Efficient method to capture carbon dioxide from the atmosphere
helsinki.fi
helsinki.fi
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.
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.
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). 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.
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.
If the latter, it might actually work. Assuming they offgas at-proportion. Which they probably wouldn’t…
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.
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.
"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/pla...
The paper: doi: 10.1038/s41586-024-08050-3
From the perspective of averting climate change it is indeed very small.
A team of scientists led by Cornell University, with support from the Department of Energy’s Oak Ridge National Laboratory, used new models and measurements to assess GPP from the land at 157 petagrams of carbon per year, up from an estimate of 120 petagrams established 40 years ago and currently used in most estimates of Earth’s carbon cycle.
Whether 157 billion tons or 120 billion tons, these numbers are large compared to anthropogenic releases. Of course most of this carbon is quickly cycled back out from land plants due to animals/bacteria/fungi consuming the biomass produced by land plants.
Having polluted and despoiled much of the biosphere, of course we'll be donating our supposed wisdom and that hard work to the future generations that will enjoy the fruits of our labors and entreasurement.
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.
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!
So it’s more like 2-3x non-fossil kWh for every 1x current fossil fuel kWh energy usage.
It’s a huge problem.
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.
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.
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.
I have definitely not argued against the laws of thermodynamics.
I'm sorry, I don't even know what you're arguing for.
They can if they want to, maybe by buying a car with lower/zero emissions at the point of use?
We're not asking people to stop breathing while there's no good DAC on the horizon, but I wonder what were the other important CO₂ producing activities you intend to do less of.
The following isn't breaking the law of thermodynamics; just wilfully ignoring it..
Gemini: >To offset a single typical gasoline car's emissions (around 4.6 metric tons CO2/year), you'd need a substantial fraction of a large DAC plant, as current large plants aim for 1 million tons/year, meaning many tiny DACs or a small portion of one large one; as of late 2025, the largest operating DAC (Mammoth) captures 36k tons, requiring about 80 such facilities to match one average ICE car's annual output, highlighting the massive scale-up needed, with projects like Texas's Stratos targeting 500k tons/year (equivalent to ~108 cars).
I agree that current carbon capture tech is very inadequate, because very little effort has been put into it. How many orders of magnitude better it can get, we don't know until we try, but I don't see any fundamental reason it can't get good enough.
Once you have a solar powered capture machine park pumping CO₂ underground, it can keep working indefinitely at little cost.
> I wonder what were the other important CO₂ producing activities you intend to do less of.
All of them. This is well under way. I don't know how many decades it will take. But that's a separate problem.
The crucial thing to understand is that even if/when all CO₂ production has ended, the produced CO₂ won't disappear by itself for thousands of years!!
So you really need to actively remove it to get back to natural levels. Which is why I think carbon capture tech must be developed.
How did plants evolve to use it as nutrients. Solar power. since humans don't need to make fuel from air these days, maybe all of that solar power should go into compute?
.. I'm not saying any laws are broken, just that there are much better (=more efficient, more promising) ways to reduce global warming, like
https://en.wikipedia.org/wiki/Passive_daytime_radiative_cool...
It already works now (no airquotes), except for DAC entrepreneurs who try to hoard attention without having paid their "attention dues" first.
*And the one humans like to ignore because there seems to be so much wiggle room
Yes!! Obviously! Buy an electric/hybrid car or at least one with good fuel efficiency. Drive it in an efficient style. Try to avoid unnecessary journeys.
That not a good logical argument as there's no guarantee that every technology can be improved enough to be better than the alternatives. e.g. Steam engine tech is bound to improve as you work on it, but it's not going to be as efficient/useful as an internal combustion engine.
History is littered with examples of tech that has been surpassed by better ideas, so the lesson to learn is to optimise the best current solution. In this instance, the best (most efficient, practical) solution is to stop emitting so much CO2 rather than a long bet that capture tech will ever be feasible - with atmospheric concentrations being so low, the scale required makes it a non-starter.
However Chinese domination, global geopolitics being changed and fossil fuel industries and countries still being extremely large and powerful make even choosing the obviously cheapest (and incidentally clean) option difficult in many parts of the world.
Nonetheless, it seems much more optimistic today in 2025 than say 2015 speaking purely based on where technology stands
In what way? China has basically dwarfed solar installations of any other country combined for the last two years, and produces so many panels and so cheap that EU and US competitors are being driven out of business.
China might be the reason we CAN make the transition actually.
The cat is out of the bag and renewables and storage is the new cheapest globally scalable energy source since the advent of fossil fuel.
Either you embrace them or get left behind.
Sure, try to cultivate a local industry, but doing it by slowing down the progress will only leave you further behind.
The chemical sector is the only reason why emissions haven't meaningfully declined yet, and I suspect it is in part due to conversion of supply chain for electrification.
The point is that they're paying a one-off cost (thus producing a peak) and they're already reaping rewards. Once they fully transition power generation to renewables and electrify transportation, what's left can be better regulated and CO2 recapture more easily scaled thanks to also R&D advances on CO2 recapture (e.g. capturing CO2 emissions from a chemical plant's exhaust). Then, even if you need more energy for CO2 recapture, you can keep scaling renewables further.
