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Vostok, the coldest place on the planet, has a temperature which averages -67C, going down to -83C in the past. Carbon dioxide freezes at -78C. Both nitrogen and oxygen freeze at much much lower temperatures.
First thing to do is create shade in Vostok. Giant tinfoilian shelters will ensure even
lower temperatures. <delete>Simple split-type heat exchangers</delete><add [ldischler]>Heat pump</add> can be added to bring down the temperature a few more degrees.
Aim is to reach -78C.
Pipeline is built, same method as oil pipelines. Carbon dioxide is pumped up the pipeline to Vostok where it freezes and can be maintained in that state with minimal additional energy input. Other gases (nitrogen and oxygen in particular) will remain in a gaseous state and be removed by running them down through a jacket on the last mile or so of the pipeline before atomospheric release, achieving a counter-current multiplier effect in pre-cooling the new incoming gases.
Local energy generation for the additional cooling will allow immediate sequestration of that carbon dioxide as well.
With sufficient carbon dioxide removal we may be able to reverse global warming even further, reducing global temperatures, and making it even cheaper to maintain solid-state carbon dioxide in Vostok.
Note that once a vast quantity of frozen carbon dioxide has been stored it will be less affected by seasonal temperature variations, making this even more efficient over time.
Additionally, due to the gas law, just by cooling the gas as it goes towards vostok, it will become more dense, creating a negative pressure differential which will remove or reduce the need for pumping stations. If it could even be used to drive a few turbines for powering the Vostok based heat-exchangers further down the pipe that would be even better.
<add [ldischler]&&[zen_tom]>This would be ineffective with an open end, but a vertical prismatic freezing pipe may serve both to effectively close the Vostok end, provide the means for moving the mass of frozen CO2 (gravity) and reduce the pressure further (see anno //But it's not closed at both ends.// and subsq.). Keeping such a degree of volumetric constraint during freezing will allow the pressure reduction to benefit from the 570x reduction in volume cf. sublimation volume at 1 atm.; given the already reduced pressures the figure of 570 is likely an underestimation</add>
<edit in view of temperature stats>
75.4C in August, average minimum temperature. Not far off. Suggest pumping up more during August to take advantage of this and then counting on shade/insulation to reduce summer warming.
In addition... one assumes that much of the heat comes from the ground below; insulation there might make a big difference; suggest nitrogen bubble layer within permafrost.</edit>
Factoids on carbon dioxide:
Density of well-frozen carbon-dioxide = 1600 kg/m^3.
Density at sublimation = 2.81 kg/m^3.
Molecular weight = 44 g/mol.
Latent heat: vaporization = 471 J/g. Note 570 times space saving without the use of energy-intensive compression facilities.
Other points of relevance:
- Even if carbon dioxide rich air cannot be found in large quantities, general air from major industrial areas can be sucked up until technology permits better targeting.
- One litre of crude oil produces about 3.4kg of carbon-dioxide over its life-cycle; saddle the oil companies with a simple requirement that 3.4kg is sequestered in Vostok for each litre they extract.
- Global oil demand is 3.8 × 10^12 litres a year, requiring 1.3 x 10^13 kg of sequestration; or 8 x 10^9 m^3 of storage. About 3 thousand square miles of 100m deep storage each year. As with all sequestration ... it's only a patch and not a long-term solution.
Wikipedia: Vostok Station
http://en.wikipedia...wiki/Vostok_Station
Slightly different temperature details - lowest reliably measured -89 °C, but average in *winter* only -65 °C [jutta, Oct 17 2007]
British Antartic Survey Temperature Records for Vostok
http://www.nerc-bas...a/vostok.temps.html
Okay, not quite as chilly as mentioned, but still a great start. [vincevincevince, Oct 17 2007]
CO2 penalty of crude oil stats source
http://www.google.c...2&btnG=Search&meta=
Linked to Google single result to allow you to 'view as HTML' [vincevincevince, Oct 17 2007]
Cosmic Background Refrigeration
Cosmic_20Background...geration#1171049599
[BunsenHoneydew, Oct 23 2007]
[link]
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I like the general idea of putting things that need cooling into cold places, but what do you mean, shade? The place is in polar winter for three months.
