This is a sapling 🌱 post and will be updated.


I was recently reading an article about climate change and increasing CO2 concentrations in the atmosphere, when an idea popped into my mind - why not use algae to sequester CO2 so that we reduce the effects of climate change?

This is by no means a novel idea and has been investigated for decades. My idea was based on a company that pitched along side mine during my startup days - ETBio. They aimed to use algae-based air purifiers to decrease CO2 and increase O2 concentrations inside buildings. I found this very cool (along with their rationale for their company name), but did not think too deeply about it till recently.

Anyway, the key idea is to use algae to sequester CO2 so that we reduce the effects of climate change. This seems like an obvious idea, in a sense. We know that CO2 in our atmosphere is increasing at faster rates than the flora on land can sequester and convert into biomass. Algae can also sequester CO2 and grow at high rates (especially compared with land flora). So if we can grow and continually store the algae, we would be able to increase the rates of CO2 sequestration and slow down CO2 build-up (maybe even reduce concentrations). So why hasn’t CO2 sequestration taken off?

To make things even more favorable for mass algae bioreactors, algae have a high concentration of lipids, making them a promising candidate for biofuel production.1 Oil companies like Shell, Chevron, and Exon Mobile actually invested2 (large sums of money?) into algae research, and it looks like US Department of Energy has a running program for it.3

Many of the algae are edible, so in addition to sequestering CO2 and making biodiesel, algae bioreactors will produce edible protein that can supplement food.4 The ISS is actually testing an algal bioreactor for the same purpose!5

Overall, to me, the benefits of developing an algae bioreactor that converts CO2 into biomass seem huge! So why then has algae growth and CO2 sequestration using algae not taken off? That is the aim of this note - to try and figure out:

  1. if it has taken off and I just don’t know about it.
  2. if the basic economics just do not make sense for large scale deployment.
  3. if it is a hard problem with a lot of technical difficulties that need to be solved before it is viable.
  4. if it is a hard problem that has been relatively ignored but the time is ripe for revisiting and making huge leaps of progress.

Intuitively, I feel like the reason it hasn’t take off might be 2 or 3, but until I do the research and methodically eliminate each of them, I will not know. So, I dug into the research (as best as I can).

Has algal bioreactors taken off?

(to be updated)

Does the economics make sense?

(to be updated)


  1. This is a cool video showcasing how algae can be converted to biofuel by applying pressure and heat (similar to how petroleum deposits were likely formed) - 



  4. Cody’s algae panel which he hopes to use for edible biomass in his mars base experiment