(205c) Integrating Green Hydrogen Towards a Cleaner Steel Industry: Design and Scheduling of a Hydrogen Production and Lohcs Storage System

Iron and steel sectors are reported to represent 7% of global emissions (IEA, 2020). Hence, emissions reduction is a priority for steel production in order to meet the proposed sustainability goals. However, it is considered a hard-to-abate activity although several strategies have been proposed for its decarbonization. Among them, hydrogen direct reduction (H-DR) combined with Electric Arc Furnace (EAF) is a promising alternative (Vogl et al., 2018). Nevertheless, the production of green hydrogen is highly dependent of the availability of renewable resources and its storage and transportation is challenging using traditional technologies. This is mainly because the extreme storage conditions directly impact the process cost and safety (Abdin et al., 2021). At this point, the use of LOHCs can be a promising solution for this sector. They can store hydrogen under ambient conditions, release it on demand and make possible to reuse oil infrastructure. At the same time, costs may be lowered compared to other traditional alternatives such as compression if heat is provided from other sources (Rosner et al., 2023). For example, the use of Solid Oxide Fuel Cells (SOFC) seems promising to meet dehydrogenation heat demand (Preuster et al., 2018).

In this work, the potential use of hydrogen coming from electrolysis is explored to meet H-DR hydrogen demand for a typical steel production plant. LOHCs are used to store hydrogen allowing to address the fluctuations in its production. Additionally, electricity demand from steel plant (mainly EAF) is covered using renewable resources (wind and solar). However, hydrogen can also be used for power generation using SOFC when renewable resources availability is low. This approach allows to reuse the released heat to be used in LOHCs dehydrogenation (endothermic step). Additionally, battery energy storage may also be considered. Hence, a design and scheduling problem is presented for demand site management within these facilities to address the power and hydrogen demands in an optimal way. An MILP is formulated to minimize the total costs and set the system scheduling considering renewable generation with hourly data resolution. The hydrogenation and dehydrogenation processes have been already optimized from a process scale perspective for several LOHCs systems in previous work (Prieto et al., 2024). These include the modelling of each process unit and specifically, the chemical reactors are modelled considering rigorous reactor assessment (Prieto et al., 2023). These results are used here for the energy storage scheduling optimization.

The optimization was carried out considering different renewable scenarios for a self-sufficient steel production plant. The optimal capacities for the different processes to provide a stable hydrogen rate for steel production are calculated together with the optimal operation in an hourly basis. Different locations have been evaluated showing the different configuration and operation of these systems. Additionally, the differences between the evaluated LOHCs systems (e.g., storage capacity, energy use, prices) in the final results are evaluated. Thus, the use of LOHCs as an energy storage system in the steel industry offers an efficient and scalable solution for its decarbonization.

Acknowledgements

The authors acknowledge the support from the Ministry of Science and Innovation MICIN (PID2023-146231OB-I00) and the FPU, Spain grant (FPU21 /02413) to C.P.

References

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