Trees respire. They breath in and out. At night time, many trees emit more CO2.
And trees don't exist in isolation as these napkin calculation articles consider them (spherical cows and all that). Every single tree on earth relies on mycorrhizal fungi for the vast majority of its nutrients. Fungi break things down release CO2.
Most of our oxygen comes not from forest but from oceans (specifically from phytoplankton, algae, and photosynthetic bacteria). Between 50-80% of it in fact. Likewise, most of the CO2 that has been captured has been captured by the ocean not by forests. About 25-30% of all human emissions have been captured by the ocean.
Forests (and grasslands) are tremendously important for ecosystems and our health but I think this focus on CO2 and oxygen is simply misleading. If that's your concern you should really be focusing on the ocean. Which IMO is in an even more dire strait than our forests
Forests and grasslands are critical for the climate because of the carbon they lock away. So long as the plants stay alive, they store carbon in the cellulose structures of roots and stems.
Conserving these ecosystems is less about their daily respiration and more about keeping existing out of the atmosphere. It's a defensive strategy. Not "carbon capture" per se but more "avoid loosing the carbon we've already captured". We're interested in the sink, not the flow.
Of course when the plant dies and decomposes or burns up, it all goes back. Long term, it's almost exactly net zero. The ONLY way to use plants for long term carbon sequestration is to make sure that plant matter gets treated or literally buried so that aerobic microbes and fungi can't break it down.
The ocean breathes in and out too. Very little carbon sinks down to the sea floor. The ocean does happen to absorb a lot of CO2, but that's from acidification rather than photosynthesis.
Yes agreed. But the organisms breath "out" much more oxygen than anything else. And yes ocean acidification is both what's driving a massive crisis and saving us from the full impacts of our CO2 output. It's not a pretty picture
You could induce artificial algea blooms. All that needs is iron and light + water soluble co2 and / or o2. If you are greedy you pump light down into the depths , go cubic instead of quadratic?
Intentional oceanic iron fertilization (OIF) is actually well-studied. Unfortunately it carries risks of ecological disruption and can lead to deoxygination (dead zones). Which would long-term hinder our ability to repeat this. It also often leads to methane and nitrous oxide emissions which are both very potent (though shorter lived) greenhouse gasses
Forests do net sequester carbon. But if you want to really sock away the carbon you harvest the trees and pyrolize it. It will give you energy (heat) you can use and elemental carbon (biochar). You could bury that a few feet under or innoculate it with microorganisms and work it into fields. Carbon in that form will sit in the soil for hundreds of years. Thousands or millions if you bury it.
I mean technically we already do this: renewable plantation timber is a widespread operation (also why I get kind of annoyed at YouTubers talking about how great the timber is in old homes - yes it's great because it was logged from 50 year old old growth forests and now they're all gone because we cut them down).
You can just buy engineered wood products that are much stronger than any old growth lumber. My family lake house built in 1970 has three gluelam trusss beams that support the roof. There are even better engineered wood products available these days.
> Most of our oxygen comes not from forest but from oceans (specifically from phytoplankton, algae, and photosynthetic bacteria). Between 50-80% of it in fact.
That fact checks out: about 70% of the earth's surface is covered by oceans. It follows that most photosynthesis, thus oxygen comes from oceans.
it looks like i'm guilty of having never really thought and done some research about this and i'm a bit ashamed to admit i fell in this trap and used to think forests and trees are the most important pieces in the system.
I don't get why media has been fixating so much on trees and forests (Amazonia!) without even mentioning ocean's role in this.
My opinion is largely colored by the IPCC Ocean/Cryosphere report. I closely followed each IPCC report and this was by far the most "doomer" of the special reports released by the IPCC. Some highlights:
- ocean acidification and deoxygination (imo the most alarming and underdiscussed doomsday scenarios of climate change): About 0.5 to 3.3% of dissolved oxygen had been lost between 1970 and 2010 which has led to the rapid expansion of Oxygen Minimum Zones ("dead zones"). Acidity has increased by 30 to 40% and at a clearly accelerating rate. That's 10 times faster acidification than at any other point in the last 300 million years
- they estimated oceans had absorbed about 90% of "excess global heat" and their ability to absorb is slowing rapidly
- up to 99% of permafrost could melt by 2100. Permafrost melting was completely unanalyzed in the 1.5C report due to lack of good data
Forests on the other hand have shown surprising resilience. And, if they survive the impending destabilization, they might in the long term (I mean looong term) even benefit from increased CO2 concentrations as they historically have.
PS the IPCC reports are more accessible than people realize. Even the technical reports are often not much more difficult to parse than the policymaker reports meant for the general public. I'd quite recommend giving them a try
Has a pretty good overview. But in brief: Changes in biosphere due to heat and decreasing pH balance due to increased CO2 can leave species unable to adapt fast enough causing deaths.
It can also cause adaptations to go haywire like temperature dependent sex determination where the ratio of male to females in eggs is set by ambient temperatures, skewing breeding population gender too much in one direction.
wholesale destruction of almost every biome. Overfishing (where 'fish' means anything that swims) with methods that destroy both the fish and the ecosystem-- have you ever considered what a trawler net destroys as it is dragged over the bottom of the seabed?
(Author here) I've added the word "indoor" to the title, which will hopefully make it harder to miss that this is not about climate change or carbon sequestration.
