Ambient Carbon Capture

It’s time to start thinking about how to subtract carbon from the atmosphere.

See also this recent article on Slate.

UPDATE: Andrew Sullivan has a roundup of the topic.

And Chris Tackett at Treehugger has an interesting take on it.


  1. I used to think it was impractical, and now I think the sooner the better.

  2. Pingback: Ambient Carbon Capture | evolveSUSTAIN

  3. "Direct air carbon capture technology" a tragicomedy of space cowboys. It might be taken as satire from which to get a point.
    Fumbling at one symptom, continuing with greed and planetary exploitation. But excess CO2 isn't the only symptom. Look at soil and what industrial agriculture is doing. This can't continue for long. We need some serious Gaia- and socio- engineering, instead of continuing spinning the Homo Sapiens (vicious) circle and inventing glitzy c20th techno business plans. Forget wet tech dreams, have a closer look at char coal, poop, and how to grow food.

    Here in Germany plus Austria and Switzerland the biochar thing is meanwhile getting quite some attention. Perhaps because we still have farmers, not all of them perverted and corrupted by fossil industry.

  4. Biochar is using real trees (or grass or farm waste etc.).

    I'm no physicist, but methinks the 2nd law of thermo poses some constraints on emulating carbon capture by photosynthesis. Not to speak of material resources and money to produce such devices.

    Photosynthesis plus pyrolysis would be free, produces energy, and enhances soil (if you add poop etc.). U.S. and Canada have abundant dead wood whose carbon needs fixation.

  5. I do not think biochar can reach the necessary scale to counteract the bulk of the emissions, unfortunately, but I am all for it and believe we should give people carbon credits for doing this.

    But they should be the same carbon credits for other sequestration methods. Now is not the time to be fussy.

  6. Michael Tobis says,

    I consider biochar to be a member of this family of strategies, not to be distinct from it.

    I agree.

    Martin Gisser says,

    methinks the 2nd law of thermo poses some constraints on emulating carbon capture by photosynthesis.

    CO2 sequestered as MgCO3, plus associated silica, have lower entropy than atmospheric CO2 and forsterite, Mg2SiO4, in mantle outcroppings beneath it. But their reaction ...

    Mg2SiO4 + 2 CO2 ---> 2 MgCO3 + SiO2

    is sufficiently exothermic that the heat increases the surroundings' entropy more than that of the reagents declines.

    So the whole process occurs spontaneously. The Second Law is on our side!

  7. Next, the CO2 has to be extracted from the sorbent and sequestered, presumably by pumping it deep underground at relatively high concentration or by binding it to minerals—a bit like how we handle nuclear waste. -- Lawrence Krauss

    So that's how we handle nuclear waste?

    How's that workin out?

    On a more serious note

    "Somebody's gotta do it"
    -- by Horatio Algeranon

    Dig the carbon up
    To bury it anew
    This is just a job
    Somebody's gotta do

  8. Read the Slate article. Broecker, Keeling, Hansen and Pierrehumbert among others are pushing for some form of CCS.

    Is this stupid as a global strategy? Yes, I am sure they would agree with that. Think of it as having first aid ready for someone doing "extreme sports". And badly at that.

    Does this constitute an argument to keep burning carbon? No, it's likely to be cheaper to replace the carbon directly - in any case there is likely to be a market failure where the beneficiaries of the carbon burning are not the ones who pay for the cleanup.

    But can we do without it? Increasingly the evidence points to the contrary, especially given the fact that we are not going to give up emissions any time soon.

  9. No disagreement to anything you said, Michael.

    The ditty was tongue in cheek. You must admit, "digging carbon up out of one hole and then reburying it in another" would probably make a good Far Side cartoon.

    But the question about nuclear waste was actually serious, since we really haven't "handled" nuclear waste, not on any large scale, at least (unless one considers Hanford "handling it" {some of us would consider that "mis-handling"}).

    Nor do we know that burying the waste will even "work" (that it will remain in place) over the long term, which is also arguably the biggest "?" with regard to "carbon capture".

  10. ...then again, maybe if we reburied it in the same hole that we took it out of.

    Will have to think about that a little.

    BTW, in case your comment was more in reply to the first ditty above (replying at all to goofiness may be a mistake), that is merely an expression of a concern that some have expressed (also about geoengineering): that it could provide an excuse to do nothing on the emissions reductions front.

    Horatio considers himself a kind of "misinterpreter of misinterpretations".

  11. Horatio Algeranon says

    since we really haven’t “handled” nuclear waste, not on any large scale, at least (unless one considers Hanford “handling it” {some of us would consider that “mis-handling”})

    Hanford waste is waste from bomb-making. The waste that is relevant to, has prevented, carbonation of the atmosphere has, as far as I can determine, been handled, not by hand, but still with complete success.

    The math of how its radioactivity builds up over time as a nuclear power establishment grows to replace the fossil fuel one is, so far, beyond me. There is the Untermeyer and Weills approximation, but it applies only to beta-decay, and much of the long-lived activity is alpha rays.

    I do know that to date, about 250 MW has accumulated (versus, I estimate, 3 MW at Hanford), in nuclear fuel retired five years or more, and this is the same ray power as exists in the uppermost 1 m of the continents.

    So schemes to bury it many metres deep are fail-safe in that if the buried containments fail, and the stuff then fails to stay in place, it will be a small fraction of the ambient radioactivity also wandering through the same rock.

    You must admit, “digging carbon up out of one hole and then reburying it in another” would probably make a good Far Side cartoon.

    Note that in enhanced weathering, the carbon that we long ago dug up, we now precipitate onto the surface. We do not rebury it.