Could you elaborate
Did you ever do a barbecue? You first burn the light, hydrogen-rich substances of the firewood, with a large beautiful flame; that flame would burn down the meat, but it burns off quickly. What remains is charcoal, the source of most heat in the firewood; it does no produce a visible flame, but emits a lot of heat. It is mostly carbon.
If you're not including the cost of later recapture, then it's not a fair comparison.
If you are including the cost of later recapture, why is it cheaper to recapture later than to do so immediately?
I. e. Collection is half the problem.
Collecting it in a way it's cheap to get it back again is potentially just less than minus half the problem.
Any atmospheric extraction has a net positive compared to that.
Because political will requires coordination, building systems and turning them on doesn't have to!
> We need to focus more on not putting CO2 into the air and less on trying to take it out.
What part of the "we" in this coordination problem doesn't require political will?
USofA was probably the only place that actively resisted the global effort.
I think people do want a better world. Greed is not universal. Most countries that grow a middle class find most people prefer to stop work. I.e. there are not that many infinitely greedy humans. And they can be taxed.
Despite neocon economic theory, most people aren't selfish. And those that are, are often happily rewarded with a plaque in their honor or a medal.
Just look at the length Trump goes to for an award.
People aren’t “greedy,” but my family in Bangladesh absolutely wants to live like my family in America, or at the very least like my family in Canada. They don’t consider that “greedy” and if you tell them it is they’ll laugh at you.
The country’s CO2 emissions per person have increased by a factor of 5x since we left in 1989, consistent with per capita GDP going up by 10x. Even on an efficient development path it’s going to go up another 5x in order to increase the country’s GDP per capita another 10x, which will put it at the level of a poor eastern european country like Hungary or Croatia. That’s the earliest anyone is even going to listen to you about CO2 reduction.
We live in a horrendously inefficient way. We ship everything from half way around the world in diesel ships, trucks, and trains, we buy shitty single-use plastic items packaged and shipped in single-use plastic packaging, we replace our phones instead of our batteries, our clothing and shoes degrade within a couple years, our restaurants and grocery stores throw away half the food they purchase, our agricultural system spends nitrogen and pesticides like they're free to grow corn as an industrial chemical component. I don't know exactly how much meat there is on that bone, but there's a whole lot of emissions we could remove that wouldn't negatively impact our lives and would probably improve them.
And that’s the steady-state number. It’s impossible to believe that these countries can become twice as efficient as Norway, which already has a fully renewable grid, while building a ton of housing and infrastructure that Norway doesn’t have to build because it’s already built.
Really? China, Indonesia, Iran, South Korea, Italy, UK, Brazil, Tanzania, North Korea, etc.?
Making the COVID response sound like one global cooperative endeavor is some serious retcon'ing.
E.G. Make CO2 extraction so cheap it's worth everyone doing it and say, make a market to sell the CO2 to farmers. Then make burying inedible bits of plants so cheap it's done on a large scale.
Then you just wait. Microeconomics takes over.
They did this with plastic clean up. By building a machine that makes plastic into fuel & construction pellets. Then stuck such a machine on a plastic poluted island and waited.
For this trick. All you require from your políticans is that they don't lie or bomb the place.
All the things silicon valley "caviar communists" say you need to stop doing are basically the dreams of a whole mass of people coming out of poverty. Nice food, traveling, having a car, having A/C, etc.
So we can either find alternatives, or slowly figure out more geoengineering projects like mass absorbing CO2 and the like.
I am definitely part of this group you describe.
This could also be a good use case for #b where CO2 is captured before being released to the atmosphere. For example factories and vehicles could be mandated to use this.
This may be part of the solution … or maybe we find a way to make a utopia where we can all agree to just stop polluting. Historically, the utopia has no precedent that I am aware of.
Only requirement is energy and there too it isn't all that expensive to pull air in from the atmosphere or to seperate CO2 from adsorbent via low grade heat (70-100c)
So far into the future this method could allow us to continue produce critical hydrocarbon materials (used everywhere from plastics to pharamaceuticals) without having to depend upon concentrated and contested oil supplies.
More than energy efficiency its volumetric efficiency that's the issue. At the moment (to the best of my knowledge) kg of capturing materials capture tens of grams of CO2. Pulling it from air is not that energy intensive but finding materials that can actually filter out CO2 from that air is difficult. If breakthroughs are made in this area it will have industrial applications. Then it won't be just sequestering.
Of course the easier solution is to plant more trees and grasses but they grow very slowly and require valuable land. Still this approach is feasible in some uncultivable lands. Crops like cottongrass[1] can grow even in tundra climate and can be valuable source of both technically imp carbon via cellulose and a means to capture CO2. We don't have to make a choice. We can do both simultaneously.
[1] https://www.fs.usda.gov/database/feis/plants/graminoid/eriva...
Firstly, it will always be more difficult and energy-intensive to extract CO2 than to just stop putting it into the atmosphere in the first place. Yet the world is nowhere near agreeing any meaningful framework on reducing emissions, and the party in power in the largest democracy in the world is in denial that a problem even exists.
But mainly, if there was an effective means of CO2 removal, who will be in charge of the dials, and who will set the targets?