As somebody who works on carbon dioxide removal at planetary scale, I was excited about your article about indoor air… but nearly every comment here seems to want to talk about the changing climate!
I don't want to stop anyone from debating the merits of using plants for carbon sequestration. But the ones explaining why my article did such a bad job of explaining those merits are kind of eye-opening, yes.
Same here, I wonder if there’s some missing conversation in the hacker news community about climate. Seems like some people really wanna talk about it even off topic.
I get to spend plenty of time working on climate already, so I was particularly interested in the indoor air pieces. Someone below suggested there’s a ventilation system alternative. I wonder what you could do with a little miniaturized direct air capture machine. Probably crazy energy inefficient and whatnot, but maybe a cool experiment.
Long ago I ordered an indoor algae system from a couple of CMU PhDs. It is very cool, it looks cool and has a nice water flow backgroundy sound, the algae grows quickly, allegedly doing the co2 consumption equivalent of 20 houseplants. Space efficient! But immaterial relative to human co2 production.
If it was circa 2010 I think I remember those guys. It was partly for people who wanted fresh algae smoothies?
How big a tank do you need to remove 1 kg of CO2 per day…
In my apartment I’m running 2 AirGradients. One in the bedroom and one in the main room.
Awesome little devices, btw. They monitor temp, humidity, CO2, TVOC, and various particulate matter metrics. They expose prometheus metrics for scraping, and can be configured through a REST API to never phone home. I’ve got grafana alerts set up to push notifications to my phone when things get to “bad” ranges.
Anyway, the big issue is that the only way I’ve found to clear CO2 and TVOC is to open windows. However, windows open means increased humidity and particulate matter, even with air purifiers running aggressively. Also, opening windows at night kind of sucks for obvious reasons. In the summer it also sucks to lose that cool air.
I found these devices you put in your window, sort of like window fans, that can open/close airflow completely, but they don’t fit in my side-opening windows.
The only other thing I can think of is some kind of home automation with a little gadget that cracks the window until the metrics are back in an acceptable range. My AC unit unfortunately does not have a mode where it takes air from outside. I know some things like this exist for opening blinds, etc, but haven’t gone down that rabbit hole yet.
Challenging in an apartment setting, but the state of the art here is an Energy Recovery Ventilator (ERV) installed in your home to continuously refresh the air.
Honestly this seems like a super long-shot but at least semi-plausible avenue for putting DAC on the sort of learning curve that took lithium batteries from "high-end camcorder" to utility-scale storage.
What does DAC stand for in this context? My brain is stuck on Digital-Analog Converter and I'm pretty sure we aren't talking about using those, but if so I'm even more fascinated by this discussion
That said, it seems intrinsically wrong-headed to me, a kind of trojan-horse technology for getting everyone else to spend money cleaning up the mess the polluter keeps spilling out into the commons.
Every dollar spent trying to extract low-concentration CO2 from ambient atmosphere is probably better-spent trying to grab it from a high-concentration source (e.g. exhaust, smokestacks) before it gets diluted.
You can sequester carbon with plants, but you can't let them decay or it will release it back into the environment (it's called the "carbon cycle" of a reason).
A startup has solved this problem the following way (for example): grow microalgae near a very dry desert, and bury it in trenches. It never decays and thus never releases CO2 due to lack of water.
Basically, we'd have to permanently stick it back underground again.
You don't necessarily have to bury the plants to sequester the carbon. A lot of oceanic carbon just sinks to the bottom and is eventually covered over, especially near estuaries that spew silt.
To me, this is great that demonstrates how ridiculous carbon capture and storage is. I just can't imagine us paying to do something like this at scale, when we have a much more straightforward alternative: Stop burning fossil fuels, and use clean energy instead. Right? Like why even both going through the effort of carbon capture, when we're still going to have to stop burning fossil fuels anyways, in order to fix the climate?
Exactly. Getting other people to behave a certain way is different from a team going off and doing something, like marine cloud brightening to raise the Earth's albedo.
Think of it like a battery. We pour sunlight into the plant at one end and then we take this gasoline from the other side of the battery and burn it. The end-result is that we have full fuel cycle powered by the Sun.
This kind of battery is useful. All human hearts together produce about the same power in beating as a Falcon 9 in the final stage but you can't use hearts like that.
Just popping in here to say that the IPCC has no model for a stable climate that doesn’t involve removing many billion tons of carbon dioxide alongside complete decarbonization, so unfortunately simply stopping emissions at this point isn’t enough. Some level of carbon dioxide removal is required to maintain a stable climate.
But I think the real problem is that we’re pushing carbon into the atmosphere that has hitherto been sequestered for upwards of millions of years deep underground and under the oceans. I.e., nothing that’s been a part of a plant, or involved in any ecosystem, on the surface or underwater for a very long time.
Do we even have enough land on the planet to grow enough plants to sequester all this additional carbon? If we reforested the whole earth, would that be enough (and over what time period)? Can enough plants grow in the oceans without turning them all into a giant algal bloom?
I don’t know but I certainly would like to see the maths that answers those questions.
But the analysis rests on 0 ventilation, which doesn’t work at all.
I think the main thing to keep in mind is plants really aren’t industrial carbon sinks. They were never evolved to be. Their biological functions are about growing and thriving, and the soil they grow in are net carbon producers.
In a broad open system, they are net carbon sinks over the long term. But any analysis in a closed system is bound to fail, you don’t even need numbers to know intuitively this won’t work.
