Carbon, Cost and Capacity: Weighted-objective Charging of Electric Buses

The public transport sector is in the process of decarbonizing by electrifying its bus fleets. This results in challenges if the high electricity demand resulting from battery charging demand is confronted with limited grid capacity and high synchronicity at bus charging sites. In this paper, we explore weighted-objective scheduling for bus charging sites to minimize the emissions associated with charging processes and to aid the operation of the electricity grid by mitigating peak consumption. In particular, we discuss and validate optimization approaches for those individual objectives, as well as their weighted combination, based on data from a real-life bus charging site in the Netherlands. The simulation results show that compared to uncontrolled charging, power peaks can be reduced by up to 40%, while time-of-use emissions associated with the charging of electric buses are also reduced significantly. Furthermore, by using a baseload recorded at a German industrial site, we illustrate the flexibility potential offered by bus charging sites, and advocate that such sites should share a grid connection with other high-load assets.