h 2 gas 49 is recirculated back to the reformed fuel and then to the stack 36 in fig6 a stream of essentially all h 2 74 can optionally be fed from first bed 44 to valve 50 prior to entry into stack 36 this invention is neither limited to solid oxide fuel cells sofcs nor their operation on natural gas any fuel cells that either use h 2 or co as their fuel can be adapted to use this system additionally recirculation rates may be adjusted to ensure proper oxygen to carbon ratio to avoid carbon deposition in an alternate embodiment shown in fig7 the two beds of fig4 and 6 are combined into a single chemical regenerator 80 where identifying numbers from fig4 and 6 are repeated this eliminates some streams of fig4 and 6 but somewhat complicates heat transfer between previous beds 44 and 46 in fig7 reference can be made to previous text for system components and flow streams the system of this invention utilizes a high efficiency fuel cell system which can run reliably at high fuel utilizations with natural gas or any carbonaceous fuel is presented the system utilizes metal redox reactions to extract fuel from a fuel cell anode gas stream which would otherwise be utilized inefficiently by direct combustion the extracted fuel can be recirculated back to the fuel cell inlet at high rates not only to ensure a high inlet mole fraction of fuel but also to increase the average nernst potential across the cell in theory a 100 electrochemical utilization of the incoming fuel overall is possible whilst.