Good question. Answering questions is called 'research'. ;-)
I'm skeptical for the same reasons as you, too. Let's see... the ocean covers 361km^2. If we could engineer a material with "cells" that were 1000x as effective at carbon capture as diatoms, and the manufactured material was 1000x more densely packed together than diatoms are on the ocean surface, then you'd need 361 square kilometers of the magic material. Which is not out of the realm of possibility, though I have no idea what the density of diatoms is and I have a sneaking suspicion that we'd be looking at more of the 3x-4x range of efficiency improvement. And of course, you need to turn the CO2 into something and deposit it somewhere, and maybe move it around lot. Which would use energy that would produce more CO2, offsetting the gains. Oh, and manufacture the stuff.
I'm thinking releasing less of the stuff and stopping forest destruction might be much more effective for a long time here...
That should of course be 361 million km^2.
[] https://en.wikipedia.org/wiki/Diatom#/media/File:Diatoms_Egg...
Similar has been tested with iron + algae and seems to work well.
The Earth's carbon cycle manages about 750 gigatons of CO2/year and humans are emitting ~30 excess gigatons a year on top. The diatoms in the ocean are happily out there processing 150 gigatons of CO2/year, but what we need to engineer is only 30 gigatons (to completely eradicate human emissions).
If we engineered diatoms to fix, say, 0.3 gigatons/year, we'd eradicate a whole integer percent of our emissions.
Heck, if we got it in the 0.03 gigatons (30 megatons/year), we've probably built something scalable and created a useful entry in our portfolio to capture carbon, sinking about 0.1% of our carbon/year.
So, don't despair, we don't have to compete with the ocean! We only need to compete with ourselves! Or maybe do despair? Because we have to compete with ourselves... fundamentally, climate change isn't a technology problem, it's a political problem.
