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Efficient method to capture carbon dioxide from the atmosphere

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Re: Efficient method to capture carbon dioxide from the atmosphere

#81

Post by jacquesm »

Yizahi wrote: post #44
cyphertruck wrote: post #2

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.

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…

> it will cook us over time, just longer.

The largest sous-vide cooking pot ever...

Re: Efficient method to capture carbon dioxide from the atmosphere

#82

Post by Ringz »

marcosdumay wrote: post #73
yodon wrote: post #48

Earlier quoted context omitted.

Do you have a citation for that 20 years estimate?

https://gml.noaa.gov/ccgg/trends/ Extending the current exponential for 20 years, we get into the 500ppm region. I don't think that's enough to need scrubbers.

Indoor is always higher ppm (how much depends on many parameters) without proper ventilation. „Proper“ should include a „Heat exchanger“ thus you don’t need to reheat fresh air.

Re: Efficient method to capture carbon dioxide from the atmosphere

#83

Post by MathMonkeyMan »

ekianjo wrote: post #78
_yb2s wrote: post #67

Earlier quoted context omitted.

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 hea…

> high CO2 levels cause cognitive impairment Sounds seriously unlikely. How would this work in practice, at the level of bodily functions?

I don't know the mechanism, but: https://www.google.com/search?q=co2+cognitive+impairment

Re: Efficient method to capture carbon dioxide from the atmosphere

#84

Post by PeterHolzwarth »

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.

Re: Efficient method to capture carbon dioxide from the atmosphere

#86

Post by gs17 »

xnx wrote: post #27
roflmaostc wrote: post #4

Earlier quoted context omitted.

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...

Biochar seems like a good option

It's a hugely underappreciated option. I'm not sure how accurate it is (or how legitimate the companies doing biochar carbon removal are), but cdr.fyi shows biochar as the top carbon sequestration method that's actually happening.

Re: Efficient method to capture carbon dioxide from the atmosphere

#87

Post by marcosdumay »

yodon wrote: post #37
cyphertruck wrote: post #2

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.

>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,…

> 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.

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.

Re: Efficient method to capture carbon dioxide from the atmosphere

#88

Post by teiferer »

Teever wrote: post #57
condensedcrab wrote: post #13

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.

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…

With ice caps melted off, just removing all the excess CO2 isn't even enough since with that reflective surface gone, more energy from sunlight stays in the atmosphere than previously when more of it was reflected back into space instead of nowadays being absorbed by the ocean.

Re: Efficient method to capture carbon dioxide from the atmosphere

#89

Post by nehal3m »

_yb2s wrote: post #67
condiment wrote: post #45

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…

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 hea…

>One solution that can help is an external air heat exchanger

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.

Re: Efficient method to capture carbon dioxide from the atmosphere

#90

Post by malfist »

lokar wrote: post #74
_yb2s wrote: post #67

Earlier quoted context omitted.

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 hea…

Really? Wow, I try to keep my place at 500-600, without that much effort.

I find it extremely unlikely that homes are routinely at 2000-3000 ppm. That is extremely high and would mean multiple people in a small area with no air exchange for a long while.

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.

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