16 ms·

If this paper is not fraudulent, this could be the tipping point against climate change. Gallium is cheap (~$300/kg), abundant (by product of Aluminum mining).

• senectus1 5y ago
  >We could start pulling more CO2 out of the atmosphere than we put in, and at that point we'd be pretty confident things won't get worse for the climate. Not sure that would be terribly efficient to pull CO2 out of the atmosphere to pump through this setup. Would be fine for many other reasons though. I wonder how it behaves with "non clean" CO2 sources. Like say at the output of a coal fired PowerStation.
• Dylan16807 5y ago
  > This process runs at 200C and 1 Bar (=0.98 ATM). Let's not be misleadingly precise. It runs at 1 atmosphere.
• boucher 5y ago
  A lot of people think carbon capture and storage has the potential to save us from climate change, but that idea ignores the scale of the situation. The world generates ~40 billion tons of CO2 a year, meanwhile the total mass of everything transported in the entire world is only around ~12b tons.
  • agumonkey 5y ago
    And then there's the fossil fuel dependency. We still need more than will be produced, even ignoring CO2 levels.
  • DennisP 5y ago
    Well we do move that 40 billion tons to the atmosphere. If we can do that, then in principle we can do the reverse. We just need an economic framework to pay for it. It's certainly going to be cheaper, in most cases, to avoid emissions in the first place. But there will also be cases, like long-haul jets, where it may be cheaper to remove the CO2 later. Plus the CO2 is already above a safe level, so we'll have to draw it down somehow anyway.
    • halpert 5y ago
      We only move a small portion of the 40 billion tons. Most of the mass of CO2 is oxygen, which was already present in the atmosphere before we combined it with carbon.
      • lmm 5y ago
        Even assuming you can do some kind of reaction in-place, CO2 is over 25% carbon by mass. 10 billion tons is still a massive challenge.
        • czbond 5y ago
          But don't we only need to "first" remove just enough of that 10 billion tons to maintain where we are now, so that we can then remove more to "go back to levels earlier in modern time"?
          • dataflow 5y ago
            Yeah, we need to go extremely carbon-negative, not merely carbon-neutral. It's so easy to forget this.
            • elzbardico 5y ago
              Why?
              • 5y ago
  • _dain_ 5y ago
    But only about 16% of that mass of CO2 was ever "transported" in the first place: the carbon atom. The O2 part appears for free because it comes out of the air the fuel is burned in. And that oxygen wouldn't be transported with carbon capture either, it would just be vented into the atmosphere again. I mean think about it, we can't be emitting more waste than we are transporting, because that waste comes from fuel, and the fuel itself is part of what we're transporting.
    • deleted 5y ago
      [deleted]
  • colechristensen 5y ago
    All of the carbon we put in the atmosphere was transported (oil, coal, etc) to the location where it was used so this rings false. Presumably the carbon will be pulled from the atmosphere on site and stored on site anyway. Maybe something like building solar arrays in semi-arid regions and mixing up the resulting solid carbon into the local soil for some ecological engineering or filling up old mining pits.
    • 0xB31B1B 5y ago
      The carbon gains 2 oxygens when combusted, tripling the weight of the original fuel
      • hamandcheese 5y ago
        Presumably it also loses 2 oxygens when it is turned back into solid carbon.
  • dataflow 5y ago
    Related, for comparison: apparently planting 20B trees/year requires only $80M/year (!) and would pull down a trillion tons of carbon over 50 years (!): https://www.youtube.com/watch?v=QyQvfaW54NU&t=14m53s https://www.youtube.com/watch?v=QyQvfaW54NU&t=14m53s
    • cjameskeller 5y ago
      But they would decay, unless something is done to sequester enough of the wood, and release much of it back into atmosphere, right?
      • dataflow 5y ago
        > unless something is done to sequester enough of the wood I think that was the idea. He's viewing it as a mass transfer problem. You "harvest" CO2 with trees, then put it back in the ground. I think the hard part is not hurting ecosystems in the process, but at this point honestly this might still be the best solution we have available.
        • denton-scratch 5y ago
          Unfortunately, the people that plant trees have economic incentives to not put it back in the ground. Timber has considerable economic value, as fuel, or contruction materials or whatever. It's hard to imagine foresters cutting down valuable trees, and then discarding them in some lake.
          • dataflow 5y ago
            I imagine it would need to be government funded, not for private enterprise. If the order of magnitude of the costs they mention are to be taken at face value ($80M/year), for the entire world, it would be absolutely trivial for the government to fund, so I don't think expect any commercial enterprise would necessarily be forced to align this with its mission.
