Do Kawasaki’s Hydrogen-Fuelled Internal Combustion Engine Proposals Hold Water
It’s a clean fuel but there are issuesby Harry Fisher, on
Petrol is going, there’s no doubt about that. But, apart from electric batteries and motors, is there an alternative to petrol as a fuel for an internal combustion engine? Kawasaki seems to think so. Is the future hydrogen?
Can Hydrogen be the fuel of the future?
In this post, we reported that Kawasaki had announced its intention to have at least 10 electric or hybrid models by 2025 and have no petrol-engined vehicles at all by 2035.
Now, of course, Hybrid vehicles are a combination of electric and an internal combustion engine, which still means - at the moment at least - a petrol-driven engine. And that will soon be unacceptable. So, what’s the answer?
Well, back in 2020, Kawasaki debuted a dual-injection version of the H2 supercharged unit. This not only used conventional port fuel injection but also a high-pressure direct injection into the cylinder when under full compression.
Now the importance of this is that it is a short development step from there to creating a hydrogen-fuelled engine and the only by-product of burning hydrogen is water. Just as importantly, the motive power for a motorcycle would remain an internal combustion engine and not an electric motor.
There are benefits to both port injection and direct injection. With port injection, the air/fuel charge has time to cool a little and cooler means denser means more charge in the cylinder. The mixture also cleans the valve seats and the extra time allows the fuel and air to mix more thoroughly, giving better combustion.
Directly injecting fuel into the combustion chamber after the valves are closed prevents petrol escaping and cools the cylinder which allows higher compression ratios and a leaner air/fuel mixture. The only issue is that it needs incredibly high pressure to inject the fuel accurately when the cylinder is under full compression. Kawasaki’s patent suggests a pressure of 1,450 psi where the port injection pressure is a mere 44 psi.
All this means that a hydrogen-fuelled combustion engine is possible and Kawasaki is clearly thinking along those lines. With normal port-injection, hydrogen gas takes up too much space so the gas/air ratio wouldn’t produce enough power. But injecting hydrogen into a cylinder full of air that’s already been compressed by a supercharger would work and would maximise potential power output.
It’s not quite as simple as that, however. How do you store the hydrogen on the bike? Hydrogen fuel cells are larger than equivalent petrol tanks. You can’t just pour the hydrogen in: it has to be put in under pressure through a sealed nozzle, so the tank has to be a pressure vessel. And that’s all before thinking about a network of hydrogen-equipped fuel stations. But the fact that Kawasaki is working on hydrogen power across all its divisions - ships and aircraft as well as motorbikes - means it is serious and is assessing all the potential technologies required.