Integrating experimental and geochemical modelling for productive carbon dioxide mineralization in the South China Sea

Reaching carbon neutrality requires innovative and scalable carbon sequestration technologies. Here, we present an enhanced ex-situ mineral carbonation method using South China Sea seawater and calcium-rich additives for carbon dioxide storage. We conducted high-pressure (50-500 atm) laboratory experiments using calcium oxide, calcium hydroxide, and wollastonite, and performed numerical geochemical simulations. Our key finding is that calcium oxide in seawater achieves the highest carbonate yield, with geochemical models indicating that the complex ionic composition of seawater significantly enhances precipitation compared to simple brines. Additionally, an analytical Monte Carlo economic analysis projects that such efficiency could reduce sequestration costs by 15%. We conclude that seawater-based carbonation is a viable strategy for permanent carbon dioxide storage, offering a practical path for scaling carbon management in coastal regions. High carbon dioxide pressure and calcium-rich additives increase carbonate formation in South China Sea seawater, which shows stronger buffering and saturation behavior than synthetic solutions, based on experiments and geochemical modeling.