*3.3. Bus, Driver and Battery Parameters*

In this section, the parameters used to determine the cost of buses, driver, and batteries are described. In the examples in this paper, we assume 12 m buses, and they have the values given in Table 1. The different size of batteries for the two types of electric buses depends on different charging strategies. Why different battery sizes are used depends on the longest time a bus can be in traffic without charging, and this will be explained more in Section 4.1. A conservative estimation of battery cost has been used. The battery price is assumed to be constant, so it is the same after seven years when the batteries are replaced. The residual battery value after seven years has also been set to zero. Table 1 shows parameter values which are relevant for Sweden 2019, mainly based on data from pilot projects. The parameter values are included to allow the reader to check and interpret the numeric results in this paper. It shall, however, be noted that development of electric buses is rapid, and the production volumes are growing fast; therefore, these parameter values can change and should not be seen as generally applicable.

For all the buses, the average power during the trip has been assumed to be 25 kW, which is based on measured energy consumption of electric buses in Sweden. It includes auxiliary loads, heating and cooling, and is a typical average value over the year. The effect that the worst-case consumption will be higher has to be considered when sizing the batteries. The economic life of the bus (depreciation period) has been set to 10 years, while the batteries have been assumed to last seven years. In the near future, batteries will most likely last 10 years, but the first generation of bus batteries may live a little shorter.

The driver wage is set to 300 SEK/h, and the driver schedules are assumed to be planned so that 90% of the driver's time can be used to drive the bus and wait during layover time or wait during charging. This means that the effective driver cost will be 333 SEK/h that there is a driver in the bus. It is also assumed that the driver must be paid during the time the bus charge at end stops, but not when charging at the depot.
