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Using energy to scrub the atmosphere of greenhouse gases

  1. Nov 8, 2013 #1
    I was wondering if someone could help me with the current and foreseeable technology to use Earth's energy (nuclear, hydro, etc.) to actually scrub the atmosphere of CO2 and other gases. I'm curious if this is even possible and how it might be done. I've been trolling the internet for this without much success.

    Thanks,
    Dirk
     
  2. jcsd
  3. Nov 8, 2013 #2

    Drakkith

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    Hmmm. An interesting question. While I don't know offhand how to scrub CO2, I can guarantee you that there is simply far too much in the atmosphere for any manmade scrubbing method to be feasible. At 397 ppm, the total amount of CO2 is simply staggering. (Something like 3x1012 tons)
     
  4. Nov 8, 2013 #3

    SteamKing

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    And you don't want to scrub ALL of the CO2, otherwise plants would starve, and eventually us.
     
  5. Nov 8, 2013 #4
    Which raises the question of what the ideal atmospheric CO2 concentration is and for whom. Even if it were possible to accurately simulate the effects of various concentrations (which I doubt), I would be surprised if there was any kind of agreement on which effects were preferable.
     
  6. Nov 9, 2013 #5

    CWatters

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    In 2012 this company demonstrated c02 capture from the air and conversion to fuel for motor sports. I suspect there might be a better use for the renewable energy you need to fun the plant...

    http://www.airfuelsynthesis.com/investment-opportunity/projects/demonstrator-unit.html

    Google found a paper on c02 capture from the air. Includes a surprising statement that appears to suggest it might be more efficient (in what terms?) to capture c02 than to avoid emitting it by building wind turbines..

    http://www.netl.doe.gov/publications/proceedings/01/carbon_seq/7b1.pdf

    I think carbon credits are currently around $13 a ton ???
     
    Last edited: Nov 9, 2013
  7. Nov 9, 2013 #6
    Prior to the industrial age, the concentration of CO2 in the atmosphere was about 290 ppm.
     
  8. Nov 10, 2013 #7
    Prior is a long time.In the past there were periods when the concentrations were higher than today.
    A very large proportion of ancient CO2 is locked away in rocks etc.
     
  9. Nov 10, 2013 #8

    mfb

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    Is that a joke?
    A dimensional analysis does not give any relevant numerical results.

    CO2 capture in the exhaust of coal power plants is still expensive, and there you have a concentration of ~20%. Why bothering with the atmosphere with 0.04%, if you have CO2 in a much higher concentration to start such a project?

    Capturing CO2 is not sufficient - you have to store it somewhere, or use it in some way.
     
  10. Nov 10, 2013 #9
    Maybe I should have been more precise. For the few thousand years of man's existence before the industrial age, the concentration was less than 300 ppm.
     
  11. Nov 10, 2013 #10

    SteamKing

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    If only someone could come up with a process to manufacture limestone.
     
  12. Nov 10, 2013 #11

    UltrafastPED

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    Grow lots of clams!
     
  13. Nov 10, 2013 #12

    Vanadium 50

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    I don't think it makes much difference whether one plans to reduce the CO2 concentration by 10% (going back to 1950's levels) or 20% (going back to 1850's levels) - it's a factor of 2 in removal: if you can remove three trillion tons, you can probably remove six trillion tons.

    If you want to do chemical sequestration, you're limited to the availability of calcium that's not already locked in carbonates.

    If you want to do biological sequestration, we can do that today by seeding oceans with small amounts of iron. This is not a popular solution, since we don't know what other effects there would be.

    If you want a closed-cycle sequestration, for every joule you produce with fossils, you need to spend half a joule for sequestration. That assumes 100% efficiency.
     
  14. Nov 10, 2013 #13
    So?

    The fact that 290 ppm is the equilibrium level in the absence of man made emissions does not necessarily mean that 290 ppm is the ideal concentration of CO2 in the atmosphere.
     
  15. Nov 10, 2013 #14

    Vanadium 50

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    ...is not the subject of this thread, and is treading mighty close to a banned topic. Let's all stay on topic, please.
     
  16. Nov 10, 2013 #15

    OmCheeto

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    Interesting indeed. I've been watching a field of plants around where I've worked for the last 10 years. They seem to get taller every year. It might just me my imagination though. But one day, someone asked; "What the hell are those"? I had not a clue and spent some time googling.

    They turned out to be Equisetum, a "living fossil".

    240px-Equisetopsida.jpg

    Given that they now only grow to 3 feet, I thought maybe they were stunted by the lack of CO2 in the atmosphere. Then I thought that they might have some recessive gene, that when reactivated, might make them grow really big again, if there was as much CO2 in the atmosphere today, as there was 100,000,000 years ago, and that they might be a simple biological solution to our "scubber" problem.

    But then I decided that I knew nothing about biology, so I didn't say anything, to anyone.
     
  17. Nov 11, 2013 #16

    mheslep

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    This CO2 into snow approach in Antarctica using some chillers powered by wind turbines seems feasible. Winter temperatures in the interior already fall close to the CO2 freezing point at 1 bar. Intermittent nature of the wind resource would be irrelevant. The proposed 1 billion tons of carbon removal per year using 20 GW (average) should have a notional onshore wind turbine capital cost of $200 billion.

    Agee, Ernest, Andrea Orton, John Rogers, 2013: CO2 Snow Deposition in Antarctica [...] J. Appl. Meteor. Climatol., 52, 281–288.
    doi: http://dx.doi.org/10.1175/JAMC-D-12-0110.1

    Abstract:
     
    Last edited: Nov 11, 2013
  18. Nov 11, 2013 #17

    mheslep

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    Does that energy calculation assume some endothermic chemical reaction in sequestration to fix the CO2? I'm curious since the Antarctica CO2-freezing scheme above claims to do considerably better. Combustion of, say, methane releases 55 kJ/g or 20 kJ/g of the CO2 product. The authors claim deposition of solid CO2 at 136 K in Antarctica requires 0.6kJ/g-CO2 (appendix D), or 33:1
     
    Last edited: Nov 11, 2013
  19. Nov 11, 2013 #18

    SteamKing

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    Oh yeah, that Antarctic plan is gonna fly. Turning the Southern Continent into an industrial park to freeze CO2. Won't be any environmental opposition there! Dead penguins? I see no dead penguins!

    Assume you built a plant at the pole which did remove atmospheric CO2. Does atmospheric CO2 migrate from the northern hemisphere to the southern hemisphere? How much CO2 migrates? How long does it take?
     
  20. Nov 11, 2013 #19

    mheslep

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    I don't consider placing wind turbines on a *continent* of five million square miles as turning it into an industrial park.

    There's also objection by some to the manned mission equipment still on the moon's surface because people placed it there. I don't give that misanthropy any credence either.
     
  21. Nov 11, 2013 #20

    SteamKing

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    Yeah, that's why we're drilling for oil in the Alaska National Wildlife Refuge right now.
     
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