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Well, instead of repeating myself manually, I'll paste in a comment of mine here from a past discussion on carbon capture: It's easy to forget why there is a b

Well, instead of repeating myself manually, I'll paste in a comment of mine here from a past discussion on carbon capture: It's easy to forget why there is a bit of a challenge to getting C02 out of the air: there's so little of it, comparatively. In order, air is, broadly, made up of the following: Nitrogen: %78.084 Oxygen: %20.946 Argon: %00.934 CO2: %00.042 The stuff is essentially beyond a rounding error - it really gives one an appreciation of the "either don't release it, or capture it at the point of release" sentiment, and for the difficulties in making carbon capture outside of these scenarios be even slightly cost-effective.

saubeidl 10mo ago
What if one started emitting Nitrogen, Oxygen and Argon in the right proportions instead to get the mix right again?
- dotancohen 10mo ago
  These gases are refined from air to begin with.
  - saubeidl 10mo ago
    Do they need to be?
    - avianlyric 10mo ago
      Where else are they going to come from? They’re all basic elements, either you separate them from air, or you have to go through an energy intensive process to liberate them from various chemicals they’ve been compounded into. But guess what, all of those chemicals are extremely valuable, such as nitrates for fertiliser, water, and Argon does really react with anything (it’s a noble gas), which is why we use it as a shield gas in processes like welding. So producing enough of those gases to somehow offset CO2 production would first require ludicrously large amounts of energy, and if we had access to that amount of clean energy we wouldn’t even be having this discussion. Plus it requires breaking down really valuable chemicals that we spend quite a lot of energy trying to produce or preserve anyway.
    - hannob 10mo ago
      Where would that come from? It's not that we have some large untapped Oxygen or Nitrogen source laying around that is not part of the atmosphere.
- GZGavinZhao 10mo ago
  My naive guess is that since CO2 takes up so few percentage, you would need an unfathomable amount of N, O, and Ar to get the mix right..?
- the_gastropod 10mo ago
  Think about the magnitude you’re talking about here. Every internal combustion engine on earth is emitting CO2. Every volcano, forest fire, coal power plant, etc. The atmosphere is massive. We’ve been, basically, doing our best to pump it full of CO2 for the last 150 years, and this is what we’ve got. Ignoring the chemical challenges with your idea here, the scale is impossibly gargantuan.
- hannesfur 10mo ago
  Interesting thought but you would need a lot of these gasses on the one hand and on the other hand it doesn’t help in working against the greenhouse effect. The greenhouse effect depends on the absolute amount of CO2 in the atmosphere, not the percentage. How much infrared light is absorbed by CO2 primarily depends on the amount of CO2 in the atmosphere.
- mort96 10mo ago
  We will unquestionably reach more than twice the CO2 concentration of pre-industrial levels (which was around 280 ppm; we're at 424 ppm now, it'll increase to beyond 560 ppm in most not-super-optimistic projections). Do you really think it's both feasible and a good idea to release so much O2 and N2 to double the mass of the atmosphere? Or even just increase it by some appreciable fraction? For the record, the atmosphere is around 5 150 000 000 000 000 metric tons. 5 quintillion kilograms. You're talking about producing metric exatons of gas. Wikipedia says that there's 300 000 to a million gigatons of nitrogen in the earth's crust; that's 300 teratons to a petaton (https://en.wikipedia.org/wiki/Nitrogen#Occurrence https://en.wikipedia.org/wiki/Nitrogen#Occurrence). If you extracted LITERALLY ALL THE NITROGEN IN THE CRUST, converted it to nitrogen gas and released it into the atmosphere, and we use the extremely optimistic 1 petaton estimate, you'd have increased the mass of the atmosphere by roughly 1/5000. That means you'd have decreased the CO2 concentration in the atmosphere ... by roughly 1/5000. From 424 ppm to 423.92 ppm.
- anotherpaulg 10mo ago
  I like the unconventional approach. A few minutes with GPT raises two issues: 1. We've raised CO2 from 280ppm to 420ppm, about a 50% increase. To dilute it back down would require 50% more total atmosphere. This would also raise the surface air pressure 1.5x. 2. How much heat is trapped is related to the absolute amount of CO2 in the atmosphere, not the fraction. So the diluted atmosphere would retain just as much heat.
