Hydrogen vehicle technologyhas come a long way since it’s invention over two hundred years ago, when a French inventor Francois Isaac de Rivaz developed an engine powered by oxygen and hydrogen ignited by an electric spark. But how do hydrogen cars work in the modern era?
While the elements that power the car have remained much the same, the technology has improved considerably: modern cars use fuel cells – and in contrast to standard engines contain no moving parts.
Key Components of a Hydrogen Fuel Cell Vehicle
- Battery or peak power battery/auxilliary: This supplies electricity which is used to start the car prior to the traction battery being engaged. The battery also powers vehicle
- Battery pack: This stores energy created by regenerative braking, and also powers the electric traction motor.
- DC/DC converter: This device converts higher-voltage DC power from the traction battery pack to the lower-voltage DC power, and is used to recharge the auxiliary battery and run vehicle accessories
- Electric traction motor: The electric motor takes power from the traction battery pack and fuel cell, driving the vehicle’s wheels – although some vehicles have motor generators with dual functions that both regenerate and power the wheels.
- Transmission: This transfers power from the electric traction motor to drive the wheels.
- Fuel cell stack: This is an assembly of individual membrane electrodes using oxygen and hydrogen to produce electricity.
- Fuel filler: Similar to what you would see on a traditional car, this is a nozzle from a fuel dispenser attached through which the driver can fill the tank.
- Hydrogen Fuel tank: This is where hydrogen gas is stored onboard the vehicle until needed.
- Power electronics controller: This controls electrical energy flow created by the fuel cell and traction battery -which in turn controls the speed and torque of the electric traction motor.
- Thermal cooling system: This system is designed to maintain a proper operating temperature range of the power electronics, motor, fuel cell and other components.
How Do They Work?
Hydrogen cars operate via a process called fuel cell technology in which a process known as reverse electrolysis takes place. Hydrogen enters the fuel cell from one or more tanks built into the FCEV (fuel cell electric vehicle) – while oxygen is drawn from the ambient air.
This combination of energy, heat and water creates electrical energy and water – which is then emitted from the exhaust as vapour. Depending on the specific driving situation, the electricity in the fuel cell either charges the battery or flows to power the FCEV directly.
The Downsides to Hydrogen Vehicles
- Expense of fuel: Hydrogen is comparatively expensive to store and move around (although it can be produced on-site).
- Cost to drivers: Currently, hydrogen cars are more pricey to run than diesel or petrol, with fuel costing drivers around £10 – £15 per kilo. The cars themselves are also relatively expensive – although with increased use over time it’s possible the price of FCEVs could decrease.
- Perceived safety risk: Hydrogen is highly flammable (however the same can be said for traditional fuels like petrol).
- Lack of available refuelling stations: Currently there are only 17 in the UK, with each station costing £1.3 million to build (Zap Map is a handy resource for drivers seeking hydrogen refuelling stations)
The Benefits to Hydrogen Vehicles
- Easy to drive: Hydrogen fuel cell cars are relatively easy to manouver, the main concern of the driver being regenerative braking.
- Quieter and less polluting than petrol engines: Hydrogen cars emit only water vapour (the only other byproduct being heat) – meaning fewer greenhouse gas emissions.
- Easy to Source: Hydrogen can be sourced from oversupply of renewable energy sources such as wind or solar, and can also be found as a by-product of industrial processes, creating the opportunity to upcycle fuel effectively.
- More efficient than petrol or diesel: Fuel cell trains draw energy from hydrogen more efficiently than standard cars do from diesel or petrol.
- Faster to refuel compared to an electric car: FCEVs are also time efficient, taking just three to five minutes for drivers to refuel.
- They can now take you further: An average range of around 300 miles per tank.
- Energy efficient: Hydrogen vehicles are able to recover energy using regenerative braking – converting kinetic energy back into electrical energy which is then fed into the back-up battery. Like other EVs, hydrogen vehicles also have an “idle off” function, which allows the fuel cell to shut down when temporarily stopped – for example at traffic lights.
- Cheaper Tax: Hydrogen fuel cell cars are classed as “ultra low emission vehicles” (ULEVs), which are taxed relatively lower than traditional vehicles. In addition to this, hydrogen drivers need not pay vehicle excise duty (or road tax), aside from a £310 yearly supplement for cars exceeding £40,000 for the first five years.
- Exempt from Congestion Charge: This applies to both the London Congestion charge and other clean-air zones like Leeds and Birmingham.
Hydrogen Sceptics
Hydrogen vehicle development remains in it’s early stages in the UK – with a degree of lingering uncertainty and scepticism around matters of cost, availability and range. Some have even gone so far as to suggest that hydrogen-powered vehicles will never catch up to their battery-powered EV competitors.
Renewable Interest
However: despite multiple hydrogen “frenzies” touting it as the next big thing in renewable fuel (resulting in a series of false starts in 1974, 2005, 2009 and 2014 respectively), hydrogen-powered vehicles haven’t dropped out of the race just yet.
Experts are optimistic that hydrogen cars offer a viable alternative to petrol engines, with technology improving all the time and significant investment into development. In the last year alone, several car manufacturers have expressed interest in hydrogen fuel cell vehicles, including Volvo and Honda.
A Question of Cost
At the forefront of this latest surge of enthusiasm is cost: hydrogen analyst Martin Tengler suggests that while the price of petrol is unlikely to diminish any time soon, the cost of hydrogen could potentially decrease.
Tengler also suggests that developments in hydrogen fuel technology bode well for other renewables like solar, suggesting that at least 33% of the world economy could be powered by clean energy for a similar price to fossil fuels – provided government-backing is available.
Are We There Yet?
With an increased focus on the effects of climate change (and urgent action taken to temper its effects) car manufacturers are looking for greener, more sustainable ways to drive.
The benefits of hydrogen-powered vehicles in terms of cost, fuel efficiency and sustainability have also earned them an enthusiastic following – at least for those who have been able to get behind the wheel.
For the majority of drivers, opportunities to drive a hydrogen fuel-cell powered vehicle are relatively scant, with only two FCEV models available in the UK – the first being The Hyundai Nexo, the second being the Toyota Mirai, of which there are currently 200 available.
Writing for The Times, Grand Tour host and proud Mirai owner James May claimed that although it was the “nicest car (he has) ever owned”, hydrogen fuel cell cars were also an “element of a much bigger energy vision to decarbonise everything…worth pursuing”.
Driving the Future of Renewable Fuel
May’s sentiments echo that of other experts, who view hydrogen not as a complete answer to carbon emissions and costly fossil fuels – but as part of a solution that could involve multiple renewable fuels (with ever-improving technology) being used together.
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