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Engineers find neat way to turn waste carbon dioxide into useful material
- gpm 6y agoSlightly offtopic, what's the easiest way to scrub CO2 from air (e.g. in a house) without using up consumable materials? Some form of pressure swing absorption?
- atrus 6y agoProbably a bunch of plants.
- outworlder 6y agoUnder a lot of light, otherwise they would consume O2 as well.
- gpm 6y agoJust in terms of numbers, you breathe out a kg of CO2 per day, you need to be growing more than a kg of plants per day to keep up with that. That's a lot of plants.
- marcosdumay 6y agoIf you are concerned about indoor CO2 concentration, the answer is to ventilate the place. No reasonable amount of plants will keep a house stable. If it's just really curiosity, well, people have been scrubbing CO2 since space travel is a thing. Wikipedia was completely unhelpful to me, but I remember there is a mineral with high CO2 selectivity that you can simply push the air though it.
- gpm 6y ago98% curiosity, 2% lack of faith in our long term ability to keep CO2 levels down to healthy levels (1000ppm is enough that we can detect minor negative effects... I have to wonder if really minor ones exist even at 400 ppm). Wikipedia was similarly not useful for me. Scuba divers and the like apparently use a one-time-use non-regenerative mineral that absorbs CO2. The space station has something that regenerates but I haven't been able to figure out what.
- namibj 6y agoIf you figure out some concrete setup, let me know. I am fairly certain that there are measurable cognitive effects at "just" 500 ppm, and good luck staying below that when you can't just sit at an open window outside of a city. 1000 ppm is btw. enough to feel uncomfortable. Cognitive impairment will be much more subtle.
- lugorrr 6y agoI am fairly certain that there are measurable cognitive effects at "just" 500 ppm Well, that would be problematic sooner or later [1]. [1] https://www.esrl.noaa.gov/gmd/webdata/ccgg/trends/co2_data_mlo.pdf https://www.esrl.noaa.gov/gmd/webdata/ccgg/trends/co2_data_m...
- gpm 6y agoIndoors that's problematic today, outdoors we have "awhile" if you make 500 your cutoff, we're only growing at ~2.4 ppm per and the yearly peak is at roughly 420 right now, we can probably count on 20 years before we hit 500 outdoors. https://www.co2.earth/co2-acceleration https://www.co2.earth/co2-acceleration
- swiley 6y agoI know older spacecraft didn’t have a regenerative material, this is the first I’ve heard about the space station. You’d have to reduce the CO2 pretty far (I’m betting reducing to CO like in TFA isn’t what you’re looking for.) I think a lot of people underestimate how much energy this takes.
- gpm 6y agoRe ISS, I've been clicking around on this a bit more, and > While cabin air processing, one carbon dioxide removal bed is in the process of regeneration. Regeneration is accomplished using pressure/thermal swing methodology. First, the two-stage pump removes the free air from the adsorbent bed and returns it to the cabin, reducing oxygen ullage. Then Kapton heaters integrated within the adsorbent bed raise the zeolite temperature, and space vacuum creates a low, partial pressure driving the carbon dioxide gas overboard. Daylight and continuous day power cycle is overlapped with the operating cycle. In the daylight power cycle, the carbon dioxide adsorbent bed heaters are only allowed to be powered on during the day portion of the cycle > [...] > The CDRA continuously removes 6 person-equivalents of CO, when operating with both C02 removal beds (dual beds) functioning. https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20050210002.pdf https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/200502... Converting CO2 into CO would be rather counterproductive (absent a reliable and efficient mechanism to remove CO), I suspect an efficient setup will involve "mechanical" filtration not chemical reactions.
- adrianN 6y agoGet a large amount of calcium hydroxide in a watery slurry. That absorbs CO2 to form calcium carbonate. Take the carbonate outside and heat it up sufficiently to form calcium oxide and carbon dioxide. Add water to go back to calcium hydroxide.
- swiley 6y agoBe careful with alkali metal hydroxides! They tend to be caustic and mixing them with water is exothermic (it can boil if you do it fast enough.) They will also react with aluminum, potentially violently and can ruin glass.
- namibj 6y agoNot really without consumables, unfortunately. But it's easy and costs about 50-200$ per human and month when you just buy the required substance, granular CaOH treated with 1~2 NaOH (by pouring a concentrated solution of it over the CaOH), from Alibaba once a year. That stuff is e.g. used for re-breathers in anesthesia. CAS 8006-28-8 is the "magic" word/number. The potential alternative, which would not use consumables, would be to just freeze it out. It's not _that_ hard, I believe an ammonia-based single-stage chiller should still suffice. Make sure to use counter-flow heat exchangers to not loose insane amounts of power. Handling the water condensation might not be that trivial, though.
- mulcyber 6y agoCasual technical diver here. It's lime (maybe something else sometime, not 100%). The process of making lime from limestone actually produces CO2, so it's use in CO2 scrubbers are more or less carbone neutral.
- pronoiac 6y agoThis looks like the same story: https://www.sciencedaily.com/releases/2020/06/200610152016.htm https://www.sciencedaily.com/releases/2020/06/200610152016.h...
- crimsonalucard1 6y agoDoesn't the net CO2 in the air increase? So you harvest CO2 to into fuel. That fuel is burned and the CO2 is released back into the air. So net difference is zero. But to harvest the CO2 you needed to generate a high amount of heat. That's extra CO2. So net CO2 is more. It depends on the cost of harvesting that CO2.
- lykr0n 6y agoYou can use Solar and other renewable energy to power the conversion process. Progress is still progress. I would much rather to pay more for net zero carbon fuel, then not do anything.
