Geological potential of hydrogen storage in the Pannonian Basin complex

Hydrogen has a growing importance in the global energy market, as hydrogen technologies are foreseen as the leaders of the energy transition. Its large-scale storage is the most practical manner to balance the weather dependency of renewable energy production and the daily (seasonal) energy demand. The large-scale storage of gases in geological formations is currently implemented for natural gas and carbon dioxide. Owing to technological developments, underground hydrogen storage (UHS) has emerged as an option providing seasonal storage capability. Nevertheless, UHS can be challenging from several aspects, including environmental and economics. Geochemical and biochemical reactions can occur leading to hydrogen loss in the subsurface space. Hence the geological potential of the UHS sites needs to be estimated. This study focuses on the geological resources of the Carpathian–Pannonian region, where two promising rock types are available, including porous sandstones and evaporites. The geological risk of hydrogen loss is discussed, and a site-selection method is introduced with respect of the regional geological storage types.