Sustainable transition of the primary steel production: Carbon footprint studies of hot-rolled coil according to ISO 14067

Abstract

A shift away from traditional carbon-based towards a hydrogen-based steel production has to be stepwise so that technological challenges can be solved simultaneously to various other challenges like the evolution of green markets, political framework as well as the creation of hydrogen supply. First bridge technologies towards hydrogen-based steelmaking are crucial to generate a stable demand for hydrogen so that hydrogen supply can follow. Injection of hydrogen into existing blast furnaces is a prominent example to reduce greenhouse-gas emissions without the ambition to reach complete carbon neutrality. A subsequent next step on the way towards climate neutrality are modern Direct reduction units. This technology is able to reduce Iron oxides by natural gas and hydrogen, respectively. Within the existing plants Direct reduction units can be incorporated in various ways over time, thus offering a gradual and in the end complete transition to hydrogen and electricity based production. Since LCA studies provide crucial input for political and market-economy decision-making, the LCA community is of great importance for giving direction of transformation processes. Like other industries, the steel industry needs an allocation approach for greenhouse gas emission savings to evolve green markets, of which the methodology shall be discussed within the life cycle community. The current study presents carbon footprint assessments (ISO 14067) of hot-rolled coil for different future production scenarios. The following production routes are investigated: - Conventional blast furnace – basic oxygen furnace route - Injection of H2 into a blast furnace - Input of H2-based direct reduced iron (DRI) into a blast furnace - H2-based direct reduction combined with electrically melting from renewable energy.