Efficient Method to Capture Carbon Dioxide From the Atmosphere
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As the world grapples with capturing carbon dioxide from the atmosphere, a lively debate erupts over the most efficient methods, with some arguing that planting trees is a straightforward solution, while others point out its limitations, such as trees respiring CO2 and eventually emitting it when they die. Commenters weigh in on alternative strategies, like converting wood to charcoal for permanent carbon capture or using wood for construction to keep the carbon locked in. The discussion reveals a consensus that tree planting isn't a silver bullet, with some highlighting the potential of biochar as a more effective carbon sequestration method. Amidst the discussion, a nuanced understanding emerges: the fate of carbon captured by trees depends on how the wood is used after harvesting.
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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.)
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...
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 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 the 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 g/l substance it totals to around 180 km^3.
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, the 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...
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).
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.
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 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.
/s
One of the subplots from the excellent Delta-V series by Daniel Suarez.
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.
One application I think is neat is that it’s a pretty robust refrigerant in a heat pump application.
And on the other end of the temperature spectrum....dry ice.
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://www.youtube.com/watch?v=zkWeZ1YPI88
https://www.youtube.com/shorts/H1rWZHNWBWo
https://en.wikipedia.org/wiki/Electrochemical_reduction_of_c...
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.
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
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.
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.
The problem is the same, the relative concentration of oxygen in air is less than 0.05% (~450pars per million). In water much less.
Even if you could make it a thousand times more efficient it would be a stretch.
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.
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.
Just extrapolate.
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.
Buildings with higher people/sqft could already take advantage of indoor co2 scrubbers today.
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.
The change in scientific literature actually causes a ~quadrupling of recommended airflow ratios for tight homes, putting strong emphasis on an ERV.
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.
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.
Edit: missed a letter
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’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
I have not noticed significant cognitive impairment (not saying it did not happen)
I am somewhat skeptical of this:
https://www.astralcodexten.com/p/eight-hundred-slightly-pois...
The hard part is capture and disposal.
have a nice day, morons.
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