AbstractThis paper describes a detailed process optimization of the mass and energy balances for multi-stage membrane systems used in coal-fired power plants. Based on the recovery rate of 50% or 90% CO2 with 95 mol% CO2 purity, different concepts using recirculation of flue gas and variation of feed gas compressor and vacuum pump on the permeate side were developed and optimized to obtain minimum energy consumption. Simultaneously, a cost model was developed to make a further analysis of the optimized concept in view of the tradeoff balance between material and energy consumption.