Innovative Energy Recovery: Thermo King's Axlepower Sets New Standards in Eco-friendly Freight Transport

The transport sector is at a turning point. With a share of approximately 22 percent of total emissions in Germany, the transport sector is one of the largest contributors to greenhouse gases. According to projections by the federal government in 2024, the sector will miss the emission targets set in the Climate Protection Act by a total of 180 million tons of CO₂- equivalent by 2023. Freight transport remains the biggest challenge.

Although trucks have also become more efficient, their per-kilometer direct emissions have decreased less compared to cars since 1995. However, since there are more trucks on the roads overall, the total share of emissions in road freight transport has increased by a good 20 percent compared to 1995 (Source: UBA). The pressure from regulatory authorities, customers, and society to find more sustainable solutions is therefore steadily growing.

Transport companies face the challenge of reducing their ecological footprint while remaining competitive. High investment costs for new technologies, infrastructure gaps, and operational constraints complicate the transition to low-emission solutions. Innovative approaches are needed that are both ecologically and economically sensible and can be seamlessly integrated into existing operations.

Energy Recovery as Key

For refrigerated transport, Thermo King, an international manufacturer of transport temperature control systems and a brand of the Trane Technologies conglomerate, has developed a solution to enable companies to transition to technologies that do not cause direct emissions despite infrastructure and financing challenges. The trailer-mounted system, named Axlepower, uses the kinetic energy generated during braking and downhill driving to store it in a high-voltage battery. This energy then powers the refrigeration unit, enabling a fully electric refrigeration operation that operates without direct emissions. The necessary energy is entirely derived from the movement of the trailer, making external charging points - as well as fossil fuels - unnecessary.

An intelligent charging system automatically switches between recuperation mode (brake energy recovery), passive mode (sufficient battery charge), and active mode (additional charging current when needed) to ensure optimal charging efficiency. This smart energy management minimizes the resistance on the towing vehicle by automatically switching between modes to ensure optimal charging efficiency.

Versatile with Considerable Future Potential

The ability to generate energy directly from the movement of the trailer makes Axlepower technology a sustainable solution for various transport requirements. For instance, the South African luxury retail chain Woolworths has been using the first temperature-controlled trailer powered by Axlepower on the nearly 1,400-kilometer route between Cape Town and Johannesburg since early 2024, demonstrating that the technology works not only in urban distribution but also on long distances.

Since its commissioning in the middle of the South African summer, the system has operated in electric mode for more than 97 percent of the time over a distance of 15,000 kilometers, without turning on the vehicle's diesel engine. By using this novel technology, Woolworths already saves about 27 tons of CO2 annually on the route with a single truck.

From an economic perspective, the technology also pays off. Recovering brake energy saves fuel costs and reduces operating expenses. Additionally, expenses for emission certificates in urban environmental zones are eliminated. The investment in the technology thus pays for itself through efficiency gains and cost savings alone.

Another advantage for traders and freight forwarders lies in the future-proof nature of the investment. Trailers are generally in use for 12 to 14 years, significantly longer than trucks. Given the increasingly stringent regulations, non-electric delivery vehicles will surely no longer have access to Low Emission Zones (LEZ) and Ultra Low Emission Zones (ULEZ) in 10 to 15 years.

With fully electric cooling like Axlepower, suppliers and freight forwarders are in a safe position in the medium to long term, as they can comply with stringent emissions regulations without needing to make additional investments. The technology is also independent of the truck, allowing its propulsion to be converted to more sustainable technologies at a later date without needing to retrofit the trailer's cooling system. Integration into telematics systems also enables predictive maintenance and range optimization. This allows the range in purely electric operation to be gradually expanded.

Cooling works even without a truck – at least until the battery is empty. | Images: Brian Ach / Thermo King; Thermo King