Vehicle routing with a heterogeneous fleet of combustion and battery-powered electric vehicles under energy minimization

Abstract

This paper compares energy minimization with minimizing distance and travel time in vehicle routing. The focus is on the influence of the objective chosen when deploying homogeneous and heterogeneous vehicle fleets. To achieve that, vehicles with different capacities and ranges as well with combustion engines as with battery-powered electric engines are taken into consideration. Results show that when deploying homogeneous fleets there are no significant differences between the optimal solutions when using energy minimization instead of distance or time minimization. Hence, the potential for reducing energy consumption of distance or time optimal solutions is very small with homogeneous fleets. By contrast, when deploying a heterogeneous fleet, a significant reduction of energy consumption in the double-digit percentage order can be achieved. On the other hand the total travel distance as well as total travel time increases. Comprehensive computational experiments show that certain fleets can be identified that consume only small amounts of additional energy compared to an idealized fleet consisting of an arbitrarily large number of vehicles of all different types. Furthermore, numerical experiments show that minimizing both the energy consumption as well as the distance, only a small number of Pareto-optimal solutions exist. The most attractive of those can be chosen easily according to practical preferences.