Modelling the Feasibility and Benefits of Vehicle-to-Grid Technology for Urban Bus Fleets: the Case Study of London

Abstract

Bus operators are increasingly seeking ways of electrifying their fleets, which is motivated by a combination of policy (decarbonization, emission standards) and economic (operational efficiency) factors. For example, in London there is now an explicit objective set by the Mayor of London to transition to a fully electric bus fleet by 2034. At the same time, the dynamic, spatially disperse but predictable nature of bus services (routes, timetables) suggests their applicability as a potential source of flexible electricity storage and supply for the grid, via adjustable charging as well as discharging (vehicle-to-grid, V2G) capabilities. To-date, simulation-based analyses have demonstrated the potential for bus fleets to support electricity grid operations, for instance by enabling more volatile renewable energy generation into the grid. The current paper advances the modelling of such benefits, by presenting a modelling framework developed using Transport for London (TfL) working timetables to map vehicle duty cycles at a 15-minute resolution. The approach defines bus archetypes using battery capacity and energy consumption, with load factors applied to account for passenger occupancy, auxiliary loads and time-of-day variations. State-of-charge dynamics were simulated for bus archetypes operating according to a real-world working timetable, with rules to safeguarded service reliability through departure floors, safety margins and export scheduling windows aligned with UK energy demand peaks. The empirical case study, based on Edgware Depot in London, indicated that fleet operating from that bus depot could shift up to 6,455 kWh in a single day, equivalent to the daily consumption of 650 UK households. Exports were concentrated in the evening super-peak, though some capacity was available during the day due to school services and certain buses dwelling in the depot during the interpeak period. Route and vehicle level analysis revealed substantial heterogeneity, with some buses unable to participate due to continuous duties, while others offered disproportionate contributions.