Atmospheric CO2 is now 50% higher than when I was born. Will we go back to the levels as at the 60s, or perhaps the beginning of the industrial revolution? Obviously that is unfavorable to the frozen regions that are now thawing - like Russia (and Greenland), who benefit from climate change.
For me at least both your arguments are not obvious.
There are a lot of things that are harder to put in the atmosphere than to remove them. Stones for example.
The second one is less of an argument, but rather a question. Why not the UN, the US, China, or Europe?
That’s not a solution either, because the developing world is not going to stop increasing their CO2 output until they fully industrialize. They’re just not. Feel free to seek reductions where you can, but don’t think of it as a solution because it’s not.
The technical problems with CO2 capture are far more solvable than the sociological problems with net zero emissions.
It's not just economics, it's logistics. Countries like Bangladesh don't have the space to build wind and solar, and they don't have the sophistication to manage long distance grids with batteries, EVs, etc. That's why they keep building more coal. They're not stupid, there is just are practical concerns these countries confront that don't exist in countries that have more central organizational capacity.
And the math just sucks. Say countries like India industrialize with a high percentage of renewables, etc., so they end up with developed economies at just double the current CO2 output of India (4 tons/capita). That would mean that the growth in CO2 output from the subcontinent alone (India+Pakistan+Bangladesh) would exceed the current CO2 output of the entire EU.
I think it’s entirely possible that giving first world money to poor nations to buy Chinese solar and batteries is a more cost effective solution to carbon emissions than paying western skilled labour wages to decarbonize energy production in the west.
Of course, I’m sure you’ll have tremendous success convincing “candy for dinner” American voters to pay third worlders to spend in China
Renewable and battery is now ( recently) cheaper than coal. They are not stupid, that’s what they’re going to build, not coal. they’ll follow chinas trajectory closely, delayed by a couple of years. It’s well underway in Pakistan, just google their 2025 solar boom
https://ember-energy.org/latest-insights/the-first-evidence-...
A lot of people simply dont have electricity. They don't have grids. Night comes, it's dark. People are buying solar panels to get electricity directly. Now they can recharge lights during the day.
> China and India continue to build huge amounts of coal power.
One factor here is finance: companies make more money building coal plants. Banks loan the money so they can make money. Solar isn't as lucrative. It's the cheapest source of energy.
[1] https://www.nytimes.com/2025/12/30/climate/solar-south-afric...
[2] https://energy.economictimes.indiatimes.com/news/renewable/g...
[3]https://www.pv-magazine.com/2025/06/23/china-hits-1-tw-solar...
But! Notice that abatement doesn't get us to 0. It merely slows the process. The remainder absolutely needs ACC. The output stream needs to be dirt cheap, the thermals need to be 100°C and not 900°C. Those sorts of things would bring ACC down to "hundreds of billions" rather than a trillion.
“Why not both?”
We need carbon taxes, tariffs on high-emitting countries and products, and support for adopting clean energy, clean transportation, and clean everything else. Lobbying and misinformation has made these actual solutions politically impossible to implement though, so we continue to waste resources on sponges.
Mann describes "Prophets" as people who see a problem and then try to prod people to change their behaviour in order to avoid it. e.g. Thomas Malthus observed that exponential population growth had humanity on track to experience severe famine, conflict, etc. that would violently and savagely bring our numbers back within the carrying capacity of the Earth. Multiple people have made predictions about when humanity would reach the brink at numerous points in the years since Malthus, but were always wrong about when the Malthusian trap would finally spring...
...because of "Wizards". Wizards are people who set about solving problems with tech. Advances like the use of fertilizer, first bat guano and then the Haber-Bosch process, followed by scientific crop breeding have effectively raised the carrying capacity of the Earth so much that, despite our exponentially ballooning numbers, there are far more calories per person available now than in Malthus' day.
Prophets are valuable for their ability to observe and raise awareness about problems. The Earth does have an ultimate carrying capacity too, which we should keep in mind even if we don't know what it is. However, the track record undeniably favours the Wizards. They get things done. Prophets hate this, because it makes it look like they were wrong. They weren't wrong. They were just too focused on an approach to the problem that rarely works.
The modern environmentalist movement is dominated by prophets. So much so, that wizards are often portrayed as the enemy. History has shown that this is wrong-headed. We should value prophets for what they do, but ignore them when they tell us not to fund the wizards.
Someone will make a trillion dollars out of this.
Soda lime, or calcium hydroxide, is the current state of the art. We use that in an anesthesia and in saltwater aquariums and in scuba rebreathers. An idealized system can capture 500 mg per gram, but in practice you only capture around 250mg/g. This outperforms the method in the article but it’s one-shot. There are interesting proposals to use this for direct capture at industrial facilities and to turn the waste material into bricks for building.
The key advantage of this new material appears to be that it can be heated and reused. That would be very valuable in an interior direct air capture use case. Think about filtering the CO2 from an office or a home to get us back to pre-industrial levels indoors.
Buildings with higher people/sqft could already take advantage of indoor co2 scrubbers today.
Just extrapolate.
Extending the current exponential for 20 years, we get into the 500ppm region.
I don't think that's enough to need scrubbers.
