Hydrogen to replace diesel? JCB working on making it happen

JCB is charging ahead with its hydrogen engine project – and rather than being secretive ahead of a commercial launch, the company has held detailed briefings to reveal all it has learnt so far.

It was only a matter of days after JCB announced it's £100m hydrogen-fuelled engine project that Tim Burnhope's phone started ringing with calls from farms and estates.

Spurred, presumably, by JCB's unequivocal conclusion that hydrogen gas fuelling an internal combustion engine is the way to go for heavy construction and farm machinery, the enquirers sought guidance on how they could tap into renewable energy resources to ‘crack’ water into ‘green’ hydrogen.

"It was a very revealing reaction," said JCB's chief innovation officer. "In agriculture, there's a great opportunity with wind and solar-generated electricity to charge a big battery box, or make hydrogen fuel, and there's a lot of interest and excitement about that potential."

Mr Burnhope and colleagues have been kept busy in recent years exploring the complex issue of how to replace diesel with a sustainable power source that suits heavy machinery and provides flexibility and speedy refuelling.

Various options have been evaluated, including electricity from batteries and hydrogen fuel-cells, and alternative fuels for internal combustion engines such as HVO (hydrotreated vegetable oil), different bio-gases, ammonia, and e-fuels that, for example, combine hydrogen and carbon dioxide (CO2).

"Batteries have a place in light equipment, as evident from our E-Tech range of products, including the 525-60E compact telehandler, site dumpers and industrial forklifts, and our electric mini excavators," said Mr Burnhope. "The electric telehandler is no heavier than its diesel counterpart and manages on £10,000-worth of 24kWh batteries because of its intermittent work cycle.

"But we’ve calculated that giving a 300hp Fastrac equivalent electric power for a solid eight-hour day would require 500kWh of batteries, adding five tonnes to the weight, costing £200,000 and increasing the machine cost by more than 2.5 times!"

JCB has also gone down the hydrogen fuel-cell route, creating a widely-publicised prototype 360° excavator to prove the technology in this demanding application. Now, says Mr Burnhope, with the benefit of experience, the fuel-cell solution is considered dead and buried as 'being too complicated for the markets we serve, and provides insufficient response for machines that need rapid power delivery.'

"The fuel-cell is a very lethargic device. Our prototype excavator had £32,000-worth of batteries to provide an initial power response before the fuel cells react – and it needed almost three times the cooling capacity of an equivalent diesel engine."

And fuel cells are expensive, he pointed out, partly because so few are made. Toyota, the biggest manufacturer, is understood to produce just 2000 a year in contrast to 20m batteries and JCB's annual output of 80,000 diesel engines.

"With regard to the alternative internal combustion fuels, we got quite excited about most of them but then discovered their downsides and disadvantages," Mr Burnhope added.

FARM POWER Operators will experience little difference between a hydrogen-fuelled Loadall and a diesel version, believes JCB

"Ultimately, we concluded that the characteristics of hydrogen gas provide the best solution for a mobile fuel with the same convenience as diesel – ie a flexible supply location and quick re-fuelling for maximum up-time – while using a power unit that we are all familiar with in terms of manufacturing, installation, usage, maintenance and servicing."

With that conclusion came a fresh challenge to his engineers from JCB chairman, Anthony Bamford: Design an engine fuelled by hydrogen that has the same power, torque and power delivery characteristics as a diesel engine.

"We have to remember that diesel is going out," said Lord Bamford. "There's no choice other than to work with an alternative – we’ve learnt a huge amount over a short period of time and are convinced that hydrogen is the best solution."

Two years later, almost to the day, that challenge was met by JCB's hydrogen engineering team, not with a conversion, insists Ryan Ballard, powertrain engineering director, 'but with a new engine carrying the DNA of our existing diesel engines'.

In the fourth quarter of 2022, small batches of the 4.8-litre JCB 448 ABH2 passed through the JCB Power Systems factory at Foston, near Derby, and by early December a landmark 50 units had been assembled.

These are now contributing to an intensive programme of validation tests, running for as little as 150 hours under very heavy load and up to 3000 hours working through the widely-differing load cycles that a production engine would experience in different machines.

Unveiling the new engine, Mr Ballard explained: "To begin with, we studied past projects converting petrol or diesel engines to run on hydrogen and found that they all failed, which told us that's not the answer. So we went back to first principles, optimising all aspects of the engine design for hydrogen, which is a very light, low density gas."

That informed the needs of fuel injection and combustion chamber design, resulting in a low pressure, low temperature system using a common rail injection system and a purpose-designed low inertia turbocharger.

"The big challenge was to achieve a perfectly homogenous mixture of this light gas and air in just 28 milliseconds, so we have indirect injection with the gas drawn in and starting to be mixed with the air coming from the turbo before the swirl characteristics of the combustion chamber – perfected by almost 160 computational fluid dynamics tests – completes the process."

The engineering team, bolstered to around a hundred by freshly-recruited engineers with expertise in metallurgy, oils and other specialist disciplines, also developed a high-tech spark plug with an acceptable service life, and an ignition system with special coils to energise it.

Subtle changes to the lubrication channels apart, the block, crank, sump and ancillaries are all shared with the diesel engine, which provides some welcome economies that also apply to cooling requirements as the engine's heat rejection is the same as the diesel's.

The quest for commonality and familiarity also extended to the noise the engine makes, said Mr Ballard: "It has a softer compression signature, so it's a little quieter than a diesel, but we wanted it to sound familiar and also feel familiar in use so that operators used to working with diesel-powered machines don't notice much difference."

Vehicles equipped with the new engine will be re-fuelled from static or mobile tanks using a combination of two high-pressure hoses, one to fill the tank, one to purge the delivery hose, with the pressure differential between the storage tank or bowser at 500 bar and the vehicle tank at 350 bar eliminating any need for a pump.

That 350 bar compression, incidentally, drops to just 20 bar for the journey to the engine so conventional low-pressure pipes can be used.

"Fuel tank capacity will be as much as the machine needs for a full working day," promised Mr Burnhope, "with maybe an auxiliary tank solution available for very high-hours operators."

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