GrInHy as a component – “green” hydrogen for steel production
The integration of new facilities into the existing infrastructure is a challenge. This challenge involves not only the flexible use of hydrogen and natural gas and reduction agents in the direct reduction process but also flexible hydrogen production based on renewable energies. After all, CO2 savings within the process are voided if hydrogen, for instance, is produced on the basis of natural gas or electrolytically using the current electricity mix.
In order to potentially produce hydrogen ourselves in the future, Salzgitter AG has been cooperating in an EU research project together with Sunfire GmbH and other partners since March 2016: GrInHy (= Green Industrial Hydrogen via reversible high-temperature electrolysis). The facilities in Salzgitter also feature the world’s currently most powerful reversible high-temperature electrolyser.
The technology of high-temperature electrolysis enables the reversible operation of the trial facilities. While, during electrolysis operation with the highest electrical efficiency levels, the technology turns industrially generated steam from waste heat into hydrogen, in the reverse case of fuel cell operation, it produces electricity and heat from hydrogen or natural gas.
The electrolytically generated hydrogen can already be used today as a shield gas enabling annealing processes to be used for steel production and replaces fossil-based hydrogen. In the future, naturally with significantly larger capacities, use as a substitute for carbon for the direct reduction of iron oxide is feasible.
Along with the proof of electrical efficiencies of more than 80% (in terms of calorific value), the test operation of the techno-economic assessment of the technology also serves as proof in the context of competitive hydrogen production.