Crack open a window. Run a fan. Have plants because they have many benefits. Reducing CO2 around you meaningfully isn’t one of them.
Related tangent: I recently bought an inexpensive consumer CO2 monitor for under $40. It confirmed my suspicion about air quality in my home office; after a few hours, levels rise above 1000ppm unless I leave a window partway open. Mid-afternoon mental fog cleared right up.
I find it especially a problem at night. Started out leaving the window open in the bedroom, but that lets in noise and wind. Current solution is leave the bedroom door open and have a window cracked open in another room. It seems to work out really well as measured by my CO2 monitor.
I mentioned this elsewhere here, but a friend told me that it’s not only CO2 that leads to that mental fog, but it’s also the VOCs in the air too. All that gets cleared out by having an open window.
I did some of the napkin math on algae a couple years ago... The fun realization is that the physical carbon has to go somewhere. So if we're trying to sequester the average american's 14 tons a year of carbon or whatever it is these days, that means you're going to have at least 14 tons of dead algae to deal with. (And a lot more weight if the algae isn't dehydrated.). That's a lot of dead algae, which demonstrates the difficulty of the problem...
In other news, have you considered ditching your car and becoming a vegetarian?
Not emitting the carbon in the first place is much easier!
I have had the same impulse to reduce CO2 to about half(Close to pre-industrial levels 200 to 280 ppm). Of course my first thought was CO2 scrubbing by chemical means, plants are obviously silly. But was convinced not to pursue given the fact that
1. Cognitive decline starts above 600 ppm according to air quality studies.
> Cognitive decline starts above 600 ppm according to air quality studies.
According to an older, small study of short duration (Mendell and Fisk at LBNL), the results of which are heavily disputed. Since 600 ppm isn't too much higher than the current level of 400+ ppm, this study is the one most commonly cherry-picked in order to instill fear in people that climate change is getting ready to damage our brains.
Just for comparison, the CO2 composition of exhaled breath is around 40,000 ppm (~4%), which is the reason that it's totally normal for CO2 concentrations in enclosed spaces like bedrooms and classrooms to reach several thousand ppm. CO2 levels in submarines average well over ten times atmospheric, and routinely reach well over 10,000 ppm.
In none of these situations have researchers found a clear and convincing long-term impact on cognitive performance. Short term yes, but our bodies and brains adapt. Some compensations appear incomplete, but others are possibly sufficient to incur health benefits from high CO2 concentrations. Notably, high CO2 levels cause blood vessels to dilate, increasing the flow of oxygen to tissues including the brain. There is in fact ongoing research into medical therapies using concentrated CO2.
As far as I am aware astronauts that were experiencing concentrations above 3000 ppm for presumably weeks to months reported mental viscosity(brain fog) and headaches.
A definite global health concern is the increase in blood bicarbonate levels which chronically impact available calcium and phosphorus levels.
Additionally the higher CO2 levels increase plant growth which impacts the plants mineral absorption, there are less naturally occurring micronutrients in our crops than there used to be just 20 years ago.
These things are far from apocalyptic but have to be taken into account going forward when updating existing food enrichment programs.
I believe you are conflating hyperbaric oxygen treatment with CO2. I could not find references to concentrated CO2 treatments. While exhaled air is about 4% CO2, breathing air with CO2 at these concentrations is immediately dangerous.
Additionally I do not believe that has been any study comparing relative cognitive performance of continuously operating in different low concentration environments, all studies focus on short term, high concentrations and for obvious practical reasons treat the atmospheric level as the baseline.
As far as we know operating in pre-industrial levels of CO2 280ppm improves, deteriorates or has no effect on cognition compared to modern levels.
The vast interior of the world's oceans are a nutrient desert. It has been proposed to grow algae by spreading silt, the same way that Saharan winds do.
I’ve always wanted to jam on how to create an indoor carbon dioxide removal system. (I think that’s what this article is about but perhaps it’s indirectly about the changing climate)
1 kg per day of material adds up fast but that assumes zero ventilation. If I simply wanted a system to keep my office below 500 ppm all day, I wonder how much material that would produce.
Anyone ever build a little carbon dioxide zapping system for indoor air quality? I’ve also heard that indoor CO2 isn’t actually all that bad but it’s VOCs that are what make me feel sluggish.
That’s cool. Is that something that you’ve built or installed?
Even if that is a better solution, I am personally curious about an indoor carbon dioxide zapper, since what I work on is carbon dioxide removal at planetary scale.
I haven't installed one yet, but plan to in my house. I'll probably end up buying an assembly, but they seem pretty spendy for what is really a very cheap BOM.
Yes, except parent is correct. Physcial and chemical mean very different and specific things in this context.
Calling photosynthesis a physical reaction is flatly incorrect no matter how you want to look at it. It is a physics reaction, sure, but "physical reaction" specifically means a Newtonian mechanical, reversible process at the macro scale.
A "chemical reaction" specifically means a (trivially) irreversible quantum/atomic reaction involving chemical bonds at the atomic/molecular scale.
Another way of looking at this is that--while it doesn't have to be edible--you have to grow plant matter inside your house at a rate equivalent to what everyone in there consumes as food.
Even if you found like an algae or something that converted CO2, light, and water into fat, 2400 kCal would be ~300g per person, per day, or not too short of a normal package of butter.
