Ah I think you're misunderstanding the question about the steel. Steel contains quite a bit of carbon (the element carbon) dissolved in the iron, on the order of 1% of the steel bulk is elemental carbon. You need to get that carbon from somewhere and coal is good source of carbon.

No research is going to replace the carbon in steel with something clean, your article is about the energy used in steel production and not the elemental carbon going into the steel itself.