With the green hydrogen starting at 4.45  US$/kg, [1] hydrogen usage seems difficult. Not only the green hydrogen is very expensive, even the gray hydrogen is uneconomical. However, hydrogen production is a possibility when there is oversupply of electric energy.

In California, renewables as solar and wind already able to provide almost 100% of the energy, avoiding fossil fuels as coal and natural gas [2]. Both windy days or sunny days offer the possibility of in-excess production of energy [2], which can be employed for cheap hydrogen production.

Usually, DRI – Direct Reduction of Iron – request high quality iron ore [3], offering a possibility for Brazil in this market. Vale is considering a hub for HBI (hot briquetted iron) in Porto do Açu in Brazil [4]. Other possible hubs are planned for Saudi Arabia, Oman and Dubai, due to the possibility of cheap natural gas [5].

This study addresses economic issues of hydrogen usage in steelmaking.

The present study investigates the advantages and feasibility of the shaft furnace in direct reduction processes, highlighting its energy efficiency and flexibility in the choice of reducing agents. The complexity of the processes involved within the furnace is addressed, dividing it into four distinct zones. Although mathematical models have been developed to predict direct reduction, their application is limited due to the simplification required in the face of the complexity of the phenomena. The integration of the shaft furnace with partial replacement of the charge by self-reducing pellets is explored, demonstrating a potential increase in process efficiency and reduction in CO₂ emissions. This study proposes a multiphase and multicomponent mathematical model to predict the internal temperature distribution of the furnace, validated by simulations on an industrial scale. The results indicate a significant increase in productivity and metalization when using self-reducing pellets, as well as, a reduction in carbon emissions when partially replacing conventional reducing gas with hydrogen. The findings highlight the importance of optimizing operational parameters to maximize the benefits of the shaft furnace in direct iron production.

This study investigates the potential of combined injection of hydrogen as fuel and pulverized charcoal (PCH) in the operation of blast furnaces, aiming to reduce carbon emissions and increase energy efficiency. Through a detailed computational model, we analyzed various operational scenarios with different rates of PCH and hydrogen injection. The results demonstrate that the partial or total replacement of pulverized coal (PC) with PCH can significantly increase blast furnace productivity, reducing coke consumption and carbon emissions. An improvement in internal material distribution and temperature was also observed, with an acceleration in burden descent and a modification in the temperature pattern in the raceway region. Furthermore, it was found that progressive increases in PCH and hydrogen injection can lead to substantial increases in blast furnace productivity, with additional reductions in coke consumption and carbon emissions. These results highlight the potential of combined hydrogen and PCH injection as a viable strategy to promote sustainability and efficiency in the steel industry, aligned with decarbonization and circular economy objectives.