NOVELTY - System comprises: a cathode compartment (14) containing a cathode electrode (22); an anode compartment (16) containing an anode electrode (20) and having at least one inlet for introducing a fuel having a hydrogen constituent into the anode compartment; an external circuit (60) making an electrical connection between the anode electrode and cathode electrode; a bioreactor including at least one inlet for introducing oxygen and carbon source, where the bioreactor comprises an aqueous solution; and a pump for circulating the aqueous solution between the cathode compartment and bioreactor.    USE - The system is useful for electrical power generation.    ADVANTAGE - The system: utilizes hydrogen as fuel and does not produce carbon dioxide, thus it is environmentally friendly; consumes carbon dioxide from atmosphere during its operation, thus helps in removing/reducing atmospheric carbon dioxide; utilizes chemolithoautotropic microorganism which exhibits very high efficiency for production of electricity; increases the voltage efficiency; eliminates the use of platinum at the cathode, thus it is economical; and produces potentially highly useful product, and biomass in the form of single-cell protein.    DETAILED DESCRIPTION - System comprises: a cathode compartment (14) containing a cathode electrode (22); an anode compartment (16) containing an anode electrode (20) and having at least one inlet for introduction of a fuel having a hydrogen constituent into the anode compartment, where the anode compartment is separated from the cathode compartment by a membrane permeable to protons; an external circuit (60) making an electrical connection between the anode electrode and the cathode electrode; a bioreactor including at least one inlet for introduction of oxygen and a carbon source into the bioreactor, where the bioreactor and the cathode compartment contains an aqueous solution having a pH below 1.2 and including the ferric ions and ferrous ions; a pump for circulating the aqueous solution between the cathode compartment and the bioreactor. The bioreactor: contains living microorganisms that are viable and active at a pH less than 1.2 and capable of oxidizing ferrous ions to ferric ions; and is in flow communication with the cathode compartment. An INDEPENDENT CLAIM is also included for production of electrical power, comprising: introducing the fuel having a hydrogen constituent into the anode compartment containing the anode electrode, in which electrochemical oxidation of the hydrogen constituent occurs to produce electrons and protons, where the protons cross a proton conducting membrane into the cathode compartment containing the cathode electrode, and the electrons travel to an external circuit and then flow into the cathode electrode in the cathode compartment, and the external circuit is connected to the cathode electrode and the anode electrode; introducing oxygen and the carbon source into the bioreactor; and circulating the aqueous solution including ferrous ions and ferric ions at a pH below 1.2 from the cathode compartment to the bioreactor, and from the bioreactor to the cathode compartment, with a reaction at the cathode electrode is reduction of ferric ions to ferrous ions by the electrons flowing to the cathode electrode from the external circuit, and simultaneously many microorganisms aerobically oxidizing ferrous ions to ferric ions in the bioreactor at the pH below 1.2, where the electrical power is obtained by electrons passing through an electrical load in the external circuit.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic illustration of a bio-fuel cell.    Cathodic compartment (14)    Anodic compartment (16)    Anode electrode (20)    Cathode electrode (22)    External circuit (60)