Power shift

Electrification in heavy transport is no longer confined to the prime mover, as e-trailers are now longer seen a wish-list item, with a wave of innovations is pushing electrified trailers from prototype to early-stage commercial deployment.

At the centre of this transition is the rapid development of electrified axles, which are transforming traditionally passive trailers into active contributors to propulsion and energy management. These systems use regenerative braking to capture energy during deceleration or downhill running, storing it in onboard battery packs that can range from 200kWh to more than 600kWh. That stored energy can then be redeployed either to power auxiliary systems or to assist the prime mover.

The SAF-Holland TRAKr and TRAKe e-axles use recuperation to recover energy and provides traction support through the electric motor. This gives more traction and stability for the semitrailer, particularly in demanding road conditions and inclines.

Australian-based VE Motion is advancing systems that use regenerative axles to reduce brake wear while harvesting energy. More advanced configurations go a step further, delivering active electric assistance of up to 295kW – enough to significantly reduce the load on the towing vehicle. In some applications, this can cut diesel consumption by as much as 50 per cent or extend the operating range of battery-electric trucks.

In Europe, regulatory progress has helped accelerate adoption, with the European Union enabling type approval for “eTrailers” and pre-series units already operating in countries such as Germany and Denmark. The 2013-2017 Transformers project focused on redesigning trucks and trailers to reduce fuel consumption and CO₂ emissions – hopefully, without needing to change existing EU regulations.

German startup Trailer Dynamics, founded in 2018, has been at the forefront, deploying around two dozen pre-series trailers equipped with integrated electric drivetrains. The company’s system is designed to respond dynamically to the driving behaviour of the tractor unit, supporting propulsion regardless of whether the truck is powered by diesel, battery-electric or hydrogen. It recently secured a €25 million loan from the European Investment Bank to advance its research.

Australia is emerging as a key proving ground. With its long distances and heavy payloads, local freight presents ideal conditions to test how electrified trailers can address the issue of range as one of the biggest barriers to zero-emission trucking. Trials are increasingly focused on using e-trailers as range extenders for electric prime movers, allowing operators to begin decarbonising without fully replacing existing fleets.

Beyond propulsion, electrification is also reshaping auxiliary systems. Refrigerated transport is a prime example, where axle-based energy recovery systems are eliminating the need for separate diesel-powered cooling units. Technologies such as Thermo King’s AxlePower, co-developed with BPW, capture braking energy and store it in high-voltage batteries to run refrigeration units both on the move and at standstill. Trials in Europe and Africa have demonstrated significant fuel savings and emissions reductions, including cuts of up to 20 tonnes of CO₂ annually in some applications.

Despite the momentum, challenges remain. The added weight and upfront cost of battery systems continue to pose barriers, although these are increasingly offset by lower fuel and maintenance costs over time. Regulatory frameworks also lag behind the technology in some markets, where fully powered trailer axles are not completely aligned with existing vehicle design rules.

There are also technical hurdles. Siemens research in 2025 highlighted that integrating powered e-axles altered the entire vehicle’s dynamics “bringing new challenges in vehicle stability”.

Electrified trailers are now widely regarded as a practical technology that can deliver immediate efficiency gains. With trials expanding, e-trailers are expected to move firmly into the mainstream by the end of the decade. In the interim, they can be viewed as a modular, scalable pathway to lower emissions, reduced fuel consumption and improved operational efficiency – without waiting for a complete overhaul of the heavy vehicle fleet.