Carbon dioxide (CO2) capture and storage (CCS) is a set of technologies for the capture of CO2 from its anthropogenic point sources, e.g., power plants, its transport to a storage location, and its isolation from the atmosphere. It is an important option to counter the increase of atmospheric CO2 concentrations and therefore to mitigate climate change, while at the same time allowing for the continued use of fossil fuels. Capture of CO2 using existing separation techniques can be applied to large point sources, i.e. power plants or industrial plants; CO2 can be easily transported using pipelines; CO2 storage can take place in geological formations, in the ocean, or by fixing it in mineral carbonates.
In this last option, called mineral carbonation, captured CO2 is reacted with metal-oxide bearing materials, thus forming the corresponding carbonates and the solid byproduct silica, i.e. naturally occurring stable solids that would provide storage capacity on a geological time scale. Natural silicate minerals, whose deposits are sufficient to fix the CO2 that could be produced from the combustion of all fossil fuels resources, as well as alkaline industrial wastes can be used in artificial processes that mimic natural weathering phenomena. Although very attractive for the permanence of storage, the application of mineral carbonation is hindered by the slowness of the reaction. To speed up the process kinetics, energy intensive mineral pretreatments are needed. Therefore the technology is not yet ready for implementation. The best case studied so far is the wet carbonation of the natural silicate olivine at high temperature and under high CO2 pressure, which costs between 50 and 100 US$/tCO2 stored and translates into a 30-50% energy penalty on the original power plant (Albany Research Center).
The objective of the proposed project is to develop an aqueous mineral carbonation process that achieves a cost and an energy penalty, which are 50% lower than the best achieved so far. This would allow mineral carbonation to become competitive with other storage options.
We intend to achieve this goal: (i) by building upon the results achieved in four years of research on the fundamental mechanisms of mineral carbonation in aqueous solutions; (ii) by exploiting the equipment and expertise accumulated in many years of research in the field of crystallization and high pressure CO2 technology; (iii) by combining deep fundamental understanding of the process with modeling and optimization (vi) by designing a complete process that includes all steps, and exploits all process integration and intensification possibilities.
Milestones of the project are: (a) characterization of silicate dissolution as a function of ionic strength and particle size; (b) characterization of carbonate precipitation as a function of temperature, pH, CO2 pressure, ionic strength; (c) characterization of mineral carbonation, i.e. the combination of the previous two steps; (d) design, simulation, optimization, lab scale implementation, and life cycle analysis of the complete mineral carbonation process.