Mercedes-Benz’s hydrogen truck options

Change is nearly always disruptive and the necessary move into low and zero emissions trucks and buses was of itself a huge challenge for an industry that has relied almost entirely on diesel fuel for the past 120 years.

Add into that mix shortages of everything, caused by a global pandemic, followed by a war in Europe and the change becomes even more radical.

In Australia, there’s general concern about the electrification of trucks, because of our high train weights, high road speeds and vast distances. We all know that current battery electric vehicle (BEV) range is limited and, while hydrogen fuel is touted as a possible alternative to diesel, there is zero – zero – infrastructure across this wide brown land to support either BEV or hydrogen long-distance trucks.

Seeking clarification of a path towards low and zero emissions trucks Down Under, we spent some time in Germany with Dr Andreas Gorbach, Head of Truck Technology and a member of the Daimler Truck board.

Refreshingly, it was soon obvious that this guy understood the global customer’s position quite well. On the question of diesel fuel phase out, Dr Gorbach was quite clear:

“The year 2039 is a pencilled-in target for the complete phase-out of diesel fuel at Daimler Trucks,” he said.

“However, that’s not a firm date by any means.

“The transition to cheap, ‘green’ fuels is dependent entirely on a vast amount of infrastructure that requires huge investment.

“If the investment is slow to occur, truck operators won’t be able to refuel their electric vehicles and we won’t be allowed to produce polluting diesel vehicles, so we’ll be in a bad position.”

What about the ‘great battery breakthrough’ that everyone is expecting, we wondered? Dr Gorbach was calm and factual with a reply that completely scotched that idea:

“Electrical output is limited by the number of elements listed in the periodic table,” he reminded those of us who should possibly have stopped clowning in the lab and listened to our chemistry teacher.

“If we could make a battery combining the lightest and the heaviest elements, giving us the highest electrical potential possible, the power density of that battery would still be only one thirtieth – 1/30 – that of the power available from hydrogen.

“That’s why Daimler Truck is pursuing hydrogen as well as battery power for zero emissions trucks.”

Interestingly, Dr Gorbach made a strong case for hydrogen combustion engines, in addition to non-combustion hydrogen fuel cells. Daimler concluded a deal with Cummins last year, for collaboration on hydrogen combustion engines.

That deal has already resulted in a prototype medium-sized Atego truck that we covered earlier this month and Dr Gorbach forecast a Cummins-Daimler heavy duty engine development later in 2022, or early 2023.

“A fuel cell hydrogen truck is most efficient at part-load, such as when travelling on an autobahn at 40 tonnes, where power demand is only around 100 kilowatts,” he said.

“But the hydrogen combustion engine is more fuel efficient at high-load demands, in hilly country, or with high train weights and road speeds.”

Mercedes-Benz GenH2 fuel-cell prototype trucks began rigorous testing in 2021, on the in-house test track and on public roads, using liquid hydrogen fuel for maximum range. The development objective is a range of at least 1000 kilometres, with a payload of 25 tonnes at a gross weight of 40 tonnes.

The start of series production of hydrogen-based trucks is planned for the second half of the 2020s.

The two stainless-steel liquid-hydrogen tanks on the GenH2 prototypes have a total capacity of 80 kilograms and are each formed from two cylinders, one within the other and vacuum-insulated.

In conjunction with Volvo Group, Daimler Truck founded a joint venture Cellcentric company in 2021, to produce fuel cells for both brands.

The Mercedes-Benz fuel-cell combines two 150-kilowatt units, feeding a battery that can provide an additional 400kW temporarily. With only 70kWh capacity, the storage capacity of the battery is low, compared with a battery-electric-truck, because it’s there only to help satisfy peak loads, when the truck is accelerating or driving uphill fully loaded. The battery is recharged by braking energy and excess fuel-cell power.

A cooling and heating system keeps all components at the ideal operating temperature, thus ensuring maximum durability.

The prototype truck shown at the IAA was powered by two electric motors, mounted on a Mercedes-Benz eAxle, designed for a total of 2 x 230kW/2 x 1577Nm continuous output and 2 x 330kW/2 x 2071Nm maximum output.

Related reading:
IAA: Mercedes-Benz eActros and eEconic battery-electric trucks
Volvo tests fuel-cell hauler
Hyundai's hydrogen heavy-duty trucks to hit the road in Germany

Daimler Truck is also working with Linde on the development of a new process for handling liquid hydrogen – sub-cooled liquid hydrogen (sLH2) – with higher storage density and easier refuelling, when compared with LH2.

Daimler Truck is planning to work with Shell, BP and TotalEnergies in establishing hydrogen filling stations along important transport routes in Europe. Daimler Truck is also a shareholder in hydrogen filling station operator H2 Mobility Deutschland.

In addition, Daimler Truck, IVECO, Linde, OMV, Shell, TotalEnergies and the Volvo Group have committed to work together to help create the conditions for the mass-market roll-out of hydrogen trucks in Europe, as part of the H2Accelerate (H2A) interest group.

We’ll continue to monitor hydrogen developments in Europe over the next few years and assess what may eventuate in Australia.