            • 5y ago
• mikewarot 5y ago
  The process oxidizes the gallium, which then needs to be reduced. That's a lot of energy input.
  • dqpb 5y ago
    There’s also a massive sun, which has alot of energy output.
    • ars 5y ago
      So use that energy directly. Why burn carbon, release CO2, capture the CO2, and use the sun to turn it back into carbon?
      • dqpb 5y ago
        > So use that energy directly This would use that energy directly. To sequester carbon. > why burn carbon I didn’t say anything about burning carbon.
        • MagnumOpus 5y ago
          This tech can only sequester CO2 without the presence of O2. Where does CO2 occur without O2? In the exhaust of power plants/engines/heaters that burn hydrocarbons. If you didn't say anything about burning carbon, you weren't paying attention.
          • dqpb 5y ago
            > This tech can only sequester CO2 without the presence of O2. Where does CO2 occur without O2? Here is a system for collecting CO2 from ambient air and discharging a stream of pure CO2: https://news.mit.edu/2019/mit-engineers-develop-new-way-remove-carbon-dioxide-air-1025 https://news.mit.edu/2019/mit-engineers-develop-new-way-remo... > If you didn't say anything about burning carbon, you weren't paying attention. Wrong.
      • HWR_14 5y ago
• alexose 5y ago
  Cool to see this research continued. I've spoken to the authors of a very similar paper, also based in Australia: https://onlinelibrary.wiley.com/doi/epdf/10.1002/adma.202105789 https://onlinelibrary.wiley.com/doi/epdf/10.1002/adma.202105... One thing I learned is that these experiments are generally done with a pure CO2 stream. The reactions taking place often compete with other molecules (especially O2), making this approach best for capturing carbon from tailpipes and smokestacks. There's still a lot of work to be done to get this sort of thing to work reliably for direct air capture (which IMO will be needed to actually draw down carbon from the atmosphere). Anyway, this research is being commercialized via a company called LMPlus (https://lmplus.com.au https://lmplus.com.au). While I appreciate that the technology is being brought to market, it probably means that future breakthroughs will occur in private labs, protected by patents and trade secret laws. We have a an urgent need to conduct more of this kind of research out in the open and to make breakthrough carbon capture technology available to everyone, for free. If you're interested in helping out on this front, please consider joining me in the OpenAir Collective discord (https://openaircollective.cc/ https://openaircollective.cc/).
  • Confiks 5y ago
    > One thing I learned is that these experiments are generally done with a pure CO2 stream. According to this comment three months ago [1] "they used 6%-20% CO2 mixtures with balance nitrogen and some water to try and approximate different exhausts including flue gas". [1] https://news.ycombinator.com/item?id=28873458 https://news.ycombinator.com/item?id=28873458
    • elil17 5y ago
      I.e. no oxygen. It would probably not be suitable for direct air capture.
      • _nalply 5y ago
        But perhaps it will be possible to filter out oxygen by a different process and let the remainder gas be filtered.
• credit_guy 5y ago
  Getting C out of CO2 require more energy than burning C to get CO2, otherwise you'd get perpetual motion. So, if you want to reduce CO2 emissions, you're better off not burning the C to begin with rather than trying to split the CO2 after the C was burnt.
  • jsharf 5y ago
    Are there any chemical carbon configurations more stable than CO2 which are solid?
    • philipkglass 5y ago
      Yes, carbonates of alkaline earth metals (e.g. magnesium and calcium) are solids at STP and more stable than carbon dioxide. See section 7.2.2 "Chemistry of mineral carbonation" in this IPCC report: https://www.ipcc.ch/site/assets/uploads/2018/03/srccs_chapter7-1.pdf https://www.ipcc.ch/site/assets/uploads/2018/03/srccs_chapte... Even at the low partial pressure of atmospheric CO2 and at ambient temperature, carbonation of metal oxide bearing minerals occurs spontaneously, though on geological time scales (Robie et al., 1978; Lasaga and Berner, 1998). Limitations arise from the formation of silica or carbonate layers on the mineral surface during carbonation that tend to hinder further reaction and to limit conversion (Butt et al., 1996) and from the rate of CO2 uptake from the gas phase in the case of aqueous reactions. The challenge for mineral carbonation is to find ways to accelerate carbonation and to exploit the heat of reaction within the environmental constraints, for example with minimal energy and material losses.
