National labs team delivers techno-economic analyses of H2 DRI scenarios for green steel

In an open-access paper published in the RSC journal Energy & Environmental Science, a team from Lawrence Berkeley National Laboratory, Argonne National Laboratory, and Pacific Northwest National Laboratory report the results of techno-economic analyses of several design and operation scenarios for H₂ direct iron reduction (DRI) systems for the production of green steel.

Hydrogen-based direct reduced iron (H₂-DRI) is an alternative pathway for low-carbon steel production. Yet, the lack of established process and business models defining “green steel” make it difficult to understand what the respective H₂ price has to be in order to be competitive with commercial state-of-the-art natural gas DRI.

… The focus of this work is to characterize plausible hydrogen end use in iron and steelmaking in a manner that can inform coupling with H₂ generation and storage systems. In this study, break-even levelized cost of hydrogen (LCOH) targets for decarbonizing the steel industry with H₂-DRI are established by comparing H₂-DRI to the commercial natural gas-based direct reduced iron (NG-DRI) process. To enable this comparison, a detailed techno-economic analysis, supported by rigorous process modelling, is conducted.

… In summary, while H₂-DRI has been investigated in literature, this study provides a comprehensive techno-economic comparison of NG-DRI and H₂-DRI configurations. While most studies integrate the electrolyzer into their analysis, it needs to be recognized that economical H₂-production and economical H2-DRI operation are two connected but distinctively separate concerns. Along those lines, we provide insights into the pure H₂-DRI economics, study H₂-DRI operating parameters and their impact upon economics as well as derive break-even/target costs of H₂ to enable economical operation.

—Rosner et al.

Simplified flowsheet of the integrated hydrogen-based DRI steel mill. Rosner et al.

The authors examined five NG-DRI design scenarios and six H₂-DRI scenarios. Among their findings:

• Renewable H₂ use in integrated DRI steel mills for both heating and the reduction of iron ore can reduce direct CO₂ emissions by as much as 85%, but would require an H₂ procurement cost of $1.63 per kg H₂ or less.

• When using H₂ only for iron ore reduction, economic viability is reached at an H₂ procurement cost of $1.70 per kg, while achieving a CO₂ emission reduction of 76% at the plant site.

• System design optimization strategies around excess H₂ ratios in the DRI top gas and the H₂ recycle pressurization can further improve performance and economics.

• Low H₂ excess ratios are particularly attractive as they reduce pre-heating energy requirements and offer integration opportunities with static recycle ejectors if H₂ is supplied at sufficiently high pressure.

• The potential of utilizing the electric arc furnace off-gas is shown to be much more synergistic with H2-DRI than natural gas-DRI and can increase the break-even H2 procurement cost by up to 7¢ per kg H₂.

Resources

• Fabian Rosner, Dionissios Papadias, Kriston Brooks, Kelvin Yoro, Rajesh Ahluwalia, Tom Autrey, Hanna Breunig (2023) “Green steel: design and cost analysis of hydrogen-based direct iron reduction” Energy Environ. Sci. doi: 10.1039/D3EE01077E