Merc’s diesel days are numbered
Mercedes-Benz Trucks has pledged to make all its new vehicles CO2 neutral by 2039. The pledge encompasses all weights and applications produced for the European market.
Speaking at a Motor Transport Roundtable, Uwe Baake, Merc’s head of product engineering, said the pledge was a big challenge, but, “nothing is more exciting for engineers.”
The direct use of green energy, meaning renewable electricity, was most efficient when provided to battery-electric vehicles. Hydrogen fuel cells were slightly less efficient, but would be better for long-haul trucks where they provided range and payload advantages.
Vehicles powered by biofuels or synthetic fuels had significant issues. Producing large quantities of biofuel would see agricultural land taken out of food production, while the production of synthetic fuels would not be energy efficient. It was likely such solutions would only be used for very specific applications such as snowploughs.
“There is no future for fossil fuels 20 years from now,” he said.
Battery vehicles would be used where work patterns were predictable, and payloads light. Hydrogen fuel cells would power heavier trucks on less predictable and long-haul applications.
In 2016, Mercedes had shown its first electric truck at the IAA Show.
“It ran, but was not a viable truck,” he admitted.
In 2018, the first eActros Generation One trucks were revealed, and these were now undergoing operator trials in Germany and neighbouring countries as the Mercedes Innovation Fleet.
This year would see the first production eActros appear in June, with the eEconic municipal vehicle to follow in 2022. UK vehicles will follow 12 months later (Transport Operator 93).
Trucks in the Innovation Fleet were supposed to be trialled with a first set of operators for six months, then passed to other fleets, but the initial users were reluctant to let them go. Operators had liked their silence and economy, and the drivers had enjoyed using them.
Questions had been raised concerning vehicle range, external electricity powergrid infrastructure, and also the vehicles’ appearance. Operators were disappointed that they did not look different to existing diesel models.
The current 18-tonners had a range of 200 km on a single charge, but production vehicles would see this extended to 350 km.
Long distance battery trucks would come in 2024, their introduction spurred by the need to reduce VECTO measured CO2 emissions from the production fleet by 15 per cent by 2025. They would offer a range of 500 km, dictated by battery weight and size, and have a 22-tonne payload at 40 tonnes GVW.
In terms of vehicle life, Mercedes was aiming to equal that of current diesel trucks: 10 years and 1.2 million km.
The next step would be hydrogen fuel cell long-haul trucks, which would appear in the Innovation Fleet in 2024 and enter production at some point between 2025 and 2030 (when the VECTO reduction target would be 30 per cent).
These would be fuelled with liquid hydrogen, have a range of over 1,000 km, and be lighter and faster to ‘refuel’ than battery trucks. They would look different to existing diesel trucks and have a payload of 25 tonnes at 40 tonnes GVW.
“Unlike other manufacturers, there will be no bridging technology from Mercedes Benz,” Uwe Baake promised. “There will be no gas fuelled or hybrid trucks. We will go straight to electric.”
The fuel cells were being developed in Daimler’s joint venture with Volvo Group (Transport Operator 97) and will be positioned in the same location as the diesel engine in today’s trucks, with much of the technical control equipment mounted on a tower behind the cab.
Liquid hydrogen was to be preferred to the gaseous form as, although it posed a technical challenge in being held at a temperature of – 250°C in double-skinned stainless-steel vacuum tanks, this was less of an issue than compressing the gas to 7,000 bar and containing it in carbon-fibre tanks.
As fuel cells worked best converting hydrogen to electricity at a constant output, the vehicles would also need a battery of around 70 kW/h capacity. This would store surplus electricity produced in low-load conditions and use it to boost the truck’s performance in high output conditions, such as hill-climbing.
