Net-Zero transition in the steel sector: beyond the simple emphasis on hydrogen, did we miss anything?

Abstract

There is an explosion of publications and of various announcements regarding the use of hydrogen in the steel sector as a way to arrive at Net-Zero steel production − particularly in Europe. Most of them describe process technologies on the one hand and commitment to implement them quickly in the steel sector in the form of roadmaps and agendas, on the other hand. The most popular process technology is H2 Direct Reduction (H2-DR) in a shaft furnace. Available technical literature, as abundant as it may be, is still fairly incomplete in making the pathway to Net-Zero explicit and credible. This paper tries to identify important issues which are not openly discussed nor analyzed in the literature, yet. Process-wise, open questions in technical papers are: (1) what are the best-fitted iron ores for H2-DR, (2) what downstream furnace, after H2-DR, can accommodate various raw materials, (3) how and how much carbon ought to be fed into the process, (4) what is the best design for the shaft, (5) should it be designed for both natural gas and H2 operations, or simply for H2, (6) how should the progress of R&D be organized from pilot plants up to full-scale FOAK plants and then to a broad dissemination of the technology, (7) what kind of refractories should be implemented in the various new reactors being imagined, etc. Cost issues are also widely open, as a function of green hydrogen, green electricity and carbon prices. How is hydrogen fed to the steel mill and what exactly is the connection to renewable electricity? Is the infrastructure that this calls for planned in sufficiently details? What is still missing is a full value chain picture and planning from mining to steel mills, including electricity and hydrogen grids. Two years after our last review paper on hydrogen, the overall picture has changed significantly. Countries beyond Europe, including China, have come up with roadmaps and plans to become net-zero by 2050, plus or minus 10 years. However, they do not rely as much on H2 alone, as Europe seems to be doing. What is most likely is that several process routes will develop in parallel, including, beyond H2-DR, Blast Furnace ironmaking and NG Direct Reduction with CCS, electrolysis of iron ore and scrap-based production in EAFs fed with green electricity, which would single-handedly support the largest part of production by the end of the century; as more and more scrap is to become available and be actually used. There is also a question for historians. The influence of Climate Change on Steel has been discussed continuously for more than 30 years. Why has the commitment to practical answers only solidified recently?