Ahtiainen, Sinikka

Halmeaho, Teemu

Karvonen, Veikko

Kukkonen, Samu

Laurikko, Juhani

Lehtinen, Annakaisa

Mäkinen, Reijo

Nylund, Nils-Olof

Pihlatie, Mikko

VTT has together with several partners created a multi-dimensional demonstration environment for electric busses and their supporting infrastructure. The on-going demonstration in the city of Espoo - part of the Helsinki Metropolitan area - is unique in many aspects. One of them is the weather: due to the local climate conditions, the ambient temperature can swing up to 60 °C between high summer and mid-winter. This certainly stresses the vehicles and their batteries to their limits at both ends of their operational range. Fur-thermore, maintaining comfortable riding conditions requires sufficient heating and cooling of the passen-ger compartment. Therefore, an energy efficient HVAC system that does not jeopardize the total energy balance of the bus is needed. Another important feature of this demonstration and field-trial run is that several different commercially available busses are operated simultaneously on the same line. This approach gives an excellent opportu-nity to benchmarking. Furthermore, the service operations in real driving are supported with in-service data acquisition and chassis dynamometer measurements in a controlled laboratory environment at VTT. Lab measurements enable more accurate determination of the energy use profile in different duty-cycles, and make possible resolving of the contribution of the on-board sub-systems. However, a battery-electric bus is not just a vehicle, but an element in a larger system that encompasses also the charging infrastructure. For coupling and charging, several different topologies are possible, and careful consideration should be given to the planning and dimensioning of the complete system. Further-more, a distributed opportunity charging system allows the reduction of battery for lower costs, but simul-taneously raises the investments in infrastructure. Nevertheless, if the charging points can be utilised by a large number of busses, the net result should be positive. Therefore, the positioning of the charging points needs to be based on the lay-out of the lines and taking into account also the schedules of the busses. Fur-thermore, the roles of different stakeholders need also to be investigated. In addition the experimental research at VTT is directly linked with modelling exercises, enabling adjusting the simulation algorithms with real-world data

VTT Research System

Electric city bus and infrastructure demonstration environment in Espoo, Finland

Electric city bus and infrastructure demonstration environment in Espoo, Finland

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