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12 Mile Deep Hole

Method of Carbon Dioxide Sequestion
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A 12.3 mile hole in the ground supports a column of gaseous CO2. The atmospheric pressure increases with depth. At the bottom of the hole, the pressure is so great (35 bar, 0 degrees Centigrade) that the gaseous CO2 condenses into a liquid. As long as the heat of condensation is allowed to escape, a continuous flow of the CO2 gas will pour into the hole only powered by gravity.

[edit] pressure@altitude(miles) 2bar@-2.2, 3bar@-3.5, 4bar@-4.4, 8bar@-7.1, 16bar@-9.6, 32bar@-12.0, 35bar@-12.3

-12.3 miles below sea level

[edit]existing ocean: depth - 7 miles; temp at depth - freezing; location - subduction zones near coastal cities

CoolSolutions, Jan 09 2008

Carbon Capture and Storage http://en.wikipedia...capture_and_storage
Wikipedia prior art of CCS [CoolSolutions, Jan 09 2008]

Supercritical fluids http://en.wikipedia...Supercritical_fluid
[Ling, Jan 09 2008]

Vostok Solid-State Sequestation Vostok_20Solid-State_20Sequestation
Similar idea [marklar, Jan 09 2008]

Great Pykrete Pyramid of Ellesmere Great_20Pykrete_20P...id_20of_20Ellesmere
blatant elf promotion [BunsenHoneydew, May 17 2011]

Deep-sea CO2 sequestration http://www.anl.gov/...ando_03-02_0140.pdf
[ldischler, May 18 2011]

[link]






       Standby for supercritical annotations...
Ling, Jan 09 2008
  

       There was a similar idea to pump CO2 to somewhere Arctic so it would cool on the way and require less additional cooling to make it solid (CO2 doesn't like to be a liquid). Edit: Found it [link]   

       Assuming your pipe went to the centre of the Earth (ignoring the heat problems) it would have a pressure of around 40 atmospheres (assuming radius of 4000km). CO2 becomes a liquid at 0C and 35 atm or 30C and 70 atm.   

       The only feasible way of doing this I can see is to pump it into a flexible container at the bottom of the ocean, but the energy needed to pump it down there would probably outweigh the benefit (Deja Vu, did someone else suggest this?).
marklar, Jan 09 2008
  

       Consider this.   

       1) The density of a gas increases with pressure. For our air that we breathe, the first three 3 miles up constitutes half the weight we feel as pressure, and the other half of the weight is contained within the remaining 100 miles of our atmosphere into the vacuum of space.   

       2)CO2's molecular weight is 44 vs. air's 29. CO2 is more than a 50% denser than air. Also, the density increases even more as we approach the liquid state (non-ideal gas).
CoolSolutions, Jan 09 2008
  

       How do you propose to separate the CO2 from the other gases with which it is mixed, and how energy-efficient would the process be ? Fractional distillation of air consumes large amounts of energy to produce LN2, LOX and argon gas .... an there's only about 0.03811% CO2 in air.   

       You can capture enriched CO2 gases from fermentation (it goes into fizzy drinks) or from flue gases (rather a dirty mix). But it all takes energy.....
8th of 7, Jan 09 2008
  

       This would be used at fossil fuel power plants, and requires NO additional energy. In fact, this process could be adapted to harvest even more energy under the right conditions.
CoolSolutions, Jan 09 2008
  

       Do you have any idea how hot it is 12 miles under the earth's surface? The current deepest hole in the world, the Kola Superdeep Borehole (12,262 meters/7.62 miles) is 180 degrees Celsius at it's bottom. going to 15,000 meters would have raised it to a predicted 300 degrees Celsius (that's 570 Farenheit), and thats still 2 and half miles short of your goal.   

       I don't have the phase diagram of CO2 handy, but I don't think it'll stay liquid, even under those pressures, when the temperature climbs to god-knows-how-high at 12 miles deep. Plus, as the Kola hole suggests, no one has ever gone nearly that deep, and they're not likely to any time soon. The Kola hole was stopped for physical reasons, not financial ones.
5th Earth, Jan 11 2008
  

       What [8th] said; the deepness of your hole tends to liquefy the CO2, but the heat at that depth has the opposite effect, by a far greater margin. Non-starter, I'm afraid.
angel, Jan 11 2008
  

       PV=nRT
zen_tom, Jan 11 2008
  

       The deep ocean temperatures are near freezing. 7 mile deep ocean subuduction zones already exist near coastal cities. Boring beneath that would require keeping the drilling equipment cold, but what the hell hole. There is a pretty big heat sink at our disposal.
CoolSolutions, Jan 11 2008
  

       To dig or not to dig; that is sequestion....
globaltourniquet, Jan 11 2008
  

       .... or drill deep into a sea of troubles, and by opposing, vanquish them ......   

