Assessment of low-carbon iron and steel production with CO2 recycling and utilization technologies: A case study in China

Highlights: • Carbon flow of green steel production plants were analyzed. • Economic feasibility of CO₂ utilization in iron and steel plant was analyzed. • High value added application of byproduct gas technologies was considered. • CO₂-CH₄ dry reforming unit to produce reduction gas for DRI production was included. Substance flow analysis (SFA) and energy and economic assessment were used in this study to analyze the utilization of CO₂ in the steelmaking system based on four scenarios: the conventional blast furnace-basic oxygen furnace (BF-BOF) process (Baseline case), the BF-BOF process with waste heat and energy recovery (Case-1), the BF-BOF process with CO₂ hydrogenation (Case-2), and the CO₂-CH₄ dry reforming process coupled with an electric arc furnace (EAF) (Case-3). The results suggest that Case-2 is competitive not only in carbon emission but also in energy consumption and economy as it reduces carbon emission and energy consumption by 136 kg and 53.7 kgce respectively. It also increases profits by 9.38 US$ per ton of steel compared to the Baseline case, thus promising to mitigate predicaments in China's present iron and steel industry. With higher levels of hydrogen in the composition of natural gas, Case-3 reduces carbon emission by 40% more than the Baseline case, but its energy consumption is close to that of the Baseline case. Besides, the production cost is 34% higher in Case-3 than in the Baseline case, owing to the high natural gas price in China. Only when the natural gas price falls to the American value, which is 70% lower than that of China, will Case-3 be economically feasible. In short, high production energy consumption and production costs lead to a lack of technical and economic impetus for Case-3 in the current market, even if it is associated with relatively low carbon emission. The key to solving this problem lies in identifying methods to realize reduced gas production with high efficiency and low cost.