Treibhausgasemissionen in der Betonstahlerzeugung

The steel industry is responsible for 7 % of global greenhouse gas (GHG) emissions. Considering rising production volumes per capita and the need to reduce overall GHG emissions to combat climate
change, it becomes clear that the steel industry needs to transform to more sustainable processes (Ryberg et al. 2018). In this study, we conduct a life cycle assessment (LCA) in the form of an environmental product declaration (EPD) for an Austrian reinforcing steel producer, the steel and rolling mill Marienhütte.
The reinforcing steel is made of 100 % recycled material in an electric arc furnace. The iron scrap is melted in the electric arc furnace and alloys are added. After the melting process in the furnace, the steel is cast into billets. The billets are then hot rolled at the same mill while still hot, saving heating energy. The reinforcing steel is rolled into rebars or coils.
The EPD follows the product category rules set by Bau-EPD GmbH, including a review by external experts. It includes the whole life cycle, from the product stage and construction process over the use phase and the end of life. The product stage includes the raw materials, transport and production of the reinforcing steel. For the construction process we consider transport and bending, while there are no notable emissions during the use phase of reinforcing steel. The end of life includes deconstruction, processing and
transport. The foreground data were provided by the steel and rolling mill Marienhütte and complemented by background data from ecoinvent v 3.5. In order to publish the acquired data and further improve the ecoinvent database, the Austrian reinforcing steel dataset was also published through ecoinvent (going
through another review process) and is available from version 3.7.
Results show that Austrian reinforcing steel has lower climate impacts than those stated in comparable studies by other producers. 42 % of the GHG emissions are due to the electricity used in the steel production and rolling process, considering the Austrian electricity mix including imports. Changing the
electricity mix to 100 % renewable resources reveals a GHG reduction potential of almost 40 % of the reinforcing steel production stage. The electricity use is the biggest environmental hotspot in electric arc furnace reinforcing steel production, and shows that a large part of the GHG emissions could be avoided
by using renewable electricity.