If your room has 2 times the open air concentration, and you are concerned if it's 2.0 times or 2.2 times, you should already be dealing with the problem.
So at 500 external you'd pretty much need continuous ERV but not necessarily scrubbers just yet.
From https://www.climate.gov/news-features/understanding-climate/..., the pessimistic projections suggest that we may reach our 700 ppm threshold by roughly 2070; 45 years from now. (The graphs are hard to read precisely)
The 300 ppm offset compared to the outside air is naturally just an arbitrary number, everything up to 1000 ppm (meaning everything up to 580 ppm more than atmospheric levels) is considered "acceptable". That means any increase in CO2 concentration will take an indoor environment which used to be considered "acceptable" and make it cross the threshold into "unacceptable". An indoor environment which would've been at 900 ppm around the industrial revolution (280 ppm) would've crossed the threshold when we surpassed 380 ppm (which was in 1965 according to https://www.statista.com/statistics/1091926/atmospheric-conc...).
let's compare the past 20 years. In 2004, the concentration was ~377 ppm. That's 47 ppm lower than what was in 2024. An indoor environment which was "borderline but acceptable" at 955 ppm CO2 in 2004 would've crossed the arbitrary 1000 ppm threshold by now, and therefore would benefit from a CO2 scrubber. The next 20 years will likely have a higher increase than the past 20 years, so there will be a larger range of currently acceptable indoor environments which will cross the 1000 ppm threshold by 2045.
TL;DR: It's complicated, 20 years is arbitrary, but as CO2 concentrations increase, indoor quality gets worse so indoor environments which were already bad will become worse. 45 years is a more realistic estimate for when your typical good indoor environment will become unacceptable, but it's a gradient.
The hard part is capture and disposal.
Noticeable cognitive impairment starts in the 700-1000ppm range, whereas it is very common for homes to reach 2000-3000ppm, especially when in a closed bedroom.
I monitor my indoor co2, but don't take any action because it's extremely rare to be above 700 or 800. I can only remember a handful of times its reached 1k ppm. And my house should be prime candidate for co2, it was built during the era of "seal all air gaps" but before ERV or HRVs. I also use pressurized co2 to inject co2 into a planted aquarium. And my dogs are terrified of open windows so they are rarely open.
This change in scientific literature actually causes a ~quadrupling of recommended airflow ratios for tight homes versus ASHRAE's previous guidelines, putting strong emphasis on an ERV. Previously, ventilation needs tended to be dominated by air quality and smell, by humidity buildup, or by theoretical house parties that maxed out the system.
This ventilation adds capital expense, but it's substantially more controllable and significantly cheaper in the long run in colder climates than 'just open a window' or 'just don't build the house so tightly sealed'. Reserve the operable window for the aforementioned house party, which is out of a reasonable design envelope.
Sounds seriously unlikely. How would this work in practice, at the level of bodily functions?
But hypothetically, what other trace contaminants would you expect to be so universally correlated with CO2 in different environments that they could account for repeatedly observing these effects in different studies? That seems implausible.
If they really want to do a robust study they need to do an intervention study with clear levels of CO2 accurately controlled and the rest of the air being identical for everything else, otherwise it's purely meaningless. (it's doable, by the way).
Several other posters in here have posted peer reviewed studies replicating these effects, but personally I find individual direct experience with my own body to be massively more generally useful when making health decisions than studies in other people, or some known mechanism.
I have one of those, it blows fresh air in through the bedroom and sucks it back out through the kitchen (loft house, this route prevents food smells from wafting into the bedroom). Aside from just feeling fresh all year, this system also prevents mosquitoes from entering in summer while still allowing air circulation, it automatically bypasses the exchanger at night to provide cool air and it has some pollen filters installed which helps with hay fever.
So great economic return and a bunch of upsides, but it does require space for the exchanger and the ducts throughout the house.
All rooms in the house have an intake or exhaust duct depending on requirements.
There is also a small control panel next to the thermostat in the living room that controls the whole system for when, ahem, your number two's are particularly odorous (or you're using the kitchen to cook for 6).
My bedroom was quite small at the time, but I measured the same effect of buildup in a larger bedroom, just the Co2 level took a little longer to reach it's peak.
In the small room it took about 45 mins to climb to about 1400 after I closed the door and went to sleep.
I'm currently trying to install some above-door vents to improve circulation but this is a topic most people don't consider at all, even though studies have shown the effects of classrooms having high Co2 concentrations on exam results and cognition.
CO2 rises really fast with people in even a large space.
I wouldn’t put too much effort into vents above a door as we’ve seen that CO2 will leak through doors and even floors/ceilings very quickly.
I'd like it to vent out into the hallway and the rest of the apartment though, so not sure what you mean by it leaking through doors? It's obviously not leaking enough, hence the addition of a vent. It's either that or keeping my door open all night which isn't feasible due to noise by other family members waking up etc.
This is the meter I am using, costs $39, and is a calibrated instrument with +/- 3% accuracy. I have an academic colleague that uses these same devices for scientific research on plant metabolism, and they are highly accurate and are optionally self calibrating just by opening a window or putting them outdoors.
https://www.co2meter.com/collections/indoor-air-quality/prod...
