J.H. Ng, K. Lee, G. Zang, P. Sun, E. Amgad
Argonne National Laboratory,
Keywords: Steel, Decarbonization, Green Technology
Summary:The steel sector in the U.S. produces 72 metric tons of CO2 annually and represents one of the largest sources of CO2 emissions. Currently, the industry employs blast furnace-basic oxygen furnace (BF-BOF) and electric arc furnace (EAF) technologies to manufacture virgin and recycled steel, respectively. Traditionally, these processes involve heavy use of carbon-based reducing agents such as coke and carbon monoxide, while also using significant natural gas, coal, and electricity inputs. This causes significant CO2 emissions due to on-site emissions and the high fossil fuel consumption. For example in the United States, BF-BOF process leads to 1990 kg CO2e/MT steel production while EAF results in 270 kg CO2e/MT, resulting in a national average emission of 791 kg CO2e/MT steel. In an effort to decarbonize this sector, new technologies such as direct reduced iron (DRI) has been developed and commercialized by using natural gas (NG). For further GHG emission reduction, technologies using H2, such as DRI-H2 or FIT, are of great interest. We investigated the steel production decarbonization opportunities for various technologies, (BF-BOF, EAF, DRI-EAF and FIT-EAF) by considering various decarbonation approaches (e.g. renewable natural gas, biochar, clean electricity and green hydrogen, carbon capture and storage (CCS), etc). In each steel production technology, the well-to-gate (WTG) emissions and levelized costs of steel production (LCOS) are calculated. From these technologies, various decarbonization approaches were examined and the potential energy demand for decarbonization was estimated. For example, by adding CCS system to the BF-BOF process, the CO2 emissions were observed to be reduced by 52% from 1990 kgCO2e/MT to 965 kgCO2e/MT. Significant reductions to emissions were also observed when comparing the traditional BF-BOF process to the newer FIT-EAF-H2 process, which has overall emissions of 653 kgCO2e/MT. When using newer DRI technology combined with the fuel switching to renewable natural gas (RNG) and clean electricity, DRI-EAF-NG technology can achieve WTG emissions of as low as 145 kgCO2e/MT.