A life cycle framework for the indirect carbon mineralization of coal ash

Abstract

A holistic, transparent life cycle assessment (LCA) of coal ash as a feedstock for indirect carbon mineralization is presented, enabling the tracking of energy and material inputs and outputs with a cradle-to-gate system boundary. We analyze the carbon storage and coproduct (e.g., rare earth element and supplementary cementitious material) recovery potential of high and low carbon storage potential coal ashes. The LCA allows for the variation of grid carbon intensity; ash feedstock elemental composition, particle size distribution and moisture content; CO ₂ source and associated separation and compression energy; extent of reagent electrochemical regeneration; and ash transport distance. We find three plausible scenarios to achieve net removal with coal ash mineralization: (1) high efficiency reagent regeneration with a clean power system, (2) feedstock-constrained deployment with coproduct displacement via avoided emissions burden and (3) reduced chemical intensity, sacrificing some mineral revenue for lower energy and reagent use.