Note 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 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.
I 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...
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 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:
Apologies for typos in GP post. Android soft-keyboard stinks.