What is a hydrogen car?

A hydrogen fuel-cell car may sound like science-fiction, but they're here and could form a major part of the motoring landscape in years to come

Most people are starting to get clued up on the differences between an electric cars, plug-in hybrid cars (PHEVs) and  hybrid cars. However, there's a fourth kind of electrified car that people often leave out of the equation – a hydrogen fuel-cell car such as a Toyota Mirai or Hyundai NEXO.

Despite being called a hydrogen car, or more accurately, a hydrogen fuel-cell vehicle (FCV), a hydrogen car is just a different type of electric vehicle. This is because while battery electric cars (BEVs) get their power from a lithium-ion battery that stores electricity, a hydrogen car's motors are powered by a fuel cell that converts hydrogen into electricity.

How does a hydrogen car work?

The key to a hydrogen car is the fuel cell. It can convert hydrogen into electricity, with the only byproducts being heat and water. Most hydrogen cars use polymer exchange membrane (PEM) fuel cells; these consist of two electrodes.

The hydrogen is stored in the form of gas in compressed air tanks and forced into the fuel cell. There, it's broken up by the catalyst, forming electrons. These electrons are harnessed and used to power the electric motor. The remaining hydrogen molecules, when mixed with oxygen, turn to water.

So, while the lithium-ion batteries in a conventional electric car store electricity, the fuel cells in a hydrogen car convert hydrogen into electricity. Many hydrogen cars also feature lithium-ion batteries, which store the electricity that has been produced.

Hence, the key difference between an electric and a hydrogen car is then where the electricity comes from. For electric cars it comes from the grid. For hydrogen cars, it comes from the hydrogen. A key advantage hydrogen cars have over electric cars is a longer driving range – often 300 miles or more – and the fact that they can be refuelled in minutes rather than hours.

Why aren’t hydrogen cars more popular?

The above distinction also explains why hydrogen cars are still in their infancy. While electric cars can be plugged into the grid, hydrogen cars have to be refuelled at dedicated hydrogen filling stations.

While hydrogen is the most abundant element in the universe, it has to be harvested and processed, which is a costly and complex process. There are just a handful of hydrogen fuel stations in the UK – although the number is growing.

The lack of hydrogen refuelling infrastructure currently acts as a barrier to the widespread adoption of hydrogen-fuelled cars in the UK. However, the government has announced a £23 million fund to accelerate hydrogen-vehicle infrastructure and uptake.

Can I buy a hydrogen car?

There are just a handful models to choose from. One is the Toyota Mirai – a hydrogen saloon car – while the other is the Hyundai NEXO, a large SUV. Both are very expensive, and you need to do your research before purchasing to make sure that there's a refuelling station near you.

Looking ahead, a new Toyota Mirai is also on the way, while BMW is working on a hydrogen-fuelled X5 and Renault plans to offer hydrogen-fuelled vans.