Electric Towing Vehicle Assignment With Charging Requirements

One of the most promising ways to reduce emissions at airports is by towing aircraft instead of taxiing with their main engines, also known as dispatch towing. One of the airports most involved with this concept is Amsterdam Airport Schiphol (AMS), as it has an emission-free target for 2030. One of the challenges with this concept is to optimize the assignment of Electric Towing Vehicles (ETVs) to maximize the effectiveness. The developed model can assign ETVs to flights and charging moments for the tactical planning phase, minimizing fuel consumption, charging cost and number of chargers. The results of the model are illustrated for two peak days at AMS. Both a small and large fleet of ETVs are assigned on both days for a northbound and southbound runway operation. The total fuel cost savings for the small fleet are 25% and 45% for the large fleet, which are similar on both days. On both days, outbound flights are the preferred direction to be towed due to the distribution of towing times. The savings per ETV are highest for a small fleet and decrease until all flights are towed. Furthermore, the load on the charging infrastructure at AMS for different fleet sizes shows what average and peak power can be expected. It is shown that ETV utilization and computation time can be improved significantly, by implementing costs on time and introducing utilization and symmetry constraints. However, with the important limitation that these improvements are observed only for small planning horizons. Finally, a sensitivity analysis on charging power showed that increasing the charging rate has a positive impact on both fuel cost savings and the minimum number of chargers required. In conclusion, this study shows the potential impact of dispatch towing at AMS in terms of fuel savings, charging infrastructure and operational challenges.