  - vscode-rest 10mo ago
    Would it increase the steady state surface air pressure by 50%, or would more molecules offgas into outer space to compensate? If the latter, it might actually work. Assuming they offgas at-proportion. Which they probably wouldn’t…
- deleted 10mo ago
  [deleted]
- Manuel_D 10mo ago
  Would that actually reduce the greenhouse effect? Intuitively, it seems analogous to putting on a less dense, but thicker blanket.
caturopath 10mo ago
Plants seem to manage it okay.
- hannob 10mo ago
  They don't, and they can't cheat physical realities either. Plants only filter out very small amounts of CO2 from the air over relatively long timeframes. That's why crop-based biofuels require such enormous amounts of space.
  - newyankee 10mo ago
    Which is something that when I try to explain to some 'environmentalists' do not get the point. The other benefits of a biodiverse green belt are great, but if tomorrow I have a concrete system that captures CO2 at 10x the level of trees over lifetime in a similar density, guess what I would like my futuristic city to look like.
  - msandford 10mo ago
    They're pretty amazing for the amount of capital cost. $50 in seed and an acre of land can sequester several to over a dozen tons of carbon per year. It might not be space efficient but it requires basically zero infrastructure.
  - 8bitsrule 10mo ago
    'Very small'?? Depends on your perspective. "The amount of CO2 removed from the atmosphere via photosynthesis from land plants is known as Terrestrial Gross Primary Production, or GPP. It represents the largest carbon exchange between land and atmosphere on the planet. GPP is typically cited in petagrams of carbon per year. One petagram equals 1 billion metric tons, which is roughly the amount of CO2 emitted each year from 238 million gas-powered passenger vehicles." The article: https://www.technologynetworks.com/applied-sciences/news/plants-are-absorbing-31-more-carbon-dioxide-than-previously-thought-392349 https://www.technologynetworks.com/applied-sciences/news/pla... The paper: doi: 10.1038/s41586-024-08050-3
    - 10mo ago
leobg 10mo ago
So then, is it really the CO2 that produces the cognitive impairment, or is the CO2 here just the proxy value that we are measuring, and the real reason for the cognitive impairment is low oxygen?
- deleted 10mo ago
  [deleted]
- xboxnolifes 10mo ago
  If the amount of CO2 is basically a rounding error, so too would be the reduction in oxygen.
- kzrdude 10mo ago
  You could climb a mountain to test your hypothesis, keeping an eye on partial pressure of O2
  - loeg 10mo ago
    We have a natural experiment. People in Denver aren't especially stupid.
- rdruxn 10mo ago
  It’s also the metabolic changes in pH. CO2 is a proxy for ph as carbon dioxide acidifies the blood as it dissolves.
- nradov 10mo ago
  Nitrogen also causes cognitive impairment. It is essentially a very weak anesthetic. If you can replace all of the nitrogen in your breathing gas with helium then you'll probably gain the equivalent of a couple IQ points (although obviously that isn't generally practical).
  - ndsipa_pomu 10mo ago
    Nitrogen narcosis is especially relevant to divers. Recreational SCUBA diving is usually limited to around 30m depth and some divers will start noticing effects (basically like getting drunk) near that depth when using air in the tanks. This is why different mixtures (e.g. trimix) are used at increased depths, though there are other important effects of breathing air at pressure such as oxygen toxicity.
thunderbong 10mo ago
I get what you're saying, but couldn't this be used in a place with high concentrations of CO2, like factory chimneys?
- cwillu 10mo ago
  That would be “capture it at the point of release”
- dmorg 10mo ago
  Yes, but these scrubbers need vast amounts of energy. Most of which emit carbon. We simply need to curb emissions. With the possible exception of basaltic rock weathering, DAC is not practical. Large DAC projects fail to reach forecasts, even when these forecasts for plants costing tens of millions of dollars only aim to extract global emissions of two or three seconds.
  - api 10mo ago
    That same money could replace a lot more emissions with other sources of energy. How much solar and batteries does it buy? It’s always struck me as a moonshot project for people who don’t understand thermodynamics. You could probably unstir the cream from the coffee with an elaborate chemical processing system costing more than what thousands of coffee makers and dairy cows cost. The only CO2 removal project I’ve seen that seems like it might be viable is ocean fertilization. That’s not a thermodynamic free lunch. You’re letting solar powered microorganisms do it. But it needs to be studied and monitored to make sure it doesn’t ruin ocean ecosystems and that enough of the carbon actually does get sequestered to make it actually worthwhile.
