What are e-trailers? They look very much like a conventional semi trailers except they have their own battery packs and an e-axle that powers some of the wheels. Instead of requiring a tractor to do all the work, e-trailers share the task of transporting cargo. By doing so, they can reduce the carbon emissions associated with freight operations.
DB Schenker is one of the largest freight carriers in Europe. In a press release on October 25, it announced it has placed an order for 2,000 e-trailers from Trailer Dynamics and Krone Commercial Vehicle Group, with the first units expected to enter service in 2024.
“This agreement marks a further step in the electrification of land transport,” says Cyrille Bonjean, executive vice president of land transport for DB Schenker in Europe. “It is essential for us to look for new sustainable solutions that can be integrated into our daily business. With the e-trailers from Trailer Dynamics, we have obtained another promising model for the future.”
Wolfgang Janda, head of network and line haul management for DB Schenker, adds: “The use of e-trailers enables early entry into the phased transition to a completely CO2-free fleet. In our view, electric trailers do not represent a transitional technology but will instead be a firm component of our commercial vehicle fleet over the long term. This marks yet another step in our efforts to reduce our environmental footprint and become net-zero by 2040.”
What Are E-Trailers?
According to Electrive, the e-trailers have their own electric drive unit that reacts to the driving behavior of the tractor it is connected to. The company says that the drive unit takes some of the load off the tractor, which can lead to fuel savings of up to 40% over a distance of 500 kilometers or more
The trailers can be equipped with 300 kWh, 450 kWh, or 600 kWh LFP battery packs supplied by CATL. The e-trailers employ regenerative braking to send electricity back to the batteries during braking. They have 44 kW AC chargers built in or can be charged by a DC fast charger at up to 350 kW.
The core of the system is a patented sensor system that records the driving dynamics of the vehicle and controls the drive of the e-trailers. The system is designed in such a way that the trailer never overrides the tractor unit. The drive control works independently so no interface to the tractor is necessary. This means that the e-trailers can be used with tractors from different manufacturers that use either gasoline, diesel, batteries, or fuel cells. That flexibility is one of the key features that led to the DB Schenker order.
The development partnership with CATL will explore battery swapping procedures for the e-trailers. While battery swapping for trucks is picking up pace in China, it has not yet gained significant traction in Europe but the advantages are clear. The batteries can be easily upgraded without dismantling the vehicle, the used batteries are more easily allocated to second life uses, and getting enough energy for a long journey takes only the time required to physically swap out the batteries, which is generally done robotically at a battery swapping station in a matter of minutes.
Emissions from freight operations are significant and must be reduced. But perhaps they can be lowered more cost effectively by powering the trailers that actually haul the cargo rather than the tractors that pull the trailers. As the old expression goes, don’t raise the bridge, lower the river.
Electric tractors from Daimler and Volvo as well as Volkswagen Group and Tesla are just coming available. E-trailers may be able to lower emissions and operating costs sooner than replacing the tens of thousands of tractors and trailers already on the road. DB Schenker certainly thinks its a strategy worth pursuing.
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