  12. Yes. There is some confusion in that carbon capture and sequestration (abbreviated CSS) has been coopted (coincidentally, by the petroleum services industry who stands to benefit) to mean a specific approach, of pipelines and reburying the CO2 in the original holes (not incidentally, forcing more petroleum out).

    The good news with this is that it is proven at scale already.

    The bad news is how. CO2 is already piped from Colorado to Texas where it is injected into petroleum deposits to enhance petroleum recovery.

    Map: .

    This is not captured CO2 but MINED CO2. Yes, humans, not content to emit CO2 from FOSSIL FUELS, actually dig up FOSSIL CO2. The scale is relatively small, but still, presumably some of it escapes and should be accounted for if we ever get around to a carbon tax regime. Anyway, piping CO2 great distances and burying it in holes is old news. Most industrial processes never get any public attention before they are implemented, and this is an example.

  13. I consider biochar to be a member of this family of strategies, not to be distinct from it.

    Here's the distinction: Except the ability to light a fire you don't need any other technology.

    I do not think biochar can reach the necessary scale to counteract the bulk of the emissions,

    (ugh, instead of looking it up I watched Bill Maher, wrote a stupid comment elsewhere - and now time is out till next week)

    I bet 0.5 GtC pure biochar per year is no problem. Actually it needs integration into farming: If done right you get synergistic effects by improving soil fertility instead of depleteing soil organic cabon: Less nitrogen loss (e.g. NO2), lots of microorganisms in the char pores fixating more carbon, large cation exchange capacity feeding more plant roots. Total, say 0.9GtC.

    The "problem" is it needs attention and care for soil and plant ecosystems. Here's the "Gaia engineering". (That problem is actually characteristic of the Late Homo S Sapiens: Head in the clouds, ground forgotten.) Here's the required socio-engineering: "Back" to small family farms. (Actually small organic farmers are still "big" globally. Now we need to take them serious and forget about the grotesque perversities of industrial agriculture.)

    Now is not the time to be fussy.




    What about the mining and milling?

  14. Martin Gisser says:

    “Direct air carbon capture technology” a tragicomedy of space cowboys ...


    What about the mining and milling?

    and Horatio Algeranon says,

    Carbon capture will save us all
    From human greed and folly
    Then we’ll really have a ball
    With no holds barred, by golly.

    Forsterite, Mg2SiO4, is one of the components of olivine, the mineral promoted as a single-use CO2 sorbent by Schuiling and Tickell.

    The mining and milling of olivine, and the strewing of it over land, are an instance of catalysis: the spontaneous reaction with atmospheric CO2 that occurs at a piece of olivine's surface is accelerated by making more surface.

    Making a tonne, 22722 moles, of CO2 by burning pure carbon yields 8.9416 GJ, 2.4838 MWh, of heat. At a typical 33 percent heat-to-work conversion rate that gives 820 kWh (coal might give a little more, being of empirical formula near CH, or a little less, if burned at a time when efficiencies were well below 33 percent).

    Processing rock to promote its precipitation of the tonne CO2 will take back some or all of those 820 kWh. I think my excerpts from Gisser and Algeranon's comments shows that they would feel providence was playing a dirty trick on us, giving the space cowboys an undeserved boost that will make their failure, and everyone's, all the worse when it inevitably comes, if this processing takes too little of the 820 kWh.

    But if it takes too much, that's one less arrow in our silver buckshot cartridge. So rather than go through the arithmetic as I have often done -- and I may again later, but the response is always silence -- I'd like them to decide what the fraction ought to be, what we, space cowboys and realists together, deserve it to be.

  15. As a photosynthesis aficionado I can't be an efficiency fetishist 🙂

    After a little look at forsterite (link above) I start liking it. Taken alone, it doesn't look a silver bullet. Just like anything else. But like biochar it looks promising an excellent ingredient for what I've been talking about:

    Forget your glitzy space age technology dreams, dear Homo "Sapiens" and have a closer look at the home base - which is the soil under your boots: We need to recarbonize the biosphere. Ambient carbon capture is just one motivation for that. Soil is the base on which our civilization rests. And most civilizations in history have failed for not recognizing that.

    I'm still doing the homework for my comment above: Cite some numbers on carbon sequestration potential of biochar and soil. The book linked above (got it yesterday) is a treasure trove of numbers, but alas no tally. Biochar is not not explicitly considered. My guess above still stands: Sequestration of 1GtC/y by doing intelligent (as opposed to genosuicidal) agriculture would be no problem.

    Lal, R.; Lorenz, K.; Hüttl, R.F.; Schneider, B.U.; von Braun, J. (Eds.) Recarbonization of the Biosphere - Ecosystems and the Global Carbon Cycle. Springer 2012, 559p. 100 illus.

    Alas I'm currently a bit overworked with my brand new job, so a synopsis will take some time.

  16. mt:

    I do not think biochar can reach the necessary scale to counteract the bulk of the emissions,

    Nothing will reach that scale. Emissions reductions is first necessity. Then we need to repair the carbon cycle -- Plus, feed a few billions of overshot population without having fossil fuel, mined phosphorus and expensive chemicals.

    My biochar/farming vision ultimately is for after the Great Crunch: Some hominids will almost certainly survive (cannibals on Greenland?) -- which might constitute the ultimate evolutionary catastrophe in the total history of Life on this planet: They might start over with destructive stupid again and again, never giving Life a chance for recovery to the heights it reached before. So, we need to establish some technique (as opposed to technology) that can be handed down to the survivors (without requiring nuclear energy, hydrocarbon combustion machines, space travel, etc. etc.) so they have a chance to do things better. Biochar farming is obviously a central ingredient to this sinister plan.

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