It might not be clearly worded, but 132.5 watts is the power used by 2 incandescent light bulbs, whereas 918 watts is the power present in the light produced by 765 light bulbs. The factor of 50 comes from the fact that incandescent lightbulbs are only ~2% efficient at turning power into light.
I don't really understand this. First of all, you can just weigh the plant, and tell how much CO2 it has captured, right?
Second of all, what does it matter how much CO2 I produce? What's harmful is the additional CO2 that goes into the atmosphere for burning fossil fuels. All other CO2 is just in the same cycle that's been happening for ever.
EDIT: My child comment is dead and vouching doesn't resurrect it, but now the post makes sense, thanks for the clarification.
Because the author of the piece is worried about the CO2 levels in their home, not about global warming. (well maybe they are worried about global warming too, but that's not what this is about)
no, we are useing solar PV to eliminate the excess carbon bieng added to the atmosphere, and plants, rocks, and many other natural processes will return CO² levels to a more moderate level.
Article is not about global atmospheric or climate phenomena, nor civilization scale industrial processes. It's about the CO^2 levels in your room due to your breathing.
but since I live in a drafty farmhouse up on a windy hill beside the ocean, my room air and the atmosphere as whole have very similar compositions, and I will continue to
treat conversations about both, the same as well.
Getting CO2 back to preindustrial levels by natural processes may take 100,000 years, IIRC. There will be some drawdown, but the ocean surface waters will become more saturated with carbon and that will stall. Over a longer time scale, CO2 will be pumped down into the deeper ocean. The true drawdown will require mineralization and precipitation as calcium carbonate, a slow process. The fossil fuel CO2 emitted each year corresponds to the calcium added to the ocean by erosion over about 100 years.
This seems trivial: if you could add enough plants to your room to reduce CO2, we could easily do the same thing at planet-scale and global warming wouldn't be an issue.
Sadly I am a bit hopeless about climate change. Even if every person on earth dropped everything and started making biochar to be buried it would not sequester enough carbon to make a difference.
Hi! I work a lot with carbon dioxide removal systems. If every person on Earth dropped everything and started making biochar, it would definitely make a huge difference. Yes, we add a lot of carbon dioxide to the air of a year, but it’s doable to remove it. Humanity has taken on much bigger challenges before and succeeded. Now that’s not to say that it’s likely. I think it’s entirely unlikely that we avert the worst impacts of climate change unless something big changes. Thankfully, we get to choose what to work on every day, and I get to choose to work on that alongside inspiring people.
(and yes, this isn’t what the article is about, but it seems like it’s what everyone is responding to)
> Humanity has taken on much bigger challenges before and succeeded.
Feel free to list them, we're basically reverse terra forming ourselves out of existence at that point, I don't think we've done anything even remotely close to that scale in such time frame
During World War II, the United States spent 40% of its GDP on the war. So we can spend big on things when we decide to.
That would be the equivalent of $12 trillion per year today, and we would clean up the climate in a jiffy with that. It would be a huge opportunity for job creation, manufacturing, innovation. It’s wild as a society we’ve convinced ourselves that stabilizing the climate is a cost instead of a massive opportunity.
> During World War II, the United States spent 40% of its GDP on the war. So we can spend big on things when we decide to.
The United States wasn’t the only one spending that much on war, that’s why we were able to do so. What incentive do countries have to spend money on carbon capture? Any money spent on that is money not being invested in generating more wealth, so there is zero incentive to move first, you’ll just fall behind and become economically and potentially physically vulnerable.
If we could convince all major powers to all spend money on carbon capture, it would work great. That’s a simple ask but an almost impossible thing to negotiate.
Otherwise, there’s no incentive to act first, there’s actually great incentive to not act first.
I desperately wish the world could work together on this problem, but I don’t see why we would given the situation.
Trees respire. They breath in and out. At night time, many trees emit more CO2.
And trees don't exist in isolation as these napkin calculation articles consider them (spherical cows and all that). Every single tree on earth relies on mycorrhizal fungi for the vast majority of its nutrients. Fungi break things down release CO2.
Most of our oxygen comes not from forest but from oceans (specifically from phytoplankton, algae, and photosynthetic bacteria). Between 50-80% of it in fact. Likewise, most of the CO2 that has been captured has been captured by the ocean not by forests. About 25-30% of all human emissions have been captured by the ocean.
Forests (and grasslands) are tremendously important for ecosystems and our health but I think this focus on CO2 and oxygen is simply misleading. If that's your concern you should really be focusing on the ocean. Which IMO is in an even more dire strait than our forests
Forests and grasslands are critical for the climate because of the carbon they lock away. So long as the plants stay alive, they store carbon in the cellulose structures of roots and stems.
Conserving these ecosystems is less about their daily respiration and more about keeping existing out of the atmosphere. It's a defensive strategy. Not "carbon capture" per se but more "avoid loosing the carbon we've already captured". We're interested in the sink, not the flow.
Of course when the plant dies and decomposes or burns up, it all goes back. Long term, it's almost exactly net zero. The ONLY way to use plants for long term carbon sequestration is to make sure that plant matter gets treated or literally buried so that aerobic microbes and fungi can't break it down.
The ocean breathes in and out too. Very little carbon sinks down to the sea floor. The ocean does happen to absorb a lot of CO2, but that's from acidification rather than photosynthesis.
