GRA said:
I think the likelihood of batteries on trailers is minimal, as it will directly reduce the trailer useful load (as opposed to putting them on the semi, where it reduces the usable total weight). In addition, trailers are as simple and stupid as possible, and thus cheap and interchangeable. It's also far easier to provide charging stations for a tractor than it is a trailer at a terminal, as the tractors are self-mobile and can easily be charged in a smaller space away from the dock, which only has a limited number of loading doors. Any trucking company has far fewer tractors than it does trailers, so providing charging spots for just the tractors is much easier. In addition, any high volume operation will normally see each door occupied by more than one trailer during a single shift, so the time available for charging each trailer will typically be limited.
^^^^ These are the types of conclusions that you arrive when you only weigh costs and do not consider cost benefits and the impact on operations.
I will double down on my prediction: Eventually NEARLY ALL semi trailers will contain batteries. Operational considerations will dictate this. Here is my reasoning:
First, some facts:
-
Drivers are the single-largest expense for trucking companies. This is the first expense that Tesla intends to eliminate in order to sell expensive trucks.
-
Behind drivers, fuel and oil are the second-largest single expense for trucking companies. It will take time to realize, but the movement to electricity-based transportation will offer huge reductions in the amount of electricity needed to move goods. In the medium term, capital expenditures will need to increase to build out the infrastructure enable this savings.
- Semi trucks are expensive. The BEST way to reduce the capital costs of a semi truck is to keep them on the road. That means parking these trucks at charging stations should be avoided whenever possible.
- Semi trailers MUST be parked for loading and unloading. This is the opportune time for charging to occur in the transportation industry.
- Charging stations are inexpensive when compared with the costs of drivers, fuel, trucks, and trailers.
- Many (most?) loads are not weight-limited, but rather are volume-limited, size-limite or simply are not full.
Now, for my predictions:
- The elimination of drivers will allow trucks to remain on the roads for a much higher fraction of the time.
- As the world electrifies transportation, electricity will become very dear, particularly on the road. Electricity costs at the depot will be lower, but will still be high. As such, trucking companies will need to avoid on-road charging whenever possible and will need to generate and store as much of their own electricity as possible. This means photovoltaics on the rooftops of warehouses and trailers. In order to keep trucks on the road, the bulk of the energy storage will need to reside on the trailers.
- High costs of electricity (fuel) will force carriers to move away from friction braking on trailers and toward regenerative braking for the bulk of braking operations. While most of this regeneration can and will be captured by the wheels on the tractor, likely 1/3 to 1/2 (or even more for safety) will need to be captured by the wheels on the trailer. It is conceivable that this regeneration could be delivered DIRECTLY to the tractor, but it would be much more efficient to capture that energy in large batteries on the trailer. This will eliminate the need for a very-high-power connection between the trailer and the tractor.
- Electric brakes will eventually replace air brakes for emergency stopping.
- Trailer batteries will serve two or more of the following valuable functions (depending on the capabilities of the trailer):
1) Capture electricity from the roof-mounted PV collection system.
2) Capture electricity from the trailer wheels during braking.
3) Provide traction power to the trailer wheels during normal operations.
4) Provide the *average* power to the tractor during operations to maintain tractor SOC. This may be on the order of 50 kW or less when stops and regeneration are figured in.
5) Power on-trailer loads such as refrigeration units, lights and emergency electric brakes.
Charging operations for trailers and trucks will be managed by operations. Trailer SOC needs to be made as high as possible during loading operations unless the load will sit in the sun for some time before departing the depot. During unloading, partial charge can be provided if at the depot or at a customer where electricity refueling is practical and has been negotiated as part of the cartage arrangement. If at all possible, truck charging should be done ONLY by the trailer. If off-trailer truck charging is required for certain long-haul operations, then that needs to be done at the depot whenever possible.
Initially, this approach to trailer-based batteries will be used in industries which are volume-limited rather than weigh-limited. But eventually, trailer-based batteries will dominate for all applications since it provides massive cost and operational benefits by keeping the trucks on the road as close to full-time as possible.
GRA said:
PV on roofs might be useful for reefers, but they'll need to be a lot less expensive.
In an electrified transportation industry, PV is no longer just an expense, but rather it is an investment that will return many times its value over time. It will sit (or ride) quietly generating fuel for the organization and increasing the amount of time that the trucks can remain on the road.
GRA said:
I expect that fuel cells will be a more likely replacement for reefer gensets,...
Did you manage to keep a straight face when typing that immediately following the sentence in which you talked about how PV needed to be less expensive? :roll: No, fuel cells will likely never see the light of day in trailer refrigerators due to the extremely high costs of the fuel cell and the extremely high cost of the fuel. There is NO payback for such a bad investment.
GRA said:
...which are mounted in a cage on the nose of the trailer or container, and with the latter at least can easily be removed when not needed (carrying non-refrigerated cargo) or swapped out for repair when necessary.
PV panels will ALWAYS be needed to create fuel for operations, so they will NEVER need to be removed. Future refrigeration units will be much smaller and lighter since they will not need to carry fuel and a genset around with them. Solar loads on the truck will also be reduced by the operation of the PV panels on the roof.
GRA said:
In addition, trailers and containers often get washed rarely, so PV will typically be operating well below max efficiency.
This is a minor operational consideration. Trucking companies need to take whichever approach gives them the highest returns. If that means cleaning PV panels on roofs, it will happen. Likely it will happen automatically each time the trailers enter the depot (or on an as-needed basis based on self-diagnostic based on efficiency considerations). Snow will be an issue in northern climates, but that is also an operational issue which can be handled.
