Techno-economic analysis of carbon dioxide capture from low concentration sources using membranes

Rising carbon dioxide (CO2) levels in the atmosphere lead to global warming, causing climate change. As such, carbon capture has become necessary to slow the increase and reduce CO2 levels in the atmosphere. Point source emissions have a wide range of CO2 concentrations, but emissions below 3% CO2 have mostly been ignored because Carbon capture from these sources has been viewed as costly and economically unsustainable. Membrane technologies are considered the most viable solution by virtue of more energy-efficient operation. Our group at Idaho National Laboratory (INL) has developed poly[bis((2-methoxyethoxy)ethoxy)phosphazene] (MEEP)-based carbon dioxide selective membranes with CO2/N2 selectivity greater than 40 and CO2 permeability greater than 450 Barrer. To understand the economics of carbon capture, a spreadsheet-based technoeconomic analysis (TEA) model was developed to consider multiple parameters, including selectivity and permeability of the membranes, performance conditions such as the number of stages, module material, electricity price, membrane price, and capital financing. The cost of carbon capture in US$/metric ton was calculated at various purities and compared with other membrane processes, cryogenic capture, solvent-based capture, and pressure swing adsorption-based capture. It was determined that a MEEP-based three-stage process had a capture cost of US$ 50.1/metric ton for 99.8% purity CO2 from a 1% CO2 feed source in nitrogen (N2). The capture cost using the best performing Pebax-based membrane was 464% higher, cryogenic capture was 60%-140% higher, pressure swing adsorption was 55%-165% higher, and chemical absorption was - 10%-110% higher than MEEPbased membrane capture, respectively.