Yes agreed. But the organisms breath "out" much more oxygen than anything else. And yes ocean acidification is both what's driving a massive crisis and saving us from the full impacts of our CO2 output. It's not a pretty picture
You could induce artificial algea blooms. All that needs is iron and light + water soluble co2 and / or o2. If you are greedy you pump light down into the depths , go cubic instead of quadratic?
Intentional oceanic iron fertilization (OIF) is actually well-studied. Unfortunately it carries risks of ecological disruption and can lead to deoxygination (dead zones). Which would long-term hinder our ability to repeat this. It also often leads to methane and nitrous oxide emissions which are both very potent (though shorter lived) greenhouse gasses
Forests do net sequester carbon. But if you want to really sock away the carbon you harvest the trees and pyrolize it. It will give you energy (heat) you can use and elemental carbon (biochar). You could bury that a few feet under or innoculate it with microorganisms and work it into fields. Carbon in that form will sit in the soil for hundreds of years. Thousands or millions if you bury it.
I mean technically we already do this: renewable plantation timber is a widespread operation (also why I get kind of annoyed at YouTubers talking about how great the timber is in old homes - yes it's great because it was logged from 50 year old old growth forests and now they're all gone because we cut them down).
You can just buy engineered wood products that are much stronger than any old growth lumber. My family lake house built in 1970 has three gluelam trusss beams that support the roof. There are even better engineered wood products available these days.
> Carbon in that form will sit in the soil for hundreds of years. Thousands or millions if you bury it.
And what is the scale that global climate change works on?
Trees do jack shit for carbon on the scale that is important.
> Most of our oxygen comes not from forest but from oceans (specifically from phytoplankton, algae, and photosynthetic bacteria). Between 50-80% of it in fact.
That fact checks out: about 70% of the earth's surface is covered by oceans. It follows that most photosynthesis, thus oxygen comes from oceans.
it looks like i'm guilty of having never really thought and done some research about this and i'm a bit ashamed to admit i fell in this trap and used to think forests and trees are the most important pieces in the system.
I don't get why media has been fixating so much on trees and forests (Amazonia!) without even mentioning ocean's role in this.
Click bait sells, therefore outrage sells. And how do you film an ocean absorbing(or not) CO2.
But you can film people cutting trees, and protests, and you can blame companies.
And the average person won't understand much about the chemistry of the oceans, the average person can barely read.
(UN literacy numbers are the equiv of a grade 6 reading capability. And again, average grade 6, not bright students).
> Which IMO is in an even more dire strait than our forests
I think you are probably right, but could you kindly elaborate and provide more details? Very curious to hear your view and learn more.
My opinion is largely colored by the IPCC Ocean/Cryosphere report. I closely followed each IPCC report and this was by far the most "doomer" of the special reports released by the IPCC. Some highlights:
https://www.ipcc.ch/srocc/Forests on the other hand have shown surprising resilience. And, if they survive the impending destabilization, they might in the long term (I mean looong term) even benefit from increased CO2 concentrations as they historically have.
PS the IPCC reports are more accessible than people realize. Even the technical reports are often not much more difficult to parse than the policymaker reports meant for the general public. I'd quite recommend giving them a try
https://science.nasa.gov/earth/explore/the-ocean-and-climate...
Has a pretty good overview. But in brief: Changes in biosphere due to heat and decreasing pH balance due to increased CO2 can leave species unable to adapt fast enough causing deaths.
It can also cause adaptations to go haywire like temperature dependent sex determination where the ratio of male to females in eggs is set by ambient temperatures, skewing breeding population gender too much in one direction.
wholesale destruction of almost every biome. Overfishing (where 'fish' means anything that swims) with methods that destroy both the fish and the ecosystem-- have you ever considered what a trawler net destroys as it is dragged over the bottom of the seabed?
And now deep-sea mining.
If the ocean is the main hero there, why is the forest still important to our health?
Rainfall
And at least the forest soil has the same amount of carbon stored.
“I couldn’t live with so many trees. They suck up all the oxygen.”
(Author here) I've added the word "indoor" to the title, which will hopefully make it harder to miss that this is not about climate change or carbon sequestration.
As somebody who works on carbon dioxide removal at planetary scale, I was excited about your article about indoor air… but nearly every comment here seems to want to talk about the changing climate!
I don't want to stop anyone from debating the merits of using plants for carbon sequestration. But the ones explaining why my article did such a bad job of explaining those merits are kind of eye-opening, yes.
Same here, I wonder if there’s some missing conversation in the hacker news community about climate. Seems like some people really wanna talk about it even off topic.
I get to spend plenty of time working on climate already, so I was particularly interested in the indoor air pieces. Someone below suggested there’s a ventilation system alternative. I wonder what you could do with a little miniaturized direct air capture machine. Probably crazy energy inefficient and whatnot, but maybe a cool experiment.
Long ago I ordered an indoor algae system from a couple of CMU PhDs. It is very cool, it looks cool and has a nice water flow backgroundy sound, the algae grows quickly, allegedly doing the co2 consumption equivalent of 20 houseplants. Space efficient! But immaterial relative to human co2 production.
If it was circa 2010 I think I remember those guys. It was partly for people who wanted fresh algae smoothies? How big a tank do you need to remove 1 kg of CO2 per day…
OK, so we can’t use plants.
What are the options, then?
In my apartment I’m running 2 AirGradients. One in the bedroom and one in the main room.
