5 ms·
Don't we have Helium anyway?
by fastball 5y ago
Don't we have Helium anyway?
- timbit42 5y agoWe don't have an unlimited supply.
- echelon 5y agoHelium is extremely limited and cannot be manufactured at any appreciable scale (you're not dealing with typical chemistry, but physics. Helium is an element.) What we have naturally comes from radioactive decay deep in the earth. This will continue for some time, but it's a fixed, slow rate. Helium evaporates into space. Once it's gone, it's gone for good. The other options we have are hydrogen (extremely reactive), heated oxygen (also reactive), methane (reactive), ammonia... It's a hard problem.
- fastball 5y agoOne more problem that will be solved by fusion energy!
- fatsdomino001 5y agoWe can theoretically do vacuum zeppelins, which is of course lighter than helium and unlimited tho it has its own problems too.
- bentcorner 5y agoI was curious about this and it looks like it's currently impossible to have a material that is both strong enough and light enough to support a vacuum balloon: https://physics.stackexchange.com/questions/71027/is-it-possible-to-create-a-vacuum-ballon-using-concentric-partially-pressured-sp https://physics.stackexchange.com/questions/71027/is-it-poss...
- zabzonk 5y ago> Helium is an element Nitpick: So is hydrogen.
- cbsmith 5y agoYeah, but only one of them is a noble gas that is rarely bound into molecules that would be found in solid form. As a consequence, it tends to just leak out of the atmosphere without a lot of sources for replenishment.
- vitus 5y agoYes. More precisely, helium is an element that doesn't readily form compounds. Hydrogen does, and as such can be extracted from, say, water via electrolysis. The secondary issue with helium is that it's much lighter than air -- this is why helium and neon are both much rarer than, say, argon (which is actually the third-most common element in the air after nitrogen and oxygen).
- zabzonk 5y ago> The secondary issue with helium is that it's much lighter than air Actually, hydrogen is lighter, and so a better lifting gas, than helium. https://www.wikiwand.com/en/Lifting_gas#/Hydrogen https://www.wikiwand.com/en/Lifting_gas#/Hydrogen
- FabHK 5y agoYes, but while hydrogen (H) has half the mass of helium (He), H is only 8% better than He in providing lift in the air, if I computed correctly (as that is generated from displacing much heavier air), so it's not a huge deal: He: 0.1786 kg/m^3 H: 0.08988 kg/m^3 Air: 1.225 kg/m^3 Air vs He: 1.0464 kg/m^3 Air vs H: 1.13512 kg/m^3 To put it differently, for helium, the lift is about 86% of the weight of the displaced air, while for hydrogen it's 93%. Both very good, and both are much better than hot air! (which gives a lift of only about 25% of the weight of the displaced air, at typical temperatures of about 120 deg C)
- zabzonk 5y agoAccording to the wikipedia page I linked to: > In a practical dirigible design, the difference is significant, making a 50% difference in the fuel-carrying capacity of the dirigible and hence increasing its range significantly But I wouldn't know :)
- treeman79 5y agoDon’t forget about “null” gas. Better the hydrogen, a few small technical problems aside. https://en.m.wikipedia.org/wiki/Vacuum_airship https://en.m.wikipedia.org/wiki/Vacuum_airship
- echelon 5y agoThat won't work on earth due to weight of materials and material strength requirements. It might work on a dense atmosphere, such as Venus.
- app4soft 5y ago> It might work on a dense atmosphere, such as Venus. Gravity also matters here.
- 123123as1asd12 5y agoImplosions would be much worse imo.
- fnord77 5y agoiirc, the germans wanted to use helium at the time, but the US more or less had a monopoly on it and would not sell to germany