NOVELTY - The membrane (20) has a set of regions (28) formed from carbonate, where the regions conduct carbonate ions. Another set of regions (30) is formed from oxygen conductive solid oxide, where the latter regions conduct oxide ions and separate carbon dioxide from gaseous molecules. The latter regions are surface treated with a catalyst that promotes transfer of the oxide ions from the latter regions to the former regions when separating carbon dioxide. A membrane body allows the carbon dioxide to pass from a side (32) to another side (34).    USE - Carbon dioxide permeable membrane for use in a zero-emission coal-based electric power plant to separate carbon dioxide from a mixture of gaseous molecules e.g. hydrogen, oxygen, carbon monoxide, nitrogen, methane, and steam (all claimed). Can also be used for a solid oxide fuel cell system, energy producing device, fuel synthesis and carbon chemistry methods, steel making processes and system, aluminum smelter and metallurgical processes to separate carbon dioxide from fuel gas and exhaust gas.    ADVANTAGE - The regions include material e.g. selective carbon dioxide permeable composition, that can be chosen appropriately, so that operational temperature ranges of the membrane can be adjusted. The material used to form the membrane can differ by cation mixture in a carbonate region and by admixtures to a solid oxide region and a carbonate region so as to enhance stability, ion permeability and selectivity of the membrane. The membrane allows gasification reaction to be performed in nearly reversible fashion, so that the reaction does not consume free energy originally available in carbon fuel. The membrane provides hydrogen at high pressures, thus minimizing energy to compress the fuel for storage.    DETAILED DESCRIPTION - The membrane is in form of a disk, plate, cylinder, cube, tube and film or sheet. The latter regions include pores and the former regions are positioned inside the pores of the latter regions. The gaseous molecules include hydrogen, oxygen, carbon monoxide, nitrogen, methane and steam. INDEPENDENT CLAIMS are also included for the following:    (1) a method for separating carbon dioxide from a mixture of gaseous molecules    (2) a method for producing a carbon dioxide permeable membrane.    DESCRIPTION OF DRAWING(S) - The drawing shows a cross-sectional view of a carbon dioxide permeable membrane.    Carbon dioxide permeable membrane (20)    Regions (28, 30)    Sides (32, 34)