Power plant post-combustion carbon dioxide capture: An opportunity for membranes

Carbon dioxide capture from power plant flue gas and subsequent sequestration is expected to play a key role in mitigating global climate change. Conventional amine technologies being considered for separating CO2 from flue gas are costly, energy intensive, and if implemented, would result in large increases in the cost of producing electricity. Membranes offer potential as an energy-efficient, low-cost CO2 capture option. Recently, working with the U.S. Department of Energy (DOE), we have developed membranes with CO2 permeances of greater than 1000 gpu and a CO2/N2 selectivity of 50 at 30 °C. This permeance is ten times higher than commercial CO2 membranes and the selectivity is among the highest reported for non-facilitated transport materials. These membranes, in combination with a novel process design that uses incoming combustion air as a sweep gas to generate driving force, could meet DOE CO2 capture cost targets. Under these conditions, improving membrane permeance is more important than increasing selectivity to further reduce the cost of CO2 capture from flue gas. Membrane cost and reliability issues will be key to the eventual competitiveness of this technology for flue gas treatment.