Research: different charging strategies for electric vehicle fleets in city logistics

The transition from diesel-driven urban freight transport towards more electric urban freight transport turns out to be challenging in practice. A primary concern for transport operators is how to find a reliable charging strategy for a more extensive electric vehicle fleet that provides flexibility based on different daily mission profiles within that fleet while also minimizing costs.

A new paper by Kin et al. assesses the trade-off between a large battery pack and opportunity charging concerning costs and operational constraints. Based on a case study with 39 electric freight vehicles that have been used by a parcel delivery company and a courier company in daily operations for over a year, various scenarios have been analyzed using a TCO analysis.

Although a large battery allows for more flexibility in planning, opportunity charging can provide a feasible alternative, especially in the case of varying mission profiles. Furthermore, additional personnel costs during opportunity charging can be avoided as much as possible by a well-integrated charging strategy, which can be realized by a reservation system that minimizes the risk of occupied charging stations and a dense network of charging stations.

The driver costs form the largest share of the TCO (i.e., between 60% and 90%, depending on the vehicle type). We excluded general driver costs from the analysis since these are the same for electric and conventional vehicles. Additional driver costs, for detours to charging points or waiting time for charging, are added to the TCO. The TCO of a small electric van without opportunity charging is already 2% lower than the TCO of a conventional small van.

It is the other way around for larger vehicles: 4% higher for large vans and 57% higher for small trucks. This significant difference between an electric and conventional truck can be explained by the (costly) large battery pack. Unfortunately, these vehicles were not yet commercially available as OEM products (at the time of this demonstration).

In the demonstration, the focus has been on the parcel delivery segment. In general, this segment is characterized by a high stop density, small vehicles, and relatively short distances. Consequently, the remaining kilometers in urban freight transport cover a high diversity in terms of mission profiles and subsequent operational requirements in charging strategies.

A fleet of multiple heavy vehicles requires heavy-duty charging infrastructure (which is expensive) but might also lead to capacity issues at the local grid around charging locations. Even though 2030 is still almost a decade away, network aggravation is a relevant issue today. Vehicles in several sectors drive relatively long distances. Even the largest battery is (currently) not sufficient to cover the required driving range. Notably, for trucks, public heavy-duty charging stations need to be developed.

Despite dropping battery prices, the difference in the TCO between a small and large battery is high for heavy-duty vehicles. An accurate analysis of the costs related to various strategies is essential. In this regard, a different approach to organizing logistics is an inevitable part of the change from a conventional to an electric vehicle. A decoupling point for swap bodies or a trailer at the city border to enable traditional transport towards and zero-emission transportation within the city is an exciting alternative to further explore for various sectors.

Read the full paper here.

Sustainability 202113(23), 13080;

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