  • not2b 5y ago
    Agreed, the only way this can be useful is to do both: stop burning carbon; use processes like this to recover the carbon from processes where there isn't a good alternative to producing CO2 output. Cement production, perhaps.
    • midjji 5y ago
      There are a number of marine processes which permanently bind carbon, and they do increase with increased CO2 concentration. Problem is that they are overwhelmed by current production. If we reduce CO2 production to zero, the earth will mostly bounce back on its own in a century or two.
• not2b 5y ago
  You need a massive amount of energy to run the process. If you could make it 100% efficient, which you can't, you have to put in as much energy to turn the CO2 into C + gallium oxide, and complete the cycle by turning the gallium oxide back to gallium metal, as you got by burning the carbon. So if you still have people using coal for energy, you have to pay more than they got. But if you could eliminate fossil fuel burning and use processes like this to reduce the amount of CO2 already emitted (a big "if" because you have to concentrate it somehow) it could be useful.
  • Dylan16807 5y ago
    > But if you could eliminate fossil fuel burning and use processes like this to reduce the amount of CO2 already emitted (a big "if" because you have to concentrate it somehow) it could be useful. It could be useful if we 'just' greatly reduce fossil fuel burning for electricity, even if we don't eliminate it and even if we still use fossil fuels for other things.
• astrange 5y ago
  > We could start pulling more CO2 out of the atmosphere than we put in, and at that point we'd be pretty confident things won't get worse for the climate. How much of the atmospheric CO2 can you actually capture with stations at ground level? I assume this isn't critical since I haven't seen anyone propose a Tower of Babel of carbon capture machines, but I'm not sure why it isn't.
  • krallja 5y ago
    Air moves.
    • astrange 5y ago
      All of the air from here to the Karman line moves over the spot you put your capture machine?
      • MauranKilom 5y ago
        Eventually, yes.
      • krallja 5y ago
        Yes, eventually. CO2 is referred to as a “well-mixed greenhouse gas” because its concentration is relatively stable across the entire surface of the earth. https://www.gfdl.noaa.gov/blog_held/6-transient-response-to-the-well-mixed-greenhouse-gases/ https://www.gfdl.noaa.gov/blog_held/6-transient-response-to-...
  • Smithalicious 5y ago
    The CO2 diffuses through the air. The same way you can make something crystallize completely out of water too, the concentration will want to equalize throughout the medium. Of course it's going to be more efficient with more air flow, I don't know how turbulent the wind really is, how I could picture it in terms of something I understand like a bottle water, but I assume pretty turbulent?
• Animats 5y ago
  Gallium is not cheap. Indium is almost as expensive. As a way to extract small amounts of carbon, this does not look cost-effective.
  • rsanheim 5y ago
    Not cost effective now. If you weigh it against the scale of death and destruction from climate change impact yet to come, that could change very quickly.
• leifg 5y ago
  > Gallium is cheap (~$300/kg) Please correct me if I get the numbers wrong but if that is the price, that means the price of 1 ton Gallium is $300,000 per ton From [another comment](https://news.ycombinator.com/item?id=29990056 https://news.ycombinator.com/item?id=29990056) I got that the ratio of CO2 to Ga would be 1 to 2. So in order to reduce 1 ton of CO2 you'll need to spend $600,000. That seems insane. Especially when the damage done per ton of CO2 is usually valued at ~$200.
  • gumby 5y ago
    The Ga is a catalyst, so it’s a cap ex not op ex. I’m dubious but open to try anything halfway plausible at this point.
    • laci37 5y ago
      The abstract says the process produces gallium oxide. We would need to recycle that into gallium, which is probably energy intensive.
  • spartanatreyu 5y ago
    Pretty sure the Gallium can be recycled.
• jandrewrogers 5y ago
  Gallium is not cheap at scale. We can only produce trivial amounts, and it is cheap because we don't have many uses for what we produce. It does not form concentrated ores which means it cannot be mined in any conventional sense. We extract it from aluminum (and zinc) refinery waste because it is relatively convenient in an industrial process sense, but the amount that can be produced this way is inconsequential. The gallium in all the known aluminum ore reserves is measured in kilotons. For this application, we would need something closer to gigatons. We could produce the necessary quantities if that was the sole objective, but the cost per gram would be closer to gold which is not great when you need gigatons.
  • nandhinianand 5y ago
    Hmm.. i was wondering how cheap it actually was .. Can we re-use the Gallium used in this process?? Can we recover it?? Sorry I haven't yet had time to deep-dive on the article.
