Membrane selective exchange process for dilute methane recovery

Methane gas is a valuable energy resource. Methane emissions are the second largest human-caused contributor to global warming. Significant quantities of the methane emissions are vented as carbon dioxide/methane mixtures from landfills and natural gas processing plants, since they are too dilute to burn or flare. This paper describes a novel membrane selective exchange process to upgrade dilute methane emission streams into useful fuel by removing CO₂ and introducing oxygen into the methane product stream. This is achieved in a single step without the need for compression. Flat sheet thin film composite membranes based on perfluoropolymers and a spiral-wound module were prepared and tested with model dilute methane mixtures. A technical and economic analysis shows that the selective exchange process is cost-effective, improves methane utilization and reduces global warming emissions.