Given we have a way to make it, we aren't going to run out of the stuff, so I just don't think this problem is that dire.
We get gasses like Argon and Neon the same way all the time. There is no helium crisis and there will never be a shortage in the next billion years.
The situation where Helium is much cheaper than Neon may end but there will always be plenty for industrial and science uses, even if balloons get more expensive.
Solar radiation producing helium in the upper atmosphere - how would you extract it from the upper atmosphere? I would have thought it doesn't mix with lower atmosphere due to atmospheric escape.
Market price for pure CO2 is only about $160 per ton. Market price of helium is like $45,000 per ton or something like that.
ELI5 version: It might be lighter than air, but that just means that it will "float" ontop of heavier things - like oil ontop of water. But all those things still obviously have a certain weight. If you put it into a cylinder it will thus under the influence of gravity still weigh down onto it, which then can easily be measured.
Suppose you have a balance scale with a "cylinder" full of air on one side. You pump out the air and put in helium. What happens to the scale?
I'm a little more comfortable with saying we do some weighings in a vacuum (say, to determine the density of air at a given pressure) than with saying we'll start with a cylinder that contains a vacuum. For example, our 40kg cylinder, when airtight and containing vacuum, will weigh less than a 40kg object should, and I think that muddles the example.
Put in helium and you'll eventually reach and exceed the parity point as you keep filling up (same weight as the air), and the ratio of how much it moves for x volume of additional filled gas tells got the additional weight.
Soon enough you'll reach 2x air weight and you'll have tipped the scale exactly.
Granted, I was also using the first sense when talking about the weight of the helium specifically. I guess in that sense my terminology could have been better.
Great explanation, thank you.
The answer is obviously not "negative two kilograms", and it's not obvious to me that the answer is "two kilograms". After all, if we weighed the same cylinder in a vacuum rather than in the atmosphere, it would presumably be heavier, but the amount of helium inside wouldn't change.
Not only is this math, we know that it's incorrect for the problem under discussion. The fact that it follows "I understand, thanks!" does not fill me with confidence in the original explanation.
So what is the weight (that is, what is the force of gravity pulling down the helium molecules without ambient air pushing it up) of helium? If you have a cylinder of a known weight, you can fill it with helium and subtract the weight of the cylinder. What's left is the weight of the helium. To measure this effect without air pressure pushing the helium up, you might need to do this in a vacuum, but the logic is there and I think my analogy fits. I weigh the chicken on a plate and subtract the plate to find the weight of the chicken.
What I was asking is "how do you weigh a gas without it spreading around and mixing with the air?" "Putting it in a cylinder" is the answer I was looking for.
That's a rather different question than you actually asked, "how do you weigh something that is lighter than air?" You might notice that not a single response takes the perspective that what makes the problem difficult is that helium will spread out or mix with the atmosphere. Lots of gases (not to mention liquids!) are heavier than air while still being fluid; weighing them doesn't pose the same problems.
> Same thing with helium, eventually it gets high enough that the neutral air molecules are sparse enough that it can float on top. It doesn't continue to rise past that point because gravity is still pulling it down.
This isn't true at all. https://en.wikipedia.org/wiki/Atmospheric_escape
Seems true to the tune of whatever exists minus 50 grams per second.
50g of helium per second would exhaust the current level of helium in the atmosphere in about 2.3 million years. (Atmospheric total mass 5.15e18 kg from wikipedia, composition of the atmosphere by volume from http://eesc.columbia.edu/courses/ees/slides/climate/table_1.... .) That may sound like a long time, but consider that the earth is 4500 million years old.
Well that's not true. The very first response, the one that started this conversation, did exactly that. "Put it in a cylinder". Boom, done. That's why I said "good answer". That's the answer to the question I had asked. You can weigh hexafluoride by putting it in a bowl because it is so dense it will not float away. Helium is the opposite. That's what I wanted to know. Because obviously helium will just float away.
This is a complicated question obviously, and goes deeper than what I asked. But you and I are asking two different questions, and for some reason you seem hell bent on just shitting on everyone else's answers with poor science and snark instead of a simple Google search that takes like 5 seconds and gives you literally all the answers you could ever want.
The point is, it makes no sense to say "the weight of the helium must be equal to the weight of the helium+cylinder system minus the known weight of the cylinder, just as the weight of a chicken on a plate is equal to the weight of the chicken+plate system minus the weight of the plate". You've got to bring in some extra information.
