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Toyota Names Upcoming Hydrogen Fuel Cell Car
An anonymous reader writes Toyota has announced the name of its new hydrogen-powered car: Mirai, which means "future" in Japanese. Toyota CEO Akio Toyoda said: "Today, we are at a turning point in automotive history. A turning point where a four-door sedan can travel 300 miles on a single tank of hydrogen, can be refueled in under five minutes and emit only water vapor."
To put this in perspective, California is aiming for 100 fueling stations by 2024 and as of May this year only 9 actually existed.
"California, Oregon, New York and five other states pledged to put more than three million zero-emission vehicles on their roads by 2025"
http://www.usatoday.com/story/...
http://www.pbs.org/newshour/bb...
Gasoline does not explode (detonate) under STP conditions, no matter what the concentration, distribution, environment geometry, you name it. It simply doesn't. In ideal situations you can get a rapid conflagration, but even that requires very specific, often hard to achieve conditions. What you linked is a page about car fires, not explosions. Simply burning the gasoline, over a period of minutes.
Hydrogen does explode (detonate) under STP conditions, given a proper environment for a DTD transition. It does burn rapidly in almost any fuel-air mixture. It ignites with a spark of only around a tenth as much energy as gasoline - even trivial static sparks and discharges from common household electronics are enough to ignite it. Liquid hydrogen is even worse - for example, if air gets accidentally entrained in liquid hydrogen, it freezes out and can detonate with properties similar to high explosives.
Both gasoline and hydrogen pool in the right condition - but while gasoline pools on the floor, especially in low points, hydrogen pools in ceilings, especially overhangs. Hydrogen does tend to dissipate faster (although this is countered by its wider combustion range). Two additional problems occur with hydrogen. One, it embrittles metals very easily, both from rapid leaks and from slow leaks. Two, when it pools, it tends to seep into pipes and then follow them to their destinations; there have been cases where a hydrogen leak in one builing has caused an explosion in a completely different building (which is why whenever pipes are in a series and one contains hydrogen, it's always supposed to be the highest up).
There are plenty of chemicals more dangerous than hydrogen, no question. But the simple matter is, hydrogen is far more combustible than gasoline. It's just a basic fact. Which is obvious just by looking at, say, NASA's hydrogen handling guidelines. I mean, any building that handles more than 10kg is supposed to have a roof that's designed to be blown off in an explosion.
On the upside, hydrogen is nontoxic, unlike gasoline! Surface environmental consequences of leaks are minimum to none, although it does destroy high-altitude ozone, at a rate that would be a serious concern if hydrogen became a common fuel given typical leakage rates.
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Isn't the temperature a result of high pressure? As in, if you jam enough atoms into a space eventually they have less room to move and get colder? I'm sort of basing this off observation of my air compressor relief valve and not science. Air duster canisters can generate frost. That kind of thing.
So pressurizing a bunch of hydrogen would mean if it ruptures and someone touches the canister, instant frostbite.
What about the "destroying everything it touches" part?
ps: I am a different AC than OP.
The Ideal Gas Law determines what happens to a gas under pressure: PV = nRT
Pressure is proportional to volume, so if you compress a gas it shrinks in volume until eventually it liquefies - but the point at which it does depends on the phase diagram for that particular gas. The properties change depending on the molecules.
If you release pressure quickly then it expands very rapidly and cools down. This is a function of thermodynamics. Similarly, if you compress a gas it will heat up for the same reason. This is common to all gases. Jamming the molecules in ever tighter will increase the temperature. Your air compressor heats up when it is compressing air because of this. When you let the pressure out, the temperature of the air drops rapidly.
Where things like hydrogen are special is that you can't liquefy them by simply pressurising it. You need to cool it down too - the triple point of hydrogen is about 22 K and the critical point is about 32 K - hydrogen simply can not be a liquid at any pressure unless the temperature is between these two values (22 K is -251 C or -420 F - cryogenically cold temperatures).
Any gas under pressure is a hazard - cylinders of nitrogen are pressurised to 300 bar and if one of those ruptures you're in a world of hurt, despite the fact that nitrogen itself is inert, but we routinely handle high pressure gasses in industrial and commercial environments. You take more precautions with a hydrogen cylinder (or any cylinder of flammable gas), but the handling procedures for flammables overlap a lot with the non-flammables like nitrogen and argon.