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Comment by WA | Hacker News Reader

There’s a nice SciFi book about this: one person got incredibly rich, because he invented artificial trees that capture a lot of CO2. Good book, unfortunately only available in German: https://www.goodreads.com/en/book/show/38356981-hologrammati...

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I often have this thought. If only one could bioengineer some kind of device that replicates itself and captures CO2 using sunlight.

Oh right. We already have those. That’s a tree. We just need to stop cutting them down maybe.

Actually cutting them down is fine as long as we re-plant and slow down the decomp of the wood (by, e.g., using it in manufacturing or building.) Bamboo's also a good candidate for this cycle. Locking up atmospheric carbon in material that's going to be around for dozens or hundreds of years is a good thing.

Bamboo is interesting, both for strength-to-weight ratio and speed of growth. Is there a side-by-side comparison on how well it performs in this respect relative to other tree species?

We do not need to find a use for the wood if we were determined that this is our carbon sequestration method and that it would be paid for by the public, i.e. that no otherwise viable business model is needed. We could put it into mines that we digged the carbon out from before - consider it paying back the carbon loans we took in the past. Or maybe use other mines for that: cavities of salt mines can be truly gigantic for example which might help with handling the material.

Edit: I did some calculations and to sequester 1 Gt of carbon we would need to bury approximately 1.7 km^3 of (fresh) oak wood. That‘s a lot, especially since emissions were over 30Gt/a in 2020.

Especially because trees have a pretty slow start on the carbon capture curve over their lifetime, the amount of CO2 they can fixate is (roughly) proportional with the total surface of the leaves assuming sufficient water is present.

It's not quite that simple.

Forests, as we're seeing right now, burn. Global trade has made this worse by spreading various pathogens and invasive creatures around the planet.

Even the ones which don't burn reach a steady state (takes centuries, but gets close in decades), where rot releasing carbon and uptake into new growth balance out.

To really fix carbon with plants, we want to grow something fast and woody, char it, and bury the char. Doesn't have to be deep, in fact working it into topsoil is a pretty good solution.

This isn't anywhere close to sufficient, but it's necessary and we should be doing a lot of it.

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