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Comment by Tuna-Fish | Hacker News Reader

> Not a surprise, since co2 is an oxide, and therefore very stable in the athmosphere. It would take a huge amount of energy to remove it,

There is an exothermic reaction that removes CO2 from the atmosphere, the formation of carbonates from weathering of silicate rocks. As this is naturally very slow, there is currently ongoing research into multiple different ways to speed it up.

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That doesn't change anything. You need a huge amount of energy to remove CO2 from the atmosphere because CO2 is a tiny constituent part of Air (~400ppm) - that means one has to move a million molecules of air across a collector (whatever that is) to remove 400 molecules of CO2. You can't do that without huge amounts of energy and a huge surface area for your collector ... on any human timescale.

Oh man. Somebody always gets a way to make problems out of the entropy of diffusion. It increases with the log of the concentration, so whatever problem you estimate to happen, it can be worked around.

On the case of silicates, a trivial work around is to just spread them around and let the same diffusion bring the CO2 into them.

Plants do. And they only need the sunlight they have where they grow.

I think that’s the “huge surface” op is talking about.

And we’re busy decreasing the surface of woodlands on the planet.

Huh I thought the world has more trees now then ever before.

I don’t know, but they could both be true. How many 5yo pine trees does it take to equal the surface area of one giant redwood?

It's really about growth rate rather than size.

The mass of air that moves past the existing fleet of wind turbines in a year is roughly a fifth of the mass of the atmosphere.

It is a civilisation sized project that will take a lifetime, but it is achievable.

Or we could just stop burning coal.

That would be very easy if we didn't benefit greatly from burning coal

Are you familiar with the term "negative externalities?"

Sure. But the benefit is way bigger than the drawback. At least that is the decision society has made.

No. People like David Koch benefit.

The rest have very little say.

Why do we talk about removing CO2 from the atmosphere but not trying to pull it out of the ocean?

What makes you think it would be significantly easier to filter out the carbolic acid from the ocean? The same difficulties apply, and water is much more viscous than air.

Didn’t carbon we’ve carelessly dumped in the atmosphere start as ocean life that sunk to the bottom, can’t we turbo charge that cycle?

Not practically. We are talking about huge scales, such that the industrial production, transport, etc., would be as much of an environmental disaster as what it's trying to solve.

Because there is an homeostasic relationship between the co2 in the ocean and the air, and it always end up balancing out automatically.

And of course its not like we have giant windmill farms all over the world that we could integrate CO2 collectors into the blades

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