Over the past several years field trials have been conducted by MTR of membrane-based CO2 capture technology at the National Carbon Capture Center (NCCC) in Wilsonville, Alabama. Prior results from 2012 to 2014 have demonstrated successful operation of a field system with full-scale spiral-wound modules treating one ton-perday of carbon dioxide in flue gas generated by a pulverized coal power plant. NCCC field trials continued during 2015 in a test campaign to show stable operation of new Polaris (TM) membranes configured in high-flux cross-flow modules and high selectivity sweep modules. Such field performance of modules, particularly spiral-wound sweep modules, is rarely reported. Parametric sweep module tests confirmed that higher air sweep rates increased CO2 removal rates, but with the drawback of higher pressure drops. Compared with theoretical countercurrent sweep operation, the field modules show about 70% of maximum CO2 removal capacity. The use of higher selectivity membrane in the sweep modules reduced the dilution of O-2 from the air stream leaving the module that would be recycled to the boiler. This trial concluded after seven months with stable performance and over 2200 h of logged data.