Kawasaki Demonstrates Hydrogen Prototype

[Hugh Janus]

Kawasaki’s hydrogen test mule recently ran some demonstration laps at the Suzuka circuit in Japan. (Kawasaki/)

Any lingering doubts over the seriousness of Kawasaki’s progress on a hydrogen-powered motorcycle for the future were decisively answered when the machine made its public debut at the Suzuka circuit on July 20 ahead of the Suzuka 8 Hours race.

The bike is part of a research project that Kawasaki says started in March 2023, although the early stages of development were clearly underway long before that as the company first showed a hydrogen-fueled version of its supercharged 998cc four-cylinder Ninja H2 engine as early as October 2021. Sketches of a future hydrogen-fueled bike were revealed in November 2022 and the real thing was unveiled in December 2023.

Kawasaki has now confirmed that testing has been underway since the start of 2024, getting to the stage where the bike was ready to be demonstrated in public at Suzuka in July. But that doesn’t mean a production version is just around the corner—the company says it is “currently conducting research and development with the aim of realizing a functioning hydrogen ICE motorcycle as one carbon-neutral option for riders in the early 2030s.”

A view of the converted supercharged H2 engine. (AutoBy/)

The bike itself uses a converted version of the Ninja H2 engine, as supercharging is all but essential on a hydrogen-fueled combustion engine. Hydrogen needs a much higher ratio of air to fuel compared to gasoline, and compressing air with a supercharger before it enters the cylinder helps achieve that goal. The conversion to hydrogen also required the engine to adopt direct fuel injection, adding hydrogen into the combustion chambers after the inlet valves have closed, because otherwise the hydrogen expands and forces air out of the cylinder.

The engine was developed as part of Kawasaki’s contribution to the HySE research association, where it works alongside Honda, Suzuki, Yamaha, and Toyota on the development of hydrogen-combustion engines for small vehicles. The hydrogen-fueled Kawasaki engine made its competition debut in this year’s Dakar rally, powering the HySE-X1 four-wheeler, but the Suzuka demonstration is the first time it’s been publicly seen in action on two wheels.

The test mule at Suzuka. (Kawasaki/)

Video of an earlier test run at the Autopolis circuit has also been released on Kawasaki’s own YouTube channel. It reveals that the bike has a hydrogen filling port on the back, feeding gas into the huge side-mounted tanks where it’s stored in an array of cylinders that can cope with vast pressure. Hydrogen fuel cell cars like the Honda Clarity store the gas at around 10,000 psi, and a clip of the fuel pump’s display shows it racing past 34 megapascals (340 bar, or around 4,900 psi) as the bike is filled, suggesting the Kawasaki’s tanks are similar to those in existing hydrogen vehicles. Even at such high pressure, hydrogen takes up much more space than gasoline carrying an equivalent amount of energy. On Kawasaki’s prototype there’s no provision for a passenger and those enormous rear panniers are used for fuel, not luggage.

It might be bulky, but hydrogen is much more energy-dense than gasoline in terms of weight, so those big rear tanks should be much lighter than they appear. Kawasaki says the bike’s whole chassis is designed to accommodate the hydrogen canisters and the fuel system.

Burning hydrogen in an internal combustion engine is much less efficient than using it in a hydrogen fuel cell powering an electric motor, but there are advantages to the hydrogen ICE idea. Perhaps most importantly, the hydrogen doesn’t need to be as pure—a fuel cell is easily damaged by any contamination in the gas, while a combustion engine is much more tolerant. But perhaps the biggest gains are from the perspective of manufacturing and marketing. Companies like Kawasaki Motors, Honda, Suzuki, and Yamaha all have well-established engine manufacturing facilities as well as all the infrastructure behind them, so hydrogen-combustion engines could be made relatively cheaply. What’s more, the engines offer a familiar noise and sensation that for many riders is an integral part of the motorcycling experience, something that electric bikes (whether powered by batteries or fuel cells) can’t match.

The original design sketch shows a much less cumbersome motorcycle, while the reality shows how much space the hydrogen tanks take up. (Kawasaki/)

Environmentally, the hydrogen-combustion engine’s emissions are nearly pure water vapor, although there can be traces of CO2 from burning engine oil. As in a gasoline-fueled engine, NOx can also be a byproduct of the combustion process, but the overall emissions are tiny compared to a conventional fossil-fuel engine. Whether that is clean enough to satisfy legislators around the globe who are increasingly pushing for zero tail pipe emissions remains to be seen.

Perhaps the most significant deciding factor over the commercial future of the project will be that of hydrogen manufacturing and distribution. That’s something the wider Kawasaki Heavy Industries group is deeply involved with, right down to building huge oceangoing ships specifically designed to carry liquid hydrogen at cryogenic temperatures around the globe, but at the moment there are still very few hydrogen filling stations and it will take a big push over the next decade to get to the point where riders in the “early 2030s” will be able to easily refill their hydrogen-combustion engine bikes.

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