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 . <EOS>