Analysis of the degradation of a Proton Exchange Membrane Fuel Cell for propulsion of a coastal vessel

The International Maritime Organization (IMO) is making efforts on reducing pollutant emissions within port areas in order to achieve the ambitious goal of zero net carbon emissions by 2050. This work analyses the effects of the cell degradation on the performance and thermal management of a hydrogen fueled Proton Exchange Membrane Fuel Cell (PEMFC) power system for ferry electric propulsion. The manuscript firstly describes the proposed models, which simulate the fuel cell system and the battery. Then, the development of both an Energy Management strategy and the optimization framework are shown. In details, the zero-order model for the fuel cell and the methodology to estimate its time degradation are described. The accuracy of the model is established through calibration with the characteristic curves of the Ballard FCvelocity™ HD6 PEMFC (150 kW) and further validated against experimental data. The model also involves energy storage and converters that connect both the fuel cell and battery to the electrical grid. The proposed online strategy for the Energy Management System considers four different operating modes and takes into account the estimated fuel cell degradation. Furthermore, the optimization framework finds the solution to achieve the best performance in terms of stack degradation over one year of ship operation, based on a real mission duty cycle. Overall, the efficiency of the fuel cell system decreases by 5%. The degradation involves an increase in fuel consumption of 14.65%. Furthermore, after the last mission, the cooling efficiency achieved through the proposed thermal management strategy is 90%.