verytrivial 10mo ago
Indeed. I've always had trouble picturing how to efficiently "unmix the cake" too. CO2 is rare and throughout the whole atmospheric column. What kind of concentration gradient can you get going to meaningfully pull it out from everywhere in human timescales? (Sorry if this nerd-snipes someone stronger with calculus than me.)
- petermcneeley 10mo ago
  Diffusion and convection would do all the work. You dont need to worry. You can see the stuff mix around https://www.youtube.com/watch?v=-aSBfn6_pUY https://www.youtube.com/watch?v=-aSBfn6_pUY
- primdahl 10mo ago
  Plants capture CO2 from photo synthesis at huge scale. That seems like a great way to capture it at a higher concentration. We’d need to handle the organic matter before natural decomposition, but quite doable.
  - lazide 10mo ago
    It’s even less energy efficient gathering up plant matter at this scale and permanently sequestering it, than getting it from the atmosphere. At least with the current technology required to harvest, move and process it. It’s why biomass is still a relatively niche ‘carbon offset’ technique. It is also highly space inefficient and time consuming to grow and store (sequester). Even if we converted all US cropland (and the US is one of the largest and most fertile countries for growing crops!) to growing trees, for example, we’d need multiple years of growth for every year of fossil carbon we currently release. And we’d all starve. There is also generally less carbon by weight than you might imagine - even hardwood is typically more water than carbon when harvested, which is a big part of the problem. To make it time efficient and also stable to store (not just rot and release the carbon immediately as methane or the like), it needs to be converted to a more stable form like charcoal or coke. Which further decreases efficiency and adds costs. Near as we can tell, it is much better to just not release it (electric cars + solar?), or geo sequester it (olivine minerals seem promising!) or capture and sequester it directly (inefficient, but hey, there are techniques that should scale like pumping back into the original fossil aquifers!). The biggest issue is economic (and hence political) - fossil fuels are energetically the equivalent of free money. It’s pretty hard to convince people to stop getting free money and pay money instead!
IshKebab 10mo ago
Also more fundamentally it's always going to be more efficient to not produce CO2 than to unproduce it. Ok maybe in a small number of circumstances there's no other option (e.g. planes), but mostly you're far better off spending your energy making solar, wind, batteries, heat pumps, insulation etc.
- BurningFrog 10mo ago
  It's hard to put my finger on why, but that's a really weird way to frame the situation. For one thing, most of us don't control any CO₂ production we can turn off. Also, even if/when we finally produced our last CO₂ molecule, the excess CO₂ will last for many centuries, and we really should get it back to lower levels. With good capture tech, you can keep keep doing some important CO₂ producing activities. Sure, it seems very unfeasible with current technology, but that is bound to improve as you work on it.
  - IshKebab 10mo ago
    > most of us don't control any CO₂ production we can turn off. Uhm what? Driving? Flying? Heating? > Sure, it seems very unfeasible with current technology, but that is bound to improve as you work on it. Improve, yes. Break the laws of thermodynamics? No. You can improve a perpetual motion machine but it's never going to be useful.
    - BurningFrog 10mo ago
      Should every car owner personally optimize the CO₂ emissions of their car? I have definitely not argued against the laws of thermodynamics. I'm sorry, I don't even know what you're arguing for.
      - abenga 10mo ago
        > Should every car owner personally optimize the CO₂ emissions of their car? They can if they want to, maybe by buying a car with lower/zero emissions at the point of use?
petermcneeley 10mo ago
And yet trees do this trivially?
burnt-resistor 10mo ago
Lying with statistics while denying science and climate change. Small things sometimes make a big difference. Get the fuck out of here with this Dunning-Kruger effect bullshit.

