Electrification of city buses in Uppsala : Solutions for managing the capacity shortage in a growing region

Region Uppsala, who are responsible for the public transport in Uppsala county, are currently building a new city bus depot. Due to capacity shortage in the transmission grid to Uppsala, the operation of the new bus depot must be adapted to a limited power output. In addition to this, the city of Uppsala aims to introduce the first electrical buses by 2021. The purpose of this study was to investigate how electrical buses of different penetration level will affect the power demand at the new city bus depot. The results showed that the current power limitation was already exceeded by 200 kW if 12 electrical buses were to be introduced. Therefore, different technical solutions were evaluated in terms of increasing the penetration level of electrical buses. These solutions were evaluated by a life cycle cost analysis. The cheapest solution was to connect the city bus depot with the regional bus depot. This is possible because the grid connection to the regional bus depot is oversized, compared to its load. However, this solution does not solve the general problem of capacity-shortage in Uppsala and the legality of it must be analyzed further. Two other solutions that were investigated were a local battery storage and a gas engine coupled with a generator at the depot. None of the solutions could solve the power problem at the depot on its own. For a scenario with more than 40 electrical buses, the different technical solutions that were investigated must be combined