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Direct conversion of CO2 to solid carbon by Gallium-based liquid metals
- Iwan-Zotow 5y ago"World primary low-grade gallium production capacity in 2019 was estimated to be 720 tons per year"
- deleted 5y ago[deleted]
- Gatsky 5y agohttps://au.finance.yahoo.com/news/aussie-team-solid-plan-carbon-083229537.html https://au.finance.yahoo.com/news/aussie-team-solid-plan-car...
- senectus1 5y agohuh... neat. I also didn't realize Gallium is one of those weird metals with a really low melting point but quite high boiling point. Melting point 302.9146 K (29.7646 °C, 85.5763 °F) Boiling point 2673 K (2400 °C, 4352 °F)
- hprotagonist 5y agometallic gallium is also remarkably nontoxic. it’s the halides that’ll getcha.
- laurent92 5y agoFunny for a metal that seems to flow like Terminator and can melt an aluminum padlock, see LPL: https://youtu.be/jeghGhVdt9s https://youtu.be/jeghGhVdt9s (It’s doesn’t melt it exactly, it destroys the structure because Gallium atoms are very small and insert themselves through).
- 01100011 5y agoIt's aluminum. Ga atoms aren't small compared to Al. It's one step down in the periodic table below Al.
- petermcneeley 5y ago> " This led to the conclusion that solid carbon and gallium oxide are the final reaction products of this process. " What happens to the Gallium Oxide? Edit: Follow up - Is pure CO2 required as input or can the input be air?
- senectus1 5y agoit has a very high melting point (1900 ˚C) and their experiment capped out at 200 °C so presumably it crystalizes and can be scooped out as well?
- kurthr 5y agoTypically, the solid oxides would be heated in a reducing (H2) environment, forming water vapor and liquid metal (or suboxide). You could get that reducing gas from hydrolysis, and solar, but it's not energy cheap (~50% efficiency).
- colechristensen 5y agoThis is a good question. Metal oxides tend to decompose at high temperatures, when exposed to reducing agents, under vacuum, or with electricity. I can’t immediately find good sources about which of these apply to gallium and would be most energetically favorable. But regardless it is certainly possible to regenerate it using only electricity possibly with intermediate but renewable substances (water, sodium chloride, etc)
- scotty79 5y agoProbably O2 is a problem because it will oxidize gallium as well.
- deleted 5y ago[deleted]
- obblekk 5y agoIf 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). This process runs at 200C and 1 Bar (=0.98 ATM). Temperature can be concentrated via greenhouses/mirrors to 200C with 0 carbon by-products, 0 advances in battery tech, 0 advances in solar tech. 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. I'm sure there's a negative view of this and something too easy that I'm missing. But right now I'm very excited.
- 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 agoA 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.
- jonnydubowsky 5y agoWhat is the carbon byproduct like at the end of this process? What happens with it? Used in soils amendments? Other uses? Sounds promising.
- cstoner 5y agoThe carbon byproduct is essentially coke, and coke already has a lot of industrial uses.
- denton-scratch 5y ago> coke already has a lot of industrial uses. Which nearly all involve converting carbon to atmospheric CO2.
- cstoner 5y agoTrue, but this source is carbon neutral. Granted, we need to be carbon negative but it could still be used for some of portion of existing supply that is carbon positive.
- colechristensen 5y agoSeems to be basically a pure carbon substance similar to charcoal.
- potiuper 5y agohttps://news.ycombinator.com/item?id=28967354 https://news.ycombinator.com/item?id=28967354 178 comments https://news.ycombinator.com/item?id=28873458 https://news.ycombinator.com/item?id=28873458 28 comments Prior: https://onlinelibrary.wiley.com/doi/epdf/10.1002/adma.202105789 https://onlinelibrary.wiley.com/doi/epdf/10.1002/adma.202105...
- Gatsky 5y agoHmmm... This is the same result basically. Weirdly, the OP paper doesn't cite this paper in Advanced Materials at all, although the OP paper was submitted 2 days before the Advanced Materials paper was published. Anyway, good to see it works in two different labs. EDIT: The Advanced Materials paper's process seems to produce carbon oxides, whereas the OP paper produces solid carbon. I suppose this is an important difference, the latter being more useful.
- narrator 5y agoThis is great! Speaking of organic chemistry breakthroughs, what would interest me is a way to efficiently turn methane into more interesting hydrocarbons. There is lots of methane on Titan and perhaps Mars that would be great feedstock for all sorts of petrochemical processes if only we could easily turn it into naphtha and paraffins, etc. I guess there's Fischer-Tropsch, as you only need H2 and CO for that, but it is woefully inefficient. How about converting CO2 to value-added hydrocarbons? This article seems to say it's possible. Imagine that, using hydrocarbons as a storage battery for electricity used to power the reaction: "Heterogeneous catalytic CO2 conversion to value-added hydrocarbons" https://pubs.rsc.org/en/content/articlelanding/2010/EE/c001514h https://pubs.rsc.org/en/content/articlelanding/2010/EE/c0015...
