In a previous article, we presented the eHaul project. We focused on the development of the Charge Planner for charging optimization in the swap station. In summary, the eHaul project is a research project focussing on the electrification of long-distance freight transport for electric trucks (eTrucks). The development of a fully automated battery swapping concept is intended to create a proof-of-concept for long-distance electric transport. The project is being carried out by a consortium of industry and research institutions, including urban energy. The swap station was officially opened and finally put into operation in November 2023.
This article deals with extended technical concepts that serve as the basis for future business models for the swap stations. This investigation is necessary because, due to their novelty, there is no experience to date regarding the economic viability of various possible uses of the swap stations. In order to counteract this situation conceptually, urban energy carried out an impact analysis as part of the project and validated the analysed scenarios with the help of simulations. The results of the analysis should help to increase the economic efficiency of the swap stations in the future and facilitate their integration into the electricity grid.
Scenario 1: Baseline - swap station with exclusive grid supply
In the first use case, the focus lies on an swap station that exclusively utilizes grid electricity to charge and exchange batteries. This example serves as a baseline and is technically the least complex compared to the expanded options.
The baseline was further enhanced with the possibility of optimized charging control. Here, the batteries are charged preferably during times with comparatively lower electricity prices. This optimization can occur either based on forecasts of future electricity prices or alternatively, heuristically by charging the batteries during nighttime hours when electrical energy is typically cheaper compared to peak demand hours during the day.
The simulations conducted revealed a potential cost savings of approximately 6% when using charging optimization and a dynamic electricity tariff compared to the approach in which only a distinction was made between a daytime and a nighttime tariff.
| Advantages | Disadvantages |
|---|---|
| Comparatively simple technical implementation | Leaves existing potential unutilised |
| Possible optimization when using dynamic electricity tariffs | Inaccurate price forecasts can impair efficiency |
Scenario 2: ReUse - utilisation of unused batteries as interim storage
The storage batteries used in the inverter station will lose some of their capacity as use progresses. The actual loss of usable capacity per unit of time depends on factors such as the usage profile, the storage technology used and the original nominal capacity. All storage technologies currently in use are affected by this wear and tear.
Due to this wear and tear, it is unavoidable that the storage batteries will no longer be suitable for use as swap batteries after a certain point in time, which depends primarily on the distances to be traveled by the carriers.
In order to continue using these decommissioned battery storage systems profitably, they can be used as intermediate storage within the substation. Based on the optimization using dynamic electricity tariffs in the baseline scenario, the additional storage capacity allows energy to be drawn at times when it is comparatively cheap. If another battery used as alternating storage has to be charged at a time when the electricity price is high, some of this energy can be drawn from the intermediate storage. This means that the average energy price can be further reduced compared to the baseline scenario.
The simulations carried out for this scenario resulted in an average reduction in the electricity price per kilowatt hour of 9% compared to the baseline scenario.
| Advantages | Disadvantages |
|---|---|
| No or low acquisition costs for the storage batteries compared to conventional storage solutions | Reused batteries are not expected to be available when the system is commissioned |
| More effective optimization when using dynamic electricity prices compared to the baseline | Development of advanced optimization algorithms required |
Scenario 3: Renewable - Swap station with own energy generation
Another way to reduce the average price paid per kilowatt hour is to equip the swap station with its own energy generation system. This concept makes particular sense if renewable energies such as photovoltaics or wind power are used.
When using self-produced energy, it makes sense to use local storage capacity. The storage batteries can serve as a buffer to decouple energy production and energy demand. This makes it possible to store energy when it is produced and consume it when it is needed.
Depending on the use of the system and the installed capacity of the renewable energy generation system, it is possible that the inverter station may temporarily produce more energy than is required. In this case, an optimized charging plan for the batteries should be created in advance in order to be able to store the excess energy. Alternatively, surplus energy can also be fed into the public grid. However, our simulations showed that maximizing self-consumption of the energy produced is the most economical solution.
Although the initial investment in the storage batteries and the renewable energy generation system is comparatively high, there is an overall economic advantage over the expected service life of the systems.
| Advantages | Disadvantages |
|---|---|
| Highest cost savings compared to other scenarios | High initial investment in renewable capacity and storage |
| Own consumption of renewable energy improves the environmental footprint of the inverter station | Intelligent battery management required for maximum efficiency |
Scenario 4: Grid services - swap station as part of the power grid
It would also be conceivable to integrate the swap station in order to offer primary control power and similar grid services. In this case, the swap station could act as part of a virtual power plant by blocking the batteries for charging or discharging at certain times. The batteries can also serve as a buffer for grid stability by absorbing or releasing energy from the grid as required.
As the provision of grid services represents a more lucrative source of income than the pure operation of an swap station, the integration of grid services can further improve the profitability of the swap station.
The problem with this concept could be that the provision of grid services could affect the operation of the swap station. For example, it could happen that the batteries are blocked for charging at a time when they actually need to be charged in order to fulfill carrier reservations.
In order to minimize these cases, intelligent battery management is also necessary in this scenario, which optimally coordinates the operation of the swap station and the provision of grid services.
| Advantages | Disadvantages |
|---|---|
| Second economic pillar makes system operators less dependent on the need to replace batteries | Grid services conceptually compete with the actual use case of the swap station |
| Contributes to improving grid stability | High technical prerequisites to be able to offer grid services |
Conclusion and outlook
The scenarios presented in this article show that the swap stations of the future can not only serve as pure infrastructure for the operation of e-trucks. Rather, they can also act as part of an intelligent power grid and thus contribute to the stability and efficiency of the power grid. The integration of renewable energies and the provision of grid services can further improve the economic efficiency of swap stations.
However, the scenarios presented in this article are only a preview of the possibilities that could arise in the future. Actual implementation depends on a variety of factors, including technological development, the regulatory framework and economic incentives.
