Technical and Economic Assessment of Post-Combustion Carbon Capture based on Chemical Absorption for Natural Gas-Fired Power Plant

Global warming concerns are increasing as a result of greenhouse gas emissions. CO2 emissions account for 90% of all greenhouse gases released into the atmosphere. Coal-fired power plants produce twice as much CO2 per unit of electricity as natural gas-fired power plants. Post-combustion Carbon Capture (PCC), utilizing solvents, is the most refined method for reducing power plant CO2 emissions. High energy consumption, as well as high capital and operating costs, must be overcome in order to commercialise this technology. Researchers have investigated alternative process configurations and novel solvents, such as potassium carbonate (K2CO3), to reduce the quantity of energy required for solvent regeneration. Aspen Plus®V11 was used to create a steady-state model of the PCC process using monoethanolamine (MEA) solvent. Using experimental data from the Separation Research Programme (SRP) pilot plant, the viability of the model at pilot scale was validated. The PCC model accurately predicted performance within a 10% error margin.
Utilizing novel solvents and modifying process configurations will reduce the cost and energy consumption of the solvent-based PCC process. Aspen Plus® V11 was used to create a rate-based model of the PCC process with K2CO3 as a solvent. Using experimental data, from the University of Melbourne's Parkville campus demonstration plant, the rate-based model was validated. The predictions (e.g., CO2 capture level, rich loading, and re-boiler duty) were within 5% error of the experimental data from the demonstration plant. The results of a technical analysis of the standard PCC process indicated that the specific re-boiler duty was lower than when using MEA solvent, decreasing from 4.97 GJ/tonneCO2 with 30 wt% MEA, to 3.45 GJ/tonneCO2 when using 30 wt% K2CO3. The economic evaluation of a large-scale PCC process revealed that a typical PCC process with 30% MEA had the Total Annual Cost (TAC) of $47.29 (MUSD /year). At 30 wt% K2CO3, the TAC decreased to $36.23 (MUSD /year). According to a large-scale economics evaluation of the PCC process, the configuration of Absorber Intercooling with an Advanced Flash stripper (AIAFS), using 30 wt% K2CO3, had the lowest TAC of all the configurations examined, at 30.27 (MUSD /year). In addition, the Cost of CO2 Capture (CCC) by AIAFS using 30 wt% K2CO3 was determined to be 36.93 (USD /tonneCO2). The research outcomes from this PhD thesis will help commercial deployment of post-combustion carbon capture for natural gas combined cycle power plant.