Cost efficient network of electric buses with battery degradation

Abstract

This paper presents an integrated optimization approach to incorporate battery degradation to design Battery Electric Bus (BEB) network. With the introduction of fast charging technology, it is possible to reduce the ownership cost of BEBs by using smaller batteries. However, this comes with more frequent charging which could increase the cost of ownership for two main reasons. First, the operator needs to invest more in establishing charging facilities. Second, frequent charging can lead to faster battery degradation and can dramatically reduce the life expectancy of batteries. In this paper, we present three types of battery degradation models and incorporate them into bi-objective mixed-integer linear optimization framework. The optimization model can be used to determine the trade-offs between the size of batteries, their life expectancy as well as infrastructure investment. We test our model on a bus line in Geneva. The results depict significant improvement in battery lifetime without increasing ownership cost.