As we explored in our ‘How Hydrogen Cars Work?’ article, the traditional combustion engine in gasoline-powered cars is replaced by a fuel cell (or a group of fuel cells) which convert hydrogen into electrical power, with water as waste.
Many people might also be aware that hydrogen is one of the most flammable gases around, obtaining one of the highest “flammability scale” ratings by the US Government. Hydrogen is also more likely to leak out of its storage container, compared to some other fuel types (for a range of reasons, including its chemical nuances).
Hence this article looks at whether hydrogen cars are safe or not, including with some fun crash test videos!
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Crash Test Videos
Our first crash test video is from the BMW Hydrogen7 car from 2005-2007, which burnt hydrogen fuel in a combustion engine (not a fuel cell):
As you can see from multiple crash tests which show multiple perspectives (including the power plant and hydrogen stores from below the car), there’s no issue at all - either with the design of the car (which is standard enough for gasoline and hydrogen cars), but more importantly there is no sign of any fuel leakage, no explosion etc.
This is a prototype of a Hyundai Tucson (their SUV car) with a more modern hydrogen fuel-cell power plant system. This is a rear hit shown from multiple angles - including an interesting view at 1:12 which shows the hydrogen tanks being very close to the damage, and again: no issue or danger signs. No fuel leakage nor explosion.
This is from the Hyundai Nexo, the hotly awaited FCEV from Hyundai - which receives 5 stars (out of 5) in the Euro NCAP safety tests. These tests are more comprehensive than the above (albeit without views of the underside), and also show no signs of worry with regard to the fuel type.
Why Hydrogen Cars Are Safe
So the videos are fairly clear: hydrogen cars don’t suddenly explode or catch fire in a crash, even a fairly high speed crash. And the EU’s official car rating agency (Euro NCAP) has awarded the Hyundai Nexo with the highest safety rating. But why?
The first answer is in our how hydrogen cars work article:
The hydrogen tank is one of the most important components here. These are heavy-duty, high-pressure storage tanks which connect directly to the fuel filler port… they weigh around 44 kg (97 lb) each. They usually only hold around 5 kg each of fuel - in other words, a hydrogen car can hold up to 10 kg of hydrogen fuel, despite their tanks weighing almost 9x this!
In other words, the storage tanks for the hydrogen are specifically designed and engineered to be high-grade, reliable and able to withstand high pressure. They aren’t going to leak anytime soon!
But if somehow they did start to leak (lets say after a massive car accident, where something pierced the storage tank with lots of force - since they wouldn’t leak easily), this wouldn’t actually be a massive risk, like it might with gasoline. This is because hydrogen is a light gas, which will simply dissipate instantly into the atmosphere, unlike gasoline which would start to pool (and then a stray flame would naturally be a big risk).
Okay, but lets say that there’s a car accident, the hydrogen tanks are pierced and there’s lots of flames are around somehow - surely this is unsafe? Well yes, in this case the hydrogen might ignite - but hydrogen is actually a rapid burner; if it did ignite, the flame would dissipate into the atmosphere fairly quickly. This would naturally be very bad if a Human was nearby this flame-ball, but the same is unfortunately true of gasoline being ignited - or lithium-ion batteries (in EVs) exploding - near a Human after an accident. Although in this very worst case, a short-lived hydrogen flame is arguably less risk than a slower-burning, more persistent flame from gasoline.
Finally, Toyota - who are really excited about the potential of their hydrogen Mirai fuel cell car - have gone to some extreme lengths when testing their Mirai and Highlander Hydrogen Hybrid. In addition of various crash tests, they’ve also put the cars inside Boeing lightning chambers and struck the car with lightning. They’ve also fired high-calibre bullets (yep, you read that right) at the hydrogen tanks, but the tank itself retains its structure and doesn’t explode nor rupture.
Whew: if it can survive airplane levels of lightning and war-zone levels of bullets (in addition to the standard car crash tests that are performed), that’s more proof that hydrogen cars are thankfully safe; not flammable nor dangerous.