FFS2 project delivers solutions to decarbonise steel production

The transition to fossil free steel requires not only new energy sources, but also system level solutions that work on an industrial scale. In the FFS2 project, VTT has addressed this challenge by developing and validating technologies that integrate electrification, hydrogen and circular material flows into existing and future steelmaking processes. The results strengthen the technological basis for industrial decision making and support a faster, lower risk transition towards fossil-free steel production

VTT validated a pilot-scale hybrid burner concept combining electrically preheated combustion air with gaseous fuels. Experiments and CFD simulations identified operating strategies—such as primary-air adjustments and high-temperature flue-gas recirculation—that can keep NOx emissions under control while maintaining high radiative heating performance. These results provide an engineering basis for industrial-scale burner designs that support flexible fuel choices and partial electrification.

VTT demonstrated with a 300 kW electrically heated rotary kiln that industrial-quality quicklime can be produced from limestone fractions with an energy consumption comparable to conventional fossil-fired systems. Because the electrified process yields a high‑CO₂ exhaust stream, it also offers improved integration with carbon capture technologies - an important element in the pathway to fossil‑free steelmaking.

A detailed techno-economic model developed by VTT shows how hydrogen valleys can integrate renewable electricity, electrolysis, hydrogen storage and hydrogen-based direct reduction (HDRI). The model reveals that flexible operation of HDRI can act as a large implicit hydrogen buffer, significantly reducing the need for storage infrastructure. For 2030 scenarios, hot-briquetted iron (HBI) production costs are estimated at 350–400 €/t using electrolytic hydrogen. During the transition period, hydrogen injection into existing blast furnaces could reduce local net CO₂ emissions by more than 20%.

Together with partners, VTT developed a Pt/TiO₂ catalyst for hydrogen release from liquid organic hydrogen carriers (LOHCs). The catalyst demonstrated superior stability, constant activity and minimal coking compared to conventional impregnated catalysts. The solvent-free synthesis method also eliminates waste and enables reproducible large-scale catalyst production.

VTT validated a TRL4 laboratory-scale process for direct reduced iron (DRI) using hydrogen carriers as reducers such as ammonia and benzene mixed into synthesis gas. The experiments showed that endothermic ammonia cracking can cool the reactor and reduce metallisation at high gas-flow rates. Carbon-based carriers, in turn, were found to promote carbon deposition, and higher benzene concentrations lowered apparent metallisation due to carbon accumulation. Overall, the results highlight the importance of careful thermal management and carbon control if hydrogen carriers are to be fed directly into DRI reactors.

VTT evaluated also process concepts using hydrogen‑rich biomass gasification gas and pure hydrogen for direct reduction of iron ore and assessed their techno‑economic feasibility for low‑carbon steel. The study found that synthesis gas reduction with a gas‑fired heater and top‑gas recycling had the lowest specific energy use and the lowest capital and raw material costs. Biomass‑gasification‑derived hydrogen with top‑gas recycling had the highest overall costs. Overall, synthesis gas reduction emerged as a cost‑effective option offering low carbon footprint, potential for biogenic CO₂ capture and improved thermal efficiency.

VTT advanced a GPU‑accelerated 3D CFD model to simulate slag foaming with biocarbon in electric arc furnaces. The tool successfully reproduced laboratory foam heights without overfitting, enabling large-scale studies of foam stability, char distribution and slag behaviour. This supports industrial optimisation of biocarbon injection strategies.

VTT also assessed biomass availability, material properties and business models for metallurgical biocarbon in the Nordics. Forestry residues were identified as the most sustainable feedstock, with key quality requirements including high fixed-carbon content, low ash and low impurities. The study highlighted the importance of local partnerships and energy-integration opportunities for commercial scalability.

VTT developed a combined hydrometallurgical process concept to recover zinc, iron and calcium from EAF dust and slag streams. Life-cycle assessment showed that secondary ZnS produced through this route has significantly lower climate impact than primary production, especially with low-carbon electricity. For cement applications, VTT found that hydrogen-based EAF slag is best suited for 15–30% replacement of cement when durability and reactivity are taken into account. This provides a realistic early-use pathway in construction while supporting the circularity of future steelmaking.

Through the FFS2 project, VTT has strengthened its role as a key developer of technologies enabling the transition to fossil-free steelmaking. The results provide concrete, near- to mid-term solutions for industry while supporting Finland’s and Europe’s long-term climate and industrial competitiveness goals.

FFS2 – Towards Fossil‑Free Steel, Phase 2 (2024–2025)

Funding: Business Finland and project partners
Partners: SSAB Europe Oy, Ovako Imatra Oy, Bet‑Ker Oy, Sapotech Oy, SFTec Oy, Hycamite TCD Technologies Oy, Luxmet Oy
Research organisations: VTT, University of Oulu, Åbo Akademi University
Project coordinator: Macon Oy
VTT’s budget: 1.8 M€ 
Total consortium budget: 9.9 M€ (Business Finland funding: 6.1 M€)
Final report and scientific publications: Towards Fossil- Free Steel Phase 2

Scientific publications - FFS2

More information about the FFS2 project https://www.ffs2.fi/