NOVELTY - A bioelectrochemical system comprises housing (102) defining internal chamber; barrier (106) disposed within housing and partially separating the chamber into first compartment (110) and second compartment (112), where the first compartment includes autotrophic or heterotrophic microorganisms disposed in it; cathode (114) disposed within first compartment and coupled to power supply (118); and anode (116) disposed within second compartment and coupled to the supply, where the carbon dioxide received within the first compartment is transformed into an organic compound.    USE - As bioelectrochemical system (claimed).    ADVANTAGE - The bioelectrochemical system stimulates microbial activity such as in biodegradation, nitrate reduction, and hydrogen production; enhances the production of organic acids from carbonaceous feedstocks; reduces the amount of CO2 released into the atmosphere; and transforms CO2 into value-added products such as organic compounds and methane, where the organic compounds include organic acids, organic salts, hydrocarbons, alcohols, amines, esters, ethers, amides, lactams, and other categories of organic compounds.    DETAILED DESCRIPTION - A bioelectrochemical system comprises housing (102) defining internal chamber; barrier (106) disposed within the housing and at least partially separating the internal chamber into first compartment (110) and second compartment (112), where the first compartment includes at least one of autotrophic or heterotrophic microorganisms disposed in it; cathode (114) disposed within the first compartment and coupled to power supply (118); and an anode (116) disposed within the second compartment and coupled to the power supply, where the carbon dioxide received within the first compartment is transformed into an organic compound. INDEPENDENT CLAIMS are included for the following:    (1) method involving receiving carbon dioxide within first compartment disposed within an internal chamber defined by housing; receiving an electrical potential across cathode disposed within the first compartment and an anode disposed within second compartment within the internal chamber, where both compartments at least partially separated by barrier, the first compartment includes at least one of autotrophic or heterotrophic microorganisms disposed in it; and extracting organic compounds from the first chamber that are derived from the carbon dioxide; and    (2) system comprising the first bioelectrochemical system disposed within first well formed in subsurface formation.    DESCRIPTION OF DRAWING(S) - The figure shows view of bioelectrochemical system.    Housing (102)    Microbes (104)    Barrier (106)    Interior (108)    First compartment (110)    Second compartment (112)    Cathode (114)    Anode (116)    Power supply (118)