Pathways for decarbonizing China's iron and steel industry using cost-effective mitigation technologies: An integrated analysis with top-down and bottom-up models

The iron and steel industry (ISI), the second largest carbon emitter, produces 16 % of China's CO2 emissions, and its decarbonization will therefore play an important role in achieving the goal of carbon neutrality. This study identifies underlying low-carbon transition pathways of the ISI towards 2050, through investigating macro-level mitigation policies and technological advances. An integrated assessment model that integrates a top-down CGE method and a bottom-up objective planning method was constructed. The results show that the combination of mitigation policies and technological measures would substantially reduce CO2 emissions in the ISI, with the remaining 140 Mt to 520 Mt by 2050. Carbon mitigation in ISI in the short term mainly benefits from the technology retrofitting, the reduction of steel demand, which accounts for 17.8 % and 32.1 %, respectively. Breakthrough technologies of scrap-based electric arc furnace (EAF), hydrogen-based direct reduction (HDR-EAF) and carbon capture and storge (CCS), would play a fundamental role in reducing the CO2 emissions especially after 2030, contributing to 32.1 %, 16.0 % and 13.8 % of emission reduction, respectively. Of the 41-technologies assessed, 8-key technologies jointly mitigate over 55 % of CO2 emissions. The cost-effectiveness and mitigation potential of technologies would provide reference to policymaker for the mitigation in China's ISI.