Electric and hybrid cars are gaining in popularity, in part because they help reduce the amount of carbon emissions released into the atmosphere. But they are not the only option for more environmentally friendly driving. Hydrogen fuel cell electric cars sound like something out of science fiction, but these vehicles have been around longer than you think. If you are interested in another alternative to the combustion engine, this is how they work.
How does a hydrogen fuel cell work?
Hydrogen vehicles are a type of electric car that use fuel cells to power the engine instead of relying primarily on a lithium-ion battery pack; they do not burn fuel like gasoline cars. As with electric vehicles, hydrogen cars do not generate any harmful emissions: the only by-product is water vapour. Since they’re EVs, you’ll also hear them called fuel cell electric vehicles (FCEVs).
Fuel cells are similar in design to a lithium-ion battery: they have an anode, a cathode, and a catalyst that triggers the separation of electrons and protons from the hydrogen gas pumped into them. Like the lithium-ion cells in an EV battery, hydrogen cars have multiple fuel cells that work at once to generate electricity. That collection of cells is called a hydrogen fuel cell stack.
Hydrogen from the car’s onboard fuel tanks is combined with oxygen inside the fuel cell stack to generate electricity through a process called reverse electrolysis. Electrons are removed from the hydrogen gas, sent through the circuit to power the engine, and combine with oxygen on the other side of the circuit to form water vapor, which is vented through the car’s exhaust.
The hydrogen tank, battery, and electric motor work together to power the FCEV. (Image: BMW)
The electricity that is generated from hydrogen fuel cells can take two paths(Opens in a new window), depending on the situation. The energy powers the electric motor directly or charges a small lithium-ion battery that helps power the motor and can store the energy for later use. This battery also captures energy from the vehicle’s regenerative braking system for later use and stores excess energy from the fuel cell stack during low-energy driving. If more is required of the motor, the battery kicks in to help.
Refueling and Autonomy
The Toyota Mirai fuel cell vehicle has an estimated range of 402 miles (Photo: Toyota)
Refueling an FCEV’s hydrogen tanks is almost as quick as filling up a car with gasoline, a huge advantage hydrogen cars have over battery electric vehicles. You just pull up to the gas station, hook up the hose, and the tank is full in about five minutes.
An FCEV can have multiple hydrogen gas tanks on board. Since hydrogen can be highly flammable(Opens in a new window) if handled improperly, those fuel tanks are thick-walled, pressurized and crash-tested to ensure safety in the event of a crash. Safety devices are also built into the vehicle that ensure hydrogen is dispersed and released if, for example, the fuel cell is removed or overheats.
Another advantage hydrogen cars have over battery electric vehicles at the time of writing is their greater range. FCEVs can go 300 to 400 miles before they need to be refueled, according to California’s Drive Clean Initiative(Opens in a new window). Battery EVs, on the other hand, have an average EV range of about 250 miles(Opens in a new window) at the time of writing this article.
The challenges of fuel cell vehicles
True Zero Hydrogen Filling Station (Photo: True Zero)
Fast refueling, electric power and the only by-product is water – sounds like the perfect green vehicle, right? Well, it could be, but unlike electric vehicles, FCEVs don’t exist yet.
For starters, although they have a longer range than EVs, FCEVs are more expensive to fuel, in part because hydrogen is so expensive to produce. It may be the most abundant element on the planet, but refining it into a form that can power a vehicle takes effort, and that effort is reflected in the cost per tank.
The FCEV refueling infrastructure is also seriously lacking at this time. exist less than 400(Opens in a new window) FCEV service stations around the world, although there are efforts to build more stations; The U.S. aims to have 1,000 online by 2030. Still, that’s far fewer hydrogen fueling stations than electric vehicle charging ports, which numbered around 110,000 in the US(Opens in a new window) from September 2021.
Another challenge FCEVs face is that while they can run emission-free, the plants that create their hydrogen fuel often do so by burning fossil fuels in a process called steam reforming(Opens in a new window). If that continues, FCEVs won’t do as much for the environment as they could, and they can’t really be called zero emission vehicles.
alternative processes(Opens in a new window) being explored include water electrolysis, which uses a renewable source such as solar to generate electricity that can be used to separate hydrogen from water.
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VEGF vs. EV
Ford’s Mustang Mach-E, an example of a battery-powered electric car (Photo: Ford)
Hydrogen vehicles have a lot in common with battery-powered cars like the Ford Mustang Mach-E (above) and the Tesla Model 3. Both battery electric vehicles and FCEVs use electricity instead of fuel, both have electric motors and batteries on board, and none emit harmful gases. The differences boil down to infrastructure, fuel, and availability.
Battery electric vehicles have a more robust infrastructure for public charging than hydrogen vehicles. While still not as prevalent as gas stations, there are now thousands of electric vehicle recharging locations across the US. Meanwhile, all hydrogen fueling stations in the US are located in California(Opens in a new window)so long road trips are out of the question.
The cost of refueling is also worth considering. Since it is currently more expensive to produce hydrogen gas for FCEVs, filling your FCEV is more expensive than for an electric car. However, a hydrogen vehicle can recharge much faster than an EV and can store excess electrical energy in its battery, allowing it to recharge while driving. Battery electric vehicles, by contrast, must be connected to the grid to recover most of their energy.
The Hyundai Nexo fuel cell electric vehicle has been on the market since 2019. (Photo: Hyundai)
Of course, the biggest problem is that FCEVs are not yet widely available in the US. Only a few manufacturers sell them to the public; Toyota Mirai and Hyundai Nexo are the most frequent names in the race currently.
Despite hydrogen’s limitations, countries around the world see it as a viable alternative energy source for everything from cars and buses to planes(Opens in a new window). If we can find a cost-effective way to make hydrogen production more environmentally friendly and build the necessary refueling infrastructure, FCEVs could mean a breakthrough for green transportation.
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