Chemical absorption is widely regarded as the most promising technology for CO 2 capture from large industrial sources in the short term. The cost of CO 2 capture from postcombustion power plants using monoethanolamine (MEA), the benchmark for chemical absorption, is currently over US$70 per metric ton of CO 2 avoided. This high cost is considered as the major obstacle to current large-scale implementation of carbon capture and storage (CCS). Thus, there has been significant focus on the development of new solvents with the aim to reduce costs. This paper provides insights into the impact of solvent properties on the cost of capture to assist in the development of new solvents based on a 500 MW supercritical black coal power plant as the emission source. The effect of solvent properties, specifically solvent loading, heat of reaction, solvent loss, and solvent concentration is examined. The effect of improvements in process design, specifically high pressure stripper operation, advanced structured packing, use of concrete for the process vessels, and advanced heat exchangers, is also evaluated. Sensitivity analysis and Monte Carlo simulation are performed to provide an estimate of the capture cost variability. The results show that the development of aqueous chemical absorption technology for CO 2 capture should focus on new solvents with good stability toward SO x and NO x , high solvent concentration (above 50 wt %), and high working capacity (above 0.35 mol of CO 2 /mol of solvent). These three parameters have the most significant impact on the capture cost. Based on Monte Carlo simulation, within a 95% confidence level, the capture cost with improved solvent properties and process design is estimated at US$62−80 per metric ton of CO 2 , with the most likely cost of US$71 per metric ton of CO 2 avoided. This number reduces to US$44−59 per metric ton of CO 2 , with the most likely cost of US$52 per metric ton of CO 2 avoided, if the flue gas desulfurization (FGD) and selective catalytic reduction (SCR) units can be eliminated.

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There has been increasing interest in the development of solvents for CO 2 capture including solvents that involve precipitation during CO 2 absorption. On the basis of Le Chatelier's principle, the CO 2 absorption equilibrium can be shifted by removing one of the reaction products, resulting in a higher absorption capacity. Two phase-change solvents are investigated: promoted potassium carbonate (where the CO 2 is incorporated in the solid phase) and potassium taurate (where the CO 2 is incorporated in the liquid phase). A high-level assessment is performed with the two phase-change solvents in order to identify key areas in solvent system design for possible cost reduction. The impacts of absorption contactor type, the addition of a solid− liquid separator, and heat integration opportunities on capture cost and total heat duty are investigated. For both phase-change solvents, the lowest capture cost is found when the CO 2 absorption is operated in a packed column and advanced heat exchanger integration is used in which the dissolution heat exchanger duty is supplied without consuming low pressure (LP) steam for the power plant. For the cases investigated, there is little difference in capture cost between the two phase-change solvents.