The following article addresses the problematic of electrification of heavy duty vehicles. The content was prepared by electro company, providing services for energy generation from renewable energy sources (Elektro Ljubljana RES, Ltd) and supported by BSC, Ltd, Kranj (RDA of Gorenjska), for the preparation of the training material for public authorities, in the scope of e-SMART project. The challenge is much more demanding, than for electrification of passenger cars and at the moment we are still way from the ideal solutions.
There are several issues related to wide introduction of battery heavy duty vehicles. Let us list them here and try to elaborate them a little later:
- Optimal charging technology
- Optimal charging location
- Needed power at charging locations
- Renewable electric energy sources for e-HDV
- Truck range vs. battery size and weight
- Alternatives – other types of powertrain (Hydrogen)
When discussing optimal charging, some data are important. Truck consumption is in the size of 100-200 kWh/100km and range is expected to be from 200 to 600 km in order to keep freight transport a viable and competitive option. That means charging session are expected to reach 0.5-1 MWh and the question is how fast such session needs to be finished. How fast should it be? Is 1 Hour fast enough?
That can require up to 1 MW of power in charging. At the beginning, simple solutions are preferred and to copy cable and plug option from personal cars charging is the easiest. Manual version is the easiest to be standardized. Only plug, while communication can be taken from personal cars.
But, can it be done manually with the size of the cable for 1MW carrying 1200 A at 800 V?
When discussing optimal charging locations, relevant question remains where to start. Destination seems to be good starting point. However, for smaller destinations in LML investment could be too high, since only few sessions can be expected dally. Depot is another, probably better option for a start, since it depends on the decision of one player (company) only. But it works only for applications with shorter ranges up to 200-400 km. It is more applicable in urban distribution with vans and not sufficient in long range applications. Higher rage is expensive due to cost of batteries and additional weight of the batteries. Therefore, for freight transport, alternative powertrains will sooner or later find a way to the market.
At the beginning, with no doubt, an issue for a charging location is required power. With energy transition, electrification of the society is very intensive already. So, distribution networks are already facing problems with increased loading and bottlenecks in their capacity.
On the other side, any charging, except depot charging, shall be fast not to lose time in delivery of goods. Fast charging means higher power. If unloading of the truck at the destination needs 30 minutes, and required range is only 150 km, required charging power is already 600 kW. Expected required power per charger will be in the range of up to 1 MW. Similar is valid for transit charging locations. With 20 charging posts, we have to provide power that MV network cannot do.
110 kV network is needed, but this is possible only on few locations in Slovenia without high investments. In Slovenia, there is potentially a good location for transit charging for example on existing petrol station Ljubljana Barje. It is located centrally in Slovenia with less than 170 km to all major border crossings. 110 kV network is only 1 km away, and there is already parking for long haul trucks there.
Certainly, from the point of view needed investment in power network, better solution remains depot charging with lower needed power.