Anyone selling house-size CO2 absorbers to keep CO2 in my house to more like pre-industrial 200ppm rather than the 800ppm that's more common of house air in cities?
You'd only need a few hundred grams of triethanolamine if you regenerate it several times a day (with a vent to outdoors), but there are probably some spill risks and maybe mist. Soda-lime is cheaper but requires inconveniently high temperatures to regenerate, which probably result in unwanted emissions requiring mitigation as well as too much energy use. Regular lime (without the soda) avoids the emissions but takes a month to absorb the carbon dioxide. Alkali-metal oxides, hydroxides, and peroxides like those discussed in the article are extremely compact and fast-acting but even more difficult to regenerate. Bioreactors with spirulina or chlorella have been tested successfully but require hundreds of kilograms of algae per person and are finicky, being prone to infection. I think it's eminently possible at a technical level, but at a political level, basically you can only do this kind of experimentation if you live in China.
An actually physically feasible thing you can do is to whitewash some walls. You need to apply about 7kg of whitewash per person per week, so you are going to need a lot of walls, on the order of 400 square meters of wall per person, because the whitewash is regular lime, not soda lime. (If you're daring enough to dope your whitewash with lye, maybe you can get by with less wall area, but you still need to keep applying the whitewash at 7kg per person per week.) You can make them out of plywood, sheetrock, sheet metal, old sheets, whatever whitewash will stick to. After a few months you will need to start throwing out 14kg of fully cured whitewash per person per week, or calcining it to make fresh whitewash. Try to get whitewash with as little chalk in it as possible.
At this small scale, dozens of kilograms per week, you might be able to calcine the used whitewash in a pottery kiln on your patio. Beware that electric kilns generally do not handle reducing atmospheres well. I'm not sure if carbon dioxide would be too much for them. I think it should be fine, but don't blame me if you ruin your Kanthal.
A caution I should have thought to include: if you do this to remove the carbon dioxide you exhale, you need to make sure you have enough ventilation that you don't asphyxiate. In the absence of carbon dioxide to tell you to seek fresh air, you won't notice the oxygen levels dropping; you'll just get stupid, then lose consciousness, then die. Homemade rebreathers have a high fatality rate. I don't think such good sealing is likely at the scale of an entire house unless it's literally underwater or something. But keep it in mind.
Honest question: Why would you want to? The average CO2 concentration in your lungs is something like 20,000 ppm, so it doesn't matter much whether ambient CO2 is at 200ppm or 800ppm. Other aspects of air quality do matter, but I'm highly skeptical about the value of capturing CO2 in your house.
Are you not familiar with any of the research linking high CO2 with harmed cognition and harmed alertness? It is manifest at as low as 800 ppm, certainly at 1000 ppm, and personally even at 600 ppm for me. There is good reason to want the preindustrial level that humans lived with for almost their entire history.
Yes, I've seen such research, but I am highly skeptical, to put it very mildly. This actually being the case is simply implausible from the physiological perspective, considering the very high (and constantly changing) concentration of CO2 in the lungs and in the bloodstream. Early research with Navy submariners was consistent with this -- no detectable impairment below 1% (10,000 ppm) and clear impairment at 3-4%. Later long term studies with 0.5% exposure (5,000 ppm) also found nothing. I put the recently popular research showing cognitive impairment as low as 600 ppm in the same mental niche as vitamin megadosing -- underpowered, low quality research with no basis in human physiology.
That said, CO2 can often serve as an easily measurable proxy for stuffy air, which can contain particulates, formaldehyde and other organic exhalations which may actually have some effect (psychological, if nothing else). But this just calls for ventilation and air filtering, not CO2 scrubbing.
It is me who is skeptical of extremely healthy test subjects in their early 20s being used to define what's healthy for the population at large. As for vitamin dosing, there is most certainly an optimal dose and form of each vitamin, somewhere between its lower and upper limits.
Offices have high ventilation but also high CO2, and the effect shows clearly in a meeting room, putting people to sleep.
The average human exhales about 1 kilogram of carbon dioxide on an average day.
Carbon makes up 27.3% of that: ~300 grams. That's the weight of a smartphone.
The logistics would be complicated, average plants aren't going to be accumulating so much mass so quickly. You would need aquariums full of algae. Just isn't worth it.
Probably way more important than lowering the CO2 is getting rid of PM2.5/PM10.
Rooftops nowadays are best used to mount solar panels. Some system growing circulating algae, be it on the roof or on the sun drenched walls while doable would have way higher at least the operating costs. Clining is one thing. If you live in the area with below zero temperatures either you drain the system or invest even more in some glasshouse, maybe thermal isolation at night or heating.
As mentioned by others, there are chemical solutions.
I mean that’s really low. If it’s cold outside you’re probable just wasting energy keeping your spaces warm with so much ventilation, making the problem worse in the process.
I think measuring CO2 is mostly only useful as a proxy for how well you are ventilating (which is correlated to the health of your air unless outside air is filled with ie small particles or smog), and when you measure 800 ppm it is more than adequate. 800 is not doing anything to the body (that we know of).
Do you want to use chemicals and devices that make the climate problem worse just to lower the CO2 concentration in your personal space? Sure it’s a small effect but not something we can all do.
IIRC 1000 is where it starts having easily detectable negative effects on human cognition, which means it has less easy to detect negative effects on human cognition at numbers lower than that.
If you own a CO2 sensor you know that even at 5000 it’s not “easily detectable”… I know what is said about cognitive abilities and CO2 but I guess that’s hard to feel yourself. Moreover I doubt those results. Humans start to die at 10%, that’s (if I’m not mistaken) 100.000 ppm.
Ive had a CO2 sensor for years, take it with me usually. In the beginning I was quite shocked, but I’m starting to doubt all the bad things said about CO2 over 1000-1500 ppm now…
Air you breathe out is around 40 thousand ppm (and higher during exertion), and the air in the lungs isn't completely replaced every breath - I doubt there's much measurable difference at the actual alveoli at the levels we're talking about. You'll probably get more of a difference if you're breathing deeper and faster, or just got up to get a coffee or similar.
And interestingly there are studies that show that breathing in air up to 3% co2 (30k ppm) "did not substantially impair either cognitive and motor performance" [0]
I've found the same. And thinking it through, I can't come up with a mechanism for how a few more CO2 molecules bopping around in a sea of nitrogen and oxygen changes anything about how my lungs exchange the CO2 in my body with air around me. These counts are ppm, nothing!
CO2 enters the blood in the body, it comes out of the lungs. If you breath too hard you loose too much CO2 and your blood pH will go up. That’s why you breathe into a bag when hyper ventilating, to keep that precious CO2 in.
