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Out of my depth here. Why are tanks of Kerosene safer than tanks of hydrogen? Pressure?
by peterlk 8y ago
Out of my depth here. Why are tanks of Kerosene safer than tanks of hydrogen? Pressure?
- montenegrohugo 8y agoHydrogen is gaseous at normal temperatures. Both Kerosene and hydrogen are flammable, but being gaseous means that the resulting exothermic reaction will happen much faster and thus the energy will be released much more violently (think:explosion). Additionally, as you said, storing hydrogen densely enough means pressured containers, or extreme cooling (like for rockets).
- gambiting 8y agoHydrogen leaks out of literally any container it's stored in, if you fill up a pure lead bottle(a 25kg bottle only holds 1 litre of hydrogen) it will be empty after 2-3 weeks of doing absolutely nothing - hydrogen molecules are so small they just permeate through any safe to handle material. Obviously planes couldn't use tanks made out of lead because of weight, so whatever material they used would leak even faster - and as hydrogen forms an explosive mixture with air, that's not a good thing.
- gst 8y agoHow do consumer-level hydrogen fuel-cell vehicles solve this issue? Does this mean you can't store them in a garage, because the leaking hydrogen could cause an explosion?
- gambiting 8y agoThey do not - you're not supposed to keep them in enclosed spaces because of this exact issue.
- icebraining 8y agoCan't you just vent to outside of the plane? It's not like they are usually in enclosed spaces.
- outworlder 8y agoHangars?
- JohnJamesRambo 8y agoHow does the metal cylinder of anaerobic gas mixture in my lab that has a percent of hydrogen in it keep it in indefinitely then?
- gambiting 8y agoDon't know - I only ever handled industrial hydrogen containers and I know they couldn't keep hydrogen in for more than couple weeks. I suspect that for it to be useful it needs to be stored as liquid, which means huge pressures = much higher leakage rate. If it's kept at gas it's probably still leaking,just not at a rate that would matter for a while.
- desdiv 8y agoOther posters already mentioned the storage factor, so I'll mention the safety factor: Hydrogen is flammable, but kerosene is not; kerosene is instead combustible. Here's the technical difference between the two[0], but in practical terms it means that you can drop a lit match or cigarette into a tank of kerosene and nothing will happen. You can even heat a tank of kerosene directly with a propane torch without igniting it[1]. [0] https://en.wikipedia.org/wiki/Combustibility_and_flammability https://en.wikipedia.org/wiki/Combustibility_and_flammabilit... [1] https://youtu.be/7nL10C7FSbE?t=105 https://youtu.be/7nL10C7FSbE?t=105
- henrikschroder 8y agoLiquid hydrogen is really, really, bad as a fuel. The energy density per mass is very high, but it's also the least dense gas, so the volumetric energy density is absolute crap, even at high pressure. A bucket of kerosene contains a lot more hydrogen atoms than a bucket of liquid hydrogen, and unlike the hydrogen, it's safe to keep at room temperature, at normal pressure, and it's neither corrosive, flammable, or explosive.
- scrumbledober 8y agoI would say kerosene is flammable...
- supermatt 8y agoFlammable has a very specific definition - it must be easily ignited at room temperature. Kerosene is not easily ignited at room temperature (e.g. you couldn't light a puddle of it with a match), so it is not considered "flammable". It does burn at room temperature though, so it is considered "combustible"