The carbon reduction potential of hydrogen in the low carbon transition of the iron and steel industry: The case of China

Greenhouse gas (GHG) reduction in China's iron and steel industry (CISI), which is responsible for more than 50% of global steel production, is essential for China's efforts to meet its carbon neutrality target. As one of the few options to achieve ultra-low GHG emissions in CISI, the GHG reduction benefits of hydrogen-based direct reduction (H-DR) are important. In this study, an life cycle (LC) assessment model in the CISI context is developed and various technology route are analyzed under a unified framework, combining hydrogen supply chain (HSC) modeling, actual data from steel plants and DR demonstration projects. The results show that under ideal HSC, compared with LC GHG emission of conventional route (2389.5 kgCO2,eq/t), hydrogen-enriched conventional route can achieve 10% GHG reduction, and if NG is used for H-DR heat supply, only 43.4% emission reduction could be achieved; if only pure hydrogen is used in H-DR, the GHG of H-DR would be close to that of scrap-electric arc furnace pathway (904.6kgCO2,eq/t) currently in China. The GHG emissions level of HSC lower than 200gCO2,eq/MJ can safeguard that the H-DR route comparable to BF-BOF route. H-DR can be rolled out across China to achieve emissions reductions only when both the HSC and electricity have low GHG emissions; both the hydrogen-enriched conventional route and the fossil fuel-based DR route can be used as transitional technologies then. In addition, this study examines the impact of analysis methods on the fairness of GHG accounting.