Dr. Wang is an Associate Professor in the Dept of Materials at Shandong University of Science and Technology of Research. His research directions: Numerical simulation of oil reservoirs, numerical simulation of underground gas storage, underground hydrogen storage, CCUS, etc. He has completed many research projects on natural gas underground storage site selection and operation numerical simulation and has extensive experience in gas underground storage. Bruno R B Fernandes is a Research Associate, Center for Subsurface Energy and the Environment, The University of Texas at Austin. His experience includes software development for oil/gas and energy storage projects. He has worked on enhanced oil recovery, CCS, and underground hydrogen storage projects. He has extensive experience with modeling, simulation, and optimization of several engineering problems. He has used commercial reservoir simulators such as CMG, SLB-Eclipse, SLB-Petrel, SLB-IX, and Navigator in several field projects. He has been in charge of UT chemical and compositional gas reservoir simulators (UTCHEM-RS and UTCOMP-RS).Dr. Baojun Bai is a Professor and the holder of the Lester R. Birbeck Endowed Chair in Petroleum Engineering Program at Missouri University of Science and Technology (S&T). He holds PhD degrees in Petroleum Engineering from New Mexico Tech and in Petroleum Geology from China University of Geoscience-Beijing. He has seven years of industry experience as a reservoir engineer and the head of conformance-control Team of RIPED, PetroChina. Dr. Bai was a post-Doctoral scholar at the California Institute of Technology before he joined Missouri S&T as a faculty member in 2006. He has more than 20 years of experience in the research areas of enhanced oil recovery, unconventional reservoir development, conformance control, CO2 sequestration and characterizations. Dr. Bai has published more than 200 papers in peer-reviewed journals and over 120 papers in SPE conferences by 2020. He served as the JPT Editorial Committee from 2007 to 2013. He serves as the associate editor for Journal of Petroleum Sciences and Engineering, Geofluids, and Petroleum Sciences. He is an SPE distinguished member. Dr. Mojdeh Delshad is a research professor in the Hildebrand Department of Petroleum and Geosystems Engineering at the University of Texas at Austin. She served as the Vice President (2013-2014) and the President/CEO (2015-2019) of Ultimate EOR Services LLC. She served as the assistant director for the Department of Energy-funded Center of Frontiers of Subsurface Energy Security (CFSES) from 2009-2014.She holds a BS degree in Chemical Engineering from Sharif University in Iran and MS and Ph.D. degrees in Petroleum Engineering from The University of Texas at Austin. She has over 30 years of experience in reservoir simulation and modeling multiphase flow, fluid property, and reactive flow with applications in enhanced oil recovery, subsurface contaminant transport and remediation, geothermal, CO2 sequestration, and porous media hydrogen storage.

• 1. Overview of UHS Technology2. Type of Underground Sites for Hydrogen Storage3. Interactions of Hydrogen-Rock-Fluid System4. Fluid Flow Mechanisms of UHS5. Numerical Simulation Techniques for UHS Chapter 6: Prospects for UHS technology