Edit: missed a letter
I am somewhat skeptical of this:
https://www.astralcodexten.com/p/eight-hundred-slightly-pois...
I have not noticed significant cognitive impairment (not saying it did not happen)
The US navy failed to detect such effects in submarine crew, even at much higher levels like 10,000 ppm.
Another reason to be skeptical is that exhaled breath is 4% CO2 (40,000 ppm!). Therefore a few thousand extra ppm in the inhaled air should not make much of a difference to the homeostasis mechanisms in our bodies.
I’m sure the CO2 was part of it but lack of circulation also means increasing temperature, especially with a bunch of people in a small meeting room. Long meetings themselves are a problem and any excuse to call it early is probably worth it even if it’s not entirely true.
I’d need to look at the study, but I also suspect the submariners would be used to high CO2, and also not experienced enough in doing focused creative or knowledge work for impaired abilities there to be detectable.
Please consider the possibility that you can accurately detect increased CO2 (it increases your breathing rate almost instantly for example) without it causing impairement.
I feel irritable, and fatigued/sleepy when CO2 is high. Increased breathing rate by itself activates an undesirable sympathetic nervous system response, that anyone can notice immediately with deliberate breathwork.
Also, it seems likely to me that the same poor air exchange that leads to high co2 causes respiratory disease to spread more rapidly, and with a higher initial viral titer.
> In this study, a systematic review and meta-analysis of fifteen eligible studies was performed to quantify the effects of short-term CO2 exposure on cognitive task performance.
> The complex task performance declined significantly when exposed to additional CO2 concentrations of 1000–1500 ppm and 1500–3000 ppm
So we're a long way from needing to scrub co2 from the atmosphere to get any work done
[•] <https://en.wikipedia.org/wiki/Heat_recovery_ventilation#Ener...>
I use a Panasonic model — readily available from Big Box Retail (~$700 + $100 in vent/conduit) — which can do 20 - 60 cfm (in my 900 sqft home this can easiliy exchange the entire volume several times per day).
Have you been telling representatives? Here's a letter I wrote to mine:
Imagine capturing CO2 to turn it into cement, used for constructions.
Pardon my ignorance, though.
It is a kind of cement that uses CO2 to cure.
I have no idea why the journalist that wrote this article choose to highlight the carbon density of the sub-header. It's almost completely irrelevant for carbon capture plants.
Another clear benefit is that it's a liquid.
Today people mostly use the substances that you called non-reversible in research plants (AFAIK, all plants are research right now). They are perfectly reversible, but that uses a lot of energy.
Looks like a perfect match to a solar plant, which provides basically free energy periodically. All you need is a large enough cistern to hold the liquid during night time.
But you don't need to store the capture medium. You use a bit more energy to make they work faster while the Sun is shining, and stop everything when it's gone.
The largest bottleneck is what you do to get rid of the CO2.
https://www.researchgate.net/post/Minimum_necessary_concentr...
It’s an interesting exercise to try to figure out what the ideal co2 level should be. Why are we fixated on preindustrial levels. I’m very open to thinking 600ppm might be more ideal than the current level.
I feel that idea has some support from things like the optimal for many crops/greenhouse plants being 800–1,200 ppm. And that Earth's vegetation has greened since the 1980s due to increased CO2.
Cost will be the biggest question. A reusable scrubber need to be cheap enough that the reduce efficiency is worth it.
Capturing CO2 at the source (power plant, etc) would be simpler to reach economic viability but without incentives it’s dead on arrival. I believe the IRA infra bill had put a price ~$50/ton of CO2 captured.
Another concern, who will pay for maintenance ? See this for why you cannot let CO2 escape from underground storage:
https://en.wikipedia.org/wiki/Lake_Nyos_disaster
If stored near a populated area, hundreds of thousands could be kill, including all animals and insects, in a matter of minutes if the "vault" has a catastrophic failure. I would rather live near a nuclear waste site than a CO2 Site.
Imagine you were growing a huge biomass that you harvest, dry out, and then store. We know how the bacteria and processes that stripped co2 from the atmosphere in the past, we just need to do that in a big way. Good thing we have places on earth that are huge and flat and growing algae won't be a problem.
And then we complement that with green energy and an attempt at net zero.
This is less of a technogical problem than it is a political one, I'm afraid.
It's a science fiction grade engineering problem and a historically unprecedented political problem. That's a tough mix to crack.
It's worth trying to delay the end of civilization, but reversing this is literally like putting the fire back in the Molotov.
If it's between immediate death and a slow one of cancer, I'm not sure your choice is the obvious one.
https://aiche.onlinelibrary.wiley.com/doi/abs/10.1002/prs.68...
https://en.wikipedia.org/wiki/Electrochemical_reduction_of_c...
We and previous generations took out a loan and the payment is coming due.
Because of the framing about degrees in celcius change people are thinking in small numbers, like "oh, it's just 1.5'C over normal. oops, we missed that, well maybe we'll get it at 2.0'C. They don't realize that if we want normal we ahve to reduce the temperaure and to do that we need to take that c02 blanket off that we've been tightly wrapping around our collective bodies for decades.
And that endeavor is nearly unfathomable. Think of all the energy used by humanity since the industrial revolution and the energy we're going to be producing in the time period that we attempt to sequester the previously poduced C02. All of that needs to be accounted for.
