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Comment by lokischild | Hacker News Reader

I have a hunch that there is no artifical process that could possibly compete with what nature already has. The answer is plants. So the solution would be a way to sustainably grow a lot of plants in a short time.

But another main factor is the destruction of the densest of those ecosystems, the rain forest on a large scale.

That is my answer, stop humans/companies/countries from destroying the rain forest on a large scale (I'm looking at brazil and neighbors) and think of ways to rebuild lost rainforest in an efficient way. I am going to wager, from the knowledge and experience I gathered in my years of living, there is no other solution that is sustainable.

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The ecosystem is more or less in a balance. Forests that are cut down will become forests again. Plants already grow pretty much everywhere where they can grow. It's still not enough.

We've spent over 200 years pumping carbon into the atmosphere from a source we can't return it to. No amount of growing forests is going to fix this issue without being able to turn those forests into carbon that's in the ground. We need to get carbon out of the carbon cycle. The natural life of plants doesn't do that.

Edit: we might be able to do it, if we can somehow turn land where forests don't grow into forests.

The system will eventually return to balance, for example few million years after all humans die out. The question is if we can keep it in such balance that allows humans to live. Maybe there's not enough space on Earth for all humans and everything they need to live + sufficient area of forests on top of that

> Maybe there's not enough space on Earth for all humans and everything they need to live ...

I recon the problem isn't what humans need to live but rather what many of them want to have.

Not only forests, but converting a desert, like Sahara, into agricultural land will help too. Same is true for ocean deserts, places where there is no upwards flow bringing nutrients from ocean floor to the surface, which is the majority of the ocean.

I think the math has been done for this and the CO2 captured by planting the Sahara would be offset by the increased warming due to the reduction of albedo effect. Which is crazy to think about.

AFAIK this was done simply by assuming the change of the color, without taking into account the change of cloud coverage, and clouds have a huge effect. So it can go both ways depending on how exactly we will be changing the climate of Sahara.

And there are many possible ways to control the climate in a smart way instead of trying to simply remove CO2. One possibility is to use ocean thermal energy conversion plants [1], to cool down tropical region of northern hemisphere, artificially re-creating conditions that cause green Sahara periodically. Aubrey de Greys new moonshot https://viento.ai/ is working on similar ideas.

[1] https://en.wikipedia.org/wiki/Ocean_thermal_energy_conversio...

You’re so close to saying the solution without getting there.

Fast growing plants are probably the most effective carbon extraction we have. Problem is when they die they turn back into CO2.

So we should bury those plants before they rot. Our excess CO2 stems mostly from dead plants and animals that have been buried. Seems sensible to put some of our excess back into the ground.

I like the idea of sort of (but not really) making coal again in a fight against climate change.

In WV we have tons of old strip mine - we should fill them up with plants and bury it.

If we did something like that I imagine the biomass under the earth would compress over time and the land above would end up shifting and causing issues for anyone that wants to use it.

Edit - Daydreaming about this scenario and I am imagining trying to sell the idea of refilling the old coal mines with biomass to folks living in coal country. An interesting and funny situation.

Which requires digging. Which requires machinery at an industrial scale. Which requires large amounts of energy. Which makes it really hard for this to not be in the perpetual motion set of solutions.

You’d have to be extracting more carbon than your diggers consume (since even today I don’t think this has electrified and capable of running on solar). Your diggers are consuming concentrated carbon compressed from plant and animal biomass under high pressure and energy over millions of years. It seems highly unlikely just growing and burying biomass is sufficient. Additionally, I’m pretty sure the CO2 is just going to leak out in large quantities since, unlike the naturally sequestered CO2 we extract from the ground, you have bacteria that can break down the biomass and let the CO2 escape as a gas. Which means we have serious additional efficiency losses.

The only solution that could work for sequestration as far as I can tell seems like an industrial process powered by nuclear because it breaks the energy cycle completely to accomplish the task. Solar is popular but I’m skeptical that renewables are up to the task that’s required to undo several hundred years of fossil fuels being the engine of the world’s industrial progress.

I can't speak to any of the details, but this is definitely an interesting approach: https://www.cnn.com/2021/05/03/business/running-tide-kelp-ca...

The majority of carbon in the soil doesnt come from plant matter. It comes from plant root exudates. Plants pump sugars and carbohydrates into the soil to feed bacteria and fungi. As long as we dont poison or till the soil, the ecosystem keeps the carbon in the soil. Some of it will cycle. That is the way it is supposed to be.

Greater than 80% of farm land soil is dead. What little carbon that is built up in a season is released in the spring when the field is tilled.

No till, diverse cover crops, and animals (a complete ecosystem) stores immense amounts of carbon in the soil.

> No amount of growing forests is going to fix this issue without being able to turn those forests into carbon that's in the ground. We need to get carbon out of the carbon cycle. The natural life of plants doesn't do that.

Taking (sustainably harvested) wood from old trees which are close to dying anyway and using this wood to build durable (lasting decades) houses would be helpful. This would channel carbon from the natural cycle into an artificial reservoir made up of buildings.

Questions left unanswered:

- would this reservoir be big enough?

- is the rate of carbon fixation sufficient?

The US has a bunch of land. A thought occurred involving the US's surplus military personnel spending their days, after waking up from their barracks in some state in the west, tending to a massive bamboo garden, including cultivation, pruning, and disposal into giant pits. The Wikipedia article for bamboo even mentions its use in carbon sequestration prominently. Having looked into this before, though, I turned up a few sources that said bamboo alone has no net negative effect on atmospheric carbon, and might actually increase it.

What about cannabis?

It grows rapidly. The fruits (bud) are valuable and the remaining plant material can be compressed and buried.

This definitely seems the most feasible. Sure, plants aren't particularly efficient, but they're also self-reproducing and self-maintaining, which is a huge bonus.

One interesting approach with plants is to pyrolise them to make biochar - essentially turn them to charcoal. You get a bit of hydrocarbon gas out of them, which you can sell to pay the bills (this is the biggest problem with any carbon capture - there's basically no way to pay the bills), and then you bury the pure carbon that you're left with.

I did a bit of research on this a while back and wrote up the calculations here:https://concretecuts.xyz/articles/biochar

Essentially we'd need to devote quite large amounts of land towards this if we wanted to compensate for our current emissions - something like 66% of the world's forests would need to be periodically cut down, with around 1% cut down and pyrolised each year.

You could probably get some easy wins with existing wood and crop waste - by my estimate we could capture 3% of global emissions just by pyrolising Europe's existing biofuel feedstocks.

my understanding from watching that crazy netflix sea documentary is that algae is the go to for oxygen production / carbon capture...anyone have ideas on which is the more important case?

Algea is only a co2 battery unless you can capture it and store the algea without it fermenting. If you just grow it in the Ocean, you need to increase the Ocean's algea carrying capacity and form it thus into a battery because dead algea gets fermented by bacteria into co2 and methane again. Also the ocean's carrying capacity for algea is currently ever decreasing due to oceanic acidity increasing from co2.

Artificially growing algea in pools and using that to make fuel/ pump it underground so the fermentation products don't get released is not nearly efficient enough to be viable. Ironically this usually also uses fertilizers which are dependent on the fossil fuel industry.

This is the mission at Terraformation[0] (no affiliation)

[0]: https://www.terraformation.com/about

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