NOVELTY - Improved fuel cell system comprises: (a) a dry air feed; (b) a source of compressed hydrogen; (c) a bypass conduit; (d) a membrane-based humidifier having an evaporation side and a condensation side; (e) a fuel cell having a cathode side, an anode side, and a moisture-laden exhaust outlet; (f) a vent; (g) valves; and (h) a controller adapted to actuate the valves in an operation mode and a startup/shutdown mode.    USE - The improved fuel cell system is useful for producing electricity.    ADVANTAGE - The improved fuel cell system comprises a membrane-based humidifier used to permeate moisture and oxygen from the moisture-laden exhaust stream to provide an N2-rich exhaust for purging of the anode.    DETAILED DESCRIPTION - Improved fuel cell system comprises: (a) a dry air feed; (b) a source of compressed hydrogen; (c) a bypass conduit; (d) a membrane-based humidifier having an evaporation side and a condensation side; (e) a fuel cell having a cathode side, an anode side, and a moisture-laden exhaust outlet, the fuel cell is adapted to react air from the dry air feed and hydrogen from the compressed hydrogen source to produce electricity and produce a moisture-laden exhaust stream at the moisture-laden exhaust outlet, where the moisture-laden exhaust outlet is in fluid communication with the condensation side and the membrane-based humidifier is adapted to permeate some of the moisture in the moisture-laden exhaust stream from the condensation side to the evaporation side to produce a dried exhaust stream from the condensation side; (f) a vent; (g) valves; and (h) a controller adapted to actuate the valves in an operation mode and a startup/shutdown mode. In the operation mode, the controller actuates some of the valves to: (i) place the dry air feed, the evaporation side, and the cathode side in fluid communication such that the dry feed is humidified by the moisture permeated from the moisture-laden exhaust stream and is fed to the cathode side; (ii) place the source of compressed hydrogen and the anode side in fluid communication; (iii) place the condensation side and the vent in fluid communication such that the dried exhaust stream is vented. In the startup/shutdown mode, the controller actuates some of the valves to: (i) place the dry air feed, the bypass conduit, and the cathode side in fluid communication; (ii) isolate the evaporation side from the dry air feed; (iii) isolate the anode side from the source of compressed hydrogen; (iv) place the condensation side and the evaporation side in fluid communication; (v) direct a first portion of the dried exhaust stream from the condensation side to the evaporation side to sweep moisture from it and vent the moisture at the vent; and (vi) direct a second portion of the dried exhaust stream from the condensation side to the anode side. INDEPENDENT CLAIMS are included for:    (1) a method of initiating operation of the fuel cell system comprising: (a) providing the fuel cell system in an inactive state; and (b) using the controller to place the fuel cell system in the startup/shutdown mode;    (2) a method of shutting down operation of the fuel cell system comprising: (a) providing the fuel cell system; (b) operating the fuel cell system in operation mode; (c) discontinuing operation of the fuel cell system in operation mode; and (d) using the controller to place the fuel cell system in the startup/shutdown mode; and    (3) a method of operating the fuel cell system comprising a dry air feed, a source of compressed hydrogen, a bypass conduit, a membrane-based humidifier having an evaporation side and a condensation side, a fuel cell having a cathode side, an anode side, and a moisture-laden exhaust outlet, a vent, and valves, comprising: (a) directing the dry air feed to the evaporation side where the dry air feed is humidified to provide a humidified feed; (b) directing the humidified feed to the cathode side; (c) directing hydrogen from the source of compressed hydrogen to the anode side; (d) reacting oxygen from the compressed humidified feed with the hydrogen to produce electricity and a moisture-laden exhaust stream; (e) directing the moisture-laden exhaust stream from the fuel cell to the condensation side where moisture permeates through the membrane of the humidifier to the evaporation side to provide the humidification of the dry air feed and to provide a dried exhaust stream; and (f) venting the dried exhaust stream.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic diagram of the fuel cell system.    Dry air feed (1)    Four-way valve (5,29)    Humidifier (13)    Condensation side (21)    Humidified feed (23)    Compressor (33)    Compressed stream (37)    Cathode side (39)    Fuel cell (41)    Anode side (42)    Moisture-laden exhaust stream (43)    Hydrogen stream (45)    Three-way valve (49)    Conduit (53)    Water trap (57)    First moisture-laden exhaust (61)    Second moisture-laden exhaust (65)    Shutoff valves (69,76,77,85)    Expander (73)    Orifice (75)    Vent (81)