The concept of the electric semi-trailer, as some have claimed, does have the potential to revolutionise the road freight industry, but not in ways you might expect.
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Some of the revolution would apply to regulations, and some of it would be to the way drivers and companies operate.
The first issue we have though, would be with importing them. Australia's width limit for trucks still stands at 2.5m, and discussions over decades to bring it in line with the EU and NZ's 2.55m or the USA's 2.6m haven't resulted in a change yet.
If we can get past that - with a regulation update, finding mass-produced models within the Aussie limit, or making them here - we encounter the next challenge, and that is the trade-off between range vs payload.
The current energy density of batteries means that if you make a semi truck that can do, say, 800km (500 miles) on a full charge, the battery pack is so heavy that there's less weight capacity left for freight under current vehicle weight limits. Real numbers (specs) are hard to find for some concepts (or just plain missing), probably because this would reveal their limitations, but it's still a deal breaker for a big part of the industry that carry loads which are heavy and not just bulky. Add the energy needs of refrigerated freight, and the range or payload come down further.
A regulation change here would partly address this. In the USA electric trucks have been granted an extra 2 tonne to their GVM (gross vehicle mass, the total weight at the wheels). Our infrastructure already seems to be maxed out in places though, so perhaps that's not the best idea.
The less revolutionary change would be simply taking over the tasks they're actually going to be good at. Just as the solar powered car doesn't make any sense until you rethink them and they stick to the applications they're potentially capable of - which is commuter vehicles that get parked in the sun and then don't cover enough distance each week to require much, or any, top-up charging from the mains - battery-electric trucks, of various sizes, could stick to doing workloads of shorter distances.
This basic idea is something Ford says they have already achieved for smaller deliveries, with their electric Transit's range comfortably exceeding the average daily distance covered with similar commercial vans.
The more revolutionary change to the industry that fully-electric semis would have to bring in to be viable for long-haul freight would be to turn it into a relay. The electric semi would be driven to a rest area with charge points, the trailer would be detached and another semi which has completed recharging would take over. Either that or build very big rest areas and just accept longer times for deliveries. This would require infrastructure to be installed, obviously, but that would be needed to go electric anyway.
The bigger problem with that method would be the actual logistics, ensuring trailers keep moving but without the cabs waiting around after completing a charge. And then there's making full use of the driver without leaving them stranded between shifts. Even if an electric semi could reliably cover 800km on a full charge (technically possible with a small enough payload, but it's still ambitious in practice given that things don't always go exactly to plan and batteries also degrade over time) most drivers would hope to cover more than that in a single day (depending on how many hours they're allowed to work under local laws; it's only nine hours in the EU, but it's 12 in the USA and Australia).
All that said, one concept that I'm amazed isn't in the conversation more is diesel-electric hybrids. Years ago, Cummins called this diesel generator option on their Urban Hauler electric semi concept a range-extender.
Just like a hybrid car, if the battery has adequate capacity to cover a reasonable distance (the Urban Hauler was claimed to get between 320 and 480km), a hybrid could be zero-emissions for its fight through traffic, it could take advantage of the other range-extending feature which is regenerative braking (lots of Australia's trucking routes have major hills to negotiate), and it could still continue on indefinitely with just a short break for refuelling (along with proper rest periods for the driver as required by law).