Awesome little devices, btw. They monitor temp, humidity, CO2, TVOC, and various particulate matter metrics. They expose prometheus metrics for scraping, and can be configured through a REST API to never phone home. I’ve got grafana alerts set up to push notifications to my phone when things get to “bad” ranges.
Anyway, the big issue is that the only way I’ve found to clear CO2 and TVOC is to open windows. However, windows open means increased humidity and particulate matter, even with air purifiers running aggressively. Also, opening windows at night kind of sucks for obvious reasons. In the summer it also sucks to lose that cool air.
I found these devices you put in your window, sort of like window fans, that can open/close airflow completely, but they don’t fit in my side-opening windows.
The only other thing I can think of is some kind of home automation with a little gadget that cracks the window until the metrics are back in an acceptable range. My AC unit unfortunately does not have a mode where it takes air from outside. I know some things like this exist for opening blinds, etc, but haven’t gone down that rabbit hole yet.
Anyone find a good way to solve this problem?
Challenging in an apartment setting, but the state of the art here is an Energy Recovery Ventilator (ERV) installed in your home to continuously refresh the air.
"Residential CO2 scrubber" seems like the sort of gadget eccentric rich people would buy, sort of a distributed DAC system.
Honestly this seems like a super long-shot but at least semi-plausible avenue for putting DAC on the sort of learning curve that took lithium batteries from "high-end camcorder" to utility-scale storage.
What does DAC stand for in this context? My brain is stuck on Digital-Analog Converter and I'm pretty sure we aren't talking about using those, but if so I'm even more fascinated by this discussion
I'm guessing: https://en.wikipedia.org/wiki/Direct_air_capture
That said, it seems intrinsically wrong-headed to me, a kind of trojan-horse technology for getting everyone else to spend money cleaning up the mess the polluter keeps spilling out into the commons.
Every dollar spent trying to extract low-concentration CO2 from ambient atmosphere is probably better-spent trying to grab it from a high-concentration source (e.g. exhaust, smokestacks) before it gets diluted.
You can sequester carbon with plants, but you can't let them decay or it will release it back into the environment (it's called the "carbon cycle" of a reason).
A startup has solved this problem the following way (for example): grow microalgae near a very dry desert, and bury it in trenches. It never decays and thus never releases CO2 due to lack of water.
Basically, we'd have to permanently stick it back underground again.
You don't necessarily have to bury the plants to sequester the carbon. A lot of oceanic carbon just sinks to the bottom and is eventually covered over, especially near estuaries that spew silt.
To me, this is great that demonstrates how ridiculous carbon capture and storage is. I just can't imagine us paying to do something like this at scale, when we have a much more straightforward alternative: Stop burning fossil fuels, and use clean energy instead. Right? Like why even both going through the effort of carbon capture, when we're still going to have to stop burning fossil fuels anyways, in order to fix the climate?
If you can find a way to get other people to stop burning carbon, let us know.
I know that sounds dismissive but I mean it. There's no magic wand.
Exactly. Getting other people to behave a certain way is different from a team going off and doing something, like marine cloud brightening to raise the Earth's albedo.
Carbon capture is already done at scale because CO2 is commercially valuable.
The proposed carbon storage is permanent in the form of carbonates. This is a variant of the Solvay process used to make washing powder.
Chalk cliffs were once the shells of sea creatures. That's a whole load of sequestered carbon right there.
I was under the impression that commercial CO₂ was produced by mining chalk.
We'll have to do both I imagine by the time we realize it's too late.
Think of it like a battery. We pour sunlight into the plant at one end and then we take this gasoline from the other side of the battery and burn it. The end-result is that we have full fuel cycle powered by the Sun.
This kind of battery is useful. All human hearts together produce about the same power in beating as a Falcon 9 in the final stage but you can't use hearts like that.
Just popping in here to say that the IPCC has no model for a stable climate that doesn’t involve removing many billion tons of carbon dioxide alongside complete decarbonization, so unfortunately simply stopping emissions at this point isn’t enough. Some level of carbon dioxide removal is required to maintain a stable climate.
The BBC did this in their 2012 documentary mini-series "How to Grow a Planet" with Iain Stewart. It was a lovely series; I highly recommend it.
OK, this was fun.
But I think the real problem is that we’re pushing carbon into the atmosphere that has hitherto been sequestered for upwards of millions of years deep underground and under the oceans. I.e., nothing that’s been a part of a plant, or involved in any ecosystem, on the surface or underwater for a very long time.
Do we even have enough land on the planet to grow enough plants to sequester all this additional carbon? If we reforested the whole earth, would that be enough (and over what time period)? Can enough plants grow in the oceans without turning them all into a giant algal bloom?
I don’t know but I certainly would like to see the maths that answers those questions.
Or… you could go outside?
But the analysis rests on 0 ventilation, which doesn’t work at all.
I think the main thing to keep in mind is plants really aren’t industrial carbon sinks. They were never evolved to be. Their biological functions are about growing and thriving, and the soil they grow in are net carbon producers.
In a broad open system, they are net carbon sinks over the long term. But any analysis in a closed system is bound to fail, you don’t even need numbers to know intuitively this won’t work.
Crack open a window. Run a fan. Have plants because they have many benefits. Reducing CO2 around you meaningfully isn’t one of them.
Outside it's not much better it's 430 ppm. Supposedly that's not enough to impact cognition.
