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Comment by jandrese | Hacker News Reader

It becomes a larger problem as the world moves away from fossil fuels like natural gas.

I'm not a chemist but are there really no alternatives? Running fusion plants to make helium seems very unlikely to become cost effective, but it would be quite the sci-fi future if we filled party balloons by bombarding hydrogen with free protons.

I guess there aren't any easy molecules to break apart to get helium either since its a noble gas. No hydrolyses type solutions because there aren't any molecules that incorporate helium. I guess radioactive decay, but even that is ultimately limited over long enough timescales.

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There are NO alternatives. There's nothing else that stays liquid at 4 K and absolutely nothing else comes close.

The article itself spells out several alternatives to buying continuous amounts of Helium: high temperature semiconductors and zero boil-off systems that don't require a continual supply.

All these "we're going to run out" stories pretend that engineering cannot adapt to changing cost structures, which is just total nonsense.

Sure, there is nothing that can be directly substituted for how we use Helium today, but clearly we're using Helium inefficiently today and the answer is that once markets force us to change, we will find more efficient ways.

The article also points out several cases where this isn't possible

> There are NO alternatives.

We use a lot in our MR scanners.

The tech is changing and magnets are using far far less.

Super-conduction at higher temperatures has made progress too.

So while you are right that nothing else stays liquid at those temps, we won’t be needing nearly as much helium in radiology in the next few years.

The new generation use something like 700ml of helium, where the standard was hundreds of litres. https://magneticsmag.com/siemens-healthineers-gets-fda-clear...

> So while you are right that nothing else stays liquid at those temps, we won’t be needing nearly as much helium in radiology in the next few years.

How many loans for MRI machines that require helium haven't been paid back yet?

I know of a few.

They use a lot when installed, but rarely need top-ups.

They are shipped full of helium and chilled, but aren’t ramped up (so aren’t superconducting magnets until after commissioning).

> It becomes a larger problem as the world moves away from fossil fuels like natural gas.

I actually remember a similar problem from some compound that was mainly formed as a byproduct of some old Canadian nuclear reactor design. As the tech gets phased out, the material is no longer available in significant quantities, with consequences for a projects that need it (like Iter).

Some things can be cheap if they are produced as a byproduct, but very expensive if they have to be obtained directly.

> it would be quite the sci-fi future if we filled party balloons by bombarding hydrogen

How dangerous are party balloons filled with hydrogen? Not a whole balloon arch obviously.

I had a science teacher that did this in class, then taped a match on the end of a yardstick and held it under the balloon. They made quite a bang. I wouldn't want to be right next to it when it went off.

Yeah I've seen that demonstration in school too. But if the teacher was willing to do it in school, with kids, how dangerous was it really?

You can get permanent hearing damage from that demonstration if you stand right next to that balloon.

Makes sense.

It would be interesting to see how many would still want to do it, knowing this.

I would.

Along with the other commenter, I'll add that a classroom is usually a lot bigger than a home dining room or other domestic party locations. That size also helps things dissipate instead of reflect. Not sure by how much but I'm sure it does something.

Plus he opened more than 1 window? Hopefully at least. Glass will reflect or shatter, both of which suck.

My chemistry teacher told us how once when he ignited helium in a test tube, the tube broke and he ended up with pieces of glass embedded in his skin. The students had face masks and he was looking the other way "just in case" for this "safe" experiment but he could have easily been blinded.

Things can always go wrong. We probably shouldn't strive for 100% safety because they we'd spend our lives in a padded cell. But we also shouldn't assume things are safe because they're common or routine.

he did not ignite helium

The triple-alpha process of a neutron star does seem unlikely in the classroom setting.

https://en.wikipedia.org/wiki/Triple-alpha_process

Sorry, meant to say hydrogen

While hydrogen-air mixes explode really readily (outstandingly wide flammability and pretty wide detonation range), and the energy released is considerable for the weight, the actual explosion does not produce a particularly high overpressure wave.

That's because the starting density of the hydrogen air mixes at near atmospheric pressure (such as in a balloon) is pretty low. Also, the balloon does not significantly contain the explosion, which reduces the danger a lot. I would not want to do it in a glass container.

Was there an experimental control?

How does that bang compare to the bang from an equally-inflated balloon full of ordinary air?

We did this. One balloon with plain air. One with pure hydrogen. One with 50/50 hydrogen and air. The one with pure hydrogen popped closer in magnitude to the pure air than it was to the 50/50 mix.

ETA: I may be misremembering, the more I think about it, the more I recall that we did not use air, we did use pure oxygen. Not like it was hard to get (and we had lots more interesting stuff than that in the lab, this was the 80s...). But the outcome I do remember. The entire point of the experiment was to examine the difference between the individual pure elements and the mix. We expected the pure hydrogen to be far more interesting than it turned out.

As a kid I took a lot of classes at the Lawrence Hall of Science in Berkeley, which was paradise for fledgling nerds. On the last day they would have a little closing ceremony with some cute little science experiment. One of my favorites was "Going Out With A Bang".

The instructors would bring out a helium balloon and a candle on a meter stick. The balloon goes pop, huzzah.

Then the twist. "Hey, wanna do it again?" All the kids would be like "meh, I guess?" They would then bring out a balloon full of hydrogen (maybe some oxygen too?). It would look identical to the first one, floating there tethered to the lab bench.

When the candle hit the second one, it made a white flash and a really sharp BANG. It was an order of magnitude louder, and you could hear the transient bouncing off the walls and echoing in the halls. It made an impression.

Pure hydrogen in a balloon produces a low, loud, very satisfying bang. Completely different from a sound of an air balloon popping. Here is a video from a very good Royal Society of Chemistry demonstration series on various unusual combustion process:

https://www.youtube.com/watch?v=Rwbyl7ywfhk&list=PLLnAFJxOjz...

Hydrogen mixed with air or with oxygen produces an ear piercing supersonic detonation, exceedingly loud and unpleasant. Not recommended for demonstrations.

Good vid. To readers - note that the playlist has other compositions

The balloon almost certainly contained a mixture of hydrogen and air (or possibly oxygen).

There are many cases in the news of accidents with sometimes a large number of party balloons filled with hydrogen or other flammable gases.

One of the larger episodes was in 2012 in Armenia, where thousands of balloons exploded during a meeting, injuring 154 people, of which 4 seriously (the video is of poor quality): https://www.youtube.com/watch?v=jWEm2sS7Dw8

A smaller, more recent episode in India: https://www.youtube.com/watch?v=FH5JwHeKnZo

a party balloon - say a cubic foot - is about 2g of hydrogen. Involves 16g of oxygen. So we're talking 18g of very fast burning, borderline detonating mass. Releases 240 KJ of energy. To compare the hand grenade - 60g TNT https://en.wikipedia.org/wiki/F-1_grenade_(Russia) - releases the same 240 KJ of energy.

How necessary are party balloons?

Methane (natural gas) is lighter than air. Give it a go. Don't get any oxy contaminating it though.

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