Optimal Design of Renewable Power-To-Hydrogen Systems for the Decarbonization of a Semiconductor Industry

Hard-to-abate industries require significant amounts of hydrogen, which is mainly used as feedstock, reducing agent and gas carrier. Currently, most of this demand is met by fossil-based hydrogen produced on-site or delivered by trailers. There is therefore huge potential to decarbonize these industries by replacing conventional grey hydrogen supply with sustainable power-to-hydrogen systems that exploit renewable energy to produce green hydrogen through electrolysis. In this work, a semiconductors production plant was considered as a case study. Hydrogen is used as gas carrier in epitaxial silicon growth and the demand is about 110 tons per year. The goal is to explore the cost-effectiveness of on-site green hydrogen production. The power-to-hydrogen system includes a photovoltaic plant, a PEM electrolyzer, a compressor, a hydrogen tank, a grey hydrogen back-up system and the electrical grid connection. The optimal system sizing was carried out by adopting the Particle Swarm Optimization (PSO) algorithm able to identify the configuration that minimizes the Levelized Cost of Hydrogen (LCOH) while ensuring the coverage of the hydrogen demand over the entire year. For a detailed techno-economic assessment, size-dependent cost functions were applied, and the lifetime of the electrochemical component was estimated based on its operating hours during the year. Results show that the cost-optimal solution is the current scenario, where only grey hydrogen is employed (LCOH equal to 4 €/kg). Different decarbonization targets (i.e., grey hydrogen share constraint in the range 0- 100%) were also investigated and the resulting LCOH ranges from 4 €/kg (full grey hydrogen scenario) to 10.85 €/kg (full green hydrogen scenario). The resulting Pareto front shows two distinct regions: the reduction of grey hydrogen share from 100% (current scenario) to 30% - corresponding to a decarbonization rate of 0% to 70% – follows a smooth trend with an LCOH increase from 4 to 6.2 €/kg (first region). Higher decarbonization rates (> 70%, second region) instead lead to a steeper increase in the LCOH, reaching 10.85 €/kg in the completely decarbonized scenario (0% grey hydrogen).