Health-conscious optimization for long-term operation of a green hydrogen production plant

This work presents a system-level Mixed-Integer Linear Programming (MILP) framework for the long-term operational optimization of a commercial-scale green hydrogen production plant integrating photovoltaic (PV) generation, Battery Energy Storage System (BESS), Proton Exchange Membrane Water Electrolyzer (PEMWE), hydrogen compression, and storage. The methodology is applied to the hydrogen production plant currently under implementation in Trieste within the North Adriatic Hydrogen Valley (NAHV) initiative and is developed over a time horizon of 87,600 h. The proposed framework minimizes the specific operational cost of hydrogen production while accounting for BESS ageing and evaluating PEMWE degradation. Two operating scenarios are investigated: Scenario 1 considers a fixed hydrogen production target of 1000 kg/day with flexible grid support through a Power Purchase Agreement (PPA), whereas Scenario 2 aims at maximizing daily hydrogen production with a constant PPA electricity supply. Results show that the operating strategy has a higher influence on both hydrogen cost and component ageing. Scenario 2 requires a more intensive use of the BESS to operate the PEMWE closer to its efficiency region and has a higher dependence on grid electricity characterized by an higher unit cost. As a consequence, the BESS lifetime in Scenario 1 is approximately 25% higher than in Scenario 2, leading to an estimated LCOE difference of about 3% between the two cases. Moreover, Scenario 2 shows an average annual hydrogen operational cost about 6.2% higher than Scenario 1, due to the greater reliance on grid electricity and lower efficiency operational processes. No significant difference is observed in the cost increase associated with degradation between the two Scenarios as them are characterized by similar daily hydrogen production levels.