- kccqzy 5y agoThe high-value hydrocarbons combust to produce CO2 and energy. So at least as much energy is needed to turn that CO2 back into useful hydrocarbons. Where is that energy going to come from? I believe so far digging these hydrocarbons from the earth is still cheaper than using any energy source to turn CO2 back into useful hydrocarbons.
- jiggawatts 5y agoDon't get your hopes up with this kind of approach. The gotcha is right there in the Abstract: "solid carbon and gallium oxide are the final reaction products of this process." This is the thermodynamic equivalent of rearranging the deckchairs on the Titanic. It achieves literally nothing except for shifting the oxygens around. They're still around, still bonded, but even harder. That's what this process doing -- reducing the carbon using a liquid metal. Reducing the gallium oxide back to the metal takes even more energy than was released by burning the C to CO2 in the first place! If you have an energy source that exceeds the world total carbon usage... then you don't need to burn carbon any more![1] At best, this could be used to convert some magical future energy source like unlimited fusion power into pure carbon, eliminating the need for coal mining. But that's it. This -- and any approach like this -- can never be practically used to counter the effects of CO2. The finance equivalent would be: "We found this new way of producing $100 that only requires $110 in expenses!" Actually not $110 at all. A sibling comment mentioned that "Gallium is cheap (~$300/kg)". For comparison, coal is on the order of $150/ton. Not kilograms. Tons. Literally 2,000x cheaper than Gallium per unit weight! So this paper proposes reducing $100 of carbon by using $200,000 of gallium. Sure, you have gallium oxide left behind that can be recycled for a bit less than $300/kg, but certainly not for $150/ton! [1] The few direct uses such as using coke to produce iron from its ore can be replaced by hydrogen gas. Similarly, groups are working on processes for iron similar to the one used for aluminium that requires only electricity as the input.
- nrdgrrrl 5y ago
- whiddershins 5y agoI’m genuinely having trouble following what you’re saying. Can you simplify. Too much co2 in the atmosphere is assumed to be a bad thing. Someone says they can sequester co2 from the atmosphere at a certain energy cost. Is your point that this energy cost is unrealizable?
- senectus1 5y agoThis solution isn't about pulling it from the atmosphere.. its about pulling it from a clean direct source.
- ineedasername 5y agoWhere would this be deployed? It seems like atmospheric concentrations would be too diffuse, and you'd need to have this process occur at the point of C02 creation, like cement plants.
- dqpb 5y agoThere’s a company called Verdox which has developed a system that can absorb CO2 at ambient levels (~400ppm) and then discharge a stream of pure CO2. Presumably one could chain that system to this system to produce solid carbon from atmospheric CO2. Put it out in the middle of nowhere, where energy storage/transportation would be uneconomical, like a desert, and power it with the sun, and maybe you’d have a decent carbon sink where otherwise there’d be nothing.
- tangjurine 5y agoIf energy efficient CO2 to carbon conversion was possible, wouldn't we just use it for energy production instead of carbon capture?
- esyir 5y agoNo, because you can never get more out of it than you put in. You can however, use it as a form of storage if you get sufficiently good efficiency.
- WalterBright 5y agoCarbon, when combined with oxygen to for CO2, releases energy in the form of heat. It's why we burn carbon in the first place - to get the energy. Turing CO2 back into C and O2 will require adding at least as much energy as was released in its formation. Where is this energy coming from?
- __turbobrew__ 5y agoThe sun
- elil17 5y agoYou can capture the CO2 and even separate the C and the O2 without using more energy than was released by the combustion for two reasons: 1. The hydrogen in the fuel remains oxidized. 2. Captured carbon (compressed CO2 gas, solid carbon) is still at a lower energy state than the source fuel (octane, etc.)
- WalterBright 5y agoThank you, that makes sense.
- mumblemumble 5y agoSo, back of the envelope, I'm no chemist, I haven't tried doing something like this on my own since high school, etc. But, if the reaction is something along the lines of 3CO2 + 4Ga => 3C + 2Ga2O3 and CO2 has a molecular weight of about 44, and Ga's is about 70, then I believe that would imply that eliminating 1 tonne of CO2 would require about 2 tonnes of gallium. How much spare gallium is there in the world? Is it anywhere near enough to put a dent in the ~1,000 tonnes per second that humans are emitting?
