This episode of DNews is brought to you by Toyota’s Hydrogen fuel cell vehicles, Leave
your mark.
Toyota, let’s go places.
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 HINDENBURG EXPLOSION, but
hydrogen does so much more than go up in flames, especially when looked after properly.
Hydrogen is atomic number 1.
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[1], 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[2], 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[3] which is
also used in moving vehicles; gasoline VAPOR is ALSO explosive.
Hydrogen can alite with airborne concentrations as low as 4-percent or as HIGH as 75 percent!
Thats a lot!
Even so, gasoline burns at even lower concentrations of 1.1 to 3.3%.[4] I read documents from specialists
in hydrogen storage and transportation safety, and they say the concern is if the gas is
trapped in an enclosed space; otherwise, you're probably alright.
Hydrogen is way lighter than air, which is why it was (theoretically) great for airships.
If you were to fill three balloons with natural gas, hydrogen and helium, [a]and let them
all go, hydrogen is going to rise at 45 mph (20m/s) - twice as fast as helium and six
times natural gas[5].
When a movie needs to make a car crash, even more terrible than car crashes really are…
they add a small fire and a HUGE tank of leaking gasoline.
Sidebar: Everyone always has a full tank of gas in movies, you ever think about that?
Anyway… What about hydrogen?
Well, gasoline evaporates slowly so when a crash does occur, it CAN drip out, but hydrogen
fuel is stored pressurized, because it doesn't WANT to be a liquid.
Tanks onboard the newest hydrogen cars to enter U.S. highways store hydrogen at 10,000
psi[6]!
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 at that point, it would be difficult to tell which wasn't as fun.
And its heavier than air vapors would pool around the crash site, providing vapors for
any resulting fires to consume.
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.
That’s hardly a Hindenburg.
BUT TRACE!
What about the FUELING STATIONS!
Hydrogen fuel infrastructure is relatively new, but people catch their cars on fire at
gas stations all the time -- 3,000 times a year[7]!
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 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 adopt
this too?
Then if a leak happens we'll all sound like chipmunks!
ADORBZ.
We'd like to take a second and give a shout out to Toyota for supporting DNews.
They were at CES this month and released their patents for new fuel-cell technology, and
revealed THEIR fuel cell car to the world, the Mirai.
They’re hoping these royalty-free patents will spurn a hydrogen-fuel-based future and
spent the last decade reducing the cost of fuel cell production 95 percent.