-
Want to remove ads? Register an account and login to see fewer ads, and become a Supporting Member to remove almost all ads.
Hydrogen vs. Battery
- Thread starter siry
- Start date
W.Petefish
Active Member
Add to that the fact that you are riding on top of a tank filled with HIGHLY FLAMMABLE HYDROGEN just waiting for a slight leak and a spark.
All practical suggestions for hydrogen systems store the hydrogen by lightly bonding it in a chemical (e.g., metal hydrides), rather than storing compressed hydrogen gas. While this doesn't address all of the safety concerns, it takes more than a leak and a spark!
The fact that the hydrogen tank will have to be at ridiculous pressure and a powerful bomb even if it doesn't ignite might be more scary.
How much will that reduce the energy efficiency because of the energy it takes to liberate the hydrogen from the metal hydride?
How about the weight of all the metal in the hydride?
Some quick googling reveals one of the most promising hydrides is LiBH4 - wouldnt that be funny if storing hydrogen used *more* lithium than lithium batteries?
JRP3
Hyperactive Member
I'm not aware of any vehicle actually using anything other than a high pressure tank.
Would love to see this video.
Wide shot of car number one. A mid sized car filled with enough electricity to let to travel 50 miles. Blow it up. Worst case style.
Car number two a gasoline car with the same amount of energy in fuel. Blow it up worst case style.
Car number three. Hydrogen with 50 miles of travel in fuel under compression. Blow it up. Worst case style.
Wide shot of car number one. A mid sized car filled with enough electricity to let to travel 50 miles. Blow it up. Worst case style.
Car number two a gasoline car with the same amount of energy in fuel. Blow it up worst case style.
Car number three. Hydrogen with 50 miles of travel in fuel under compression. Blow it up. Worst case style.
Some have used cryogenic liquid hydrogen. BMW comes to mind.
At any rate, I support research into efficient hydrogen storage (including solid state metal hydrides). There are a variety of applications where it would be useful. I just think that promising it (or waiting for it) in an automotive application is a distraction and a poor use of resources.
stopcrazypp
Well-Known Member
To be completely fair, in some cases it's still much safer than gasoline (which tends to pool on the ground). Since hydrogen is so light and the ignition point so low, any leak tends to go straight up and burn off fairly quickly (see an article with a leaking hydrogen connector; it's not quite the same as a tank puncture but it illustrates some similar points):
http:// http://evworld.com/article.cfm?storyid=482
The only dangerous part is if you are in an enclosed area (so the flames will burn the rest of the car, a building, or people, etc) or if leak is directly below the passenger area (which might burn the passenger area instead of just the cargo area). I see the probability of the latter happening being higher now than previously because most of the newer hydrogen cars tend to mount multiple tanks under the passenger area rather than a large tank in the cargo area (for space efficiency reasons, much like why most BEVs have the batteries under the passenger area).
Outside of those two situations, I'm more worried about the highly pressurized tank. Instead of the fairly controlled release shown in that article, I'm worried about the explosion that might happen from an external fire. I don't know if a highly pressurized carbon fiber hydrogen tank will react exactly the same way as highly pressurized carbon fiber CNG tank in an external fire, but here's the result in a CNG Civic after an external fire (looks like a car bomb went off):
http://www.cleanmpg.com/forums/gene...xplosion-dialup-warning-many-photos-7555.html
That's pretty scary to me. It poses not only a danger to the passengers of the vehicle, but also to other bystanders and first responders (since shrapnel is sent flying when the tank exploded). Unlike fires involving other vehicles, where you are primarily in danger if you are inside that vehicle during the fire, fires involving high pressure tanks pose a danger even if you are nearby.
Last edited:
Except that there is no other gas in existence that ignites under such a huge range of concentrations, 4% to 74% in air. Gasoline in comparison only ignites with concentrations between 1.4% and 7.6%. It also burns so hot the flames can be almost invisible, mainly emitting UV.
As you say, it does have the advantage of being buoyant. But that CNG tank explosion picture you showed is truly scary.
W.Petefish
Active Member
Knock the valve off of one and see how many lives you have left... and people are afraid of an O2 tank going sideways.
Tell that to this guy:
(Incidentally this movie scene was thoroughly debunked by Mythbusters.)
Attachments
In the lab we always referred to that possibility as an unguided torpedo.
Last edited by a moderator:
Tell that to this guy:
(Incidentally this movie scene was thoroughly debunked by Mythbusters.)
http://www.youtube.com/watch?v=NkhtTPU9KjM&t=0m57s
Last edited by a moderator:
I love the Mythbusters, they are very entertaining. However sometimes their methodology is flawed. Among other things - science requires repeatability and one experiment is not always conclusive.
Here is another entertaining read:
How Not to Do It: Liquid Nitrogen Tanks. In the Pipeline:
Here is another entertaining read:
How Not to Do It: Liquid Nitrogen Tanks. In the Pipeline:
Well sure, it's an entertainment show, and they don't really have the time to do truly proper experiments.
Incidentally, they did a show where they defeated the safety features of a hot water tank, and the rupture was quite similar to the one in that article. It went right through the roof of a miniature house they built (and due to viewer feedback they repeated the experiment with a more robustly built house, with the same result). Scary suff indeed.
W.Petefish
Active Member
Also known as "rat chasing". (Insert Mythbusters reference here.) The brown pants factor is off the scale if you see one actually go flying.
Last edited by a moderator:
Similar threads
