Membrane processes for carbon capture from coal-fired power plant flue gas: A modeling and cost study

Favorable economics of electricity generation will be crucial to the successful implementation of post-combustion carbon capture. Hence, the US DOE has set a goal of <35% for the increase on the cost of electricity (COE) due to CO2 capture. For meeting this goal, there is thus a growing need to perform a cost analysis of emerging separation methods. This paper goes through a detailed modeling and cost-sensitivity study of a promising membrane-based process for carbon capture: the air-sweep process. We have studied the impact of membrane performance, selectivity and permeance, on the COE increase and the capture cost. The effects of operating parameters as well as the membrane price on the overall cost were determined. Cost calculations show a COE increase of about 33% along with a capture cost of <$24/t CO2 for the air-sweep process to achieve 90% CO2 recovery and 95% purity of the CO2 product. This process operates at close to atmospheric feed pressure and requires a low membrane module price of $27/m2, a CO2/N2 selectivity of about 140 combined with a high CO2 permeance of 3000 GPU. Although the required membrane properties have not yet been achieved, this research emphasizes quantitatively the need to improve the present membranes to realize a purely membrane-based process for the above application.