Techno-economic analysis of mixed battery and fuel cell electric bus fleets: A case study

Electric city buses are promising to reduce traffic-related emissions in city centres as their drive train emits zero local emissions in an urban context. However, battery electric buses (BEBs) have limited driving range and long charging times. Although this can be managed, as city buses operate on predetermined routes, fuel cell electric buses (FCEBs) can meet more operational requirements in terms of range and charging. Thus, many bus network operators want to design a mixed full electric bus network with BEBs and FCEBs, which involves several complex and interdependent planning tasks. We extend an existing planning model to accommodate the planning of BEBs and FCEBs with their respective charging and fuelling infrastructure, and apply it to a real-world case study. Our results indicate that a heterogeneous BEB fleet with a mix of depot and opportunity charging results in lower total costs than a depot charging concept or a homogeneous FCEB fleet. We additionally find that a heterogeneous fleet including FCEBs and BEBs with a mix of charging concepts can be beneficial under specific circumstances. More specifically, the results indicate, that FCEB are a viable technology to supplement full electric bus fleets as soon as the costs for FCEB fall below 625,000€or the costs for hydrogen fall below 4.33 €/kg H2. Interestingly, rising energy prices would not increase the utilization of FCEBs, but rather influence the choice of BEB-types.