Decarbonizing Aviation Ground Operations 2025

While the initial investment on the conversion of existing diesel buses to electric drivetrains is €5.11 million for retrofitting, the annual operating expenditure is €4.95 million, and a 25% salvage value is assumed. Retrofitting offers a pragmatic, lower-cost pathway to electrification, with the lowest initial capital outlay among all scenarios (see Figure 6). The retrofit cost is set at 50% of a new electric bus, and 50% of capex is subsidized by government support. The scenario assumes a 2:1 bus-to-charger ratio (each charger supporting two buses) and incorporates a significant battery replacement cost (35% of bus price) around the ninth year. While maintenance costs are slightly higher than for new electric buses, the overall TCO is close to the battery-electric case, and potentially lower when factoring in government incentives, making this scenario particularly attractive for operators seeking to decarbonize with limited budgets and minimal operational disruption. The relatively low electricity and infrastructure costs further enhance the cost-effectiveness of this scenario. If the boundary conditions and the economic wealth of the airport make it feasible to invest in a new purpose-built electric bus fleet, the initial investment is assumed to be €9.3 million for buses (including approximately €1 million for charging infrastructure, with the remainder allocated to vehicle procurement). Annual operating expenditure is €4.91 million, considering a 25% salvage value at end-of-life (as in the previous case). While the upfront investment is higher than for retrofitting, the new electric fleet benefits from improved reliability, advanced features and lower maintenance costs.The electric bus fleet scenario leverages a 3.9% annual learning rate for e-bus costs and a 50% government subsidy on capex, which helps offset the higher initial outlay. Battery replacement is a significant cost in year nine, where the model has assumed that this important maintenance is happening at the same point in time for retrofitted and electric buses, as the maturity of the technology is equivalent. TCO per km (see Figure 5) is slightly higher than in the retrofitted scenario, mainly due to higher capex, but still substantially lower than diesel or hydrogen, when factoring in government grants. The scenario is well-aligned with long-term sustainability and regulatory objectives, offering a balance between operational efficiency and environmental performance. If the technology of choice is hydrogen (supplied from off-site production), this scenario requires the highest initial investment, particularly for vehicles and refuelling infrastructure. The total estimated capex is €18.47 million, split between €12.52 million for bus purchase, and €5.96 million for the refuelling station. Annual opex is €5.45 million, with driver salaries and hydrogen fuel costs as major contributors. While the refuelling station’s upfront capex is modest relative to the bus fleet, its opex remains low. The scenario’s TCO is driven by high driver costs and the relatively high cost of hydrogen fuel compared to electricity. However, hydrogen offers operational flexibility and rapid refuelling, which may be advantageous for high-utilization or long-range applications. While the economics remain challenging without cost reduction or policy support, potential revenues from carbon trading mechanisms, such as the European Union’s Emissions Trading System (ETS)17 could strengthen the business case. The availability and treatment of such credits, however, depend on evolving policy frameworks, and may not apply equally to other technologies such as battery-electric buses. Decarbonizing Aviation Ground Operations: Alternative Bus Technologies 19