Optimising infrastructure and energy supply for coordinated charging and refuelling of a zero-emission fleet at a carrier’s depot

Abstract

Logistic companies are making concrete plans to adapt their fleets to meet their greenhouse gas (GHG) emission targets, to get higher sustainability ratings, to lower their dependency on rising oil and gas prices, and to decrease their ongoing and maintenance costs. Regardless of the reasons that drive the company to do so, this comes with requirements for changes to logistic bases. The base gets equipped with charging systems to charge the electric fleets and different possibilities are explored to fuel a potential hydrogen fuel cell truck fleet. On-site photovoltaic (PV) systems produce electricity to reduce the dependence on the grid and storage systems make the energy more available and storeable for peak demand times. Options to provide hydrogen for hydrogen fuel cell trucks include on-site electrolysers or the provision via pipeline infrastructure. These energy facilities are collectively described using the wording "technology portfolio" of the logistics company in this work. The core objective of this work is to optimise this portfolio and determine the minimum costs of meeting the energy demand of all fleets of a specific logistics base. For this purpose, a model is created that takes the energy flows of the fleets as well as the recovery of the PV system and bidirectional storage behaviour into account. To solve this task, a linear optimisation model is formulated. The input data were obtained from a logistics company that provided characteristics of fleet and other logistics data for a depot. In this work, the aim is to give an overview of how the cost-optimal technology portfolio could look like for this specific base and its current fleet. As the energy prices in the spot market are highly volatile, the impact of the electricity pricing scheme is analysed. Further, the coordination of charging and fuelling processes are considered. Seasonal differences in energy demand, such as the Christmas or Black Friday peak, or the summer low, and their impact on the technology portfolio are also analysed in this work. The results of the base case indicate the levelised cost of energy at 12.01 cent/kWh, deducted from including the OPEX as well as the CAPEX for the entire technology portfolio and grid-related fees. The PV system of maximum possible capacity is deployed, but no battery storage is installed, while a hydrogen storage of significant size is included in the model. The provision of external hydrogen, for example via pipeline or truck delivery, is rarely used, which means that most of the hydrogen demand is met using the electrolyser on-site. Despite known drawbacks of battery-electric trucks, a shift to pure battery-electric fleets is highly recommended to lower the overall energy demand as this case offers a boost in efficiency. The only case where the usage of hydrogen fuel cell trucks would offer an advantage would be at a hydrogen price of about 5€/kg or lower.