Underground hydrogen storage has emerged as a pivotal component of the low-carbon energy transition, providing a viable solution to the intermittency of renewable energy sources. The distinctive physical and chemical properties of hydrogen, together with its interactions with surrounding rocks and fluids, introduce unique challenges for subsurface storage. This perspective presents recent advances in experimental and modeling efforts of underground hydrogen storage from a multi-scale perspective, highlighting that established methods from hydrocarbon recovery and carbon dioxide storage remain valuable for studying hydrogen systems, yet effectively translating and scaling the relevant physical processes requires renewed attention. Improving the purity and recovery efficiency of stored hydrogen will be central to guiding future reseach on hydrogen storage in geological porous media.

Enhanced CO₂ mineralization and geologic CO₂ storage have received increasing attention as two prominent approaches in combating climate change and fostering sustainable development of human society. This paper aims to explore three emerging areas of research within the realm of enhanced CO₂ mineralization and geologic CO₂ storage, including enhanced rock weathering, numerical modeling and validation of CO₂ storage accounting for the interplay of various trapping mechanisms, and the examination of how reservoir heterogeneity influences the migration of CO₂-brine multiphase flow. Discussions highlight the effectiveness of the spectrum induced polarization for monitoring changes in petrophysical and geochemical properties of rocks during enhanced rock weathering. Additionally, the multi-scale heterogeneity of geological formations needs to be carefully characterized, due to the fact that it plays a vital role in CO₂ migration. Further research is required to achieve accurate and reliable simulations of convective mixing for field-scale applications.