and numerical simulations, whereas little attention has been so far directed on potential sites selection. This study presents a site selection and feasibility study considering the Cavanella Formation (lower Miocene, Northeast Italy) as potential reservoir for hydrogen storage. This unit comprises medium to fine glauconitic sandstones. The presence of the Cavanella Formation in the subsurface of the Friuli Plain is widely documented and the unit is easily identified in seismic lines. A preliminary petrophysical characterization of the Cavanella Formation was carried out on sampling collected from outcrops. The site selection study was based on interpretation of publicly accessible seismic lines, well logs, thin sections, and literature data. Each potential site was evaluated, attributing a storage feasibility index through a designed scoring matrix developed by us and based on literature reservoir characteristics needed for hydrogen storage. Results suggest that the Cavanella Formation could have good petrophysical characteristics for hydrogen storage and that potential storage sites could exist. The scoring matrix has already been tested on underground hydrogen storage sites currently in use worldwide and has proven reliable. The identification of possible sites for hydrogen storage and their petrophysical characterization can have significant impact on the deployment of this new technology, therefore helping the energy transition to renewable sources.