TECHNOLOGY FOCUS - ELECTRICAL POWER AND ENERGY - Preferred Membrane: The proton exchange membrane is made of substantially inert material having pores of less than 10 mum diameter.Preferred Apparatus: The bioreactor and the cathode compartment contain dissolved nutrients to facilitate growth of the chemolithotrophic microorganisms. The bio-fuel cell system further has a voltage control unit and reagent control unit. The voltage control unit applies and controls voltage on the cathode to control ratio of electrical production to biomass production, by varying microbial cultivation parameters. The reagent control unit controls ratio of ferrous ion and ferric ion concentration, and concentration of dissolved nutrients, for varying microbial cultivation parameters which in turn controls ratio of electrical production to biomass production. Alternately, the bio-fuel cell system comprises chemolithotrophic microorganisms immobilized on cathode, aqueous solution free from iron. Reaction at the cathode is a biological reduction of oxygen, and is given by O2+4H+4e-=2H2O, the electrons in the reaction are transferred from the cathode and attached to the microbial cells. Alternately, the bio-fuel cell system has cathode comprising ferric copolymer containing redox couple, chemolithotropic microorganism immobilized on the copolymer.Preferred Reaction: The electrochemical oxidation reaction is oxidation of hydrogen at the anode and is given by 2H2=4H++4e-, and the overall bio-fuel cell reaction is given by 2H2+O2=2H2O.Preferred Process: The ferric ions are re-circulated back to the cathode compartment. The chemolithotrophic microorganisms immobilized on cathode facilitates microbial immobilization.Preferred Solution: The aqueous solution in contact with the chemolithotropic microorganisms is a capillary layer, coating the chemolithotropic microorganisms and cathode.Preferred Electrode: The cathode is made from a chemically inert electrically conducting material. The cathode has layer of porous material, solid plate of material, or fibrous layer of material chosen from carbon, nickel and stainless steel.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Nutrients: The dissolved nutrients are ammonium sulfate, potassium phosphate, magnesium sulfate, potassium chloride, calcium nitrate, calcium chloride and/or sulfuric acid.Preferred Catalyst: The catalyst is gold, platinum, palladium or lead.Preferred Fluid: The fluid containing oxygen and carbon dioxide is oxygen-containing gas, preferably air, or aqueous solution containing dissolved oxygen and carbon dioxide.Preferred Compound: The chemically inert material is silicon dioxide powder or gel, aluminum oxide or calcium sulfate.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Fuel: The fuel having hydrogen constituent is hydrogen gas, methanol, methane and/or ethanol, preferably hydrogen gas.    TECHNOLOGY FOCUS - BIOTECHNOLOGY - Preferred Microorganism: The chemolithotrophic microorganisms are Acidithiobacillus ferroxidans, Leptospirillum ferroxidans, Acidimicrobium Alicyclobacillus, sulfobacillus.