Multidimensional sustainability implications of alternative iron and steel industry decarbonization strategies in China

The urgency of a rapid and deep decarbonization of the iron and steel (IS) industry cannot be overstated in pursuing China's carbon neutrality target. Beyond CO2 emissions, the IS industry is also responsible for numerous non-climate impacts. We explored the impacts of alternative decarbonization options of the IS industry on economic cost, water, energy, CO2, and air pollutant emissions from a systematic perspective. While all decarbonization pathways yield co-benefits on air pollutants emissions for the IS industry, the profiles of carbon leakage and spillover effect depend strongly on technology choice. Mitigation scenarios focusing on hydrogen- based direct reduction result in increases of CO2, SO2, and NOx emissions from upstream energy supply. In CCS-led scenarios, fuel substitution could result in an expansion of charcoal-making and corresponding emissions of particulate matter. Thus, policymakers must consider the proper combination of upstream energy supply chain and decarbonization options for IS to avoid undesirable outcomes.