DHL creates it own hybrid UNCONVINCED by the diesel-electric hybrids
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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 1,10Orpm-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 dieseldriven 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 Rol."
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 next week's CM for more information.