Are hydrogen fuel cell trucks any good?

One of the zero emission technologies which is likely to have a big impact on Australian trucking in the future is using hydrogen as a fuel.

At the recent Truck Show X in the Hunter Valley, we got to try a couple of very different uses of hydrogen as part of the test drive program, and came away with good and bad news...

Over the past decade many big-hitters in the automotive and trucking world have been trying to 'crack the code' and come up with a way to commercialise the use of hydrogen fuel cells.

In many ways these are very similar to the electric trucks that we already see on our roads, but instead of using large heavy batteries to drive the electric motor, the system uses a hydrogen fuel cell to supply the electricity needed by the driveline.

An interesting take on hydrogen to help in lowering carbon emissions, has been developed in New Zealand and is now available in Australia. The principle behind this technology is that it introduces a precisely quantified amount of hydrogen into the cylinder of a normal diesel engine as part of the combustion process.

The hydrogen replaces a certain percentage of the diesel, meaning that the combustion process uses less diesel and therefore produces less carbon dioxide.

Driving a fuel cell truck, in this case a Shacman prime mover, is a very different experience for a truck driver.

Where electric trucks are always very quiet when active, a fuel cell needs to be started up and the various systems which activate the fuel cell and the hydrogen tanks (stacked at the rear of the cabin) do generate a bit of noise.

It's all very familiar in the driver’s seat, with a steering column stalk controlling forward and reverse and another familiar looking stalk which replicates the work of an engine brake.

However, this set-up relies on a power regeneration process, whereby the truck is slowed by using the electric motor to regenerate charge in the batteries fitted to the truck.

On the road, this regenerative braking proves to be much more effective than the diesel engine versions.

There are five positions on the lever and only the first two can be used on a bobtail prime mover, because any more retardation would lock up the drive wheels.

The driver can see an on-screen bar, which shows how much power they're using and how much regeneration is going back into the battery pack, when slowing the truck.

On the screen, to the right indicates power being used, and to the left indicates regeneration is taking place.

The 240kW fuel cell is configured as a single unit and it sits where the ICE engine is normally fitted, alongside other ancillaries like cooling, ECUs etc. Attached to this is an electric AC compressor, which looks like a large turbo, pushing cooling air into the back end of the fuel cell.

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The truck has 117kWh of battery capacity onboard, and the hydrogen fuel cell keeps the batteries topped up to between 50 and 75 per cent fully charged, in order to drive the electric motor and driveline.

Apart from this innovative driveline, the rest of the truck functions pretty much the same as any other prime mover on the road.

However, one thing you do notice almost immediately is just how quiet it is sitting in the driver seat and bringing the truck up to highway speed. If there's any noise in the cabin it's just a bit of road noise or some wind noise from the airflow around the cabin, when reaching cruising speed.

The set-up, with the hydrogen storage tanks on a frame at the rear of the cabin, stores 70kg of hydrogen and can hold the gas at up to 350bar. As the hydrogen is used, that pressure decreases.

Altogether the prime mover weighs 12.2 tonnes; a couple of tonnes heavier than a diesel engined prime mover. Set up as a 46 tonne semi, the test truck comes in at 7.6 tonnes on the steer axle (okay for trials), but a working truck would need the fifth wheel moving back to get under the planned 7.5 tonne limit.

Shacman reckons that when fully loaded the truck is achieving about 12.4kg per 100km. If that is the case, 63kg of usable hydrogen works out to be able to give a functional range around 500km.

Refuelling time can be relatively quick with the truck’s ability to take 60g a second, with the right refuelling infrastructure. Unfortunately, there's very little good hydrogen refuelling infrastructure anywhere in Australia, and this will be the constraining factor for these fuel cell trucks when they come online.

Climbing up into the Change Fuel Technologies’ Volvo FH 780 prime mover is a much more familiar experience.

Sit down in the driver’s seat, click in the seatbelt, turn the ignition on, select drive, release the brakes and set off down the road.

Apart from the graphics on the Volvo truck, the only asepct which makes you realise this is something different is the large aerodynamically shielded stack of hydrogen tanks fixed to the rear of the cabin.

The engine is the normal Volvo 780hp diesel unit but with just a bit extra, so from the driver’s point of view it's just like driving a diesel. However, this truck is actually dual fuel. It doesn’t run purely on hydrogen at any point, but it does substitute a proportion of hydrogen mixed with the diesel.

The amount of hydrogen being introduced is set by the control system using data from the ECU signal from the Volvo engine. The unit is calibrated so that the engine does not develop more power than the manufacturer’s set limits in their specification.

If the truck runs out of hydrogen, the system just reverts to a 100 per cent diesel fuel burn.

Once out on the road, the driver’s attention is drawn to a screen just above their head on which a graphic shows just how much hydrogen is being used as a percentage of fuel going into the engine.

The hydrogen is vented into the engine via the manifold and the gas leaves the tank at 350 bar, but this is regulated down to 10 bar for injection into the air stream. The truck carries 250 litres of diesel and is carrying around 25kg of hydrogen.

Out on the road, the truck behaves like a diesel, but watching the substitution rate (or the rate at which gas and diesel are combining), accelerating hard will see a rate of 25 per cent or less.

But when cruising speed is reached and the right foot is less insistent on the accelerator, the number will climb up over 35 per cent. Taking it really easy will get that reading up over 40 per cent, and heading towards 50.

“With 1300 heavy trucks on the road, we started to investigate what the future vehicles for our group would look like,” explained Gareth Wishart, who has a number of roles for two New Zealand enterprises, Change Technologies and HW Richardson Group.

“To do these long distance heavy payloads, about 30 tonnes of payload in New Zealand that’s 58 tonnes GCM. To do that with diesel, 600km, and the topography in the South Island, we’re talking about 350 litres of diesel to do that job, and you're most likely to be carrying more fuel than that on board," he said.

“On the Change trucks we’ve got this combination of factors here, about 1200kg of weight on the truck, carrying about 250 litres of diesel, and around 25kg of hydrogen gas.

"We’re combining the two fuels together, and by doing that, you're actually starting the work to get the infrastructure ready and the fuel where it needs to be to refuel the low emission vehicles. We’re also getting the comfortability of the drivers around carrying fuel, so they stop saying things like it's a Hindenburg or a hydrogen bomb on their truck.

“HWR is a group committed to investigating how we could support the future of fuel in New Zealand using the 125 fuel stops that we have, and we've embarked on a journey to build up refuelling for hydrogen.”

HWR has assessed the capital costs for the truck in its lifespan and reckons it costs 6-12 cents/km. The company has found willing customers that will give HWR up to a 10 per cent increase in rates, allowing the company to offset those costs in the New Zealand emissions reduction regime.

This year’s concerns about fuel availability have also led to increased interest in using a fuel like hydrogen which can be produced in New Zealand, or Australia.

Hydrogen pros:

Cons: