Hydrogen direct reduction of iron

technology

The route that removes carbon from primary steelmaking by changing the reducing agent. In a direct-reduction shaft furnace, iron ore pellets are reduced in the solid state below the melting point; the conventional version uses reformed natural gas, and the hydrogen version uses hydrogen alone, so that the reaction product is water rather than carbon dioxide. The sponge iron produced is then melted in an electric arc furnace, usually with scrap, to make steel. The chemistry has been demonstrated: the Swedish HYBRIT consortium of SSAB, LKAB and Vattenfall produced hydrogen-reduced sponge iron at its Luleå pilot and delivered the first steel made from it to Volvo in 2021. What has not been demonstrated is the economics at scale, and the reason is arithmetic rather than metallurgy. Reducing a tonne of iron takes tens of kilograms of hydrogen; producing hydrogen by electrolysis takes on the order of fifty kilowatt-hours per kilogram at system level; so a plant of ordinary commercial size needs electrolysers of hundreds of megawatts and a firm supply of low-carbon electricity measured in terawatt-hours a year. That is why the announced projects cluster in northern Scandinavia, in Spain and in places with exceptional wind or hydro resource, rather than beside the existing steel plants of the Ruhr, Anshan or the American Midwest. Not a place.

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