Unlocking the H2 potential in Saudi Arabia: Exploring serpentinites as a source of H2 production

The global transition to a low-carbon energy future has ignited interest in hydrogen as a clean and versatile energy carrier. NW Saudi Arabia contains vast tracts of mantle-dominated Neoproterozoic ophiolites overlain by a sedimentary cover in the north, NE and east. Our research explores the untapped potential of Saudi Arabia's ophiolite serpentinites as a possible source of hydrogen generation through serpentinization and related processes. H 2 is commonly derived from serpentinization, which primarily involves the hydration of minerals rich in iron and magnesium (e.g., olivine), resulting in the formation of serpentine and H 2. Serpentinites are formed by reaction between fluids and mantle rocks, and hydrogen and methane are released in extreme reducing conditions. Under strongly reducing conditions, the formation of magnetite generates hydrogen during serpentinization, following reactions such as: 3Fe 2 SiO 4 + 2H 2 O = 2Fe 3 O 4 +3SiO 2 +2H 2 . (1) We have conducted a comprehensive assessment of serpentinites in the Arabian Shield, employing the Geographic Information System (GIS) to locate Arabian ophiolites with the largest ultramafic segments. Ophiolites studied include Jabal Ess, Jabal Wask, Bi'r Tululah, and Jabal Tharwah. After ophiolite identification, we delineated fractures and measured fracture density to provide insight into the potential of serpentinite fractures on the amount of possible hydrogen seepage, or natural accumulation in case of an overlying seal. Our goal is to do spatial analysis that can be a guide to the most favorable environment for geologic H 2 exploration; as such, this does not however, provide an estimate of the total H 2 storage capacity. A complimentary H 2 anomaly survey however, will ground-truth the results of this study. • The Arabian Nubian Shield is comprised of numerous serpentinite-dominated ophiolites. • The possibility of natural hydrogen accumulations within these ophiolite massifs are indicated by the permeable zones of fracture density maps. • The shield is overlain by a sedimentary cover in the east which may act as an effective seal.