Technical and Environmental Assessment of New Green Iron Production Strategies using Hydrogen

In order to assess the decarbonization potential and overall environmental benefits of new reduction pathways in the ironmaking industry, using hydrogen to produce Direct Reduced Iron (DRI), a coupled approach combining process simulation for rigorous technical and energy evaluation of iron ore conversion and Life Cycle Assessment (LCA) for environmental assessment was developed and extended to two alternative renewable heating strategies: (i) electric gas heating and (ii) solar reactor heating. The entire hydrogen-based ironmaking process, including conversion in a shaft reactor, gas and solid heating, gas recycling, and electrolysis, was therefore simulated. The hydrogen-based reduction of iron ores in the shaft reactor was modeled using a rigorous reactor model describing the reduction of multi-layer iron ore pellets in countercurrent gas–solid moving beds, with the particularity of representing the dual influence of particle size and temperature on conversion. The remainder of the process including gas recycling and hydrogen production, was simulated using ProSim software. The hydrogen-based green ironmaking scenarios were then compared to MIDREX NG, a leading natural gas-based reduction technology. Hydrogen-based scenarios, powered by the French electricity mix, reduce carbon footprints by 53 % for electric gas heating and 57 % for solar reactor heating, potentially reaching 82 % (− 0.79 kgCO2-eq/kgDRI) with low-carbon electricity (hydro, nuclear). Compared to MIDREX NG, the energy requirements of both hydrogen-based scenarios are primarily determined by the use of electricity for hydrogen production, illustrating the importance of hydrogen production for the assessment of future hydrogen-based green ironmaking.