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.

I am not against doing research in this area, please do, it is interesting and likely has many applications but global CO2 removal isn't one of them. Nothing proposed, including this, is within any orders of magnitude of a viable solution. The only solution we have is put less in the air in the first place. This tech looks interesting for transporting CO2 but that doesn't mean it sequesters it and even if sequestration was solved the scales here are massive. If we don't have the political will to reduce the amount going into the air then what makes anyone think we would have the political will to build out some system to capture and sequester? We need to focus more on not putting CO2 into the air and less on trying to take it out.

At current rates of emissions, we’re only about 20 years away from people needing to install CO2 scrubbers in their homes.

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.

Direct air capture imo can’t escape the scaling problem - when the feedstock has CO2 at ~400 ppm the economics simply won’t work out despite various oil companies backing one off systems around the globe.

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.

A better title would be "More efficient method to capture CO2 from the atmosphere." The method is not objectively efficient, but may be more efficient than other methods (solvents/sorbents) used for DAC.

Economics rules everything. How much does this cost vs simply planting trees, when the value of harvesting the trees is included? Since tree farms are generally profitable, and wood is expensive, it seems this method is likely to be economically less efficient.

The thing people don't think about with regards to CO2 capture is that you have to get the atmosphere in order to capture CO2 from it. You essentially have to suck the entire atmosphere into these carbon capture facilities.

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 best carbon capture device is the ocean, and for the last 10 years or so huge amounts of free-floating sargassum seaweed have grown in warm ocean waters around the world. Nobody is certain why the sargassum has appeared in such volume lately, but it's plausible to speculate that increased CO2 in ocean water plays a role. As far as I can see the only remotely efficient way to sequester carbon at scale is to leverage the ocean by gathering the seaweed and dumping it on marginal or desert land, both to trap the carbon and fertilize the soil, thus promoting additional carbon-binding plant growth.

This seems like the actual work of the article: https://pubs.acs.org/doi/10.1021/acs.est.5c13908

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.

Subsurface storage vaults for biogenic carbon is likely the most energy and cost efficient way to sequester carbon at this time. Wet vaults for biochar and dry vaults for carbon casting blocks are promising. These methods can help mitigate embodied emissions related to low carbon energy sources such as renewables and batteries. Also, it can buy time for concrete and steel to decarbonization while clean infrastructure scales. These carbon capture methods are modular, deployable across wide geographies, biomass agnostic, and have low energy inputs in comparison to DAC and point source capture. The trick will be avoiding land use diversion while maximizing photosynthesis across all not agricultural lands. This method can also be useful for carbon currency creation which I believe is a precursor for atmospheric GHG stabilization.

Storage vaults for biogenic carbon is likely the most energy and cost efficient way to sequester carbon at this time. Wet vaults for biochar and dry vaults for carbon casting blocks are promising. These methods can help mitigate embodied emissions related to low carbon energy sources such as renewables and batteries. Also, it can buy time for concrete and steel to decarbonization while clean infrastructure scales. These carbon capture methods are modular, deployable across wide geographies, biomass agnostic, and have low energy inputs in comparison to DAC and point source capture. The trick will be avoiding land use diversion while maximizing photosynthesis across all not agricultural lands. This method can also be useful for carbon currency creation which I believe is a precursor for atmospheric GHG stabilization.

One thought I had was to go a very cold place and freeze CO₂ out of the air, about -80°C.

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.

The article doesn't mention the energy costs directly. The fluid is good for at most 100 cycles, probably less, to release the captured CO2 requires heating the fluid to 70C, and then you still have the problem of disposing the CO2 in some way. All cost energy.

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.

Just use lye to baking soda. You could in theory make an efficient roundtrip.

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 CO2 captured by the compound can be released by heating the compound at 70 °C in 30 minutes.

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.

This solves only part of the problem: it captures CO2 and can release it later. But you still need to figure out what to do with this CO2, how to turn it into something useful.

It seems like the focus should be on capturing carbon dioxide from the oceans. Carbon dioxide in the atmosphere is extremely diffuse, but the oceans absorb it in large quantities and as a result it becomes much more dense which makes capture fundamentally more efficient.

I read somewhere that electrolysis of marine water could emit enough oxygen, while also harvesting hydrogen, to counter CO2 emissions, but I can’t find the source, has anyone heard of it before or am I filling the gaps of my memory with generated garbage?

Without knowing much about the details of it, this might be interesting to evaluate as a potentially economically more attractive alternative to DAC in the supply chain of e-fuel production?

Never mind the CO2 released in making the ingredients and recycling them.

Just plant a tree, harvest it to make lumber.

The article's method might be useful in a submarine or spacecraft.

Sounds like this would be great on a long haul space mission where carbon capture is small scale, but very important!

Tired of EU "nag screens" ?

https://archive.ph/SjcLx

how about trees? just a thought.

Keep it in the ground.

Trees!

> If we don't have the political will to reduce the amount going into the air then what makes anyone think we would have the political will to build out some system to capture and sequester?

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?

I think you have a point. It could be difficult to justify the cost of carbon capture based on sequestration alone. One of the reasons I think this might still work is that captured carbon can be used to create platform chemicals (various hydrocarbons) using the fischer tropsch process. Electrofuels are using direct air capture to generate fossil replacements.

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...

Sequestering CO2 where it's highly concentrated, e.g. at power plants or cement factories exhausts, would be one way to emit less.

There are applications where weight still makes battery storage impossible. By capturing carbon, we may give ourselves the ability to harvest fuel from the air instead of the ground. Given the sometimes negative cost of electricity, this could make it more cost effective to do so. If we replace fossil fuel drilling with sequestration then we are at net zero.

