11
$\begingroup$

I understand that on Earth, we mainly get our helium from natural gas deposits, which traps helium atoms generated from radioactive decay. Would this process still work on a terrestrial planet without fossil fuels like natural gas? If not, could there be another way for people on this planet to mine helium on a commercial scale?

$\endgroup$
6
  • 8
    $\begingroup$ Pretty sure that the helium is trapped with the natural gas because of the underground enclosed spaces, not specifically because it's natural gas. So you'd need underground caverns (even tiny porous ones) in which the helium accumulates. It's just not very economically viable to be pumping out all that gas just to get trace helium (and I'm not sure what methods for recovery would work best) geology.com/articles/helium/…. $\endgroup$ – DWKraus Mar 8 at 3:05
  • 2
    $\begingroup$ Willk gave a real answer with full research. I just have a general understanding about what I suspected was the truth. By the time I started looking into it in more depth, he already had the answer out there. $\endgroup$ – DWKraus Mar 8 at 3:19
  • 1
    $\begingroup$ Note that methane is not necessarily fossil. It may as well be primordial (see colder planets and their moons in the solar system) and/or of inorganic origin (some of our deposits MAY be inorganic). $\endgroup$ – fraxinus Mar 8 at 20:34
  • 1
    $\begingroup$ For a planet with life to not have fossil fuels, the geology must be such that the gases,liquids and solid organic residue of past life is not trapped underground. It is inconceivable for there to not be such residues, with a surface teeming with life.(not to mention primordial hydrocarbons). If there are no structures that trap oil and gas, there are also no structures that trap helium. $\endgroup$ – PcMan Mar 9 at 6:51
  • 1
    $\begingroup$ @PcMan Fossil fuel precursors are created by anaerobic environments; if there are sufficient anaerobic microbes that can fully break down organic matter before it can become lignite (coal precursor) or kerogen (petroleum precursor). If you look at it the right way, we're pretty lucky to have fossil fuels in the first place, especially coal! $\endgroup$ – Thegs Mar 9 at 18:37
28
$\begingroup$

You can have helium without hydrocarbons.

You are aware that the process that produces helium is radioactive decay; unrelated to hydrocarbons. Hydrocarbons and helium are associated because people looked for hydrocarbons and underground domes that can trap one gas can trap others too.

Recently some people went prospecting for helium, starting with considerations about where there would be rocks that could produce helium and geologic features to trap it.

https://www.chemistryworld.com/news/scientists-unearth-one-of-worlds-largest-helium-gas-deposits/1010122.article

Working with Helium One, an exploration company, the team realised this process is occurring now in the east African Rift Valley, which crosses nine African countries including Tanzania. ‘We found multiple places in the Tanzanian Rift where you have geothermal pools,’ says Ballentine. ‘In that water it’s bubbling gas and that gas isn’t carbon dioxide, it’s not hydrocarbons, it’s nitrogen with helium contents up to 10%, which is phenomenal.’ Commercial gas deposits, which contain a large amount of carbon dioxide and methane, only contain approximately 0.3% helium.

Pretty slick! So too in your world. Helium prospectors would find domes with accumulations of helium.

The nitrogen piece is not clear to me and I went digging. If anyone else wants to read up I found a thesis which goes into some detail: http://etheses.dur.ac.uk/12573/1/Full_Thesis_Danabalan_2017_with_corrections.pdf?DDD15+

I took away that there is a lot of nitrogen underground because there is a lot of nitrogen above ground. Geologic circumstances that trap gas trap nitrogen. Nitrogen is also found with hydrocarbons. If you have a dome that traps helium there will probably be other gases in there with it, but if your world does not have hydrocarbons then none of those.

$\endgroup$
1
  • $\begingroup$ That is really cool! Thanks for sharing the article about the Tanzanian deposit. This problem has been bugging me for a while, so the info is much appreciated :) $\endgroup$ – DISPLAYNAME Mar 8 at 3:12
7
$\begingroup$

If you want to produce Helium, you can always stock on alpha emitters radioactive materials, like Radon, Polonium or Americium: any alpha particle is nothing more than a Helium nucleus, which once captured two electrons and dissipated its kinetic energy is ready to use.

Alpha particles, also called alpha rays or alpha radiation, consist of two protons and two neutrons bound together into a particle identical to a helium-4 nucleus. They are generally produced in the process of alpha decay, but may also be produced in other ways.

For safe to handle amounts of radioactive material the amount of produced Helium might be negligible, so be ready to use a generous amount of shielding around your production site.

$\endgroup$
1
  • 5
    $\begingroup$ Whilst your answer is basically correct, I would point out that there are more convenient alpha emitters in the world... polonium is very rare and americium is synthetic. Looking for anywhere that radon is a risk would seem to be the easiest approach, though the yields are likely to be quite low... $\endgroup$ – Starfish Prime Mar 8 at 9:37
5
$\begingroup$

You could extract it directly from the atmosphere.
At high cost but with good availability.

Admittedly the process would be energy inefficient, as the concentration of Helium is a very low 5 ppm by mass. But the total reserves are huge. There is a lot of Helium in the Earth atmosphere. In total, some 26800 million tons of the stuff.
This figure would be rather similar for any planet with an Earth like gravity and magnetic field. The Helium is not primordial but generated via alpha-decay of radioactives. The magnetic field is just needed to slow down stripping of high exospere Helium by the solar wind, as Helium really loves to go out into outer space.

$\endgroup$
1
  • 3
    $\begingroup$ Yep, as a worst and last-resort approach, this will always work on a world with helium anywhere. Because if the planet has helium, it's in the athmosphere as well. It's just the worst of all the approaches to getting helium (unless the planet's athmosphere is drastically different in regards to having just a ton of more helium) $\endgroup$ – Hobbamok Mar 8 at 15:16

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.