Hydrogen is not tame—the element brings to mind rockets, fire, and explosions. This association is for good reason too. Hydrogen is an extremely flammable gas often used as rocket fuel. But hydrogen cars are no futuristic technology. Toyota has sold nearly 11,000 hydrogen fuel cell cars as of December 2020, and the Hyundai Nexo hydrogen powered car has gone through the full set of tests from the Insurance Institute for Highway Safety and received the highest possible safety rating, meaning it definitely didn’t explode. But how are hydrogen powered cars sustainable, or even safe? Unlike conventional fuel powered vehicles, the hydrogen is never ignited or brought close to ignition (the hydrogen tank is lined with kevlar in case this occurs by mistake), but since hydrogen cars produce their own electricity and don’t use combustion, they’re more complicated than a conventional electric or gasoline powered car.
All three hydrogen cars available for purchase are powered by hydrogen fuel cells. These fuel cells take fuel from a tank, just as gasoline cars do, but in this case, the fuel is extremely pressurized hydrogen. The hydrogen gas is not burned (burning the hydrogen fuel would either make this a rocket car, or more likely cause it to explode), but is instead chemically combined with oxygen to make water. This process releases electricity and is considered extremely clean since the only byproduct is water (pure enough to be drunk), which is released from the tailpipe as water vapor. This process is similar to what happens in a battery, except a battery contains a limited supply of fuel, whereas a hydrogen car can be refilled. The electricity can be used to run the car as a normal electric car does.
This all seems like a complicated way to go about making electricity, though. What are the benefits and drawbacks of hydrogen cars, and could they be a more sustainable option for the future than electric cars? We can begin by looking at the benefits of hydrogen cars. Since hydrogen cars store their fuel more densely than electric vehicles do, they are generally capable of traveling farther distances. Furthermore, despite revolutionizing developments in charging for electric cars, hydrogen cars can still be fueled up much faster, which is not surprising considering that 1kg of hydrogen fuel holds 236 times more energy than 1kg of lithium ion batteries (used in electric vehicles). Hydrogen cars also do away with the challenge of considering what happens to lithium ion batteries at the end of their life. Hydrogen fuel cells have a lot of benefits, so what’s the catch?
Electric cars have a few benefits over hydrogen cars. One of these benefits is fuel efficiency. According to Forbes, the total energy loss in an EV from energy generation to use in the car is 20 percent, whereas in hydrogen cars, the total energy loss is a whopping 62 percent. Another enormous challenge for hydrogen car drivers is infrastructure. While there are 26,000 electric vehicle chargers in the US as of July 2020, there were less than 45 hydrogen refueling stations in the US as of 2019. The infrastructure for hydrogen powered cars is years behind the infrastructure for electric cars, which makes the adoption of hydrogen cars difficult for the average consumer. But while all of these obstacles represent substantial challenges, there is one challenge which makes hydrogen cars extremely impractical as a solution for climate change.
Hydrogen is the most common element in the universe. But unfortunately, pure hydrogen does not exist naturally. Hydrogen must be produced from other compounds such as natural gas, water, and fossil fuels. While there is a clean process for doing this—the reversal of the electrolysis of water—it requires a lot of energy and is extremely expensive. Most hydrogen today (about 95 percent) is instead produced with the cheaper method of natural gas reforming, which produces carbon dioxide and carbon monoxide, two greenhouse gases. To compound this problem, the process of getting natural gas can often cause damage to the environment (drilling, fracking, etc.).
To conclude, hydrogen powered cars themselves are extremely clean; they produce no emissions and allow cars to travel longer distances than most electric vehicles. However, hydrogen cars face practical challenges which make them unlikely to succeed as a solution for climate change in the near future. Looking forward, it is possible that reversing the electrolysis process of water could become more efficient and cheaper with new breakthroughs or new methods of extracting pure hydrogen are developed. However, it is far more likely that our future highways will be ruled by electric cars.