Underground Hydrogen Storage in Saudi Arabia: Opportunities and Challenges

Hydrogen (H₂) is anticipated to play a crucial role in Saudi Arabia's transition to a low-carbon economy as an alternative clean fuel. The conversion of fossil fuels through steam methane reformation produces blue H₂, with captured carbon dioxide (CO₂) being stored in geological formations. Saudi Arabia's strategic location and recent policies promote renewable energy and green H₂. However, establishing an industrial-scale H₂-based economy necessitates a suitable large-scale storage solution. Underground hydrogen storage (UHS) emerges as a prominent option, offering significant storage capacities in the Giga- and Terra-Watt-hour range, effectively addressing seasonal fluctuations in supply and demand from renewables. Therefore, the present work aims to evaluate the opportunity of UHS in Saudi Arabia and assess potential geological formations (salt caverns, deep saline aquifers, and hydrocarbon reservoirs) and key technical challenges to be addressed for UHS integration in the energy grid. This includes criteria for site selection, storage capacity calculations, and other critical scientific research areas to be studied. The paper reviews the geological settings in Saudi Arabia that are potentially suitable for UHS, Red Sea basins, and sedimentary formations in the eastern basins at the Arabian plate. The results highlight the requisite fundamental experimental and numerical studies for a complete understanding of H₂/brine behavior within formation rocks, including geo-bio-chemical reactions prone to occur during the UHS process. The analysis of H₂ thermo-physical suggests a more operational challenge than storing CO₂ or natural gas. Commercial demonstration of UHS is crucial, while all the ongoing field tests of UHS (pure H₂) worldwide are still in their early stages. Regionally, deep salt caverns and saline aquifers with closed structures or regional seals provide the best structural traps for UHS due to their tight and secure seal system. Down-dip aquifers and sedimentary packages in the eastern basins at the Arabian platform are more attractive and safer options. The discussed analysis of UHS potential in Saudi Arabia sheds light on its integration possibility into the circular carbon economy (CCE) framework to achieve a net-zero emission by 2060.