Why Houseplants Cannot Actually Remove Your Daily CO2 Emissions
So you want to use plants to reduce CO₂
I calculated the energy and space required for plants to neutralize human carbon dioxide output. The physics reveals you would need nearly 18 square meters of ferns, thousands of watts of red light, and daily harvests of kilograms of new plant matter. The conclusion is that indoor gardening is ineffective for air quality, and opening a window remains the only practical solution.
Build an industrial indoor farm, weigh it, wait two weeks, weigh it again, and divide the increase in weight by your own body mass to find the fraction of your CO2 you are actually removing.
- culi
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
- dynm
(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.
- newsomix9xl
The grow lights are only needed at night.
You can leverage a sunny window for free.
I would have liked a more how many plants can do it, rather than the its impossible route.
AI says a snake plant and spider plant can produce oxygen night & day. Now assume I live in a tiny hovel (kinda true) how many plants do I need for "net oxygen surplus" (?)
Apparently, AI says, high yield crops of say wheat under intense LEDs or Spirulina make for optimal oxygen producers.
So 15 m^2 of spirulina in an aquaponics garden with intense led fixtures to supplement natural light might do it.
- prhn
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?
- asdfman123
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.
- ninefathom
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.
- chrisweekly
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.
- bartread
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.