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QUESTION

I'd like a nation in the world I'm working on to be able to transport natural gas and hydrogen, for fuel and possibly ballooning. Natural gas pipelines and cylinders were first invented in ancient China, but while impressive, these were rather leaky. I'd like it if the inhabitants of this world could store gas over time, and transport it over distance, rather than relying just on proximity to a reserve.

  • Can my world invent reliable gas cylinders early? How large and efficient could they potentially make them?

NOTES

In general, the technology hovers between classical and medieval, but there are some important exceptions. They possess most metals and woods, but there are large regions of the world that do not have iron or nickle, and this culture may eventually be included among them. In terms of relevant unusual materials, assume also they have:

  • Vulcanized rubber, from sulfur.
  • Bamboo and silk equivalents.

They are familiar with creating relatively complex devices from building automated textile mills and similar technologies. There are good conditions for the exchange of ideas and invention in general. Chemistry, in particular is ahead of the game, so other materials may be available if necessary and plausible. Otherwise I prefer to keep things as outlined.


Finally, this question is related, but distinct.

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  • $\begingroup$ (Re: hydrogen assume they have a relatively plausible alternate world source, perhaps a hydrogen producing plant that can be farmed.) $\endgroup$ – Era Jan 30 '18 at 20:49
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    $\begingroup$ Modern humans generally can't store hydrogen for long time without leaking. Permeating stands in the way. For reference: en.wikipedia.org/wiki/Hydrogen_storage $\endgroup$ – Mołot Jan 30 '18 at 20:50
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    $\begingroup$ There is no problem with having low-pressure gas cylinders, can can be fashioned out of many materials. But for high-pressure cylinders, you will need steel or a hard alloy. $\endgroup$ – Alexander Jan 30 '18 at 20:58
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    $\begingroup$ Just a side note: when you see a claim of ancient Chinese technology, look where it came from. You have to be careful of Joseph Needham. That guy made a lot of claims about things that the Chinese discovered that are poorly vetted at best. Of course, Chinese scholars back those claims, but proof is often ambiguous at best. Furthermore, all your gas cylinder claims come from Robert Temple who is more or less a conspiracy theorist. TLDR: Tang China did not have natural gas or gas cylinders. $\endgroup$ – kingledion Jan 30 '18 at 21:11
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    $\begingroup$ @Era That is hard to say, you have to look at each one. I just followed your link to Wikipedia, and it struck me as fishy. To be clear, Needham is the most respected researcher of Chinese technology, so don't assume his statements are false. But in my opinion, he likes to claim very early dates for things that aren't always corroborated by other researchers. In any case, I didn't know who Robert Temple was until I followed the references on your Wikipedia link. So you have to investigate each one, independently. $\endgroup$ – kingledion Jan 31 '18 at 1:24
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Make your gas on site via hydrocarbon cracking.

https://en.wikipedia.org/wiki/Cracking_(chemistry)

It requires some spiffy tech to compress gas and keep it compressed. But it takes very little tech to tote an urn of crude oil around. Long chain hydrocarbons (like crude oil) can be "cracked" into smaller molecular weight fractions. This is done industrially using heat, pressure and catalysts. Your primitives have discovered a mineral which serves as a catalyst to enable low temperature cracking of long hydrocarbons. When they set up their balloon, they can set up the cracking pots underneath and let the warm methane and hydrogen float up into the balloon.

For a work of fiction, having urns of black goo and weird chemical reactions might be cooler than Flintstonesque bronze CO2 tanks.

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  • $\begingroup$ This sounds really neat, I may actually make another question around it. How feasible is it that such a mineral could physically exist, even if unknown to us? Looking at the article it seems like normal temps required are very high. $\endgroup$ – Era Jan 30 '18 at 22:45
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    $\begingroup$ These folks crack hydrocarbons into carbon and hydrogen at 823K which is 1021 F. That is not that hot - a campfire gets that hot. And you have plenty of fuel for a fire - for example, the carbon byproduct of your cracking (charcoal!) once the hydrogen is driven off into your balloon. $\endgroup$ – Willk Jan 31 '18 at 15:09
  • $\begingroup$ Very coal, do you have any idea where I should look to get figures on how much hydrogen/methane gas might be produced per liter (or what have you) of oil? $\endgroup$ – Era Jan 31 '18 at 19:30
  • $\begingroup$ (I meant to type "very cool", but the typo is oddly appropriate.) $\endgroup$ – Era Jan 31 '18 at 19:30
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    $\begingroup$ It would definitely light them on fire if there were oxygen to burn them with. So you need to exclude oxygen when you do it. If this sort of thing interests you, read on the manufacture of charcoal. Wood (basically carbon with hydrogen and some oxygen) is heated in the absence of oxygen - originally under big piles of dirt. The oxygen and hydrogen are driven off (along with volatiles) and what is left is almost pure carbon. But if you heated wood in the open air you would have a bonfire. $\endgroup$ – Willk Feb 1 '18 at 13:11
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Vessels capable to withstand pressure, that are simultaneously reliable and cheap are pretty hard to manufacture.

But you do not need pressure to use and transport gases. This is how 19th century limelight looked like:

enter image description here

(A) is a sack made out of skin and filled with hydrogen. Weight (B) provides pressure.

Similar technology was used in 20th century as well. This is car that stores gas in a sack on its roof(other examples):

enter image description here

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The Flying Sorcerers by David Gerrold and Larry Niven actually depicted exactly that problem. The protagonist needed large amounts of hydrogen (produced by electrolyzing water) stored away, which did prove itself to be a challenge.

Notably, they (the protagonist and his associates) didn't completely solve that problem, since they did have considerable leakage from their rubber-coated cloth balloons.

While longterm storage is definitely difficult, dirigibles in service were filled with hydrogen... well, until the Hindenburg ... using comparably low-tech means, meaning moderately airtight balloons may suffice.

If you go with pipelines, nothing prevents you to use the material you'd take for balloons to seal any cracks and seams. Maybe if you use clay pipes, cover them with a rubber coating to seal the pores.

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