The HyBeSt project, funded under the code 03SFK3P0‑2 and carried out within the Copernicus research programme, set out to create a hybrid heating system for the steel industry that could use renewable electricity to pre‑heat combustion air and thereby reduce fossil fuel consumption. Over a 44‑month period from 2019 to 2023, the consortium—led by tkSE, with partners ArcelorMittal and Salzgitter Flat Steel—progressed through seven work packages that covered data collection, concept design, demonstrator construction, laboratory testing, and finally a pilot run in an operating plant.

The core technical achievement was the development of a hybrid‑heated radiation tube (Strahlrohr) that combines conventional gas heating with electric pre‑heating. Each tube has a nominal power of about 50 kW. In the 15 hot‑dip galvanising lines that were in operation in Germany during the project, roughly half were horizontal lines that use this tube type. The consortium estimated that 10–12 tubes per plant could be replaced by the new hybrid design. For the horizontal lines of tkSE alone, a full conversion would provide 2.5–3 MW of flexible heating capacity; the other partners’ plants added another 1.5–1.8 MW, giving a total German flexibility potential of 4.0–4.8 MW. Extending the analysis to the global market, the team identified more than 600 hot‑dip coating lines worldwide, of which about 50 % use the same tube type. Assuming 10 tubes per line at 50 kW each, the worldwide flexibility potential reaches roughly 150 GW, although this capacity would be distributed across continents and would not be available simultaneously.

The demonstrator, built in a technical institute, was first tested under controlled conditions to validate the heat transfer and electrical integration. The tests confirmed that the hybrid tube could deliver the required temperature profiles while allowing rapid adjustment of the electric pre‑heating component. In the final work package, the system was installed in a production plant and operated for several weeks. The pilot run showed that the hybrid tube could be switched between gas‑only, electric‑only, and combined modes without compromising product quality, and that the electric component could be modulated to match renewable supply fluctuations.

The project’s scientific contribution lies in demonstrating a practical, scalable hybrid heating concept that can be retrofitted to existing steel‑processing equipment. By providing a measurable flexibility window—up to 150 GW globally—and by reducing fuel use in key processes such as hot‑dip galvanising, the HyBeSt system offers a tangible pathway for the steel sector to align with the energy transition. The consortium’s findings are expected to inform future policy and investment decisions, and the demonstrator’s design files and performance data will be made available to industry stakeholders.