CO 2 -free Steel Production by Means of Hydrogen. Prof. Dr.-Ing. Marc Hölling. 24. Oktober 2019. Prof. Marc Hölling. International Hydrogen Symposium. 1. CO 2 -Emissions by the German Steel Industry. ≈ 19.000.000 cars. Steel Industry (GER). =. • Total CO 2 -Emissions of Germany