DHL creates its own hybrid
Unconvinced by the diesel-electric hybrids offered by truck manufacturers, DHL Supply Chain has commissioned an innovative 14-tonne GVW hybrid of its own.
It has just started work for NHS Supply Chain, the operation run by DHL for the NHS, working out of a DC near Maidstone, Kent making deliveries to hospitals and clinics within the M25.
DHL’s hybrid is based on a 14-tonne GVW Daf LF55. Unlike hybrids from Mercedes-Benz, Volvo and Fuso, among others, it uses a series rather than parallel driveline. This means that the diesel engine – a four-cylinder, 4.5-litre Paccar FR/Cummins ISB – never directly powers the truck.
Instead, the engine runs in a fuel-efficient speed corridor of 1,100rpm-1,600rpm, driving an electrical generator. This provides power for the 120kW (161hp) electric motor connected via the truck’s shortened prop-shaft to the original drive-axle. The standard clutch and gearbox have been removed.
The other unusual aspect of DHL’s hybrid is that it has no bank of lithium-ion batteries to store electrical energy. Instead, it uses ultracapacitors to act as a small short-term buffer energy store. These are capable of being charged rapidly – mainly via regenerative braking – and delivering their power to supplement the electrical output from the diesel-driven generator during times of peak load, such as acceleration or hill climbing.
The vehicle was developed and built for DHL by Magtec, a Sheffield-based manufacturer of hybrid and electric-drive components.
“We’ve tried parallel hybrids,” explained DHL Supply Chain innovation manager Ian MacAulay, citing a two-year trial with an 18-tonne Volvo and a year’s experience with Daf’s LF hybrid. “Neither gave us the right level of savings to achieve an acceptable RoI.”
DHL wants CO2/fuel savings of at least 20%, compared with diesel Daf LFs working alongside the hybrid.
Following in-service trials, DHL expects to be able to make a decision next year about buying more hybrids.
- See tomorrow's Commercial Motor magazine for more.