Future environmental impacts of global iron and steel production

Kurzfassung

The iron and steel industry is not only responsible for up to 9% of global greenhouse (GHG) emissions, but also associated with other environmental impacts. Anticipated growth in steel demand thus poses significant challenges to climate and environmental objectives. This study evaluates the future life cycle environmental impacts of global steel production, accounting for the adoption of emerging production technologies, including carbon capture and storage (CCS), hydrogen-based or electrified processes. We couple state-of-the-art life cycle assessment (LCA) models of current and future steel production routes with multi-sectoral, internally consistent scenarios for future energy and steel supply from the integrated assessment model (IAM) of IMAGE. This approach provides a comprehensive assessment of regional and temporal environmental impacts for three climate mitigation pathways: a 3.5 °C baseline, a <2 °C- and a 1.5 °C-target. Results demonstrate that electrified steel production technologies, both directly and indirectly powered, offer the highest GHG reduction potential achieving up to −95% by 2060 compared to current coke-based processes, provided that decarbonized electricity is used. They thereby clearly outperform CCS technologies for coke-based processes. Nevertheless, it is unlikely that global steel production will reach net-zero GHG emissions by 2060, with its emission intensity decreasing by −33% (3.5 °C-baseline), −56% (<2 °C-target), and −79% (1.5 °C-target) compared to 2020. Considering future steel demand growth, global annual GHG emissions may only be reduced by up to −67% by 2060, from 3.7 in 2020 to 1.2 Gt CO2-eq. per year. Cumulative emissions from steel production could thus consume 18–30% of the global end-of-the-century 1.5 °C carbon budget and 9–14% of the 2 °C budget by 2060. Our analysis reveals that the decarbonization scenarios could shift burdens from climate change to other impact categories, such as ionising radiation, land use, or material resources. The drivers of rising impacts are diverse and caused by different processes, e.g., electricity generation, furnace slag treatment, metal mining, or chemical production. Achieving sustainable steel production requires not only rapid decarbonization and demand reduction but also targeted process-specific interventions throughout the entire life cycle to mitigate future environmental impacts.