Research of the Impact of Hydrogen Metallurgy Technology on the Reduction of the Chinese Steel Industry’s Carbon Dioxide Emissions

Figure 7 shows the steelmaking technology path in the BAU scenario. From 2020 to 2050, the modeled future steelmaking technology is dominated by the converter steelmaking process, supplemented by electric furnace steelmaking technology. The steel production of converter steelmaking decreases, and the production of electric furnace steelmaking steadily increases. The production of converter steelmaking drops from 947 to 399 million tons, a reduction of 57.86%. The production of electric furnace steelmaking increases from 117 to 222 million tons, an increase of 89.67%. When considering the modeled proportion of steel production in different steelmaking technologies, the proportion in converter steelmaking is seen to gradually decrease, and the proportion in electric furnace steelmaking to increase. The proportion in converter steelmaking decreases from 89% to 64.25%, and the proportion in electric furnace steelmaking increases from 11% to 35.75%.

The modeled ironmaking technology path in the BAU scenario is set out in Figure 8. From 2020 to 2050, the future ironmaking technology remains dominated by the ordinary blast furnace; the proportion from hydrogen-rich blast furnace ironmaking gradually increases, and the application of the hydrogen-rich shaft furnace–direct-reduction iron process is limited. Hydrogen metallurgy has great potential to reduce emissions, but it lacks technical maturity and its cost economy needs to be improved. Therefore, the ordinary blast furnace ironmaking remains dominant in the BAU scenario, and the hydrogen metallurgy technology is mainly based on the hydrogen-rich blast furnace ironmaking process. From 2020 to 2050, iron production is modeled to fall from 909 to 322 million tonnes, due to falling steel demand and increasing scrap resources. As the proportion in ordinary blast furnace decreases, the proportion in hydrogen-rich blast furnace ironmaking gradually increases, while the proportion in hydrogen-rich shaft furnace–direct reduction iron remains relatively small. The proportion in ordinary blast furnace iron production decreases to 73.88%, the proportion in hydrogen-rich blast furnace ironmaking increases to 20.48%, and the proportion in hydrogen-rich shaft-furnace–direct-reduction iron increases to 5.65%.

The modeled technical path of pre-iron production in the BAU scenario is set out in Figure 9. From 2020 to 2050, the coke, sinter, and pellets produced by coking, sintering, and pelletizing shows a downward trend in the BAU scenario. Coke production drops from 423 to 136 million tons, a 67.87% decrease; sintering production falls from 954 to 234 million tons, a decline of 75.49%; and pellet production drops from 318 to 216 million tons, down 32.09%. Of these, coke is the most important component in blast furnace ironmaking. However, as new ironmaking technologies, such as large-scale blast furnace and hydrogen metallurgy are developed and applied, the coke ratio may continue to decline, from 0.47 to 0.42 tons/ton, a decrease of 9.28%. In addition, due to the increase in the proportion of pellet and sinter in the blast furnace burden structure, the modeled consumption of sinter per ton of iron in China continues to decline, from 1.05 to 0.73 tons/ton, a decrease of 30.81%; iron pellet consumption continues to increase, from 0.35 to 0.67 tons/ton, an increase of 91.73%.

The modeled CO₂ emissions for steel production in the BAU scenario are set out in Figure 10, which shows that the largest proportion of CO₂ emissions is consistently produced by ironmaking in steel production. From 2020 to 2050, the modeled proportion of CO₂ emissions in ironmaking decreases from 61.86% to 58.51%. Despite trending downward, it continues to account for more than half of the iron and steel production CO₂ emissions. Pre-iron CO₂ emissions are the second largest source of emissions in the steel production process, decreasing from 34.23% to 31.67%. The CO₂ emissions are lowest, but the expected proportion increases slightly from 3.91% to 9.82%, due to the increase of electric furnace steel.

The modeled CO₂ emissions of the pre-iron process in the BAU scenario are set out in Figure 11, which includes CO₂ emissions from coking, sintering, and pelletizing. From 2020 to 2050, the total CO₂ emissions in the pre-iron process trends downward, from 738 to 237 million tons, a 67.84% decrease. Of this decrease, the CO₂ emissions in the sintering process decreased the most. The CO₂ emissions in the coking process drop from 357 to 112 million tons, a decrease of 68.50%. The CO₂ emissions in the sintering process drop from 296 to 96 million tons, a decrease of 76.74%. The CO₂ emissions in the pellet process decline from 85 to 56 million tons, a decrease of 34.29%. From a proportion of CO₂ emissions perspective, coking accounts for the largest proportion of CO₂ emissions, but trends downward, falling from 48.39% to 47.40%, while the proportion of CO₂ emissions from sintering decreases from 40.05% to 28.97%. The proportion of CO₂ emissions from pellets increases from 11.57% to 23.64%, due to the increasing proportion of pellets in the blast furnace burden.

The modeled CO₂ emissions in the ironmaking process in the BAU scenario are set out in Figure 12. In the BAU scenario, CO₂ emissions from ordinary blast furnace ironmaking are the main source of CO₂ emissions. From 2020 to 2050, the total CO₂ emissions fall from 1.333 billion tons to 438 million tons, a 67.12% decrease. Of this decrease, the CO₂ emissions of ordinary blast furnace ironmaking decrease from 1.333 billion tons to 347 million tons, a decrease of 73.98%. However, the proportion remains high, reaching 79.13% by 2050. Hydrogen-rich blast furnace ironmaking and hydrogen-rich shaft furnace–direct reduction iron technology are projected to be widely used, although their respective CO₂ emissions are relatively low. By 2050, the CO₂ emissions of the two reach 55 and 0.13 million tons, respectively. The proportion of CO₂ emissions in the ironmaking process are 17.91% and 2.96%, respectively.

The CO₂ emissions of the steelmaking process in the BAU scenario are set out in Figure 13. In the BAU scenario, CO₂ emissions from steelmaking show a fluctuating downward trend from 2020 to 2050, falling from 0.84 billion tons in 2020 to 0.74 billion tons in 2050, a fluctuating decrease of 12.61%. Of this fall, the CO₂ emissions of converter steelmaking decrease from 30 to 0.08 million tons, a decrease of 74.91%. Electric furnace steelmaking only directly produces small CO₂ emission, but the indirect emission of electricity is the main reason for its high total CO₂ emissions. From 2020 to 2050, the CO₂ emissions from electric furnace steelmaking increase from 0.54 tons to 0.66 billion tons, a 22.12% increase, and the proportion of CO₂ emissions from electric furnace steelmaking increase from 64.21% to 89.73%.

Figure 14 shows the modeled impact of steel production changes, scrap steel use, and hydrogen metallurgy technology application on CO₂ emissions in the steel industry in the BAU scenario. From 2020 to 2050, the decline in steel demand leads to a decrease in CO₂ emissions, which fall from 2.156 to 1.258 billion tons. The use of scrap steel and the application of hydrogen metallurgy technology may further reduce CO₂ emissions, producing a total emission reduction of 509 million tons. Of these, scrap steel use reduces CO₂ emissions to 952 million tons in 2050, while applying hydrogen metallurgy technology reduces steel industry CO₂ emissions to 749 million tons in 2050. The modeled average contribution of scrap steel use to CO₂ emission reduction in the steel industry is 60.15%, and the average contribution of hydrogen metallurgy technology application to CO₂ emission reduction is 39.85%.