Ionic liquid-based CO2 capture in power plants for low carbon emissions

Carbon capture using an ionic liquid as the solvent has been considered to be an effective way to reduce CO2 emissions. This study aimed to investigate ionic liquid (IL)-based carbon dioxide capture and storage processes compared with the MEA-based process from a power plant's flue gas. Ionic liquid 1-Butyl-3-methylimidazolium Bis(trifluoromethanesulfonyl) ([bmim][Tf2N]) was used as the solvent. The COSMO-SAC model was selected as the property method for all of the simulations. Based on sensitivity analysis optimization, the optimal process was obtained and the energy saving ratio (ESR) and primary cost saving ratio (PCS) were calculated. The results showed that the ionic liquid-based process performed better than the process using traditional organic solvents monoethanol-amine (MEA) in terms of cost. Due to the non-volatility of ionic liquids, two flash tanks were used instead of the solvent recovery stripper. The ionic liquid process led to 30.01% savings on energy consumption and 29.99% savings on the primary cost. The specific electricity of the CO2 storage was 237 kWh/t (CO2) and 124 kWh/t (CO2) in the two processes. Because the output pressure of CO2 from the IL-based process was lower than that from the MEA-based process, more energy consumption was required.