NOVELTY - The device comprises a unit (1) for production of fuel gas and a unit for production of oxidizing gas, where the fuel gas and oxidizing gas are intended to supply a fuel cell (8) in which the fuel gas and oxidizing gas chemically react together to produce electrical energy, an conditioning unit for the fuel gas and oxidizing gas, valves, and a circuit (11) adapted for cooling the fuel cell and operated by a pump. The conditioning assembly comprises a drying unit (3) for partially extracting the water contained in a first gas in gas production-storage operating mode.    USE - The device is useful for producing electricity by a fuel cell, where the electricity is useful for a motor vehicle (claimed) and naval or aeronautical applications.    ADVANTAGE - The device ensures direct, efficient and economical production of electricity by fuel cell with high yield and without any damage to the fuel cell.    DETAILED DESCRIPTION - The device comprises a unit (1) for production of fuel gas and a unit for production of oxidizing gas, where the fuel gas and oxidizing gas are intended to supply a fuel cell (8) in which the fuel gas and oxidizing gas chemically react together to produce electrical energy, an conditioning unit for the fuel gas and oxidizing gas, valves, and a circuit (11) adapted for cooling the fuel cell and operated by a pump. The conditioning assembly comprises a drying unit (3) for partially extracting the water contained in a first gas in gas production-storage operating mode passing through the unit before storage under pressurized gas, two valves (6, 7) respectively upstream and downstream of the drying units, a gas storage unit (5) under pressure of the gas, and a moisturizing unit after removal from storage and decompression of the gas. The valves are adapted, in a first state, to configure the device for electricity generation in a gas storage-production operating mode, when connecting the production unit of the gas in series, the drying unit and storage unit under the gas pressure, and are adapted, in a second state, for configuring the power generation device in the operating mode of fuel cell by allowing the passage of the fuel gas and/or oxidizing gas through the drying unit for feeding the fuel cell. The drying unit provides gas humidification at a temperature of 60-80 degrees C in fuel cell operation mode by partial restitution of water extracted from the gas in the gas production-storing mode. The fuel gas and the oxidizing gas are hydrogen gas and oxygen gas respectively and are hydrogen gas and air respectively. The hydrogen and oxygen gas production units are combined into a production unit by electrolysis of the water obtained from a water storage tank (12) connected to the fuel cell. An air generating unit is an air compressor. The drying unit is crossed by the first gas and a second gas in the fuel cell operating mode, and is constituted of a drying column comprising drying granules that are silica gel type. A temperature of the drying unit is obtained by heat exchange with the cooling circuit of the fuel cell. The unit for hydrogen storage is done in the form of metal hydrides.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic view of a circuit of fuel gas and/or oxidizing gas of the fuel cell.    Production unit (1)    Drying unit (3)    Gas storage unit (5)    Valves (6, 7)    Fuel cell (8)    Cooling circuit (11)    Water storage tank. (12)