  • raverbashing 5y ago
    The alloy is completely reusable as per TFA, I'm not sure why gigatons are needed...
    • scotty79 5y ago
      How fo you turn gallium oxide back into gallium? Hiw do you separate it from carbon or from indium?
      • Iwan-Zotow 5y ago
        > How do you turn gallium oxide back into gallium? electricity? Cathode and Anode?
      • DennisP 5y ago
        From wikipedia, "Ga2O3 is an intermediate in the purification of gallium." https://en.wikipedia.org/wiki/Gallium(III)_oxide https://en.wikipedia.org/wiki/Gallium(III)_oxide So we'd turn the gallium oxide back into gallium the same way we did in the first place, when we made the gallium. I'm guessing we can also come up with chemical reactions for the other two. However, you're right that gallium production is quite low. It's a byproduct of zinc production from bauxite, and we get only a few hundred tons per year. Wikipedia doesn't say what the potential might be if we gallium were the main product. https://en.wikipedia.org/wiki/Gallium#Production_and_availability https://en.wikipedia.org/wiki/Gallium#Production_and_availab...
• throwaway81523 5y ago
  If you have to put as much energy into splitting the C from the O2 as you got from burning the C in the first place, that means giving back all of the energy that was extracted by the fossil fuel economy for however much carbon you want to convert. That means not just stopping the fossil fuel economy but basically running it backwards enough to undo decades of its output. Since fossil fuels are being burned as fast as ever and we can't even slow that down (Biden selling new coal leases in the US, etc.), running it at full speed backwards seems like a pipe dream. If we're going to be that utopian, we might as well think bigger and get started on a Dyson sphere.
• pjc50 5y ago
  > 319 μmol h−1 That's ... not a lot.
• api 5y ago
  It has to be endothermic. Otherwise you could run a coal plant and get net power while getting your carbon back. Second law says nope. Could still work of course if it used solar heat or surplus industrial heat. If it was low maintenance you could deploy in places like the Sahara. Lots of free heat there. Edit: gas on the other hand could in theory be burned without CO2. A lot of the net energy there is the hydrogens combining with oxygen to form H2O. You could use fuel cells for maximum conversion efficiency and then recover the carbon.
• luckystarr 5y ago
  Even if this works and this were marketable today, we still have to take into account the amount of time to scale up production capacities for the reactants and the devices which would to the extraction. On top of that the necessary subsidies to make it economically interesting to have it be deployed far and wide. Don't get me wrong, if this works we HAVE to do this. I'm just not very optimistic that it could save us at this point. We'd still be fucked, just a little less so.
• midjji 5y ago
  Its not fraudulent, its a good idea, and likely useful in niche large chemical plants. It is also useless against climate change. The the paper uses a simple input of CO2 and nitrogen. Though O2 could be added as well, as the gallium will simply react with it too. After all, More energy is released by gallium reacting with O2, than by carbon reacting by O2, or it would not happen in the first place. In the atmosphere, CO2:O2 is say 400:1 meaning you need 400 times more gallium. The next step would be to separate the gallium from the gallium oxide, which is energy intensive, though this can be climate neural using nuclear. To do so would require hundreds of times the global energy production from coal, oil, and gas. And if you have built these, why not just use them instead, global warming would already be effectively stopped. It also cannot be used in car catalyzes, providing an anoxic reaction chamber which can collect and separate the outputs simply isn't feasible at small scale. The carbon would be in a fine powder, likely to spontaneously react with O2 if exposed to air, either slowly, or if given a spark, very rapidly indeed. The gallium also should not be released into the environment. Not only would large scale use of this tech make it very expensive, gallium is also mildly toxic. However, because it is rare in our environment, there are few if any studies on the impact of long term low dose gallium poisoning. As a result, its a comparable to lead, a few decades ago. Not saying its as deadly, just saying its a metal we are rarely if ever exposed to, known to be mildly poisonous in the short term. And this is before you add the problems of contaminants in fuel, and partial combustion. For similar reasons it also cannot be used in aviation.
  • VBprogrammer 5y ago
    Just think of how much money your could make selling the carbon as 100% eco-friendly charcoal...
    • midjji 5y ago
      Most farmers do just that^^
  • 300bps 5y ago
    At first I ignored the entire HN submission because I've been taught that carbon sequestration will never be a solution to atmospheric carbon. On a whim I clicked on the comments though expecting the first comment to be, "This will never work, because..." So I was happy to see that the top comment was actually positive! Then I saw your response.