Oz said,
RR, what you should have been banging on about as a replacement for coal is-
Actually Oz what I'm banging on about is keeping CO2 out of the atmosphere so it reverts to it's natural level found before the industrial revolution.
The hydrogen is to provide the energy to melt the ore. If carbon has to be added later for strength/hardness so be it. The quantity involved is negligible compared to the amount used in smelting.