(130e) Dilute Methane Utilization Using A Membrane Gas Exchanger

Methane is a valuable energy resource and also the second largest contributor to global warming, after carbon dioxide.  With almost twenty-one times the global warming effect of an equivalent mass of carbon dioxide, methane accounts for 10% of U.S. greenhouse gas emissions.  Significant amounts of these emissions are dilute mixtures of methane and an inert gas (most commonly carbon dioxide), with a methane content below 40%.  These dilute methane streams are not combustible when mixed with air, due to the low Btu values, and therefore, they are often vented.  A need exists for an efficient technology to convert these waste streams into useful fuel, reducing global warming emissions.

This presentation will describe the development of a new membrane process to convert dilute, non-combustible methane/carbon dioxide gas mixtures into methane products that can be mixed with air and used as fuel.  The approach is based on an innovative membrane device to selectively exchange carbon dioxide with oxygen from air.  The resulting gas has a higher oxygen content and a lower carbon dioxide content than the feed gas, and is combustible when mixed with ordinary air.  Results are reported for new high-performance membranes and modules that were fabricated and tested under simulated industrial conditions for concentrating methane.  The energy efficiency and economics of the new membrane gas exchanger are analyzed, and the fuel value of the gas produced more than offsets the cost of the new process.