saubeidl 10mo ago

What if one started emitting Nitrogen, Oxygen and Argon in the right proportions instead to get the mix right again?

dotancohen 10mo ago
These gases are refined from air to begin with.
- saubeidl 10mo ago
  Do they need to be?
  - avianlyric 10mo ago
    Where else are they going to come from? They’re all basic elements, either you separate them from air, or you have to go through an energy intensive process to liberate them from various chemicals they’ve been compounded into. But guess what, all of those chemicals are extremely valuable, such as nitrates for fertiliser, water, and Argon does really react with anything (it’s a noble gas), which is why we use it as a shield gas in processes like welding. So producing enough of those gases to somehow offset CO2 production would first require ludicrously large amounts of energy, and if we had access to that amount of clean energy we wouldn’t even be having this discussion. Plus it requires breaking down really valuable chemicals that we spend quite a lot of energy trying to produce or preserve anyway.
  - hannob 10mo ago
    Where would that come from? It's not that we have some large untapped Oxygen or Nitrogen source laying around that is not part of the atmosphere.
GZGavinZhao 10mo ago
My naive guess is that since CO2 takes up so few percentage, you would need an unfathomable amount of N, O, and Ar to get the mix right..?
the_gastropod 10mo ago
Think about the magnitude you’re talking about here. Every internal combustion engine on earth is emitting CO2. Every volcano, forest fire, coal power plant, etc. The atmosphere is massive. We’ve been, basically, doing our best to pump it full of CO2 for the last 150 years, and this is what we’ve got. Ignoring the chemical challenges with your idea here, the scale is impossibly gargantuan.
hannesfur 10mo ago
Interesting thought but you would need a lot of these gasses on the one hand and on the other hand it doesn’t help in working against the greenhouse effect. The greenhouse effect depends on the absolute amount of CO2 in the atmosphere, not the percentage. How much infrared light is absorbed by CO2 primarily depends on the amount of CO2 in the atmosphere.
mort96 10mo ago
We will unquestionably reach more than twice the CO2 concentration of pre-industrial levels (which was around 280 ppm; we're at 424 ppm now, it'll increase to beyond 560 ppm in most not-super-optimistic projections). Do you really think it's both feasible and a good idea to release so much O2 and N2 to double the mass of the atmosphere? Or even just increase it by some appreciable fraction? For the record, the atmosphere is around 5 150 000 000 000 000 metric tons. 5 quintillion kilograms. You're talking about producing metric exatons of gas. Wikipedia says that there's 300 000 to a million gigatons of nitrogen in the earth's crust; that's 300 teratons to a petaton (https://en.wikipedia.org/wiki/Nitrogen#Occurrence https://en.wikipedia.org/wiki/Nitrogen#Occurrence). If you extracted LITERALLY ALL THE NITROGEN IN THE CRUST, converted it to nitrogen gas and released it into the atmosphere, and we use the extremely optimistic 1 petaton estimate, you'd have increased the mass of the atmosphere by roughly 1/5000. That means you'd have decreased the CO2 concentration in the atmosphere ... by roughly 1/5000. From 424 ppm to 423.92 ppm.
anotherpaulg 10mo ago
I like the unconventional approach. A few minutes with GPT raises two issues: 1. We've raised CO2 from 280ppm to 420ppm, about a 50% increase. To dilute it back down would require 50% more total atmosphere. This would also raise the surface air pressure 1.5x. 2. How much heat is trapped is related to the absolute amount of CO2 in the atmosphere, not the fraction. So the diluted atmosphere would retain just as much heat.
- vscode-rest 10mo ago
  Would it increase the steady state surface air pressure by 50%, or would more molecules offgas into outer space to compensate? If the latter, it might actually work. Assuming they offgas at-proportion. Which they probably wouldn’t…
deleted 10mo ago
[deleted]
Manuel_D 10mo ago
Would that actually reduce the greenhouse effect? Intuitively, it seems analogous to putting on a less dense, but thicker blanket.

