Investigating route gradient and thermal demand on hydrogen fuel cell electric bus energy consumption

In 2022 in the UK, the transport sector was the largest single contributing sector to greenhouse gas emissions, responsible 34% of all territorial carbon dioxide emissions [1]. In the UK there is growing uptake in zero emission powertrain technologies, with the most promising variants based on battery electric or hydrogen fuel cell electric configurations. Given the limited number of fuel cell electric buses currently in operation in Europe, vehicle models and simulations are one of the few methods available to estimate energy consumption and provide the necessary increased confidence in operating range. This paper investigates the impact of route characteristics, thermal demand and coefficient of performance of different heat source configurations on the operational energy consumption of fuel cell electric buses. Using a MATLAB/Simulink model, the total energy demand of a vehicle operating in different route/elevation profiles is considered. The findings from this study show that implementing a waste heat recovery system, which recovers excess heat produced by the fuel cell system, in a traditional heat pump based HVAC system can reduce the amount of excess fuel consumption required for providing HVAC services by up to 70% over the course of a duty cycle, so long as high levels of waste heat can be recovered. It also shows that through the use of waste heat recovery systems it is possible to replace the heat pump based HVAC system with a much simpler positive temperature coefficient heater system and still achieve or improve upon the performance of a traditional heat pump based HVAC system.