The steel industry is working on solutions. According to the Leadership Group for Industry Transition, at least 73 green steel projects are in progress. But the researchers say the technology just isn't there yet.

"These technologies still face serious technical, economic, and social challenges, and have yet to be implemented at scale," said Takuma Watari, a researcher at the National Institute for Environmental Studies in Japan and the paper's first author, in a news release. It's still unclear whether enough electricity will be available in the future to power these innovations, he said.

Better processes for recycling steel scraps into high-quality materials are needed, the researchers write. They call for partnerships between the steel industry and users in a variety of sectors. But the current system "is incompatible with a zero-emission future," they write.

Eoin Treacy's view

Electric arc furnaces rely on scrap steel and the major steel producers in developed countries have been busy securing scrap supplies over the last decade. If global steel production is to grow, then relying on scrap to provide carbon content is not going to be sufficient. That means either production new steel is going to have to become much more carbon efficient or the global sector will need to contract significantly to meet carbon emissions targets.

This article from NewAtlas today highlights how the big the promises of future efficiencies are but also how long it would take to even get a test facility built. Here is a section:

And that's just the UK; somewhere around 70% of the world's steel is currently produced using BF-BOF plants. The potential scope of the decarbonization opportunity here is absolutely enormous.

But – and there's always a but – this is currently nothing more than a research paper, the first-principles calculations around the idea. The team is yet to prototype such a facility, and there are some unknowns it wants to look into before moving forward.

Firstly, coke is used as a structural support in blast furnaces, and the team says research is needed into how badly heat and mass flows would be affected if it was taken away. Secondly, the team says more research should focus on reducing the energy requirements of nitrogen/carbon monoxide separation. And thirdly, experiments will need to be done over a period of years before the replacement rate of the perovskite materials can be understood.

Permanently high prices for carbon are required to ensure these kinds of solutions are even considered.