Integration of carbon dioxide with geothermal energy: Technology, challenges, and opportunities

The integration of carbon dioxide sequestration with geothermal energy extraction represents a promising pathway toward simultaneous decarbonization and renewable energy production. However, a persistent gap between theoretical predictions and field performance has impeded the commercial deployment of CO 2 -geothermal systems. This review critically synthesizes two decades of research encompassing CO 2 Plume Geothermal (CPG), CO 2 -enhanced geothermal systems (CO 2 -EGS), and hybrid energy storage configurations, with particular emphasis on reconciling modeling predictions with field observations. Analysis of key demonstrations, including the Southeast Regional Carbon Sequestration Partnership (SECARB) Cranfield thermosiphon trials and the Kızıldere CO 2 reinjection campaigns, reveals that multiphase flow dynamics limit the sustainability of thermosiphons under conditions that numerical models predicted would support stable circulation. Conversely, CO 2 -induced cloud-fracture networks achieve breakdown pressures considerably lower than those of water-based stimulation, while generating complex fracture distributions that may reduce seismicity risk. Recent advances in corrosion-resistant materials—including Glass Reinforced Epoxy liners with service lives exceeding 10 years, Ni–W coatings providing approximately 5 years of protection, and corrosion-resistant alloys offering the lowest lifecycle costs for operations beyond 20 years—have addressed previously critical barriers, compared to polymer coatings that require replacement every 2–3 years. Four priorities emerge for a commercial-scale transition: turbine designs that tolerate substantial water mass fractions, real-time multiphase flow monitoring systems, integrated techno-economic models that capture stacked revenue streams, and field-validated chemical stimulation protocols. This synthesis provides a framework for advancing CO 2 -geothermal technologies from demonstration to deployment scale.