Studies on the CO2 sequestration, geothermal energy upgrade and valuable minerals recovery via the agent-assisting geologic CO2 carbonation

Abstract

The significant disparity between carbon emissions and forest carbon sinks drives China's efforts on CO₂ sequestration to achieve carbon neutrality. However, long-term CO₂ leakage and economic uncertainty remain the limiting factors. “Geologic agent-assisted carbonation” is an emerging technology that converts CO₂ into stable geological carbonate while recovering the exothermic heat energy, nickel and cobalt. This study demonstrated that the geologic agent-assisted carbonation processes could enhance permeability, reaction surface area, and rock porosity, achieving a similar effect as the CO₂ phase transition jetting, thus accelerating the reaction process. A novel application of experimental data and simulation models is employed to forecast that geologic agent-assisted carbonation can significantly increase reservoir temperatures and CO₂ sequestration rates, particularly in low-temperature conditions. The results indicate that, when both the initial peridotite formation and the injection fluid temperature are both 90 °C (low-temperature geothermal grade), the average temperature of the peridotite increases to 150.2 °C (high-temperature geothermal grade) after 2 years, with an annual average of 64,000 tons of CO₂ sequestered. Each ton of sequestration, under the conditions simulated in this study (e.g., low-temperature geothermal grade and specific rock formations), can yield economic benefits ranging from $122.7 to $193.3. The heat and mineral production from this process offer profitable compensation for the consumption in the Carbon Capture, Utilization, and Storage projects.