The intent was to forecast 30-min peak demand, instantaneous peak demand and fleet energy consumption at each depot to support AT in its plan to achieve full fleet electrification by 2030. AT and Vector are using the interactive outputs during the transition from diesel buses towards a fully electric fleet.
The report provides an overview of the methodologies used to calculate the fleet energy consumption for scheduled daily bus runs. BOLT (Battery Optimisation Lifecycle Tool) was used to integrate bus schedules, revenue and non-revenue trips as well as route topography to simulate speed profiles for each bus block. This speed profile was then used along with ridership information to calculate the energy consumption of different powertrains in buses ranging from 9m long to 18m long articulated buses. These results were used in the interactive BOLT Post-Process (BOLT-PP) tool to assess the impact of battery degradation, different charging rates and different charging strategies on peak power demand along with the rate of electrification of each depot.
The simulations demonstrated that increasing charger output power led to increasing peak demand and showed the potential for higher losses and increased energy consumption. However, chargers running at a higher rate can reduce the number of chargers required at the depot. When batteries reached their recommended end-of-life, the daily energy consumption for the fleet increased by 9% overall which needs to be considered for future infrastructure upgrades. Lastly, the simulations showed that it is possible to achieve significant peak load reduction by managing charging rate to take advantage of the bus idle time at the depot.