Why it is so important to push for a Circular Steel Economy

What a big step! Great that thyssenkrupp Steel will replace two blast furnaces with H2 direct reduction plants (DRI) by 2030. From then they aim to produce 3 mio tons of greensteel.

Beside thyssenkrupp in Duisburg other leading steel producers like voestalpine in Linz or Arcelor Mittal in Hamburg are working towards a clean reduction process of iron ore replacing coal by hydrogen to produce green pig iron (which is the basis for the following steel production process).

But how about the energy demand?

At least 600 Nm³ or 54 kg of hydrogen are required for the production of one ton pig iron . The electrolytic production of 54 kg H2 requires 3 MWh of energy resulting in a total green energy demand of 9 TWh for 3 mio tons of pig iron at thyssenkrupp in Duisburg.

Assuming two thirds of the entire production volume of thyssenkrupp of 11 mio tons of crued steel are based on pig iron and therefore going through the blast furnace the requirement for green energy would be about 22 TWh.

Some figures for comparison:
World steel production: 1864 mio tons (2020)
World pig iron production: 1300 mio tons (2020)
German steel production: 35.7 mio tons (2020)
German pig iron production: 22.5 mio tons (2020)
Austrian steel production: 7.4 mio tons (2019)
German wind energy production: 132 TWh (2020)
Austrian total electricity production: 73.4 TWh (2019)

Let’s focus on Austria:

76,5 % or about 5.7 mio tons of Austria’s steel production comes from pig iron production. The remaining 23.5 % are coming from scrap and are already closing the recycling loop. As we can assume a similar energy demand as indicated above for the green iron production about 17 TWh would be required to convert the Austrian pig iron production volume to hydrogen technology.

This is almost the entire renewable energy production of all river power plants in Austria which generate 22.6 TWh per year [1]!
And it would also be in the range of the entire electrical energy demand for all passenger cars in Austria, if they all would be electric!

Considering this huge demand for renewable energy it is becoming clear that, in addition to these positive and enormous technological efforts, we should aim for a significantly lower pig iron consumption overall and therefore have to foster circular concepts that will lead to a much lower iron ore requirement in the future.