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Comment by angel_j | Hacker News Reader

Energy is needed to separate CO2 into carbon and oxygen. At the individual molecular scale, this can't be much. How many can I separate at once with my hands?

If we invent a device that helps us to physically separate oxygen from carbon, humans and farm animals could do it. It would be like milling grain, or washing clothes.

Idea: create filters which are big enough for carbon to pass through, but not oxygen. Then "squeeze" a bunch of air through, and wipe away the carbon on one side. Like a cheesecloth made of carbon nanotubes...

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Fun idea - very back of the envelope math is if you could convert energy into strictly breaking CO2 bonds, the amount of energy it takes is 805 kJ/mol (from Google). WolframAlpha says this is roughly the caloric content of a biscuit, or 30 min of sports [1]. This would then separate 22.4 L or one mole of pure CO2.

There are approximately 1E20 moles of CO2 in the atmosphere (very rough math)[2,3]. This could take a while, especially considering efficiency would probably be 10% of this idealized system. However, this filtering idea isn't bad, I don't know of any filter like this for splitting CO2, but something is almost certainly being worked on for just general sequestration of CO2 from other atmospheric gasses.

[1] https://www.wolframalpha.com/input/?i=805+kJ

[2] http://www.wolframalpha.com/input/?i=(5.148E18+kg)%2Fmolar+m...

[3] https://micpohling.wordpress.com/2007/03/30/math-how-much-co...

A biscuit! Breakfast 4 carbon credits...

I saw a nanofilter that could remove salt from water.

If you can puncture a material with ultra-violet lasers, the holes might be the right size to filter carbon; that is my guess, based on these results https://phys.org/news/2014-10-oxygen-molecules-carbon-dioxid...

What if we would make such an advanced filter, and then make it mandatory in cars. That way cars would 'clean' the air. You'd need to find a process that scales though, so that the 'dirty' filters are processed in a way to get out the carbon and use it somewhere.

Make sugar with the pure carbon, a la photosynthesis?

Use electrolysis to split water, get the Hydrogen and Oxygen, insert Carbon, excrete glucose...

Or make direct fuels out of it :P /s (that would not work, otherwise you've created a perpetuum mobile). Would be interesting if you could use your car's surface as a kind of anode.

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