Stimulated Serpentinization for Geologic Hydrogen: A Review of Experimental, Modeling, and Field Studies

High Resolution Image Download MS PowerPoint Slide Geologic hydrogen, also referred to as “white” or “gold” hydrogen, is naturally generated through multiphysical processes within the Earth. Among these processes, serpentinization─a hydration reaction of mafic and ultramafic rocks (e.g., peridotites and pyroxenites)─is a significant source of geological hydrogen. Additionally, “orange hydrogen” has been proposed as an engineered approach in which carbon-enriched water is injected into iron-rich subsurface formations to stimulate hydrogen generation and potentially enable CO 2 mineralization for low- or negative-emission hydrogen production, although the coupled reaction mechanisms and long-term effectiveness remain under active investigation. This review synthesizes the current understanding of serpentinization-driven hydrogen generation, with an emphasis on novel experimental, modeling, and field-based insights. We critically examine key parameters such as temperature, pressure, pH, grain size, and transition metal effects, and present a consolidated framework linking mineralogical evolution with hydrogen yields. A central contribution of this work is the identification of critical knowledge gaps that limit current progress. These include the lack of standardized experimental methods, limited understanding of self-limiting feedback mechanisms and surface area evolution under in situ conditions, and the scarcity of relevant thermodynamic and kinetic data for many rock-forming minerals. Furthermore, we explore emerging research frontiers such as reaction-induced fracturing, CO 2 –H 2 coreactivity, and the catalytic role of trace metals, which hold promise for engineering “stimulated serpentinization” as a viable pathway for scalable geological hydrogen production. By integrating perspectives across geochemistry, geomechanics, and reactive transport, this review outlines pressing research agendas and future directions to accelerate the transition from natural hydrogen discovery to engineered subsurface energy systems.