As car manufacturers look for alternatives to petrol- and diesel-fuelled internal combustion engines (ICE), one potential option to be developed is hydrogen cars.
But are hydrogen cars a real alternative to the battery electric cars that carmakers now see as the future of zero-emissions motoring?
We consider the current state of hydrogen and electric cars, compare what each offers and look at which ones we’ll be driving in the future.
What is an electric car and how does it work?
Electric vehicles (EVs) are powered by electricity, stored in a rechargeable battery array, which drives an electric motor: the motor then creates a magnetic field that turns a rotor shaft, which drives the car’s wheels. Most electric cars use one motor, but some models have two motors (usually one at the front axle and another at the back), offering more power.
Battery packs in EVs comprise stacks of lithium-ion cells, like the ones in a smartphone or laptop battery. The batteries are rechargeable, so must be plugged into a mains outlet to charge, either at home or at a public chargepoint.
EVs also feature regenerative braking, which takes energy from the wheels when the driver applies brakes, which would previously just have been lost, and uses it to top up the battery.
What is a Hydrogen car and how does it work?
Hydrogen cars are technically hydrogen fuel cell cars, because they’re fitted with a fuel cell that is essentially a small hydrogen-fuelled power station.
High-pressure hydrogen gas is pumped into the car’s fuel tank, which combines with oxygen from the air around it and is fed to the hydrogen fuel cells, where it comes into contact with the anode and cathode. An electrochemical reaction takes place, the hydrogen molecules breaking into protons (water) and electrons (electricity) to power the car.
The water is waste and the only emission from a hydrogen car – as you can see in Mat’s review of the Toyota Mirai below. The electricity produced is stored in a battery, which powers a motor that moves the wheels, like a regular EV.
Pros and cons of electric cars
Pros of electric cars:
Infrastructure: Compared to hydrogen cars, electric cars have a pretty advanced charging infrastructure, with home, workplace and public charging networks. In contrast, there are just 15 hydrogen fuelling locations in the UK.
Cheaper: Even though EVs are more expensive than petrol or diesel cars, they are more affordable than the couple of models on sale, the Toyota Mirai and Hyundai Nexo. The cost and convenience of recharging batteries isn’t matched by that of pumping hydrogen, either.
Maintenance: EVs have very few moving parts, so maintenance is far easier and quicker, without the need for oil changes. Adding a fuel cell – a portable power station, in effect – to a car adds a lot more complexity if issues arise.
Emissions: Electric cars run silently and produce no pollution or emissions. Hydrogen cars are much the same, although they do emit water as a by-product of the electrochemical reaction.
Cons of electric cars:
Limited range: After being used to being able to travel hundreds of miles on a tank of petrol or diesel, the range of an EV is one of its biggest drawbacks, along with the time it takes to charge a battery.
Battery lifespan: The lifespan of batteries will be limited and we’ll need to find ways of recycling them sustainably. We might also need to develop ways to replace old batteries with new ones.
Limited charging stations: The rollout of EV charging infrastructure is happening, but there are questions about whether it’s happening fast enough. There’s certainly an argument that we’re not yet ready for a nation of EV drivers.
Pros and cons of hydrogen cars
Pros of hydrogen cars:
Refuelling: Filling a hydrogen car’s tank will only take a few minutes, much as we do now with petrol or diesel. The hydrogen is stored at a low temperature and high pressure, so it takes no time to pump.
Range: Hydrogen cars offer a 400-mile range from a single tank of fuel. In comparison, only a few high-end EVs have battery packs large enough to come close to such a range.
Zero emissions: A hydrogen car might emit water, but that’s harmless, so it is a zero-emission vehicle when it comes to CO2 or the myriad other pollutants from an internal combustion car.
Cons of hydrogen cars
Gas pumps: With the limited refuelling options in the UK – there are less than 20 hydrogen fuel pumps across the entire country – hydrogen cars are not a viable option for most drivers.
Expensive: The two hydrogen models on sale are not cheap to buy and refuelling isn’t cheap, either.
