Performance evaluation of a hybrid hydrogen fuel cell/battery bus with fuel cell degradation and battery aging

Public transportation is an effective way to reduce emissions and decrease in fossil fuel consumption challenges. The idea of employing green energy systems in public transportation can significantly change the quality of life in the near future. In this regard, the hydrogen fuel cell bus which uses hydrogen as a main fuel and utilizes small battery systems for the rest of the required energy demands is simulated and investigated in this research study. Additionally, two real driving cycles are employed for dynamic modeling. Therefore, to fill the gaps in the field of public bus performance, heating, ventilation and air conditioning (HVAC) systems, fuel cell degradation, and battery aging, a precise model is presented in the Simcenter Amesim software. Time-dependent thermal loads and variations of passenger numbers are also considered for the HVAC system. Machine learning techniques are employed to predict fuel cell degradation and battery aging. The model is based on calendar and cyclic aging phenomena. Finally, the performance of the hybrid bus is evaluated during operation. Results show that more than 60% of energy is consumed in electric motors and increasing the number of passengers directly affects the amount of energy consumption reaches the maximum of 28 MJ for 40 passengers and additionally affects the final cabin temperature. After 2000 h of operation, the ammount of hydrogen consumption increased by approximately 10% compared to a new bus due to fuel cell degradation. In addition, the capacity loss of the battery reaches 17.6% after a year for the maximum ambient temperature of 36 °C.