And then there's the surplus energy roiling around in the system now, and the collapse of food webs.
I don't see how we get our way out of this in the next 50 years.
When you compare round trip efficiencies and economics it makes sense to just not burn the hydrocarbons to begin with.
For the atmospheric one, grow trees and algae
They underestimate the scale of the intervention that will be required to stave off the potential end of human civilization as we know it. If we have any hope of continuing to live at something resembling the quality of life that we've grown up in it will require radical science fiction like developments.
We're going to need things like space based solar shades to regrow glaciers and icepack, advanced breeding and cloning and ecosystem engineering to reconstruct collapsing food webs, and I think the big picture thing is that we're going to need to engineer people to reduce susceptibility to addictive food and manipulative marketing.
Chances are, developed countries won't be hit that hard, at least for a generation or two.
Recent article: https://www.theguardian.com/environment/2025/nov/28/africa-f...
What is unsaid is that we need to sequester CO2 for hundreds of years—often far beyond the lifespan of the trees. Trees are short term storage, and sometimes the storage is a lot shorter than popular imagination purports.
But left out to rot and yeah, the fungus and bacteria will ultimately consume the wood and release CO2 as a byproduct.
I am currently building a wooden house this way. Wooden frame, wooden exterior, wooden floors, even wood-based insulation (https://huntonfiber.co.uk/). The isolation has the shortest life span and it is expected to last at least 60 years.
On the other hand if the wood is used for construction or furniture it will not emit.
- With more wood available it’s more economical to use it as a building/manufacturing material over other emissive sources (concrete, steel, plastic)
- We can replant the same area multiple times
- Even if we plant crops for biofuels, it’s closer to carbon neutral than burning fossil anyway
Every move we can make towards planting (and managing) more of the surface of the Earth is an improvement, without waiting for miraculous new technology.
In this case, it looks like they get CO2 as a gas. It's cheaper because you don't have to use energy to undo the burning, but it's difficult to store for a long time.
(I'm not sure if someone tried to make a fake underground bog in abandoned mine. Just fill with wood and water to keep the oxygen low and make the wood decompose slowly.)
Last time it took plants millions of years, and that was before things started eating wood. I’m pretty sure that we’ll have to have a hand in the process if we want to reduce CO2 levels in timespans shorter than geological.
Not really, forest fires happen and then a few hundred of years of sequestered CO2 gets released back in an instant.
Organic material with oxygen gas floating around is not stable.
Sequestering carbon into the ocean might be a better strategy. Not flammable and not subject to stupid capitalism effects around land prices.
You'd need to find a way to sequester carbon without it leaching in the water.
https://marine.copernicus.eu/ocean-climate-portal/ocean-carb...
Physics rules everything, once you start trying to run at scale.
The density of carbon per unit volume in solid materials of interest doesn't vary that much, whether you sink it in trees or in exotic materials like diamonds. That means you can calculate the volume of material required so sink a desired amount of atmospheric carbon.
If you want to have a measurable impact on the atmosphere, say dialing it back to 1980 CO2 levels, you're talking not about making a pile of stuff but about making a mountain range that's a mile high and hundreds of miles long.
Now figure out how many trucks you're going to need to move that much material from where your sequestering machine is to where your pile of stuff is.
Or if you want to dump that material in the ocean (which someone else will certainly object to), extend your calculation to figure out how many container trucks worth of material you need to dump into the ocean every hour to accomplish your atmospheric cleanup in whatever amount of time you choose (a decade? If it takes a century, that's not fast enough).
And finally think about surface to volume ratios. You're trying to sink it into a volume, but you can only get the gas into the volume through its surface, so the speed of your process is limited by surface area.
If you want to do it with trees, my personal spitball estimates are that you probably need to plant somewhere between the entire state of Connecticut and the entire state of Colorado to have the kind of impact one would want (there's more subtlety to tree calculations than one generally likes to admit, so feel free to come in with way higher numbers than I did).
Which brings us back to economics. If you have a well-managed forest of that size and scale, someone is eventually going to come along, maybe in 100 years, maybe in 500 years, and say "hey if we cut this down, we could burn the wood to heat our homes" and all that carbon goes back into the atmosphere, so you actually need to sink it into something that is energetically unfavorable for recovery, which means you also need to expand a huge amount of energy to sink the carbon into that energetically unfavorable state.
Just to put it into numbers, wikipedia has the total amount of CO2 on the global warming page, if we assume it's in a 2 kg/l substance it totals to around 180 km^3.
It's a literal mountain chain of plastic. We do have uses for it, but it's a lot.
1). Wikipedia does have a citation [1] saying 2,450 gigatonnes of CO2 have been emitted by human activity, of which 42% stayed in the atmosphere and 34% dissolved in the oceans, with the rest already sequestered by plant growth and land use. As we start to pull CO2 out of the atmosphere, it will begin to be emitted from the oceans as well; therefore, let's assume we have to recapture all excess atmospheric and oceanic CO2:
:: 2450x10^9 tonnes CO2 x .66 fraction to sequester ~= 1.6x10^12 tonnes CO2.
2) Let's convert the CO2 to something more stable for long-term storage: HDPE.