Related tangent: I recently bought an inexpensive consumer CO2 monitor for under $40. It confirmed my suspicion about air quality in my home office; after a few hours, levels rise above 1000ppm unless I leave a window partway open. Mid-afternoon mental fog cleared right up.
I find it especially a problem at night. Started out leaving the window open in the bedroom, but that lets in noise and wind. Current solution is leave the bedroom door open and have a window cracked open in another room. It seems to work out really well as measured by my CO2 monitor.
I mentioned this elsewhere here, but a friend told me that it’s not only CO2 that leads to that mental fog, but it’s also the VOCs in the air too. All that gets cleared out by having an open window.
Of course, do it with vats of plant cells in floating oceanic CO2 factories. Not in your living room.
Or, just let the oceans recover, let the mollusks return to the bays and shores, let them do their efficient thing.
This guy actually built an algae farm to test how much you need to breathe. https://youtu.be/AAbyUaLN2QA
What if the plants were algae?
Here's a real world* example:
https://www.youtube.com/watch?v=AAbyUaLN2QA
*youtuber
I did some of the napkin math on algae a couple years ago... The fun realization is that the physical carbon has to go somewhere. So if we're trying to sequester the average american's 14 tons a year of carbon or whatever it is these days, that means you're going to have at least 14 tons of dead algae to deal with. (And a lot more weight if the algae isn't dehydrated.). That's a lot of dead algae, which demonstrates the difficulty of the problem...
In other news, have you considered ditching your car and becoming a vegetarian? Not emitting the carbon in the first place is much easier!
I have had the same impulse to reduce CO2 to about half(Close to pre-industrial levels 200 to 280 ppm). Of course my first thought was CO2 scrubbing by chemical means, plants are obviously silly. But was convinced not to pursue given the fact that
1. Cognitive decline starts above 600 ppm according to air quality studies.
2. Levels below 200 ppm are actually dangerous.
> Cognitive decline starts above 600 ppm according to air quality studies.
According to an older, small study of short duration (Mendell and Fisk at LBNL), the results of which are heavily disputed. Since 600 ppm isn't too much higher than the current level of 400+ ppm, this study is the one most commonly cherry-picked in order to instill fear in people that climate change is getting ready to damage our brains.
Just for comparison, the CO2 composition of exhaled breath is around 40,000 ppm (~4%), which is the reason that it's totally normal for CO2 concentrations in enclosed spaces like bedrooms and classrooms to reach several thousand ppm. CO2 levels in submarines average well over ten times atmospheric, and routinely reach well over 10,000 ppm.
In none of these situations have researchers found a clear and convincing long-term impact on cognitive performance. Short term yes, but our bodies and brains adapt. Some compensations appear incomplete, but others are possibly sufficient to incur health benefits from high CO2 concentrations. Notably, high CO2 levels cause blood vessels to dilate, increasing the flow of oxygen to tissues including the brain. There is in fact ongoing research into medical therapies using concentrated CO2.
As far as I am aware astronauts that were experiencing concentrations above 3000 ppm for presumably weeks to months reported mental viscosity(brain fog) and headaches.
A definite global health concern is the increase in blood bicarbonate levels which chronically impact available calcium and phosphorus levels.
Additionally the higher CO2 levels increase plant growth which impacts the plants mineral absorption, there are less naturally occurring micronutrients in our crops than there used to be just 20 years ago.
These things are far from apocalyptic but have to be taken into account going forward when updating existing food enrichment programs.
I believe you are conflating hyperbaric oxygen treatment with CO2. I could not find references to concentrated CO2 treatments. While exhaled air is about 4% CO2, breathing air with CO2 at these concentrations is immediately dangerous.
Additionally I do not believe that has been any study comparing relative cognitive performance of continuously operating in different low concentration environments, all studies focus on short term, high concentrations and for obvious practical reasons treat the atmospheric level as the baseline.
As far as we know operating in pre-industrial levels of CO2 280ppm improves, deteriorates or has no effect on cognition compared to modern levels.
Always seemed like algae or cyanobacteria are the only real nature based options that could be scaled up.
4.6 kg is easily dwarfed by just one of the trees on my lot.
I do like the math though. Gonna be very useful for space colonization
The vast interior of the world's oceans are a nutrient desert. It has been proposed to grow algae by spreading silt, the same way that Saharan winds do.
I’ve always wanted to jam on how to create an indoor carbon dioxide removal system. (I think that’s what this article is about but perhaps it’s indirectly about the changing climate)
1 kg per day of material adds up fast but that assumes zero ventilation. If I simply wanted a system to keep my office below 500 ppm all day, I wonder how much material that would produce.
Anyone ever build a little carbon dioxide zapping system for indoor air quality? I’ve also heard that indoor CO2 isn’t actually all that bad but it’s VOCs that are what make me feel sluggish.
I think what you really want is an Energy Recovery Ventilator. It cycles in fresh air and uses an intercooler to limit the heat and humidity loss.
That’s cool. Is that something that you’ve built or installed?
Even if that is a better solution, I am personally curious about an indoor carbon dioxide zapper, since what I work on is carbon dioxide removal at planetary scale.
I haven't installed one yet, but plan to in my house. I'll probably end up buying an assembly, but they seem pretty spendy for what is really a very cheap BOM.
Bamboo it is.
> Real plants do photosynthesis through a physical process
(nit) it is more accurate to call this a biological process, or chemical process
Saying "physical process" makes me think of inclined planes, free-body diagrams, and EM fields.