- yumraj 5y agoWhile I agree with you, upon quick search it seems Ga2O3 is an intermediate in the purification of gallium[0] So, process can be created wherein 3CO2 + 4Ga => 3C + 2Ga2O3 => 4Ga + ... => 3CO2 + 4Ga .... basically, the Gallium oxide is reconverted to Gallium to be used in CO2 capture. [0] https://en.wikipedia.org/wiki/Gallium(III)_oxide https://en.wikipedia.org/wiki/Gallium(III)_oxide
- neltnerb 5y agoI believe that converting Ga2O3 back into gallium metal should not necessarily release any CO2, just the O2 that I suppose was originally in the atmosphere anyway. You should be able to do it with heat, electrolysis hydrogen + heat to reduce it, or electrolysis itself. Theoretically you can do these all with electricity. It makes way more sense than when I see carbonates brought up as a way to sequester things at least, since the thing being cycled has no carbon in it at least.
- mumblemumble 5y agoThough, if we have enough clean electricity generation capacity to convert that gallium oxide back to gallium without releasing more CO2 than we had sunk in the first place, then one wonders why we're rube goldberging it rather than eliminating the carbon-intensive processes altogether. In other words, this doesn't sound to me like a solution to our clean energy problems, so much as a cool thing we might be able to do on a mass scale after our clean energy problems have already been solved.
- ncmncm 5y agoWe have already learned the most cost-effective way to capture and sequester CO2: pump CO2 as dissolved in ocean surface water down to the ocean depths. There is no danger of overloading the depths with CO2 or acidity. The sheer volume of deep ocean water to disperse the surface CO2 into is overwhelmingly greater than what could be pumped from the surface in even the largest conceivable process. Gallium can serve as no part of a practical solution.
- tempestn 5y agoDo you have a reference for this? Pumping CO2 into the depths of the ocean seems energy- and infrastructure-intensive, and I'm curious how you'd keep it there. If work has been done on modeling and/or measuring feasibility I'd be interested to read it.
- ncmncm 5y agoThere was a paper on HN just a last week. Park a floating wind turbine on a buoy out in deep water, to be paid for with carbon credits. The amount of CO2 sent down is exactly measurable from pH and volume. The wind turbine doesn't need an expensive generator with 6 tons of rare-earth magnets, it can couple straight to the pump mechanically or hydraulically. https://news.ycombinator.com/item?id=29912896 https://news.ycombinator.com/item?id=29912896 Except at certain well-known places, very little mixing happens naturally. Of course we need thousands or tens of thousands of them, not just one, but there has to be a first one.
- DoingIsLearning 5y ago> There is no danger of overloading the depths with CO2 or acidity. The sheer volume of deep ocean water to disperse the surface CO2 into is overwhelmingly greater than what could be pumped from the surface in even the largest conceivable process. Do you have any source or actual maths on that claim? As in the aspect that pumping CO2 into seawater would not significantly increase ocean acidification? I thought ocean acidification is basically one of those extinction level events. It affects the building of shells in crustaceans and the ability for fish to hunt (see shark electroceptors) it basically is a catalyst to disrupt the food chain all the way up to us, no?
- cat_plus_plus 5y agoGreat, now how does one convert Gallium oxide back to Gallium? No shortcuts here, need either abundant energy or abundant reactant where we can just throw away the reaction product. Alkaline minerals are example of the later.
- esyir 5y agoLooking at the gallium trioxide reduction, it seems that you can first reduce it to Ga2O with Hydrogen (water as byproduct), Gallium suboxide then decomposes into it's components at temperatures above 500 C. Feasibility of this is an exercise to the reader (I have no clue).
- scotty79 5y agoElectrolysis
- jokoon 5y agoEven if it works, it's like filtering the ocean. Even it will capture CO2 (with a high energy cost, assuming it's nuclear energy), CO2 is diluted in the atmosphere. They would like to plug this to coal and gas plants, but that will not be enough. Humanity is too dependent on technology and carbon energy, today it's unthinkable, taboo and controversial to tell everyone to reduce their standard of living, to live a sober life, to work less, to eat less meat, because it's just too complicated to separate ecology from social inequality. Instead, you have big oil trying to save itself by any means they can find, including trying things that don't make sense with physics.
- deleted 5y ago[deleted]
- redcarbonbiz 5y agoRemember CO2 capture from a flue gas stream does not reduce our existing atmospheric CO2 concentrations which are higher than they've been in over 3 million years (10X longer than we've been a modern species and 300X longer than we've had modern civilization). We MUST achieve atmospheric reductions soon (per the IPCC) which means some kind of rapidly scalable DAC and/or CDR. Solid Carbon is a key pathway there - but also remember the density of the solid carbon matters if you want to sequester carbon faster by handling the same amount of stuff. This research produces "flake" carbon (which appears to be less dense. From a rapid sequestration standpoint, the optimal form of solid carbon is denser. Probably graphite produced from zero fossil energy. The challenge is low-cost production and identifying new/expanded use-cases for graphite as a sequestration medium (new markets and new materials need developed here). This research is important and barking up the right tree but there's a lot of room for optimization if rapidly scalable sequestration is the objective.