PNNL

Abstract

Earth’s upper crust is the original reactor vessel, with the capability to host multiphase fluids, gases, minerals, and biota while driving mass and energy fluxes across large gradients. Carbon mineralization in mafic-ultramafic rocks is emerging as a foundational platform for coupling subsurface geochemical reaction capabilities with energy production, critical mineral recovery, and resource management. Mafic-ultramafic formations contain highly reactive minerals like olivine and pyroxene that dissolve and release cations upon interaction with CO2-rich fluids, enabling rapid precipitation of carbonate minerals and further opportunities for engineered, energy-related applications. CO2-enhanced mineral recovery leverages CO2-fluid-rock interactions to mobilize metals like nickel, cobalt, and chromium into extractable brines while simultaneously storing CO2. These strategies promote energy security and a resilient domestic supply chain for critical minerals essential to energy and manufacturing. Technologic and scientific advances from carbon mineralization, including reactive transport modeling, geochemical tracers, and in situ sensing, are being applied to enhanced geothermal systems, aquifer storage and recovery, compressed air energy storage, and waste isolation. This Review is organized around five key concepts: Reactor, Reactants, Reactions, Operations, and Outlook, that frame the Earth as a reactor and unify the physical and chemical processes underlying these applications.