- travisporter 6y agoIt’s actually strange that no gas company is advertising something like this. I’ve seen so many industries advertise even the tiniest carbon offsets but why can’t BP or Exxon sell a net zero or at least low emissions fuel
- effie 6y agoIt is really strange to you that oil company is not advertising a product that they don't have, a product which would compete with their regular product, a product which is hard to sell (more expensive and dubious value)? From the standpoint of these companies, there is plenty of oil down there, making synthetic one has no upside.
- travisporter 6y agoWell, maybe not synthetic, but what if they said "use this gas for 10% more, we planted a tree for every gallon" or whatever. Even if it was complete bs, I'd think about it
- perl4ever 6y agoI do not understand the concept that a property of a sum of a bunch of numbers somehow applies to those components. Whether something is net zero depends on what you are adding it to; it's not inherent in that thing. It's like, if you have a pile of blue things, then the pile is also blue. But other characteristics do not work that way. If you have a pile of things that each weigh 1 lb, then the pile does not weigh 1 lb.
- Animats 6y ago“We used an open flame, which burns at 2000 degrees, to create nanoparticles of zinc oxide that can then be used to convert CO2, using electricity, into syngas.” Is this a real catalyst? (That is, it doesn't get used up in the process.) Or do they have to keep making more zinc oxide clouds to keep the process going? The paper summary is unclear about the energy inputs to this process. Costs $10 to read the paper.
- philipkglass 6y agoIt's a real catalyst. Full paper here: https://sci-hub.tw/10.1002/aenm.202001381 https://sci-hub.tw/10.1002/aenm.202001381 I don't think it will have industrial significance any time soon, though. Catalysts and processes for the reverse water-gas shift reaction are better developed. The hope is that electrochemical catalysts like this can combine the electrolysis process for making H2 and the syngas production step into one, with lower equipment costs. It's hard for me to believe that it will overtake better established industrial processes. It's very hard to take a maybe-better process from lab scale to industry when there's already an established pair of processes that get to the same outcome. My prediction: electrolyzers and catalytic processes will continue to be optimized separately, and combining those modules will continue to be more predictable and affordable than all-in-one electrocatalytic approaches like this.
- elcritch 6y agoDo you have more resources regarding the current state of art for the separate processes?
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- bit_logic 6y agoEvery time there’s a discussion about synthetic carbon fuels, there’s the same frustrating replies. I want to reply to those with one statement: the whole point is to use excess power from solar/wind. There’s always the same replies pointing out how it’s more efficient to use the power directly in EV batteries, laws of thermodynamics, and other similar things. Those completely miss the point. Solar/wind is going exponential and we have a big problem of storing excess power. Massive really massive amounts of batteries is one option. But converting that into carbon fuels that work directly in existing infrastructure and is effectively carbon neutral is a good option too. That’s where the discussion should be, not pointless arguments about efficiency of EVs.
- regularfry 6y agoI was going to ask if anyone knew what the efficiency of this process was. Obviously we can't get a perpetual motion machine out of it, so it must be taking more energy to form the syngas than gets released from the fuel in the first place, right?
- lstodd 6y agoRight.
- ZeroGravitas 6y agoYou don't need carbon to store energy, you can just stop at hydrogen (or use nitrogen to make ammonia). Processes can be refitted to use pure hydrogen or it can just be added in small increments to existing gas burning plants. Replacing anything that burns fuel with carbon in it with alternatives that dont is a better solution.
- p1mrx 6y agoLots of homes and buildings use natural gas for heat. It would be nice to replace that with something carbon neutral, but the infrastructure can't handle hydrogen levels above 10-20%.
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- credit_guy 6y agoThe application doesn't really make sense the way they explain it: use CO2 from a power plant to produce syngas. If the power plant burns methane, you might as well produce syngas straight out of methane, and short-circuit the step where you produce CO2. From the net energy usage point of view, you are better off (otherwise, you just found a recipe for perpetual motion). Where this could make sense is energy storage. Say you are next to a large solar power plant, and you want to store the excess energy produced during the day and release it at night. Batteries are too expensive, pumped water requires some mountains, etc. With this, you store a quantity of CO2 in some tanks. At day you generate syngas and consume electricity, and store it in some other tanks. At night, you burn the syngas, get some of the initial electricity back, and store the CO2 back in its tanks.
- deleted 6y ago[deleted]
- pm90 6y agoYou’re correct but It still makes sense as a way to get existing power plant operators on board the green energy train. It’s probably cheaper to retrofit an existing plant to harvest the generated co2.
- nine_k 6y agoThis makes complete sense if you replace a power plant that produces electricity with an industrial process that produces heat, e.g. a blast furnace. Then you can grab the waste CO₂ and turn it into something useful (ultimately liquid fuel, plastics, etc) by using the cheap solar energy, of which we often have a surplus at daytime. This has the downside of only operating efficiently during sunshine, or needing a power transmission line from somewhere under sunshine currently (e.g. during local night).
- deleted 6y ago[deleted]
- ajuc 6y agoHow are they converting CO2 into H2+CO? Where is the hydrogen coming from?
- thereisnospork 6y agoWater. In a conventional CO2 electrolyzer (electricity + CO2 -> CO + O2) where CO2 is dissolved in water (plus salt) H2 is the standard byproduct per H2O + electricity -> H2 + O2. The concept of CO2+H2O directly into H2 + CO is neither novel nor useful, as dedicated green-H2 production is more efficient. This is an example of 'meh' level work being puffed up.
- woodandsteel 6y agoSynfuels are very important for saving the climate. Yes, we need to eventually move all transportation to batteries, and we now have the technology to do that with cars and increasingly with trucking. But for ocean ships and long-range airplanes we are nowhere near ready for that. And hydrogen fuel cells are not nearly good enough. So at least for many years the only way to make some important forms of transportation carbon-neutral will be synfuels