Do hydrogen cars have a future?

If we truly want sustainable vehicles on our roads, elimination of all environmental impact must be the goal, rather than simply nibbling around the edges of fuel efficiency. The battery-powered electric vehicle revolution is well underway, but what about other options? 

In the current technology race, hydrogen cars remain super-niche but score positively in opinion polls for their strong range and lack of behavioural change. Time to find out if hydrogen-powered cars could provide further help or just hype.

How do hydrogen cars work?

Hydrogen fuel electric cars are technically hybrid vehicles because they rely on two fuel sources: a regular battery and a hydrogen fuel cell. There’s a Professor Brian Cox brain’s-worth of H2-fuelled witchcraft going on here, but basically, a proton exchange membrane fuel cell uses compressed hydrogen and oxygen from the air to produce electricity. This electricity then powers an electric motor that drives the wheels. The only bi-product from this entire process is water. 

We’ve enjoyed the super-rare pleasure of visiting a hydrogen filling station and can say that the refuelling process is pretty similar to filling a car with petrol or diesel. You swipe your bank card on the pump, lock the fuel nozzle into place and allow 700 bars of pressurised hydrogen to flow. Within a few minutes the entire process is complete, signed off by the sound of a humpback whale surfacing somewhere in the distance. That big ol’ whoosh is actually depressurised gas being expelled from the on-site hydrogen storage tanks that feed the pumps. In fact, the only thing that does feel different is moving the economy scale from a ‘miles per gallon’ metric to ‘kg per 100km’.

How clean is hydrogen?

How clean hydrogen is will depend on how the hydrogen is produced in the first place. The cleanest process is electrolysis, whereby you put a current through pure water to split out hydrogen from the wet stuff. If the process is done using renewable energy, it’s known as green hydrogen. If it’s connected via the grid, then it’s called yellow hydrogen. 

The source of electricity is particularly important because the electrolysis process itself is about 75% efficient. That means you only get 75% of the energy you started out with, which translates to higher costs yet cleaner air.

The other hydrogen-making process involves treating natural gas or methane with hot steam. During this process, the methane splits into its four hydrogen atoms while the one carbon atom gets bonded to oxygen and goes off into the atmosphere as carbon dioxide. This is known as grey hydrogen or, if the carbon dioxide can be captured and stored, it’s called blue hydrogen.

OK, so only green hydrogen is actually green?

Yep, that part really is as clear as water. If a car or truck could be powered by green hydrogen, that would be awesome. Unfortunately, it’s the grey and blue hydrogen that you’ll see heavily promoted, most often by the fossil fuel lobbies. That’s because it uses lots of natural gas in the process, a resource that will diminish in importance and value as energy conscious home owners inevitably switch from conventional boilers to heat pumps.

The problem is that two percent of the world’s carbon emissions already comes from the grey hydrogen process for things like fertiliser. For context, that’s almost the same as the entire aviation industry, so we need to make more efforts to clean up hydrogen.

How many hydrogen filling stations are there in the UK?

According to UK H2 Mobility, there are currently 14 hydrogen filling stations in the UK, five of which are located within the M25. Sounds limiting but there are just two hydrogen cars on sale: the Toyota Mirai and Hyundai Nexo. By contrast, there are already more than 100 pure electric cars on sale and roughly 35,000 public EV charging devices.

Unfortunately, existing filling station infrastructure can’t be used for a hydrogen fuel pump, either. Because hydrogen is incredibly difficult to store and transport, these filling stations will require lots of adaptation, and enough space to have an electrolysis set-up on site that (hopefully) embraces green hydrogen. All possible, but it just makes it a trickier and more expensive design challenge, which may help to explain the limited growth.

So does hydrogen have a future?

Green hydrogen has lots of value, but based on the lack of vehicle choice and incredibly limited fuelling options, it’s difficult to rationally promote. We may still see some advances in certain sectors of the automotive industry, such as the heavy goods vehicles. With the passenger car market fully embracing electric cars rather than hydrogen fuel cell vehicles right now, it would be both better to see and easier to justify the use of hydrogen in other applications, such as decarbonising fertiliser, with the production of ammonia, or in the steel industry, replacing coking coal in the reduction process of iron oxide to make iron.