Comment We can do most of the work with hydrogen. (Score 1) 192
Most of the carbon used in steelmaking is consumed reducing the iron oxides to iron in the smelting process. That job can be done with hydrogen, if you have excess energy to electrolyse it from water.
Then you can use a small amount of carbon as an alloying agent - likely from coal but it could be from CO2 of we were working to capture it at the time.
This all doesn't make sense now, of course. Iron smelting is one place that coal use remains logical.