NOVELTY - The method comprises contacting a gas stream with an anode of a bioelectrochemical device as a gas-continuous stream, and controlling a humidity level of the gas stream such that the humidity of the gas stream is 40% before entry of the gas stream into the bioelectrochemical device. The anode: contains microbes that oxidatively degrade the gaseous compounds while producing electrical energy or hydrogen gas by the oxidative degradation, and a proton-conducting liquid film on its surface and/or interior portions; and is sufficiently porous such that gas is permitted to flow through the anode.    USE - The method is useful for producing electrical energy or hydrogen gas from a gas stream containing gaseous compounds including mercaptan compound and/or carbon monoxide oxidatively degradable by microbes such as Rubrivivax gelatinosus, Butyribacterium methylotrophicum, Clostridia, and Rhodospirillus rubrum (all claimed), where the electrical energy or hydrogen gas is useful as a fuel source to power a process including a fuel refining, biomass-processing, steam-methane reforming process, and hydrogenation such as hydrodesulfurization or Fischer-Tropsch process, Claus process, Merox process, and catalytic water-gas shift process.    ADVANTAGE - The method is capable of effectively and energy efficiently producing electrical energy or hydrogen gas from a gas stream with less energy consumption, optimal performance and increased electrical power output and without any wastage, and reduces or prevents the moisture loss during the production of hydrogen gas.    DETAILED DESCRIPTION - The method comprises contacting a gas stream with an anode of a bioelectrochemical device as a gas-continuous stream, and controlling a humidity level of the gas stream such that the humidity of the gas stream is 40% before entry of the gas stream into the bioelectrochemical device. The anode: contains microbes that oxidatively degrade the gaseous compounds while producing electrical energy or hydrogen gas by the oxidative degradation, and a proton-conducting liquid film on its surface and/or interior portions; is sufficiently porous such that gas is permitted to flow through the anode; and is present in electrical communication with a cathode of the bioelectrochemical device. The liquid film is maintained by an anode wetting process. The microbes are present in the form of a biofilm on the anode. The anode is a three-dimensional electrode, and comprises a form of elemental carbon. The anode is previously rendered hydrophilic by a suitable surface treatment process, which is a plasma treatment process. The anode possesses a porosity value of 50%, and a specific surface area of 5000 m2/m3. The proton-conducting liquid film has a thickness of 1-10 microns. The humidity level of the gas stream is controlled by passing the gas stream through a column of water. The gas stream emanates from a petroleum refining operation. The bioelectrochemical device is operated such that hydrogen gas is produced at the cathode by operating the bioelectrochemical device under the conditions that the cathode is constructed of a hydrogen producing material and is deoxygenated. The cell potential of the bioelectrochemical device is adjusted by application of an external voltage such that hydrogen is produced at the cathode. The bioelectrochemical device is operated such that the cathode electrochemically reduces reducible species other than hydrogen ions. A cation-permeable material is present in direct contact with the anode and cathode, and separates the anode and the cathode. The gas stream contains carbon monoxide and mercaptans, and emanates from a biomass gasification operation. The microbes on the anode are arranged for effecting a water-gas shift reaction. The electricity or hydrogen is produced from the bioelectrochemical device involved in an operation that produces the gas stream.    DESCRIPTION OF DRAWING(S) - The diagram shows a vertical gas-phase bioelectrochemical system with use of a filter or membrane for separating anode from cathode.