caturopath 10mo ago

Plants seem to manage it okay.

hannob 10mo ago
They don't, and they can't cheat physical realities either. Plants only filter out very small amounts of CO2 from the air over relatively long timeframes. That's why crop-based biofuels require such enormous amounts of space.
- newyankee 10mo ago
  Which is something that when I try to explain to some 'environmentalists' do not get the point. The other benefits of a biodiverse green belt are great, but if tomorrow I have a concrete system that captures CO2 at 10x the level of trees over lifetime in a similar density, guess what I would like my futuristic city to look like.
- msandford 10mo ago
  They're pretty amazing for the amount of capital cost. $50 in seed and an acre of land can sequester several to over a dozen tons of carbon per year. It might not be space efficient but it requires basically zero infrastructure.
- 8bitsrule 10mo ago
  'Very small'?? Depends on your perspective. "The amount of CO2 removed from the atmosphere via photosynthesis from land plants is known as Terrestrial Gross Primary Production, or GPP. It represents the largest carbon exchange between land and atmosphere on the planet. GPP is typically cited in petagrams of carbon per year. One petagram equals 1 billion metric tons, which is roughly the amount of CO2 emitted each year from 238 million gas-powered passenger vehicles." The article: https://www.technologynetworks.com/applied-sciences/news/plants-are-absorbing-31-more-carbon-dioxide-than-previously-thought-392349 https://www.technologynetworks.com/applied-sciences/news/pla... The paper: doi: 10.1038/s41586-024-08050-3
  - 10mo ago

leobg 10mo ago

So then, is it really the CO2 that produces the cognitive impairment, or is the CO2 here just the proxy value that we are measuring, and the real reason for the cognitive impairment is low oxygen?

deleted 10mo ago
[deleted]
xboxnolifes 10mo ago
If the amount of CO2 is basically a rounding error, so too would be the reduction in oxygen.
kzrdude 10mo ago
You could climb a mountain to test your hypothesis, keeping an eye on partial pressure of O2
- loeg 10mo ago
  We have a natural experiment. People in Denver aren't especially stupid.
rdruxn 10mo ago
It’s also the metabolic changes in pH. CO2 is a proxy for ph as carbon dioxide acidifies the blood as it dissolves.
nradov 10mo ago
Nitrogen also causes cognitive impairment. It is essentially a very weak anesthetic. If you can replace all of the nitrogen in your breathing gas with helium then you'll probably gain the equivalent of a couple IQ points (although obviously that isn't generally practical).
- ndsipa_pomu 10mo ago
  Nitrogen narcosis is especially relevant to divers. Recreational SCUBA diving is usually limited to around 30m depth and some divers will start noticing effects (basically like getting drunk) near that depth when using air in the tanks. This is why different mixtures (e.g. trimix) are used at increased depths, though there are other important effects of breathing air at pressure such as oxygen toxicity.

thunderbong 10mo ago

I get what you're saying, but couldn't this be used in a place with high concentrations of CO2, like factory chimneys?

cwillu 10mo ago
That would be “capture it at the point of release”
dmorg 10mo ago
Yes, but these scrubbers need vast amounts of energy. Most of which emit carbon. We simply need to curb emissions. With the possible exception of basaltic rock weathering, DAC is not practical. Large DAC projects fail to reach forecasts, even when these forecasts for plants costing tens of millions of dollars only aim to extract global emissions of two or three seconds.
- api 10mo ago
  That same money could replace a lot more emissions with other sources of energy. How much solar and batteries does it buy? It’s always struck me as a moonshot project for people who don’t understand thermodynamics. You could probably unstir the cream from the coffee with an elaborate chemical processing system costing more than what thousands of coffee makers and dairy cows cost. The only CO2 removal project I’ve seen that seems like it might be viable is ocean fertilization. That’s not a thermodynamic free lunch. You’re letting solar powered microorganisms do it. But it needs to be studied and monitored to make sure it doesn’t ruin ocean ecosystems and that enough of the carbon actually does get sequestered to make it actually worthwhile.

