Hydrogen-powered cars are hitting the road this year, and eventually one will be in a crash. What would happen? Would it explode?
When you think of hydrogen you probably think of the Sun or the Hindenburgs explosion. However, hydrogen does so much more than go up in flames, especially when looked after properly.
Hydrogen is atomic number one—the bestest element. It burns efficiently resulting only water vapor and tiny amounts of nitrates when done at high temperatures.
It's made by electrolysis, which is essentially using electrical energy to split water into hydrogen and oxygen.
The first ideas of using hydrogen gas as a fuel cell were published in the late 1830s, and now, 185 years later, fuel-cell cars are heading onto the roads. We already use it for rocket engines, so why not for cars?
When we think of hydrogen on the road, we might worry about tiny little Hindenburgs driving around out there, which couldn't be further from the truth.
Hydrogen gas is very explosive, it's true, even more so than natural gas which is also used in moving vehicles. Gasoline vapor is also explosive. Hydrogen can alight with airborne concentrations as low as 4% or as high as 75%! Thats a lot! Even so, gasoline burns at even lower concentrations of to 3.3%.
Hydrogen is way lighter than air, which is why it was theoretically great for airships. If you were to fill 3 balloons with natural gas, hydrogen and helium, and let them all go, hydrogen is going to rise at 45 mph (20m/s) - twice as fast as helium and 6 times natural gas.
Well, gasoline evaporates slowly so when a crash does occur, it can drip out. However, hydrogen fuel is stored pressurized, because it doesn't want to be a liquid. Tanks onboard the inside these newest hydrogen cars to enter U.S. highways store hydrogen at 10,000 psi.
This means, if a crash were to occur between a gasoline car, and a hydrogen car where both of their fuel reservoirs were punctured, the hydrogen car would be safer, fuel-wise. If there was a fire, the hydrogen would burn completely and rapidly, whereas gasoline would burn more slowly as it vaporizes.
But when you combine a pressurized tank and a lighter-than-air gas like hydrogen, the result will likely be dissipation rather than combustion. Which means it would almost instantaneously escape into the atmosphere.
Where to Refill Your Hydrogen Fuel?What about the fueling stations! Hydrogen fuel infrastructure is relatively new, but industrial application has been going already for a long time.
Not knowing people catch their cars on fire at gas stations all the time—3,000 times a year!
NASA has used liquid hydrogen since the middle of the last century to lift astronauts into orbit, and so far it's been pretty okay. If a hydrogen leak is detected, they use helium to flush the liquid hydrogen out into the air, so it quickly dissipates. Helium is a noble gas, which means it's super stable and doesn't really combust. With the right safety precautions in place, maybe hydrogen fueling stations will adapt this too.