7 ms·

Totally out of my depth here, but does cooling the gas down have the added benefit that it'll be heated by the earth whilst stored?

deleted 5y ago
[deleted]
notatoad 5y ago
what would be the benefit to it being heated by the earth during storage? all the temperature management here looks to just be counteracting the temperature changes that naturally occur when you compress or expand a gas. i imagine if you compressed it and then pumped hot air into water-filled caverns you'd get some negative effects of thermal shock.
- halpert 5y ago
  Hot air should have higher pressure, so theoretically you could get more displacement. But your pumps also have to work harder to create a pressure differential. Hard to say which effect would be bigger.
- locuscoeruleus 5y ago
  Wouldn't the cooled down gas expand when heated leading to higher pressure, so you need to pump gas down?
JohnL4 5y ago
I'm guessing not. Earth's heat is way lower down. Think of a cave: always cold. I think what's going on is they're taking the heat out and storing it more efficiently than just dumping it down the ground, where (1) it would leak away, representing energy loss, and (2) as it leaks away, the air would lose pressure. (It would leak away b/c it's harder to insulate an entire mine, basically.) So, they pull it out ahead of time and put it back in when they decompress the air (which I think would add pressure back in due to heating a gas and maybe reduce problems caused by super-chilling other plant hardware? Anyway, seems fitting to add back what you took out if you're shooting for a closed system.)
- Raidion 5y ago
  This isn't correct. Deep mines are notoriously hot, because you're digging towards magma. Google says temps increase by 3° C for every 100m.
  - emptysongglass 5y ago
    Naive question but couldn't our forerunners who otherwise succumbed to cold in harsher climates have exploited this fact to dig subterranean villages and towns? What's the element I'm missing as to why they didn't?
    - cortesoft 5y ago
      That it is really hard to dig down 100m without modern digging equipment.
    - WiseWeasel 5y ago
      Difficulty of digging with the tools they had, inability to stabilize the structure to prevent cave-ins, lack of pumps to remove accumulating water, insufficient ventilation and filtration technology/unable to deal with poison gases, inability to light their environment without contributing to the poor air quality, difficulty accessing resources like food and clean water, lack of desire to live in a damp, dusty hole.
    - sulZ 5y ago
      Digging 100m down is difficult and dangerous
    - inglor_cz 5y ago
      Pre-industrial holes may collapse long before you reach -100 meters. Even -5 meters is a challenge in certain places. Also, digging (or rather drilling) in bedrock is hard without motorized equipment and good steel. Also, supplying fresh air down there is a problem. Also, preventing the mine from flooding is usually a huge problem. Mining is hard and a lot of people lost their lives doing that. That said, if your only intent is to get a bit warmer, you may basically try a good cave. Caves tend to have temperatures above freezing for the whole year.

deleted 5y ago

[deleted]

notatoad 5y ago

what would be the benefit to it being heated by the earth during storage? all the temperature management here looks to just be counteracting the temperature changes that naturally occur when you compress or expand a gas. i imagine if you compressed it and then pumped hot air into water-filled caverns you'd get some negative effects of thermal shock.

halpert 5y ago
Hot air should have higher pressure, so theoretically you could get more displacement. But your pumps also have to work harder to create a pressure differential. Hard to say which effect would be bigger.
locuscoeruleus 5y ago
Wouldn't the cooled down gas expand when heated leading to higher pressure, so you need to pump gas down?

JohnL4 5y ago

I'm guessing not. Earth's heat is way lower down. Think of a cave: always cold. I think what's going on is they're taking the heat out and storing it more efficiently than just dumping it down the ground, where (1) it would leak away, representing energy loss, and (2) as it leaks away, the air would lose pressure. (It would leak away b/c it's harder to insulate an entire mine, basically.) So, they pull it out ahead of time and put it back in when they decompress the air (which I think would add pressure back in due to heating a gas and maybe reduce problems caused by super-chilling other plant hardware? Anyway, seems fitting to add back what you took out if you're shooting for a closed system.)

Raidion 5y ago
This isn't correct. Deep mines are notoriously hot, because you're digging towards magma. Google says temps increase by 3° C for every 100m.
- emptysongglass 5y ago
  Naive question but couldn't our forerunners who otherwise succumbed to cold in harsher climates have exploited this fact to dig subterranean villages and towns? What's the element I'm missing as to why they didn't?
  - cortesoft 5y ago
    That it is really hard to dig down 100m without modern digging equipment.
  - WiseWeasel 5y ago
    Difficulty of digging with the tools they had, inability to stabilize the structure to prevent cave-ins, lack of pumps to remove accumulating water, insufficient ventilation and filtration technology/unable to deal with poison gases, inability to light their environment without contributing to the poor air quality, difficulty accessing resources like food and clean water, lack of desire to live in a damp, dusty hole.
  - sulZ 5y ago
    Digging 100m down is difficult and dangerous
  - inglor_cz 5y ago
    Pre-industrial holes may collapse long before you reach -100 meters. Even -5 meters is a challenge in certain places. Also, digging (or rather drilling) in bedrock is hard without motorized equipment and good steel. Also, supplying fresh air down there is a problem. Also, preventing the mine from flooding is usually a huge problem. Mining is hard and a lot of people lost their lives doing that. That said, if your only intent is to get a bit warmer, you may basically try a good cave. Caves tend to have temperatures above freezing for the whole year.