verytrivial 10mo ago

Indeed. I've always had trouble picturing how to efficiently "unmix the cake" too. CO2 is rare and throughout the whole atmospheric column. What kind of concentration gradient can you get going to meaningfully pull it out from everywhere in human timescales? (Sorry if this nerd-snipes someone stronger with calculus than me.)

petermcneeley 10mo ago
Diffusion and convection would do all the work. You dont need to worry. You can see the stuff mix around https://www.youtube.com/watch?v=-aSBfn6_pUY https://www.youtube.com/watch?v=-aSBfn6_pUY
primdahl 10mo ago
Plants capture CO2 from photo synthesis at huge scale. That seems like a great way to capture it at a higher concentration. We’d need to handle the organic matter before natural decomposition, but quite doable.
- lazide 10mo ago
  It’s even less energy efficient gathering up plant matter at this scale and permanently sequestering it, than getting it from the atmosphere. At least with the current technology required to harvest, move and process it. It’s why biomass is still a relatively niche ‘carbon offset’ technique. It is also highly space inefficient and time consuming to grow and store (sequester). Even if we converted all US cropland (and the US is one of the largest and most fertile countries for growing crops!) to growing trees, for example, we’d need multiple years of growth for every year of fossil carbon we currently release. And we’d all starve. There is also generally less carbon by weight than you might imagine - even hardwood is typically more water than carbon when harvested, which is a big part of the problem. To make it time efficient and also stable to store (not just rot and release the carbon immediately as methane or the like), it needs to be converted to a more stable form like charcoal or coke. Which further decreases efficiency and adds costs. Near as we can tell, it is much better to just not release it (electric cars + solar?), or geo sequester it (olivine minerals seem promising!) or capture and sequester it directly (inefficient, but hey, there are techniques that should scale like pumping back into the original fossil aquifers!). The biggest issue is economic (and hence political) - fossil fuels are energetically the equivalent of free money. It’s pretty hard to convince people to stop getting free money and pay money instead!

IshKebab 10mo ago

Also more fundamentally it's always going to be more efficient to not produce CO2 than to unproduce it. Ok maybe in a small number of circumstances there's no other option (e.g. planes), but mostly you're far better off spending your energy making solar, wind, batteries, heat pumps, insulation etc.

BurningFrog 10mo ago
It's hard to put my finger on why, but that's a really weird way to frame the situation. For one thing, most of us don't control any CO₂ production we can turn off. Also, even if/when we finally produced our last CO₂ molecule, the excess CO₂ will last for many centuries, and we really should get it back to lower levels. With good capture tech, you can keep keep doing some important CO₂ producing activities. Sure, it seems very unfeasible with current technology, but that is bound to improve as you work on it.
- IshKebab 10mo ago
  > most of us don't control any CO₂ production we can turn off. Uhm what? Driving? Flying? Heating? > Sure, it seems very unfeasible with current technology, but that is bound to improve as you work on it. Improve, yes. Break the laws of thermodynamics? No. You can improve a perpetual motion machine but it's never going to be useful.
  - BurningFrog 10mo ago
    Should every car owner personally optimize the CO₂ emissions of their car? I have definitely not argued against the laws of thermodynamics. I'm sorry, I don't even know what you're arguing for.
    - abenga 10mo ago
      > Should every car owner personally optimize the CO₂ emissions of their car? They can if they want to, maybe by buying a car with lower/zero emissions at the point of use?

petermcneeley 10mo ago

And yet trees do this trivially?

burnt-resistor 10mo ago

Lying with statistics while denying science and climate change. Small things sometimes make a big difference. Get the fuck out of here with this Dunning-Kruger effect bullshit.