The capture and storage of CO2 (CCS) as a greenhouse mitigation option is becoming an increasingly important priority for Australian industry. Membrane based CO2 removal systems can provide a cost effective, low maintenance approach for removing CO2 from gas streams. This study examines the effect of membrane characteristics and operating parameters on CCS costs using economic models developed by UNSW for any source-sink combination. The total sequestration cost per tonne of CO2 avoided for separation, transport and storage are compared for the separation of CO2 from coal fired power plants and natural gas processing. A cost benefit analysis indicates that sequestration of gases of high purities are dominated by compression costs which can be off-set by utilising membranes of higher selectivity coupled with higher permeability to reduce the required transmembrane pressure.