The future of carbon capture: Basalt’s role in low-hydration CO2 sequestration

Abstract

Mitigating climate change demands innovative solutions, and carbon sequestration technologies are at the forefront. Among these, basalt, a mafic volcanic rock packed with calcium, magnesium, and iron, emerges as a powerful candidate for carbon dioxide (CO₂) sequestration through mineral carbonation. This method transforms CO₂ into stable carbonate minerals, ensuring a permanent and environmentally safe storage solution. While extensive research has explored into basalt’s potential under high hydration conditions, the untapped promise of low water content scenarios remains largely unexplored. Our ground-breaking study investigates the mineral carbonation of basalt powder under low water conditions using supercritical CO₂ (sc-CO₂). Conducted at 50 °C and 15 MPa with a controlled moisture content of 30%, our experiment spans various time points (0, 7, 14, 21, and 28 days). Utilising advanced X-ray diffraction (XRD) and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), we unveil the mineralogical and morphological transformations. The results are striking: even under low water conditions, basalt efficiently forms valuable carbonate minerals such as calcite, siderite, magnesite, and ankerite. The carbonation efficiency evolves over time, reflecting the dynamic transformation of the basalt matrix. These findings offer pivotal insights into optimising CO₂ sequestration in basalt under low hydration, marking a significant leap toward sustainable carbon capture and storage.