Screening of Additives for Rapid Carbon Mineralization in Saline Aquifers

Atmospheric concentrations of carbon dioxide (CO₂) continue to increase at a high rate due to the burning of fossil fuels. Hence, Carbon Capture and Storage (CCS) are needed on a large scale and over time to cater this issue. Mineral carbonation differs among all CCS strategies about providing the most certain and permanent route of sequestration by transforming the CO₂ into stable solid carbonates; therefore, it is the most secure process. Nevertheless, one of the main shortcomings of natural mineralization is slow reaction rates, which are commonly several hundred and thousands of years at normal subsurface reservoir conditions. This paper explores a new, hastened format of CO₂ mineralization with the mixture of chemical motivators- Barium Hydroxide (Ba(OH)₂), Strontium Chloride (SrCl₂), and Glutamic Acid Diacetate (GLDA) into a synthetic prepared brine representing saline aquifer structures. Several laboratory experiments were run at a constant reservoir-pertinent temperature of 60 oC utilizing an artificial-brine and dolomite matrix. CO₂ gas was bubbled through the solutions with various additive concentrations; pH evolution and solid precipitation were tracked over 48 hours. The findings show that some combinations, especially 0.02 M Ba(OH)₂, 0.02 M SrCl₂ coupled with 0.1% GLDA had showed fast reactions in alkalinity and color carbonate formation, which was ascertained through XRD. The results challenge the traditional assumptions of the periods necessary in terms of the geological storage of CO₂ and the possibility of chemical augmentation to be subjected to mineralization in hours. The study, therefore, addresses a very large literature gap, providing a potentially scalable and productive pathway towards rapid CO₂ mineralization within carbonate aquifers, and with direct related implications to the application of large-scale CCS technologies.