       "You can't appreciate Shakespeare until you've read him in the original Klingon...."
8th of 7, Jan 11 2008
  

       as [5th Earth] explained this is bad science and will not work.
jhomrighaus, Jan 11 2008
  

       //(35 bar, 0 degrees Centigrade)// Now class, can anyone tell me what the temperature of the Earth's crust is, at a depth of 19 680 metres?
Anyone?
Well, look, is it likely to be anywhere near the freezing point of water at STP?
<pause>Well, is it?
No-one got an answer?
<pause>Right then, that'll be a three week detention for the whole class.
AbsintheWithoutLeave, Jan 11 2008
  

       This turned from 350 feet to 12 miles. The math still is beyond me. Water is heavier than air, and maybe the column could be less deep. Perhaps pumping the CO2 down under a column of water would keep it safe. You could pump it into methane clathrate beds and get the methane out in return. Then burn it and pump the CO2 back down.
bungston, Jan 11 2008
  

       Now that's an interesting point [bungston]. There was a BBC documentary recently (My, how the Beeb has dumbed-down recently) where the presenter was igniting gas pockets frozen in Siberian lake ice.
It struck me that since methane is a far more potent greenhouse gas than CO2, maybe what we ought to do is like billions of tea lights all across Siberia in the Spring to burn off the methane as it is released from the thawing lakes thereby reducing the impact on Global Warming.
I respectfully submit my idea to the Nobel committee, and expect a prize by return-of-post.
Thank you.
AbsintheWithoutLeave, Jan 11 2008
  

       //what we ought to do is like billions of tea lights//   

       Do you think you get a Nobel prize for proposing that we enjoy some number of billions of tea lights? I mean, I like a lot, but I don't think I can like billions.
globaltourniquet, Jan 11 2008
  

       Did I say "like"?
I did of course mena [sic] "light"
AbsintheWithoutLeave, Jan 11 2008
  

       I think methane is more a greenhouse gas because it has more carbon locked up inside the molecule... burning off methane, I think would not help any; it just makes *more* less-potent greenhouse gas. (could be wrong here)
FlyingToaster, Jan 11 2008
  

       Congratulations, you've invented the volcano.
DenholmRicshaw, Jan 11 2008
  

       As it turns out, Methane (Also known as CH4) has less carbon, by volume, in it than Carbon Dioxide (CO2) It is also lighter than CO2. And, thankfully, CH4 breaks up in the presence of ultraviolet light.   

       While I would like billions of lit tea lights floating about in the bogs of siberia, I suspect that their heat going so close to one of the ice caps, and causing explosions of methane might actually help to speed global warming. I propose billions of black lights instead. I also propose some awesome siberian rave parties if global warming permits them.
ye_river_xiv, Jan 12 2008
  

       Pressure under water increases at 1atm per 10m.
marklar, Jan 12 2008
  

       Not withstanding all of my previous colleague’s wonderfully expressive elaboration of scientific matters, but has anyone stopped to consider the simple detriment to this plan. Even if in theory it worked for a moment, it would quickly equalize the pressure, and the flow would stop almost as quickly as it started. Being that a vacuum would not be in existence during the time of creation. And at your required level (even though the temp would have been increased as I agree with those other who have mentioned) the “liquid” would fill the little level making it NOT the required depth or temp anymore, therefore requiring another hole to be dug or expansion which would cause the inevitable collapse of the project.
The collector, Jan 12 2008
  

       The other points are a show-stopper. Not objecting the "bad science" tag.   

       But just to point out that none of us can be sure about not having an area on earth's crust at 12km depth without that heat. Your considering that all earth's crust is under the same conditions. I'm not sure that was researched. All deep digs were done looking for ancient geologic layers, not for solid unheated layers, which MAY exist.   

       On the other hand checking that out could be dangerous: What happens if lava reaches the research dig? What happens if while digging they reach a cavity and the sea itself pours into somewhere it wasn't before - and then steams out somewhere (not that it isn't doing that already).
pashute, May 15 2011
  

       //Methane (Also known as CH4) has less carbon, by volume, in it than Carbon Dioxide (CO2)// Surely they have almost exactly the same amount of carbon by volume, in the gaseous state.   

       Methane is a more potent greenhouse gas because it has a higher emissivity in the thermal infra red.
spidermother, May 17 2011
  

       Personally, I am glad all the BTUs we have released are not lost.   

       Imagine the scale of that loss --- a mere centry to radiate eons of acculated solar energy into space...
madness, May 18 2011
  

       and that is madness.
WcW, May 18 2011
  
      
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