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Here’s my crazy idea: nuclear powered high pressure differential centrifugation. Under centrifugal force fluids separate into bands based on mass. The same pri

by jf- 8y ago

Here’s my crazy idea: nuclear powered high pressure differential centrifugation. Under centrifugal force fluids separate into bands based on mass. The same principle as oil and water separating under gravity. Use giant centrifuges to spin compressed air until it separates into bands, then extract the bands corresponding to greenhouse gasses. I don’t know the energy requirements for this or if there is a better way of doing it. But if you’re looking for blue sky thinking, that’s what I’ve got.

idoh 8y ago
What do you do with the CO2 once you've isolated it?
- jf- 8y ago
  Put it through a process to solidify it. You may be able to extract other useful gasses from the air to help with this. If the end result were stable, either put it in landfill or use it as fuel, so it becomes an energy reservoir. Then it’s closed loop, the energy is generated by nuclear and expressed via the expenditure of the manufactured fuel and subsequent recapture.
- rpowers 8y ago
  Feed it into a massive underground greenhouse?
lchengify 8y ago
Huh ... this is kind of a fun idea. Kicking this around a bit, it's similar to how you separate U235 from U238 for enriching Uranium. I wonder if you could back into the energy requirements from that process (assuming it isn't classified). https://en.wikipedia.org/wiki/Zippe-type_centrifuge https://en.wikipedia.org/wiki/Zippe-type_centrifuge
WhompingWindows 8y ago
Liquids have differential densities which allows them to spread into layers. If you have "compressed air" that separates into bands, you're just talking about compressing the air into a liquid phase so it can then be extracted as above. The triple point of carbon dioxide is -57 C and 5.1 atm, so in other words you'd have to get colder and higher pressure than that to even produce the liquid. Then you'd have to spin it down while it's pressurized and cooled. Could you math it out from there and compare it to the Sabbatier reaction or to just plain old trees? I doubt you'll extract CO2 cost effectively that way.
- jf- 8y ago
  I’m not sure that compressing to a liquid would be necessary. https://energyeducation.ca/encyclopedia/Gas_centrifuge https://energyeducation.ca/encyclopedia/Gas_centrifuge , which is describing the uranium enrichment process mentioned by Ichengify, states that the separation occurs while the uranium is still a gas, with the heavier fraction just being scooped out. Also taking a quick look at the natural separation of gasses in Earth’s atmosphere, it seems that the uppermost layer consists mostly of hydrogen, helium and CO2, and that’s just under gravity. I’m not a chemical engineer, but I’ll have a stab at what the energy for the process might be. No promises that I can reach an answer.
perlgeek 8y ago
I really like the idea. However, I get the impression that gas centrifuges are really high-maintenance. Is that right? Or does that only apply to the Uranium enrichment case?
- jf- 8y ago
  Thanks! Honestly I don’t know. However, since basically all the search results I’m getting are for uranium enrichment, I’m guessing gas centrifuges are not in common industrial use for any other purpose. That probably means they aren’t well optimised. The most relevant published literature I’ve found is this: http://www.mate.tue.nl/mate/pdfs/5250.pdf http://www.mate.tue.nl/mate/pdfs/5250.pdf Which is exactly about the separation of CO2, but for natural gas production. The throughput was uneconomical in their case, however it does establish that the principle is sound, it may just need a (possibly very considerable) amount of development. I haven’t exactly done an exhaustive search though, so there’s probably more out there.

by jf- 8y ago

idoh 8y ago

What do you do with the CO2 once you've isolated it?

jf- 8y ago
Put it through a process to solidify it. You may be able to extract other useful gasses from the air to help with this. If the end result were stable, either put it in landfill or use it as fuel, so it becomes an energy reservoir. Then it’s closed loop, the energy is generated by nuclear and expressed via the expenditure of the manufactured fuel and subsequent recapture.
rpowers 8y ago
Feed it into a massive underground greenhouse?

lchengify 8y ago

Huh ... this is kind of a fun idea. Kicking this around a bit, it's similar to how you separate U235 from U238 for enriching Uranium. I wonder if you could back into the energy requirements from that process (assuming it isn't classified). https://en.wikipedia.org/wiki/Zippe-type_centrifuge https://en.wikipedia.org/wiki/Zippe-type_centrifuge

WhompingWindows 8y ago

Liquids have differential densities which allows them to spread into layers. If you have "compressed air" that separates into bands, you're just talking about compressing the air into a liquid phase so it can then be extracted as above. The triple point of carbon dioxide is -57 C and 5.1 atm, so in other words you'd have to get colder and higher pressure than that to even produce the liquid. Then you'd have to spin it down while it's pressurized and cooled. Could you math it out from there and compare it to the Sabbatier reaction or to just plain old trees? I doubt you'll extract CO2 cost effectively that way.

jf- 8y ago
I’m not sure that compressing to a liquid would be necessary. https://energyeducation.ca/encyclopedia/Gas_centrifuge https://energyeducation.ca/encyclopedia/Gas_centrifuge , which is describing the uranium enrichment process mentioned by Ichengify, states that the separation occurs while the uranium is still a gas, with the heavier fraction just being scooped out. Also taking a quick look at the natural separation of gasses in Earth’s atmosphere, it seems that the uppermost layer consists mostly of hydrogen, helium and CO2, and that’s just under gravity. I’m not a chemical engineer, but I’ll have a stab at what the energy for the process might be. No promises that I can reach an answer.

perlgeek 8y ago

I really like the idea. However, I get the impression that gas centrifuges are really high-maintenance. Is that right? Or does that only apply to the Uranium enrichment case?

jf- 8y ago
Thanks! Honestly I don’t know. However, since basically all the search results I’m getting are for uranium enrichment, I’m guessing gas centrifuges are not in common industrial use for any other purpose. That probably means they aren’t well optimised. The most relevant published literature I’ve found is this: http://www.mate.tue.nl/mate/pdfs/5250.pdf http://www.mate.tue.nl/mate/pdfs/5250.pdf Which is exactly about the separation of CO2, but for natural gas production. The throughput was uneconomical in their case, however it does establish that the principle is sound, it may just need a (possibly very considerable) amount of development. I haven’t exactly done an exhaustive search though, so there’s probably more out there.