NOVELTY - Producing hydrocarbon products, comprises: (a) providing a substrate comprising carbon monoxide and optionally hydrogen to a bioreactor (4) containing at lest one microorganism; and (b) fermenting the culture in the bioreactor to produce at least one hydrocarbon product, and a post fermentation substrate, where the substrate of step (a) comprising carbon monoxide is produced by carbon dioxide reforming process.    USE - The method is useful for producing hydrocarbon products, which are ethanol, 2,3-butanediol (both preferred), propanol, butanol, acetate, butyrate, propionate, caproate, propylene, butadiene, isobutylene, ethylene, gasoline, jet fuel and diesel fuel (all claimed).    ADVANTAGE - The method: facilitates the recycling of methane, hydrogen, carbon dioxide and carbon monoxide in a carbon dioxide reforming process and reduces the energy loss associated with intermediate steps, hence it is cost effective; achieves desired retention time and reduces or eliminates the requirement of hydrogen for producing sulfur free methanol; improves the efficiency of the fermentation, when compared to conventional methods; provides the hydrocarbons, which are easily transported and delivered in a usable form to industrial, commercial, residential and transportation end-users.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a system for producing the hydrocarbon product, comprising: the bioreactor containing the culture of microorganisms adapted to produce the hydrocarbon product by fermentation of carbon monoxide and/or hydrogen containing substrate, where the bioreactor is adapted to receive the carbon monoxide and/or hydrogen containing substrate from a carbon dioxide reforming module (10); the carbon dioxide reforming module; and means for supplying the substrate comprising carbon monoxide and/or hydrogen from the carbon dioxide reforming module to the bioreactor, where the carbon dioxide reforming module comprises a carbon dioxide reformer configured to produce the substrate.    DESCRIPTION OF DRAWING(S) - The figure shows the system and method for producing hydrocarbons.    Bioreactor (4)    Pressure swing adsorption module (6)    Carbon dioxide reforming module (10)    Digestion module (12)