- Convert mass of CO2 to mass of carbon:
:: 1.6x10^12 tonnes CO2 x 12/44 mass fraction of C in CO2 ~= 4.4x10^11 tonnes C
- Convert mass C to mass HDPE; assume HDPE is effectively (CH2)n. Then:
:: 4.4x10^11 tonnes C x 14/12 mass fraction CH2 to C ~= 5.2x10^11 tonnes HDPE
3) That's a lot of plastic! How much volume? Wikipedia says HDPE is ~930-970 kg/m3; let's be conservative again and take the low figure:
:: 5.2x10^11 tonnes HDPE x 1.0/0.930 m3 per tonne HDPE ~= 5.5x10^11 m3 HDPE
4) Those are cubic meters; how about cubic kilometers?
:: 5.5x10^11 m3 x 1.0/1.0x10^9 km3 per m3 ~= 5.5x10^2 km3
In other words, if you turned all the [excess potentially climate-change impacting] CO2 that humanity has emitted since 1850 into plastic (a process that would certainly emit a large additional CO2 fraction given the industrial buildout required) then we'd end up with about 550 cubic kilometers of the stuff. Coincidentally, that's about the volume of Mount Everest according to an intermediate calculation in [2].
So, a mountain of carbon: more than a pile but less than a mountain range.
[1] https://en.wikipedia.org/wiki/Carbon_dioxide_in_the_atmosphe...
[2] https://www.quora.com/What-would-the-estimated-weight-of-Mou...
This suggests a long term approach of building solar powered carbon capture plants in subtropical deserts, they capture it and convert to graphite, which is then spread out under the solar panels.
I once did the math on this, using the specs for currently available solar powered carbon capture, and it came out to something like if we used 100 years worth of the current production annual production of solar panels for this we could carbon capture at a rate that could drop the atmosphere from current levels of CO2 to pre-industrial levels in a few years even if we do not reduce emission rates.
So...not practical now, but might be feasible as a very long term project that over many decades builds out enough capacity to get things under control as long as we can keep everything from going to hell over that time.
1. Even if we do magic and emit nothing, we still need to remove CO2 from the atmosphere or it will cook us over time, just longer.
2. We would need an enormous area for forests (which i great), which would mean a lot of intervention, like resettling people, demolishing and constructing new buildings, a lot of machinery time to move people to and from the new forests, a lot of planting and forest maintenance involved. And add he work to cut and bury resulting wood. If you would sum all the incidental emissions from this process it would rapidly become much less efficient (if at all).
Without either CO2 capture or a sun shade of some sort, the CO2 levels and temperature will only ever increase, just like now.
The largest sous-vide cooking pot ever...
Using something like this to capture carbon from an exhaust pipe might be viable, but scrubbing CO2 out of the atmosphere is not even remotely viable. There's just too much air out there.
The problem is the same, the relative concentration of oxygen in air is less than 0.05% (~450pars per million). In water much less.
How long and how many terawatts of power do you think it'll take to suck a significant fraction of the earth's seawater through a capture facility?
If you look at a chart of historic temperature levels, pretty much every significant change on that chart corresponds to a mass extinction.
So yes, the earth does die. The earth has died many times before and it's currently happening again. The rock itself will still be here but us and pretty much everything else that lives here will be wiped out by climate change. The only question is how long it will take, and as you can see it's going fast.
This is not controversial, except for ignorant people who refuse to face the facts. This is what climate scientists have been warning us about for our entire lives.
Doesn't matter whether you believe it, it's happening.
This is why climate scientists have been saying for a hundred years that we need to stop producing all this CO2, because we can't take it back. We can't just fix it. We can't just get back all the ice that's melted and keeps melting, we can't unthaw the permafrost. We can't stop all the methane and other climate gases that have been trapped under ice for millions of years from being released and making it even worse. We just can not do it.
We were warned, we ignored the warnings and now we're seeing the consequences.
The world's largest pump (according to a quick search) can pump 60,000 liters per second. The oceans contain over 1.3 billion cubic kilometers of water. One cubic kilometer is a trillion liters. It would take this pump - the largest pump in the world - 192 days to move one cubic kilometer of water.
Let's be charitable and say we can make a noticeable dent in ocean CO2 if we could only process 1% of the ocean's water per year. That's about 13 million cubic kilometers. Let's be generous and say one of these pumps can do 2 cubic kilometers a year even though it's a bit less. So we'd need 7.5 million of these pumps - and of course we'd also need each of them to be connected to a facility that's capable of processing all the water as quickly as the pump can supply it.
This is the problem with carbon capture. We can't build many/large enough capture facilities to make a difference.
Even if you could make it a thousand times more efficient it would be a stretch.
I feel like anything I hear about that teases net negative sequestration at scale eventually falls apart or is found to be akin to a perpetual energy machine that eventually is debunked.
Why would it gather more CO2 over there than it does where it already is?
For those curious about numbers for 2025, a couple links: https://optics.marine.usf.edu/projects/SaWS/pdf/Sargassum_ou... https://abcnews.go.com/International/scientists-concerned-re...
