Process for producing polycarbonate, comprising at least the steps of producing at least chlorine and hydrogen by chloralkali electrolysis of alkali metal chloride, preferably sodium chloride, in aqueous solution, providing a purified CO 2 gas stream produced by a method containing at least the steps of: providing a CO 2 gas stream, purifying the CO 2 gas stream of secondary constituents, in particular of nitrogen oxides, sulfur compounds, dust, water, oxygen and HCl, optionally by adsorption, gas scrubbing or catalytic treatment to obtain a gas stream of purified carbon dioxide, introducing hydrogen together with the purified CO 2 gas stream into an RWGS reaction zone and reacting the reactants according to the principle of RWGS to afford a product gas mixture containing not only unconverted reactant but also steam, CO and optionally byproducts, in particular lower hydrocarbons, especially preferably methane, separating the water of the steam from the product gas mixture, separating unconverted carbon dioxide from the gas mixture of the RWGS reaction obtained from the separation, in particular by amine scrubbing, and recycling the unconverted carbon dioxide into the RWGS reaction, separating the hydrogen unconverted in the RWGS reaction from the gas mixture of carbon monoxide and hydrogen obtained after the separation, in particular using a coldbox, and recycling the separated hydrogen into the RWGS reaction, introducing the remaining carbon monoxide from the separation into the phosgene synthesis, supplying the previously formed chlorine into the phosgene synthesis, synthesizing phosgene from carbon monoxide and chlorine, reacting at least phosgene with at least one diol to afford at least one polycarbonate. producing at least chlorine and hydrogen by chloralkali electrolysis of alkali metal chloride, preferably sodium chloride, in aqueous solution, providing a purified CO 2 gas stream produced by a method containing at least the steps of: providing a CO 2 gas stream, purifying the CO 2 gas stream of secondary constituents, in particular of nitrogen oxides, sulfur compounds, dust, water, oxygen and HCl, optionally by adsorption, gas scrubbing or catalytic treatment to obtain a gas stream of purified carbon dioxide, providing a CO 2 gas stream, purifying the CO 2 gas stream of secondary constituents, in particular of nitrogen oxides, sulfur compounds, dust, water, oxygen and HCl, optionally by adsorption, gas scrubbing or catalytic treatment to obtain a gas stream of purified carbon dioxide, introducing hydrogen together with the purified CO 2 gas stream into an RWGS reaction zone and reacting the reactants according to the principle of RWGS to afford a product gas mixture containing not only unconverted reactant but also steam, CO and optionally byproducts, in particular lower hydrocarbons, especially preferably methane, separating the water of the steam from the product gas mixture, separating unconverted carbon dioxide from the gas mixture of the RWGS reaction obtained from the separation, in particular by amine scrubbing, and recycling the unconverted carbon dioxide into the RWGS reaction, separating the hydrogen unconverted in the RWGS reaction from the gas mixture of carbon monoxide and hydrogen obtained after the separation, in particular using a coldbox, and recycling the separated hydrogen into the RWGS reaction, introducing the remaining carbon monoxide from the separation into the phosgene synthesis, supplying the previously formed chlorine into the phosgene synthesis, synthesizing phosgene from carbon monoxide and chlorine, reacting at least phosgene with at least one diol to afford at least one polycarbonate.