Sequestering Carbonates

Pennsylvania Serpentine Quarry source: O'Connor p.8

Once the carbonate has been formed, it will need to be returned to the mines from which the magnesium or carbonate mineral was extracted. Because the carbonate product is thermodynamically favored, the sequestration will be truly permanent with no chance for the carbon dioxide to escape into the atmosphere. There is no transportation cost associated with the actual storage of the carbon dioxide because the material formed will be stored at the mine. (Note: If the plant producing the carbon dioxide is not at the location of the mine then there will be transportation costs associated with bringing the CO2 to the mine.) Goldberg proposes that it will take two tons of serpentine or 1.5 tons of olivine to dispose of one ton of CO2.

The actual sequestration process is basically a straightforward burial of the mineral carbonates as landfill. The technology for such a burial is relatively basic and very well developed. The bulk of the money for research and development for mineral sequestration are devoted to improving the reaction rates and extent of reactions for the conversion of CO2 to carbonate. The only real issue, a change in volume, with sequestration is noted by Yegulalp et al: “Since volumes increase in the process, some modification of the local terrain’s profile is unavoidable.” This, however, is not of too much concern because of experience with other reclamation projects.