I would think measuring the correct weight would be:
(weight of empty cylinder) + (weight of air volume that the cylinder could contain at atmospheric pressure) - (measured weight - positive or negative)
If you measured e.g. an empty cylinder, you'd end up with only the weight of air volume in cylinder at atmospheric pressure, which would be correct.
(weight of helium) = (measured weight) + (buoyancy force, which is the weight of an equal volume of air at the appropriate pressure) - (weight of cylinder)
> That's because the weight of the gas cylinder is relative and you got the point of reference wrong: The base weight is when it's a vacuum inside the cylinder, because otherwise it doesn't even displace the air which you don't want to measure for your reference weight, making it appear heavier. Whatever you add inside the gas cylinder now will make it heavier and the difference you get is the weight of the gas.
If you want to actually weigh using a scale, then put it in a container, measure the total mass accurately and then subtract the mass of the container and the buoyancy due to the atmospheric pressure gradient. The remainder is the mass of the gas.
EDIT: never mind. if anyone was buying this at market value, it doesn't make sense for the buyer to store it indefinitely.
EDIT: Thanks for the correction.
Technologically, yes... But the last time I looked into this it is extremely costly in terms of energy (ratio of megawatt-hours consumed by equipment vs. the amount of helium you can compress into tanks). Not very dissimilar from saying "Hydrogen can be easily retrieved from sea water". Yes, it can, it just takes an immense amount of electricity to run the electrolysis process. So unless you are located next to a $100 million photovoltaic plant covering a large section of desert, or are located somewhere else that electricity is incredibly cheap (hydroelectric plants on the Columbia river), it's questionable if the economics work out.
But supposing they did produce the absurd amount of energy they could potentially create, would a purpose-built nuclear powered hydrogen plant be capable of obviating any hydrogen deficit, and eventually create a surplus? And then, so too, with helium, via a separate process?
PV and wind are perfectly suited toward essentials because they are sources of energy we'll never feel guilty about. We should use and perfect methods of energy extraction that are conscionable, so that we have ideals methods of providing for ourselves.
Meanwhile, to produce surpluses, and exploit gains for experimental luxuries, use riskier methods. This balances the premise of the risk, such that you don't push the risk taking too far, out of desperation for a necessity. Rather than worry about a power failure at a hospital, accept a negligible decline against production targets at a plant, and temporarily shut down the pile, for safety's sake, whenever needed. No?
I think you may need to rethink your use of the word "easily" there.
There are some good comments here, which explain why satisfying current demand for helium via fusion is nowhere near practical: https://www.reddit.com/r/askscience/comments/12r2s7/helium_i...
That's how we got the big stockpiles in the first place.
Helium is produced naturally in any radio isotope that undergoes alpha decay.
What's your point exactly?
[1] https://en.wikipedia.org/wiki/Helium_production_in_the_Unite...
The main source for Helium-3 which is the one we are in shortage of was and is the US nuclear weapons program primarily through the decay of tritium.
The increased demand post 9/11 primarily by the federal government (He3 is used in neutron detectors) combined the reduction of the US weapons program caused a shortage.
Here is the FAS report from 2010, it's not the only report on the matter but it is very detailed. https://www.fas.org/sgp/crs/misc/R41419.pdf
Why not call it helium decay, since alpha particles are just helium nuclei? Or is this a case of "alpha particles" being named that before we knew what they are?
Beta decay is positrons, and gamma radiation is just light. Hence why we call the energetic end of the spectrum "gamma rays".
Alpha Decay is just a low mass form of cluster decay.
https://en.wikipedia.org/wiki/Alpha_decay
I'm not sure there is any conceivable way to use that in manufacturing helium gas at an industrial scale.
Although artificially raising the price of diamonds seems to have been an effective strategy for the diamond industry, that is in part because they found a marketing angle where the high price of a diamond engagement ring is a strong emotional signal between a prospective couple. In most markets, people simply are not going to pay more for something than it benefits them. Raising the price can have the consequence of pushing people to go look for other alternatives.
Price has to be reflective to some degree of underlying value or benefit. Further, if creating helium comes at the cost of destroying more real value than it creates, this is simply a lose-lose prospect across the board, regardless of the price tag you can attach to helium.
> That's expensive, of course
You need to pick one.