I think the key to lowering the temperature would be height, not shade. |
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Good point on the shade, although it wouldn't be as effective as adding shade in the sahara, it would still have some effect in reflecting the rays of the sun, and infra-red radiation from surrounding areas. |
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I noticed the wikipedia page mentioned low levels of carbon-dioxide in the air without explaining why. |
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Interesting! Maybe that's just what you get in a place where nothing lives. (Waiting for experts to chime in.) |
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// levels of carbon-dioxide in the air //[vincevincevince] / [Jutta] It could be that it's so cold that it turns to liquid and falls like rain. |
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The slight problem here is that it is so cold there because nothing is warming it up. If you start pumping in warm CO2 there it will warm up. You'd want it to get very near liquid while going down a very long pipe. |
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//One liter of crude oil produces 3.4 kg of carbon dioxide. \\ Are you sure? I thought one liter of crude oil would way less then 1 kg, because I expect it to float on water? |
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As I understand it, the amount is more because only the carbon comes from the fuel, the oxygen is from the air. |
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I like the principle of this idea. You could build a network of pipelines accross the world connected to every coal power plant. Compared to other methods of CO2 sequestration this is thermodynamically efficient since little pressurization is required. |
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Instead of buring more fossils to keep the CO2 cool, you could use giant parabolic reflectors directed into the night sky (temperatures over Antarctica can reach -100 C at high altitudes) |
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A lot of bad science here:
//Vostok, the coldest place on the planet, has a temperature which averages -67C, going down to -83C in the past.//
The minimum temperature doesn't matter. The warmest period is what's important, when all that dry ice evaporates again. The average temp during the summer is -30 °C. Even the average during the winter is higher than the sublimation temp of CO2.
//First thing to do is create shade in Vostok.//
Do you even know where you are? It's cold there in the winter because it's dark 24/7. It's cold there because the earth is exchanging heat with the sky, which is really cold. Put up tinfoil and you're insulating the earth, not cooling it. Same deal in the summer. If you insulate, how do you get colder than -30C? Where does that heat go?
//Simple split-type heat exchangers can be added to bring down the temperature a few more degrees.//
There's nothing simple about this, and there's a major difference between heat pumps and heat exchangers. You need a heat pump. And you need a lot of power to run that heat pump.
//Carbon dioxide is pumped up the pipeline to Vostok where it freezes and can be maintained in that state with minimal additional energy input.//
Pumping takes a lot of energy and produces a lot of heat. The only reasonable way to get CO2 there is to liquefy it at coal or oil burning power plants, then ship it in tankers, then pipe it overland for a thousand miles uphill. If you're going to liquefy it, better to pipe it offshore into the deep ocean.
//Additionally, due to the gas law, just by cooling the gas as it goes towards vostok, it will become more dense, creating a negative pressure differential which will remove or reduce the need for pumping stations.//
Nonsense. If this were true, air would rush down from the stratosphere to where it is denser.
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[ldischler], thanks for the intelligent anno. Hoping you will get back to me regarding the below... |
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//The warmest period is what's important//
The mechanism of warming is important I think. It appears to be from the sun (as indicated by seasonal changes); in which case reflection/shade might do well. Note that shade does not necessarily need to be shade from visible light. |
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//Put up tinfoil, and you're insulating the earth.//
Very good point, unless you are insulating yourself from the earth as well (see comment upon embedding nitrogen bubbles into permafrost). |
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//You need a heat pump.//
Okay, great addition! Have modified the description. |
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//Pumping produces a lot of heat.// Energy can be used to pump it up there, the additional CO2 being added to the stream. The minimal energy focus is on maintaining it there. |
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//The only reasonable way to get CO2 there is to liquefy it at coal or oil burning power plants, then ship it in tankers, then pipe it overland for a thousand miles uphill.//
Natural gas seems to get pumped long distances just fine... |
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//air would rush into the stratosphere where it is less dense.//
Totally different situation, in my opinion of course; the main difference being that this is a constrained system. If you imagine a long pipe, closed at both ends, full of a gas at atmospheric pressure. You then freeze one end, and measure pressure at the other; the pressure will reduce itself considerably; and when measured relative to atmospheric pressure, it will in fact be a negative pressure. If cooling alone is insufficient, then keeping the volumetric constraint in Vostok during freezing (570x volume reduction over sublimation point gas density, even more over the density at the inlet end of the pipeline) you will have an even greater differential pressure effect. |
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//If you imagine a long pipe, closed at both ends//
But it's not closed at both ends. In your scheme it's sucking air at one end and spitting out cold CO2 at the other. That's open at both ends, and there's no driving force.