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.

> The only solution we have is put less in the air in the first place

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.

We'll need this tech later. If and when we get emissions to net zero we'll still have too much CO2 in the air. Better to have begun the research now.

We need this even if emissions went to zero overnight. World is a big place, can do more than one thing at a time.

Removing CO2 from the air is a pipe dream for several obvious reasons.

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.

Unfortunately, Technological solutions are more politically feasible than attempting to reduce via restrictions and regulations that require intense global coordination that does not exist.

You are 100% right that we _should_ be focusing on reducing emissions, but the reason we would prefer to capture-and-sequester is... money. We make money by emitting C02, and it looks like we will also pay to have it captured again. Is this madness? Also yes.

Someone will make a trillion dollars out of this.

There are 4 different categories of fixing the global CO2 challenge: a. Remove CO2 from atmosphere b. Prevent adding new CO2 from reaching atmosphere

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.

You might think it is silly to do this, but what if carbon emission trading makes this profitable?

Maybe we need to genetically engineer special of trees that are active only during the day and sleep at night. Photosynthesis at daytime and Dormancy at nighttime for maximum CO2 conversion.

"The Wizard and the Prophet" by Charles C Mann sets up an interesting duality that I think more people should be aware of.

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.

This. The fossil fuel industry continues to overflow the tub with CO2, but instead of turning off the tap, we keep trying to invent a better sponge.

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.

I'm going to have to disagree in a (hopefully) nuanced way. First, I just ran an end-to-end continent scale simulation of CO2 sequestration for the US, as is. To put it bluntly: there's no way outside of magical pocket sized fusion that will make this work. If you add full ground transportation abatement; full power abatement; and, then, use dedicated thermal sources, then the final cost is ~1 trillion a year. And, that's after all the positive upsides to the economy. There's a bunch of "almost unlimited upside" to be had from not having to move Miami, Houston, etc., but it's too complicated to model. However, just the healthcare implication upsides are roughly parity, disaster included.

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.

Zoidberg is always worth quoting.

“Why not both?”

Thank you

There's no general will, it's not specifically political will. Emitting less CO2 means doing less things or doing them for much more money due to high taxes to discourage it (and also disproportionately affect poor people). Other than some luddites I've never met anyone that genuinely was willing to sacrifice eating a nice steak or going on vacation unless they are millionaires, and that's only because those people know they can do it as much as they want. You have a huge mass of people getting lifted from poverty that will tell you to fuck off if you tell them that now they are finally out of eating rice and starving they can't have a steak, because of CO2.

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 think it’s little appreciated that high CO2 levels cause cognitive impairment, and with the same amount of (often very poor) air exchange, higher outdoor concentrations can push indoor spaces to levels that cause impaired cognition and poor sleep. I’ve already been seeing this in my home, and will often open windows even when cold just to keep co2 levels reasonable. One solution that can help is an external air heat exchanger, which can exchange air with the outdoors without compromising your homes heating and cooling like an open window will do.

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.

> The ease of releasing CO2 is the key advantage of the new compound.

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.

160F, non toxic, this already sounds like something that could feasibly be used in the home. I would already be interested in installing one. And would absolutely love to see what it would do to school performance.

The hard part is capture and disposal.

Do you have a citation for that 20 years estimate?

Could something like this be used to make cement?

Imagine capturing CO2 to turn it into cement, used for constructions.

Pardon my ignorance, though.

You can heat definitely heat NaHCO3 to get CO2 and NaOH back. It just takes a lot of energy.

"outperform" by only one metric too often fails usefulness. It's a one shot unless you heat the calcium carbonate to 900C, the compound in the article only requires 70C, and has quite a bit of ability to re-process CO2 absorption multiple times. Although solar ovens could reach over 900C, probably too dangerous for residential use.

citation for the co2 scrubbers in home need?

Just to counter your extreme prediction, if co2 levels halve from here all life on earth goes extinct.

https://www.researchgate.net/post/Minimum_necessary_concentr...

Comparing it to sofnolime (the more common used scrubber material for rebreathers), the cost sits around $10 per kg.

Cost will be the biggest question. A reusable scrubber need to be cheap enough that the reduce efficiency is worth it.

Maybe we just need to make cyanobacteria that multiplies faster.

But we still need to remove all the excess co2 that we released into the atmosphere since the start of the industrial revolution if we want to reduce the temperature back to what it was before we started disrupting the natural state of the plane.

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.

I agree, plus were would one store the CO2 ? To get back to "1980", I really doubt puling CO2 from the atmosphere will ever work.

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.

Capturing CO2 at the source will always be worse than removing the source. At the same time, capturing CO2 from the air will stay necessary until we do it.

DAC is unsustainable, and shouldn't be a primary offset mechanism. What would be more sustainable is less net emissions and using something else like oceanic biomass CCS by taking advantage of blooming kelp and/or phytoplankton and then processing it for sequestration using floating, automated harvesting rigs.

The problem is you cannot plant enough trees around the globe to offset our CO2 emissions. Also, a forest only absorbs CO2 while alive. Once it dies, it emits CO2 too. You would need to permanently store the wood somewhere (submerging in water, etc).

Recent article: https://www.theguardian.com/environment/2025/nov/28/africa-f...

>Economics rules everything

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.

In the order of importance:

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.

I agree. Plants are not very efficient (1% or 2%) but they include packaging the CO2 in a stable form. You can store the grain or wood for long periods of times.

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.)

Planting trees is not effective since it takes decades to capture the carbon, but the next years are crucial for determining long term climate developments.

Roads maybe?