We have conducted comprehensive exergy analyses of three integrated gasification combined cycle with carbon capture and storage (IGCC-CCS) power plant configurations: (1) a baseline model using Selexol™ for H₂S/CO₂ removal; (2) a modified version that adds a H₂-selective membrane before the Selexol™ acid gas removal system; and (3) a modified baseline version that uses a CO₂-selective membrane before the Selexol™ acid gas removal system. While holding the coal input flow rate and the CO₂ captured flow rates constant, it was determined that the H₂-selective membrane case had a higher net power output (584 MW) compared to the baseline (564 MW) and compared to the CO₂-selective membrane case (550 MW). Interestingly, the CO₂-selective membrane case destroyed the least amount of exergy within the power plant (967 MW), compared with the Baseline case (999 MW) and the H₂-membrane case (972 MW). The main problem with the CO₂-selective membrane case was the large amount of H₂ (48 MW worth of H₂ chemical exergy) remaining within the supercritical CO₂ that exits the power plant. Regardless of the CO₂ capture process used, the majority of the exergy destruction occurred in the gasifier (305 MW) and gas turbine (~380 MW) subsystems, suggesting that these two areas should be key areas of focus of future improvements.