> Nobody is certain why the sargassum has appeared in such volume lately
For the record 2025 volumes specifically, the ABC article notes that sudden phosphorus flushes as a result of multi-year drought-hit watersheds finally being flushed out likely contributed. Ocean ecology at scale is usually highly correlated with nutrient density.
https://oceanvisions.org/ocean-alkalinity-enhancement/
But in general carbon absorption by oceans leads to acidification and habitat destruction.
And the superbase is 1,5,7-triazabicyclo [4.3.0] non-6-ene
It is an anime based technology. Other amines in water-based solutions also get regenerated at about <200C. It is great to find new molecules to do this work but as I usual, these marketing articles sensationalize the actual work.
There’s the katabatic winds off of the glaciers in Greenland and Antarctica, which could help things go through.
But I soon realised that CO₂ is so potent, that it’s so such a small proportion of the air that not much would be taken out.
There’s some renewable storage systems that liquify air, that could remove CO₂ but they don’t mention it;,but air liquification doesn’t seem to be growing fast as an option.
The other one from mere A-level chemistry is buffer solutions and using chemical reactions in the Oceans, apart from iron seeding for life, but a chemical that precipitate an insoluble carbonate. Not ideal raining down precipitates, or using the Ocean as a test tube.
A given locale has some metric, based on local generation sources, for grams of CO2 emitted per kWh or whatever. How much CO2 is released to capture 1 gram of CO2? If it is close to a gram or more, this is not worth considering. Maybe one day zero-carbon energy sources become so inexpensive we could contemplate wide-scale CO2 capture, but we aren't anywhere close yet.
Anyway - CO2 in the atmosphere is here to stay. Much more "realistic" approach is to decarbonize the ocean and let the ocean absorb the atmospheric CO2.
the time requirement alone makes it tricky to be used directly at the source of carbon emissions. this might be efficient but unsure about effective.
I can't find a good link now, but at least it's the only method I know where it's not obvious that requires a huge amount of energy that makes the whole process net negative.
For example:
https://www.pnas.org/doi/10.1073/pnas.0805794105
Peter Kelemen has written a lot of papers on this topic.
Here is a more recent paper that I wrote together with Peter and others currently in review:
https://eartharxiv.org/repository/view/9651/
This is more about the mechanics of how the rock breaks to allow fluids to move around.
And here is another paper currently in review that we coauthored about how we know there’s gas moving in the system and therefore hydrogen is being produced:
https://essopenarchive.org/users/543018/articles/1363688-eni...
Tbh I have no idea why we didn’t submit these to arXiv instead of these other preprint servers.
I think it's worthy of its own submission as well (besides being very on topic on this subject here too).
/s
One of the subplots from the excellent Delta-V series by Daniel Suarez.
IDK, build houses out of limestone like we have been doing for ages.
Electro Carbon https://www.electrocarbon.ca/en
https://sustainablebiz.ca/clear-the-runway-electro-carbon-be...
Their process for generating potassium formate is greener than standard methods. It does require electricity as an input but that can come from renewable, green sources.
Potassium formate is used in de-icing products, fertilizer, heat transfer fluids, drilling fluid, etc... so a useful, monetizeable output comes out of the process.
Disclosure - Know the founders personally. Wanted to shoutout their work. No financial ties to the company.Chemistry is not at all my expertise & I don't have details on their process beyond what's on the website.
Just plant a tree, harvest it to make lumber.
The article's method might be useful in a submarine or spacecraft.
It seems like we have not yet done the full circle, but we are close.
One application I think is neat is that it’s a pretty robust refrigerant in a heat pump application.
CO2 is fairly inert. This makes it useful. Welding steel is a typical example of something you can use CO2 to shield. There are many other examples in the chemicals industries of things like that where you want to do something at a "higher than natural on earth" temperature to make a reaction happen or happen faster but you don't want that reaction to happen with oxygen all around.
And on the other end of the temperature spectrum....dry ice.
On a much smaller scale I've been hoping for a small solar powered CO2 compressor to exist so I could use it for mosquito traps. The state of the art for those right now is burning propane for the CO2 combined with a scent emitter for the human smell to attract female mosquitos.
Synthetic materials is another. For example carbon electrodes for batteries.
The one exception is making synthetic fuels, but in the vast majority of applications it’ll be cheaper to use electricity from clean sources (renewables/fission/fusion/unicorn farts) directly rather than pay all of the efficiency losses of electricity -> thermal -> chemical -> thermal -> (end use).
Ballpark, running a car on synfuels takes 10x the energy of running it on batteries charged directly from renewable sources.
To remove 10ppm of atmospheric CO2 from the atmosphere (which would do nothing to sustainably lower CO2 in the atmosphere) would require processing 10ppm of the entire atmosphere. That is one in 100.000 parts of the atmosphere. The entire atmosphere is around 5x10^18 kg, so we need to process 5x10^13 kg of air. Which is 50 million million (no typo) kilos of air.
The industrial task of doing this unfathomably large and by itself would have no long term Impact.
Human fabricated carbon capture from ambient air is a complete fools errand only promoted by the scientific illiterate or those who benefit from scientific illiteracy. You can essentially just look at the first graph on wikipedia and see that it is never going to work: https://en.wikipedia.org/wiki/Carbon_dioxide_in_the_atmosphe...