An alternative to electric cars: Can hydrogen power really save the internal combustion engine? | Opinion

Making the combustion engine and all the supply processes required to run it carbon-neutral, or at least almost carbon-neutral, would surely be the ideal compromise between the need to reduce reliance on fossil fuels without upsetting motoring traditionalists.

The good news is that there is a way - hydrogen. While it's not widely used in practice, hydrogen can be burned in place of traditional combustion engine fuels like petrol and diesel, while producing almost no gas emissions.

The bad news is that the development of this technology is currently in its early stages, and it might take a lot of convincing (and money… mostly money) to make it happen. So, how likely is it that hydrogen will play a big part in the future of motoring?

Arguably the biggest proponent of hydrogen as a power source for transport, both as a means to power electric motors as in fuel-cell electric vehicles (FCEVs) and via combustion, is Toyota.

Toyota has a history of concepts built to run on hydrogen in some way, and currently has one of very few FCEVs in production, the Mirai.

In Australia, specifically at its Altona headquarters in Victoria, Toyota even has a hydrogen production facility powered by a combination of its solar array and mains power - somewhat less renewable given the use of fossil fuels in the grid - that is mostly used for powering the few Mirais on lease.

In Australia, specifically at its Altona headquarters in Victoria, Toyota even has a hydrogen production facility powered by a combination of its solar array and mains power.

But late in 2023, Toyota announced a test bed for a different type of hydrogen-powered transport in the form of a HiAce Commuter bus, fitted with a twin-turbo 3.5-litre V6 engine like the one used in the Tundra in the US… but refitted to burn hydrogen rather than petrol.

All it took for the engine to be able to run on the most abundant element, Toyota said, was to replace the injectors with some that would suit hydrogen, while the fuel tanks fitted under the floor of the bus were borrowed from the Toyota Mirai.

And, while it drives much like a regular combustion-powered vehicle, it has its drawbacks in its current form. Forgiving the way it's tuned (it makes just 120kW and 354Nm, but we'll come back to that), the van's range is currently less than 200km.

Toyota has a history of concepts built to run on hydrogen in some way, and currently has one of very few FCEVs in production, the Mirai.

The brand's Hydrogen Factory President Mitsumasa Yamagata told CarsGuide at the prototype's reveal that they plan to find ways to maximise the engine's efficiency, likely with hybridisation, to improve the range.

While those drawbacks are fairly major, Toyota says one of the largest benefits is the ability to use existing manufacturing infrastructure - the engine production lines that exist can build essentially the same engines for hydrogen as they already do for petrol or diesel.

And it's not like hydrogen doesn't have other advantages over battery electric vehicles. Hydrogen can be transported to remote areas (though the means would need to be carbon-neutral or close-to) and it also means less need for harmful battery materials to be mined.

Hydrogen can be transported to remote areas (though the means would need to be carbon-neutral or close-to) and it also means less need for harmful battery materials to be mined.

But if hydrogen is to become a major part of the way we power transportation in the future, it doesn't make sense for it to be with combustion. The lightness of hydrogen and the lower reliance on batteries is still true for FCEVs, and the electric motors that drive FCEVs can be more powerful than the initial testing bed that is the combustion hydrogen HiAce.

Which brings us back to the reason for its low outputs - emissions. Burning hydrogen still produces some byproducts, one of which is water when plenty of oxygen is present. But burning hydrogen at high temperatures (a higher output from the engine would need more energy) also results in production of more nitrogen oxides. Even without emitting carbon dioxide, creating nitrogen oxides just raises an alternative issue - another harmful byproduct.

Then there's the simple fact that it's quite a challenge to produce hydrogen in the quantities required to run a city's, let alone a country or the world's, cars and trucks on hydrogen as a replacement for traditional fuels.

Burning hydrogen still produces some byproducts, one of which is water when plenty of oxygen is present.

The energy required to produce hydrogen (which itself wouldn't necessarily be renewable), then to transport it, and then its limited efficiency within the combustion process itself (similar to that of diesel, we were told by Toyota engineers) means a lot of wasted energy along the way to turn the wheels.

Relatively little of the energy used in that process actually makes it to the end, whereas most of the energy produced to power an electric car makes it to the wheels - there's relatively little power loss when grid power is plugged directly into a vehicle, and again between the battery and wheels.

One report from the US Department of Energy and the Environmental Protection Agency found electric vehicles "convert over 77 per cent of the electrical energy from the grid to power at the wheels" as opposed to "about 12 per cent to 30 per cent of the energy stored in gasoline to power at the wheels".

How likely is it that hydrogen will play a big part in the future of motoring?

So back to that question: how likely is it that hydrogen will play a big part in the future of motoring?

Probably not. And if so, it would be an odd choice given the alternatives available.

As with the way different fuels are used for various purposes now, there might be an application where hydrogen combustion is the most sensible choice at some point, in the same way that low-emission synthetic fuels might end up being used in aviation or heavy industry where batteries would simply be too large.

But the use of hydrogen as a direct fuel rather than a power source for batteries and electric motors is likely to be a very small part of the future, if at all. Will your passenger car or SUV run on hydrogen combustion? It's not likely.