Assessing the Risks of Stimulated Serpentinization of Ultramafic Rocks for Geologic Hydrogen Production

Geologic hydrogen production via serpentinization offers a promising pathway to clean energy, as it produces no carbon emissions. Under various subsurface conditions, serpentinization can be stimulated in ultramafic (olivine-rich) rocks by injecting water to induce this hydrogen-generating process. However, this process requires modifying rock properties to increase reactive surface area and maximize hydrogen production, which introduces various environmental and economic risks that remain largely unexplored. This study investigates the alteration of the mechanical properties of ultramafic rocks during serpentinization and whether it contributes to the risks associated with this process. Laboratory-stimulated serpentinization experiments were conducted under various conditions, followed by mechanical tests to assess changes in the mechanical properties of the rocks. Serpentinization resulted in a reduction of the uniaxial compressive strength (UCS) by up to ~12%, with reaction temperature influencing the observed effects. These findings provide preliminary insight into the mechanical effects of serpentinization and its potential risks, informing the development of safe and viable geologic hydrogen projects.