CO₂ utilization from power plant: A comparative techno-economic assessment of soda ash production and scrubbing by monoethanolamine

CO₂ utilization for soda ash production via sodium hydroxide (NaOH) route was compared with the conventional CO₂ scrubbing via monoethanolamine (MEA) route for the first time. The techno-economic and sustainability implications of these routes were assessed and compared; CO₂ was considered to be captured from a natural gas combined cycle (NGCC) power plant. Process equipment were designed and sized from the estimation and simulation of process materials and energy requirements. Capital expenditure (CAPEX), cost of electricity (CoE), cost of CO₂ avoided (CoA), and operational expenditure (OPEX) were estimated to compare the economic viability of the NaOH and MEA processes. Sensitivity analysis was carried out to investigate the effect of soda ash and NaOH prices on the process economics. Significant energy savings would be achieved from the NaOH process because this process eliminates the solvent regeneration and CO₂ compression steps associated with the MEA process. The electricity requirement of the NaOH process was 35 kWh/t CO₂, which was only 7% of the electricity requirement of the MEA process. NaOH process showed a total CAPEX of M$ 99.31 and an OPEX of M$ 18.68; this CAPEX was only 65% of that of the MEA scrubbing process. Sensitivity analysis showed that the cost of CO₂ capture would be offset at a soda ash selling price of 18 $/t. NaOH process offers higher sustainability potential for CO₂ utilization because it reduces the parasitic energy requirements and high initial capital cost associated with MEA scrubbing process.