BENGALURU, Sept 1 (Reuters) - Swedish steelmaker SSAB (SSABa.ST) said on Wednesday it had partnered with Daimler"s (DAIGn.DE) Mercedes-Benz to introduce fossil fuel-free steel into vehicle production, with prototype parts for body shells planned for next year. SSAB plans to supply the market with fossil-free steel at a commercial scale in 2026, using the HYBRIT system to replace coking coal, traditionally needed for iron ore-based steelmaking, with electricity and hydrogen.Green steel venture HYBRIT (Hydrogen Breakthrough Ironmaking Technology) is created and owned by SSAB, Swedish state-owned utility Vattenfall (VATN.UL) and Swedish miner LKAB. Mercedes-Benz expects that by 2039 its new passenger car fleet will become carbon dioxide-neutral along the entire value chain. SSAB had in June partnered with Volvo Cars to jointly explore the development of fossil-free steel for use in the automotive industry.