NOVELTY - Operating a molten carbonate fuel cell comprises: (a) providing a hydrogen-containing stream to an anode portion of a molten carbonate fuel cell; (b) controlling a flow rate of the hydrogen-containing stream to the anode; (c) mixing anode exhaust with a hydrocarbon stream; and (d) separating a portion of the molecular hydrogen from the steam reforming feed.    USE - The process is useful for operating a molten carbonate fuel cell (claimed), which can be used for producing electricity and enhancing power density.    DETAILED DESCRIPTION - Operating a molten carbonate fuel cell comprises: (a) providing a hydrogen-containing stream comprising molecular hydrogen to an anode portion of a molten carbonate fuel cell; (b) controlling a flow rate of the hydrogen-containing stream to the anode so that molecular hydrogen utilization in the anode is less than 50%; (c) mixing anode exhaust comprising molecular hydrogen from the molten carbonate fuel cell with a hydrocarbon stream comprising hydrocarbons, where the anode exhaust mixed with the hydrocarbon stream has a temperature of 500-700 degrees C; (d) contacting a portion of the mixture of anode exhaust and the hydrocarbon stream with a catalyst to produce a steam reforming feed comprising one or more gaseous hydrocarbons, molecular hydrogen, and carbon oxide; (e) separating a portion of the molecular hydrogen from the steam reforming feed; and (f) providing a portion of the separated molecular hydrogen to the molten carbonate fuel cell anode as a portion of the hydrogen-containing stream comprising molecular hydrogen. An INDEPENDENT CLAIM is included for a molten carbonate system comprising: (a) a molten carbonate fuel cell configured to receive a hydrogen-containing stream comprising molecular hydrogen at a flow rate so that hydrogen utilization in an anode of the molten carbonate fuel cell is less than 50%; (b) one or more reformers operatively coupled to the molten carbonate fuel cell, at least one reformer is configured to receive anode exhaust from the molten carbonate fuel cell and hydrocarbons, and is configured to allow the anode exhaust to sufficiently mix with hydrocarbons to partially reform some of the hydrocarbons to produce a reformed product stream, where the reformed product stream comprises molecular hydrogen and at least one carbon oxide; and (c) a high temperature hydrogen-separation device that is part of, or coupled to, at least one of the reformers and operatively coupled to the molten carbonate fuel cell, where the high temperature hydrogen-separation device comprises one or more high temperature hydrogen-separating membranes and is configured to receive a reformed product stream and to provide a stream comprising at least a portion of the molecular hydrogen to the molten carbonate fuel cell.