//The mechanism of warming is important I think. It appears to be from the sun (as indicated by seasonal changes); in which case reflection/shade might do well. Note that shade does not necessarily need to be shade from visible light.//
By insulating, you won't get any cooler than the air temperature. If the air temp is -30C in the summer, how does it get any lower? And if you dump the latent heat of freezing CO2, where does it go? |
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Pumping liquid CO2 is going to be difficult - CO2 will only form a liquid at pressures of over 5atm - which is probably managable, but significatly increases the (energy, and financial) cost of running such a pipeline. |
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On the upside, if the CO2 is pumped under pressure, releasing it into normal atmospheric pressure will probably cool it enough to sublime directly into its solid form without any additional cooling required. |
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On the downside of that, the great engines required to pump all this CO2 up to the pole will more than make up for any cooling effect provided in the heat and fuel they produce themselves. |
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I'm not a fan of sequestation - which can only ever be a temporary solution at best - unless it is performed in such a way as to have useful secondary purpose. |
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But if we are going to expend the effort, for the same cost of implementing a great civil engineering project like this, we could irrigate the Sahara, sequestering CO2 in plants, that people could eat, and which could provide a habital for threatened species - I'd rather do that than build a great big pile of dry ice. |
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//But it's not closed at both ends.//
Very important point indeed. By my calculations, if the Vostok end of the operation was a prismatic vertical freezing pipe of 100m length and 10m diameter, there would be potentially up to 3.1x10^4 m^3 of dry ice within it. Equivalent to a 55k ton weight. The force produced by this weight would both add to the pressure reduction required, and suffice to move the dry ice out of the tube. Increasing freezing power will increase length of frozen tube, decreasing it will allow for a reduction in downward pressure. <e>Of course, you'd have to smash lengths off it as they came down (introduce deliberate faults by injecting a spray of something else every 10m?).</e> |
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//prismatic vertical freezing pipe// I like that a lot - a gravity-driven cooling plant. As the weight is pulled downwards, it lowers the pressure, encouraging more freezing, which adds to the weight, which lowers the pressure further...[+] for that idea alone. |
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//we could irrigate the Sahara, sequestering CO2 in plants// Whilst the Sahara might be a bit out of range, the pipeline will necessarily produce significant amounts of water as more humid gases are moved towards Vostok. It's got to go somewhere; intelligent routing could allow this to be tapped off anywhere before water freezing point. |
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//Pumping liquid CO2 is going to be difficult// it would be very hard to do it by applying positive pressure to the source alone; but pressure reduction due to various processes as described near or at Vostok should be a much more efficient method and would result in gaseous flow which has a much lower frictional penalty than fluid flow anyway. Note that it might take a year or so to build momentum in a gas. |
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//And if you dump the latent heat of freezing CO2, where does it go?// More tricky questions. I don't know enough about the technology available here; can anyone help? |
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Please be aware that Vostok is over 11,000 ft elevation - are you sure that increasing the density of CO2 is going to make it flow uphill? |
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//11,000 ft elevation// My fluid dynamics isn't that hot - when you're pushing air up a hill, what kind of load is involved? |
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// //And if you dump the latent heat of freezing CO2, where does it go?// More tricky questions. I don't know enough about the technology available here; can anyone help? // |
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Have a look at the extensive discussions at Cosmic Background Refrigeration. [link] |
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Also, don't we already have a mechanism for distributing gases around the world, for free? It's called "the atmosphere". |
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As I read your idea, you're proposing a great wad of dry ice sitting exposed on the surface, and dependant on human infrastructure to keep it frozen? Doesn't that seem a little dangerous? |
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Fifty to a hundred years from now, we're all basking in the comfort of our newly-stabilised global ecosystem, when a power failure/meteor crash/slight temperature variation at Vostok releases decades of greenhouse gases *in*one*go*. No, thanks. |
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Burying the CO2 deep into the icecap might help, especially if you can find a depth where the temperature is -well- below CO2 freezing. But even then, you'll have to make sure the icecap itself isn't melted by global warming or we have the same problem. |
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cf permafrost, methane, runaway feedback. |
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So I suggest: extract atmospheric CO2 in situ and bury it deep in the icecap. |
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[vince]I like your idea and apologize for not seeing it before posting mine. |
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