quality:corruption
H direct reduced ironmaking

Alternatively, hydrogen can be used in a shaft furnace to reduce the iron oxides. Only water is produced as the by-product of the reaction between iron oxide and hydrogen, and results in emission-free iron-making. Known as hydrogen direct reduction (HDR), this is the most prominent among green steel technologies. This differs from conventional steel making processes, in which carbon in coke is used as the reductant (to strip oxygen from iron ore), which creates iron and carbon dioxide. Where hydrogen is generated from a renewable energy source as both thealternative reductant and the fuel, the greatest gain in CO emissions is achieved. As of 2021, only ArcelorMittal in France, Voestalpine in Austria, and TATA in the Netherlands were committed to using green hydrogen to make steel from scratch.

HDR is employed in the HYBRIT project in Sweden. However, this approach requires a substantial amount of renewables to produce the needed renewable hydrogen. For the European Union, it is estimated that the hydrogen demand for hydrogen-based steelmaking would require 180 GW of renewable capacity.