The impact of the performance degradation on the optimal design of the hydrogen systems.

The integration of hydrogen-based energy systems is crucial for decarbonizing stationary applications, where fuel cells can enhance grid flexibility and reduce emissions. However, fuel cell degradation affects efficiency, lifetime, and cost-effectiveness, influencing optimal system design. This thesis investigates the impact of degradation on the techno-economic feasibility of hydrogen energy systems by optimizing a multi-energy framework integrating photovoltaic panels, battery storage, and fuel cells. A MATLAB-based Mixed-Integer Linear Programming (MILP) model is developed to incorporate performance degradation into system sizing and operational strategies. Three degradation models are analyzed. The first, based on load spectrum analysis, highlights that start-stop cycles and high-power operation significantly reduce fuel cell lifetime, which is much lower than the expected 40,000 hours for stationary applications. The second, a dynamic efficiency decay model, demonstrates that degradation progressively lowers system efficiency, making hydrogen-based power generation less competitive over time. The third, a linearized degradation model, enables MILP integration, allowing degradation-aware optimization without excessive computational complexity. Results show that hydrogen price is a key determinant of fuel cell feasibility. At low prices (2 CHF/kg), fuel cells are economically viable, while at higher prices (6 CHF/kg and above), they are excluded from optimal system designs, favoring PV and grid imports. Neglecting degradation effects overestimates system performance and cost savings, underscoring the need for realistic degradation-aware optimization. This study contributes to the development of cost-effective and resilient hydrogen-based energy solutions, offering insights into fuel cell longevity, optimal control strategies, and their role in sustainable urban energy systems.