Design and Techno-Economic Analysis of a Carbon Capture and Storage By Mineralization (CCSM) Process Using NaOH As an Alkaline Feedstock

As CO°©₂ capture technologies are approaching the commercialization stage, storage of the large amounts of CO₂ expected from the capture has emerged as a major problem. The conventional large scale storage method of injecting CO₂ into strata or ocean bears some critical problems such as adverse effects on the environment and potential leakage to atmosphere. For that reasons, the approach of carbon capture and storage by mineralization (CCSM) is getting much attention as it converts CO₂ into chemically more stable mineral carbonates, e.g., calcium carbonate (CaCO₃), magnesium carbonate (MgCO₃), which are also valuable industrial raw materials. In this work, a CCSM process using sodium hydroxide (NaOH) as an alkaline feedstock is designed by integrating the well-known chlor-alkali process with a CO₂ absorption process. In the designed process, NaOH solution made from electro-chemical reactions within the chlor-alkali process is transported to the CO₂ absorption process for capture and conversion of CO₂ (in flue gas emitted from a pulverized coal power plant) into sodium bicarbonate (NaHCO₃) and sodium carbonate (Na₂CO₃). The designed process should overcome the insufficient alkalinity supply and slow carbonation rate problems which are the main challenges in the existing CCSM processes. In particular, the designed process is suitable for our native country of Korea in consideration of the low electricity price and high accessibility to brine. First, the designed process is implemented in the commercial process simulator of AspenPlus^TM. Second, a techno-economic analysis of the designed process is carried out for a comparison with the standard carbon capture and storage (CCS) approach using the MEA absorption and injection into ocean, which is most close to commercial operation. Economics of the designed process are analyzed in terms of cost of CO₂ avoidance ($/ton CO₂). Finally, a sensitivity analysis is performed to find influential parameters of the designed process with respect to overall economic performance.

Figure 1 Schematic diagram of the designed CCSM process

 

References

[1] R. R. Chandran and D. T. Chin, Electrochimica Acta, 1986, 31, 39.

[2] G. Heddle, H. Herzog, and M. Klett, "The economics of CO2 storage," Massachusetts Institute of Technology, Laboratory for Energy and the Environment, 2003.