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Comment by graeme | Hacker News Reader

It is simply not feasible to lower co2 in a space with a few plants. Ventilation is the only method that works.

This is trivial to test. Just get a monitor, walk into a room with plants, close door, and start breathing. Check change in co2 after 15-30 min.

Vent the room, remove plants, repeat. Results should be equivalent.

Plants store co2 by growing. They do not grow quickly enough to deal with emissions from your breath.

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To put a number on it, you exhale ~2.3lb of CO2 a day. You should also consider that much of a plants mass is water, so it would require a significant amount of plant matter to scrub the air.

I once did the math, and found that an algae tank can theoretically offset a person’s entire CO2 emissions but that it would require a large external tank and I was living in an apartment at the time.

There have been studies on indoor plants and air quality. The most well-known of which, I believe, was the NASA Clean Air Study [0]. The study suggested 1 plant per 100 sq. ft. but a space station obviously isn't the same thing as a dwelling.

[0]: https://en.wikipedia.org/wiki/NASA_Clean_Air_Study

That’s air quality, not co2. Air quality usually means particulates and VOCs.

Oof, you're totally right. Thanks for the correction!

Once you have the carbon in biomass, what do you do with it? Dry it out and heat it enough to make biochar?

Very good question. I had two avenues in mind, fungus and compost.

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