Comparison of hydrogen-fueled powertrains for urban bus applications — design, modeling, and energy management

Nowadays, there is a growing consensus that hydrogen can play a key role in decarbonizing Heavy-Duty Vehicle (HDV) fleets as it can be produced from renewable energy sources and supply both Internal Combustion Engines (ICEs) and Fuel Cells (FCs). This research paper proposes a fair and comprehensive comparison between two different hybrid H2-fueled powertrains for urban bus applications. The two case studies are a H2-Hybrid Electric Vehicle (HEV) featuring an ICE and a Fuel Cell Electric Vehicle (FCEV). We thoroughly modeled the hybrid H2-fueled powertrains, paying particular attention to the development of their energy management strategies. We adopted a standard Equivalent Consumption Minimization Strategy (ECMS) for the H2-HEV. For the FCEV, where the FC aging represents a limit to reach competitiveness with H2-ICE, we developed a modified version (ECMS𝑤∕𝑑𝑒𝑔 ) designed to both limit FC degradation and minimize fuel consumption. Finally, we benchmarked the energy consumption of the hybrid H2-fueled powertrains, on a Tank-To-Wheel (TTW) basis, against a conventional ICE vehicle, a diesel HEV, and a Battery Electric Vehicle (BEV). This work demonstrates that hybrid H2-fueled powertrains can represent valid pathways to decarbonize urban bus fleets, allowing to reduce the energy consumption of a diesel ICE bus by an average of 29% (H2-HEV), and 42% (FCEV).