Production: The production of hydrogen can be energy-intensive and often rely on various non-renewable sources, which counteracts the zero-emissions nature of a hydrogen car.
Eight key difference between hydrogen vs electric cars
Range
The driving range of EVs depends largely on the size of a battery and size of the car. More expensive EVs with larger batteries tend to have longer ranges. Typical EV ranges currently range from around 100 miles to around 350 miles. Hydrogen cars, on the other hand, offer a better driving range along – and a shorter refuelling time. The distance a hydrogen can cover ranges from 400 to 600 miles, depending on the size of the tank.
Refuelling
The UK currently has very few hydrogen filling stations, so hydrogen vehicles lack the required infrastructure to make it possible for large numbers of drivers to adopt the technology. Even with the current adolescent state of charging in the UK, you can find thousands of charging stations for EVs.
Refuelling time
It only takes around five minutes to pump the high-pressure hydrogen gas into the tank of a hydrogen car. In comparison, an EV can take up to 20 hours or more to charge, using a standard domestic plug, but even the fastest public chargers will take 20 minutes to top up the battery.
Environmental impact
While driving a hydrogen car, the only emission it releases is pure water vapor, while the process of taking in oxygen from the surrounding air also means filtering out ultrafine particulates. Although EVs don’t emit any pollutants, they can have an impact on the environment, with the manufacturing and disposal of EV batteries leading to concerns about resource depletion.
Efficiency
Converting hydrogen into electricity in a fuel cell is a complex process, so a hydrogen car is already at a disadvantage compared to an EV. In fact, even though hydrogen cars are more energy efficient than ICE cars, EVs still outdo them in the efficiency stakes. EVs can convert 80% of the electricity in the battery into energy, while hydrogen cars currently convert a maximum of about 40%.
Safety
Hydrogen cars use hydrogen in gas form, which is highly inflammable, to create the electrical energy to move the wheels. Advanced designs and safety precautions make driving hydrogen vehicles a little less risky, but drivers are still sitting on top of a tank full of inflammable gas. With EVs, the safety concern is based on lithium-ion batteries being exposed to fire. Although EVs come with a few risks, driving an electric car is safer than a hydrogen-powered one.
Emissions
Neither hydrogen nor electric cars produce CO2 emissions directly from their exhausts. However, a considerable amount of CO2 is released during the manufacturing process of both electric and hydrogen cars, and the manufacturing process of producing electricity and hydrogen.
Costs
EVs are more expensive to buy than the ICE cars we’re used to driving, but the cost is starting to fall as manufacturers start to benefit from the efficiencies of mass production. Hydrogen cars are even more expensive than EVs, with the Hyundai Nexo and Toyota Mirai both costing in the range of £60,000-£70,000
Is hydrogen power or electric power better?
As the two technologies currently stand, EVs are set for world domination over the coming decades, with hydrogen consigned to limited use on longer-range and heavier vehicles.
Part of the reason for that is the costs of producing hydrogen and storing it under high pressures and at very low temperatures. Producing hydrogen on the kind of industrial scale required for transport use takes large amounts of fossil fuels and the use of methane, which is an even more potent greenhouse gas than CO2. There are renewable methods – and these might yet yield advances in hydrogen production – but they are more expensive, so hydrogen production uses CO2-intensive methods that are self-defeating as we strive for Net Zero.
With expensive fuel that is hard to come by, there seems little chance of hydrogen cars becoming mass-market products. The only hope will be someone developing a cheap and easy way of extracting hydrogen – which is, let us not forget, the most abundant chemical substance in the universe – for use in vehicles.
On the other hand, EVs use electrical energy directly from the grid to charge a battery and power the vehicle. There are concerns about how we generate that grid electricity, but the UK is increasingly using renewables, which will lower the amount of CO2 being emitted when generating what powers EVs.
The other concerns about EVs – the rare earth materials being used in batteries and the range of EVs – could also be addressed by technological development. If you look at how automotive technology has developed in the last few decades and consider that we’re at the start of the EV revolution, advancement is probable, not just possible. Using different elements and chemistries in batteries could revolutionise ranges and make them more recyclable and sustainable.
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