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The source you're citing talks about 4.4 kg estimated per m^2 for algae in the open ocean, and notes that the maximum known rate is 9.16, so around 9 * (44/12)
by avar 7y ago
The source you're citing talks about 4.4 kg estimated per m^2 for algae in the open ocean, and notes that the maximum known rate is 9.16, so around 9 * (44/12) = 33 kg per m^2/yr converting C to CO^2, or around 11 square meters.
In terms of CO^2 sequestration it doesn't seem implausible to fit a farm of that area in something the size of an apartment..
Of course the energy/water use would be insane, hopefully you could funnel sunlight in, or just open the window. But as a thought experiment that ignores the economics of it think more space station than apartment.
Critically, you need on the order of N m^2 of sunlit area on your culture, not N m^2 of floor space. If you image search "phytoplankton culture" you can see that people grow these in bottles or thin plastic bags under artificial lighting, maximizing the surface area.
You can easily fit 11 m^2 in one square meter like that under standard 250 cm ceiling height. Just have a stack every 20 cm.
- dredmorbius 7y agoNote that the article refers to both carbon and carbon dioxide fixation. CO2 weighs more than the carbon it contains, by a lot. Carbon has an atomic weight of 12, CO2 a molecular weight of 44 (12 + 216), or just shy 4x the mass of the carbon* component of CO2. The 4.4 kg I gave was carbon, the 16.3 kg CO2. Your 9.16 kg refers to CO2, fixed per square meter per year, which is less than the CO2 fixation value I'd used. That is, http://carbon.ycombinator.com http://carbon.ycombinator.com are making a more conservative estimate of about 56% the maximum observed rate. That increases rather than decreases the required area. At 9.63 kg/(m^2yr) you'd need 39.8 m^2, or 429 ft^2, of algae to offset one person's CO2 exhalation. Using GNU units: You have: (1kg/day)/(9.16 kg/(m^2*yr)) You want: m^2 * 39.873602 / 0.025079249 You have: (1kg/day)/(9.16 kg/(m^2*yr)) You want: ft^2 * 429.19589 / 0.0023299385 You have: 9.16/16.3 You want: % * 56.196319 / 0.01779476 Apologies for typos in GP post. Android soft-keyboard stinks.
- avar 7y agoI understand the difference, but perhaps I misunderstood the article. What it says (and you're correctly referring to) is: > We will be conservative and say that our algal beds fix 2.5 kg of C per square meter per year and 2.5 kg of C works out to 9.167 kg of CO2. But then a couple of paragraphs later: > the maximum CO2 assimilation rate of algal beds which we will say is 9.167 kg of C per square meter per year. I.e. they first mention a conservative "2.5 kg of C" in the context of the ocean, followed by a "maximum rate". 9 kg of carbon is around 33 kg of CO^2. Maybe they meant "kg of CO2" in that second paragraph, it's certainly suspicious that it repeats the same 9.167 number, but why would they call that number both "conservative" and "maximum assimilation rate", hrm...
- dredmorbius 7y agoThat looks sloppy on their part. Point for my OP was just to note that a couple of potted plants wouldn't keep your apartment breathable.