| Abstract |
This study provides a critical review of Underground Hydrogen Storage (UHS), emphasizing its potential as a viable energy storage option despite several associated challenges. These challenges include microbial degradation, chemical reactivity, unique thermophysical characteristics, and geomechanics considerations. Effective and secure UHS operation requires careful site selection, management, and a thorough understanding of hydrogen's behavior under various geological and operational conditions. Our review examines the significance of hydrogen's physical properties, H2-fluid-rock dynamics, redox-driven geochemical interactions, microbial activities, and geomechanical risks influencing UHS performance, safety, and containment. Additionally, we discuss the importance of optimal material selection and operational strategic development to maximize UHS efficiency and minimize associated risks. While global projects and ongoing research form a solid foundation for UHS development, ensuring UHS effectiveness and safety requires further investigation. This article also identifies the main knowledge gaps and future research directions for effective deployment of UHS projects. |
, Hichem A. K. Chellal 
