Why Hydrogen?
When discussing how to drive more sustainably, most of the conversation is around hybrid, plug-in hybrid, or electric cars. But there is another option available to some drivers looking to reduce their carbon footprint: hydrogen.
Currently available in very limited markets, hydrogen cars are an interesting and viable way to go zero-emissions – and will surely be a part of the overall transportation mix in the future. At the moment, lack of choice and a very sparse refueling infrastructure are limiting factors for most buyers.
While the cars aren’t widely available, hydrogen is. In fact, it’s the most abundant element on earth by quantity (though not by weight). Hydrogen is also very energy-dense: 100 times more energy-dense than a typical lithium-ion battery. It can be produced from several domestic resources – including bio-resources or renewable electricity via electrolysis – so its production can be environmentally-friendly.
One major benefit of hydrogen is refueling. A hydrogen-powered vehicle can be filled up in a similar amount of time as a gasoline vehicle. This is a major advantage over battery-powered cars, which can take much longer to recharge.
Different Types of Hydrogen Vehicles
Hydrogen cars can be roughly divided into two categories: hydrogen fuel cell vehicles (which operate like electric cars) and hydrogen combustion vehicles (which operate similarly to gasoline cars). Both types of vehicles produce zero emissions – but they work in very different ways.
Hydrogen Fuel Cell
Hydrogen fuel cell cars may sound like a new thing – the first mass-production fuel cell cars for America, the Hyundai Nexo and Toyota Mirai, will be delivered in 2022 – but fuel cells are technology that pre-date the automobile.
In essence, a fuel cell combines hydrogen and oxygen in the presence of an electrolyte to produce electric current. In fact, fuel cells were used in the 1960s in America’s Gemini and Apollo spacecraft, where they provided crews with electricity and water, which were generated by stored hydrogen and oxygen.
A hydrogen fuel-cell vehicle is an electric vehicle – just without a plug. There’s no big battery to recharge. Instead, you simply fill a tank with compressed hydrogen gas, which takes about five minutes. From the pressurized fuel tank, the gas flows to a fuel cell system, which combines the hydrogen with oxygen from the air. A chemical reaction produces electric current – and water, which is the car’s only emission.
Hydrogen fuel cell vehicles are relatively lighter and less complex than gasoline vehicles – and because they don’t rely on a huge battery to derive decent driving range, they are relatively lighter than battery-powered electric vehicles.
Hydrogen Combustion
Unlike a hydrogen fuel cell vehicle, which creates electricity that powers an electric motor, a hydrogen combustion engine looks, sounds, and behaves like a gasoline engine – except for the fact that it burns hydrogen and produces no noxious tailpipe emissions. Like a fuel cell car, a hydrogen combustion car only emits water.
The advantage of hydrogen combustion engines for automakers is faster time to market – because they can adapt existing engineering, including the fuel systems on-board a vehicle. Hydrogen burns quicker than gasoline, making powertrains very responsive and exciting.
On the other hand, hydrogen combustion cars are more mechanically complex than hydrogen fuel cell cars, which consist of a simple, reliable electric motor and a fuel-cell system. Hydrogen combustion cars have lots of moving parts like a gasoline car and thus come with more frequent maintenance.
Drivers of hydrogen combustion cars will also share some of the drawbacks of hydrogen fuel cell vehicles. These include an expensive pressurized hydrogen storage tank and a lack of refueling infrastructure in much of the U.S.
Disadvantages? Hydrogen gas takes up a lot of space and requires a big tank – or, in liquid form, needs a pressurized and cooled container, which is expensive.
The Future
While it is not new, hydrogen is currently a very niche technology in the automotive world. Only one hydrogen fuel cell vehicle is currently available for sale to the American public, the Toyota Mirai sedan, and no hydrogen combustion vehicles are on sale.
The problem for the earliest adopters of hydrogen driving may be finding where to fill up. As of early 2022, fewer than 50 publicly accessible hydrogen filling stations exist in America. However, the state of California has almost 40 – so if you live or work near one of these stations a Mirai, Nexo, or a future hydrogen-powered vehicle may be a viable option.
Hydrogen infrastructure is bound to improve over time – not least because it’s an ideal fit for commercial vehicles. Hydrogen fuel cells, which are light and simple compared to batteries and offer faster refueling times, are a more likely path to “greening” America’s semi-truck fleet than batteries. In order to provide the range that long-haul transport requires, the required batteries would be too heavy – massively compromising usable payload – and would take too long to charge to be practical.
If you’re a driver that frequently takes long trips – or doesn’t have regular access to charging at home or work – hydrogen may ultimately be a better option to greening your drive compared to battery-electric. You may just have a little bit of a wait before there are enough choices in terms of vehicles and refueling.
