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Helium is a non-renewable resource drilled out of the ground, of which there is a global 'crisis' shortage[1]. Hydrogen is easy to make in vast quantities and cheaper. But more importantly, while they have similar lift capacities on paper (Helium ~90% of Hydrogen), in practice they don't - https://www.airships.net/helium-hydrogen-airships/ has an explanation and calculations.

Hydrogen lift airships set off fully inflated and vent Hydrogen along the way for control of altitude and to stop their lift cells expanding too much as they rise into lower pressure air; Helium is too expensive to vent casually, so they have to start less inflated to protect the lift cells, and other concerns so Helium lift ends up with half the payload carrying capacity, less fuel, shorter flight distances.

And, nb. the deadliest airship disaster was the USS Akron which was was a Helium lift airship which crashed in a storm with 73 deaths and 3 survivors. It's not as simple as Hydrogen = danger, Helium = safe.

[1] https://www.forbes.com/sites/omerawan/2022/11/10/the-helium-...




Yeah hydrogen sounds like it could even be safer given that you get a larger buoyancy buffer to fight downdrafts? It's a real public misconception that it just explodes from all those oxyhydrogen experiments at chemistry class, but pure hydrogen such as in airships just slowly burns, much like any other fuel we fill our planes with.

The main problem is still that you need to contain a large volume, which will inevitably get pushed around by wind more than you can compensate for.


I wonder if you could use a fuel cell to get power from the hydrogen you'd otherwise vent.


If fusion power takes off, could you produce helium as a by-product?


Basically, no: https://www.jerf.org/iri/post/2922/

And that assumes perfect capture, too.

If you're going that route it'd probably be better to just use hot air with the energy.


Nice! Thanks.


There's a fusion startup called Helion near Seattle working on this, it'll be really exciting if it pans out at scale.

This video was a fascinating watch: https://www.youtube.com/watch?v=_bDXXWQxK38


Probably, but the amount would be tiny. ITER is trying to generate 500 megawatt from a half-gram of hydrogen.


if we figured out fusion, it would alter the economics of all of this

why not fusion powered ships/trains/airplanes


> why not fusion powered ships/trains/airplanes[?]

What could possibly go wrong?


Afaik what makes fusion hard is maintaining the conditions that allow fusion to occur. Because of this, it’s quite safe - if anything goes wrong, it’ll just stop working.


Safe? Really?

I expect that the containment vessels will get very radioactive.

But all a bit hypothetical, since none exist


Yes they do exist, link elsewhere in this thread, Helion have a 7th generation nuclear fusion reactor fusing once every ten seconds or so. https://www.youtube.com/watch?v=_bDXXWQxK38

(It's not surplus of power, but it is repeatable fusion actually happening).


That is not a fusion reactor


We already have fission powered ships and submarines.



Sense prevailed, and we do not have civilian mobile nuclear reactors.

The military are mad. Mad and bad. It is in the job description.

We would all be better off if none of them (the military) existed




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