*Article* **Lifetime Analysis of Energy Storage Systems for Sustainable Transportation**

**Peter Haidl 1,\*, Armin Buchroithner 1, Bernhard Schweighofer 1, Michael Bader 2 and Hannes Wegleiter 1**


Received: 15 October 2019; Accepted: 23 November 2019; Published: 27 November 2019

**Abstract:** On the path to a low-carbon future, advancements in energy storage seem to be achieved on a nearly daily basis. However, for the use-case of sustainable transportation, only a handful of technologies can be considered, as these technologies must be reliable, economical, and suitable for transportation applications. This paper describes the characteristics and aging process of two well-established and commercially available technologies, namely Lithium-Ion batteries and supercaps, and one less known system, flywheel energy storage, in the context of public transit buses. Beyond the obvious use-case of onboard energy storage, stationary buffer storage inside the required fast-charging stations for the electric vehicles is also discussed. Calculations and considerations are based on actual zero-emission buses operating in Graz, Austria. The main influencing parameters and effects related to energy storage aging are analyzed in detail. Based on the discussed aging behavior, advantages, disadvantages, and a techno-economic analysis for both use-cases is presented. A final suitability assessment of each energy storage technology concludes the use-case analysis.

**Keywords:** flywheel energy storage; FESS; e-mobility; battery; supercapacitor; lifetime comparison; charging station; renewable energy storage
