Influence of Hydrogen Production in the CO2 Emissions Reduction of Hydrogen Mettalurgy Transformation in  Iron and Steel Industry

The transformation of hydrogen metallurgy is a principal means of promoting the iron and steel industry (ISI) in reaching peak and deep emissions reduction. However, the environmental impact of different hydrogen production paths on hydrogen metallurgy has not been systemically discussed. To address this gap, based on Long-range Energy Alternatives Planning System (LEAP), this paper constructs a bottom-up energy system model that includes hydrogen production, iron and steel (IS) production, and power generation. By setting three hydrogen production structure development paths, namely the baseline scenario, business-as-usual (BAU) scenario, and clean power (CP) scenario, the carbon dioxide (CO2) emissions impact of different hydrogen production paths on hydrogen metallurgy is carefully evaluated from the perspective of the whole industry, and each IS production process. The results show that, under the baseline scenario, the hydrogen metallurgy transition will help the CO2 emissions of ISI peak at 2.19 billion tons in 2024, compared to 2.08 billion tons in 2020, and then gradually decrease to 0.78 billion tons in 2050. However, different hydrogen production paths will contribute to the reduction or inhibit the reduction. In 2050, the development of electrolysis hydrogen production with renewable electricity will reduce CO2 emissions by an additional 48.76 million tons (under the CP scenario), while the hydrogen production mainly based on coal gasification and methane reforming will increase the additional 50.04 million tons CO2 emissions (under the BAU scenario). Moreover, under the hydrogen production structure relying mainly on fossil and industrial by-products, the technological transformation of blast furnace ironmaking with hydrogen injections will leak carbon emissions to the upstream energy processing and conversion process. Furthermore, except for the 100% scrap based electric arc furnace (EAF) process, the IS production process on hydrogen-rich shaft furnace direct reduced iron (hydrogen-rich DRI) have lower CO2 emissions than other processes. Therefore, developing hydrogen-rich DRI will help the EAF steelmaking development to efficiently reduce CO2 emissions under scrap constraints.