It's all physics at the bottom. Nature doesn't have APIs.
Yes, except parent is correct. Physcial and chemical mean very different and specific things in this context.
Calling photosynthesis a physical reaction is flatly incorrect no matter how you want to look at it. It is a physics reaction, sure, but "physical reaction" specifically means a Newtonian mechanical, reversible process at the macro scale.
A "chemical reaction" specifically means a (trivially) irreversible quantum/atomic reaction involving chemical bonds at the atomic/molecular scale.
Ok yeah, that’s fair. I missed the distinction.
> but "physical reaction" specifically means a Newtonian mechanical, reversible process at the macro scale.
Or friction.
Another way of looking at this is that--while it doesn't have to be edible--you have to grow plant matter inside your house at a rate equivalent to what everyone in there consumes as food.
Even if you found like an algae or something that converted CO2, light, and water into fat, 2400 kCal would be ~300g per person, per day, or not too short of a normal package of butter.
Get an HRV/ERV if you can't open a window.
How is it that 132.5 watts is 3 light bulbs but 918 watts is 765 light bulbs? Is there a typo?
It might not be clearly worded, but 132.5 watts is the power used by 2 incandescent light bulbs, whereas 918 watts is the power present in the light produced by 765 light bulbs. The factor of 50 comes from the fact that incandescent lightbulbs are only ~2% efficient at turning power into light.
That one final number is all one needs as a reply for "but they help a little".
I don't really understand this. First of all, you can just weigh the plant, and tell how much CO2 it has captured, right?
Second of all, what does it matter how much CO2 I produce? What's harmful is the additional CO2 that goes into the atmosphere for burning fossil fuels. All other CO2 is just in the same cycle that's been happening for ever.
EDIT: My child comment is dead and vouching doesn't resurrect it, but now the post makes sense, thanks for the clarification.
> what does it matter how much CO2 I produce
Because the author of the piece is worried about the CO2 levels in their home, not about global warming. (well maybe they are worried about global warming too, but that's not what this is about)
no, we are useing solar PV to eliminate the excess carbon bieng added to the atmosphere, and plants, rocks, and many other natural processes will return CO² levels to a more moderate level.
Article is not about global atmospheric or climate phenomena, nor civilization scale industrial processes. It's about the CO^2 levels in your room due to your breathing.
oh no!
realy?
but since I live in a drafty farmhouse up on a windy hill beside the ocean, my room air and the atmosphere as whole have very similar compositions, and I will continue to treat conversations about both, the same as well.
Getting CO2 back to preindustrial levels by natural processes may take 100,000 years, IIRC. There will be some drawdown, but the ocean surface waters will become more saturated with carbon and that will stall. Over a longer time scale, CO2 will be pumped down into the deeper ocean. The true drawdown will require mineralization and precipitation as calcium carbonate, a slow process. The fossil fuel CO2 emitted each year corresponds to the calcium added to the ocean by erosion over about 100 years.
> plants, rocks, and many other natural processes will return CO² levels to a more moderate level.
No... How can you be this delusional? This is cult like behavior: something will fix it somehow, eventually, don't ask about details
This seems trivial: if you could add enough plants to your room to reduce CO2, we could easily do the same thing at planet-scale and global warming wouldn't be an issue.
Sadly I am a bit hopeless about climate change. Even if every person on earth dropped everything and started making biochar to be buried it would not sequester enough carbon to make a difference.
This article isn't about climate change. It's about using houseplants to absorb the CO2 you exhale in your house.
Hi! I work a lot with carbon dioxide removal systems. If every person on Earth dropped everything and started making biochar, it would definitely make a huge difference. Yes, we add a lot of carbon dioxide to the air of a year, but it’s doable to remove it. Humanity has taken on much bigger challenges before and succeeded. Now that’s not to say that it’s likely. I think it’s entirely unlikely that we avert the worst impacts of climate change unless something big changes. Thankfully, we get to choose what to work on every day, and I get to choose to work on that alongside inspiring people. (and yes, this isn’t what the article is about, but it seems like it’s what everyone is responding to)
> Humanity has taken on much bigger challenges before and succeeded.
Feel free to list them, we're basically reverse terra forming ourselves out of existence at that point, I don't think we've done anything even remotely close to that scale in such time frame
During World War II, the United States spent 40% of its GDP on the war. So we can spend big on things when we decide to.
That would be the equivalent of $12 trillion per year today, and we would clean up the climate in a jiffy with that. It would be a huge opportunity for job creation, manufacturing, innovation. It’s wild as a society we’ve convinced ourselves that stabilizing the climate is a cost instead of a massive opportunity.
> During World War II, the United States spent 40% of its GDP on the war. So we can spend big on things when we decide to.
The United States wasn’t the only one spending that much on war, that’s why we were able to do so. What incentive do countries have to spend money on carbon capture? Any money spent on that is money not being invested in generating more wealth, so there is zero incentive to move first, you’ll just fall behind and become economically and potentially physically vulnerable.
If we could convince all major powers to all spend money on carbon capture, it would work great. That’s a simple ask but an almost impossible thing to negotiate.
Otherwise, there’s no incentive to act first, there’s actually great incentive to not act first.
I desperately wish the world could work together on this problem, but I don’t see why we would given the situation.
Agreed! My point is that it’s possible financially, but yes the incentives are messy.
It's going to be ok.