Sunfire's world's largest high-temperature electrolyzer in Salzgitter is an important part for the Salzgitter Group's sustainability plans. After four years, the partners of the H₂ project GrInHy2.0 draw a positive conclusion.

With a record production of almost 100 tons of green H₂ for the climate-neutral production of green steel, Salzgitter AG and the electrolysis manufacturer Sunfire successfully complete the EU-funded GrInHy2.0 (Green Industrial Hydrogen) project.

Green H₂ is key to climate protection and the decarbonization of industries. Also in the steel industry, pioneers such as Salzgitter AG are introducing innovative technologies with SALCOS – Salzgitter Low CO₂ Steelmaking – to use the gas of the future for climate-neutral steel production. With GrInHy2.0, Salzgitter AG continued its successful cooperation with Sunfire to integrate novel electrolysis technologies for H₂ production in an industrial environment.

Since 2019, the project partners have been operating a high-temperature electrolyzer from Sunfire with an electrical connected load of 720 kW on the premises of Salzgitter Flachstahl – the plant is considered the world's largest and most efficient of its kind.

Dr. Alexander Redenius from the Salzgitter Mannesmann Forschung said, "GrInHy2.0 is an important part of our SALCOS project for CO₂-reduced steel production. Green H₂ is essential for producing low-CO₂ steel, as it reduces carbon emissions very efficiently. With GrInHy2.0, we have gained valuable insights into the integration of electrolysis into our production processes."

The green H₂ produced is fed directly into the hydrogen grid of Salzgitter Flachstahl – to date, almost 100 tons of the gas have been used in annealing processes and galvanizing plants for steel finishing. The partnership between Sunfire and Salzgitter AG is to continue beyond GrInHy2.0.

"For the transformation of steel production towards hydrogen-based processes, the criteria of availability and cost-effectiveness are becoming increasingly important. Therefore, high-temperature electrolysis is a very interesting technology in the field of steel production, which we will continue to support intensively," said Redenius.

Already at the beginning of the year, the Sunfire electrolyzer set new efficiency standards: For the first time, the project partners were able to demonstrate an electrical efficiency of 84 %el,LHV – this corresponds to an energy requirement of only 39.7 kWh/kgH₂. In addition, the system produced up to 200 Nm³ (standard cubic meters) of green H₂ per hour. No other operator has previously been able to demonstrate such high numbers.

The electrolyzer is based on the innovative solid oxide electrolysis cell (SOEC) technology and runs at operating temperatures of 850°C. The system utilizes industrial waste heat and renewable electricity to split steam into its components hydrogen and oxygen.

"GrInHy2.0 is an important lighthouse project for Sunfire, in which we successfully demonstrated our SOEC technology on an industrial scale," said Christian von Olshausen, Sunfire CTO. "At the same time, we have gained valuable insights for the further technical development. Projects like this lay the foundation for rapidly scaling electrolysis technologies worldwide."

In addition to Salzgitter Flachstahl, Salzgitter Mannesmann Forschung and Sunfire, the SMS Group company Paul Wurth, Tenova and the French research institution CEA are also part of the project.