Need someone to tell me this idea is stupid (Co2 capture)

[adam7288]

I am seeking out someone to crush my dreams and help avoid wasting my time.

The idea which I'd like to spend a few years prototyping essentially boils down to distilling dissolved air into its constituent components. Clearly, with the goal of isolating co2, and doing this in a manner which is more efficient than current methods available.

The idea is simple but unproven:

Stage 1: dissolve air into water or some other solvent, using a compressor (I have some practical experience with this with aquariums and aquatic plants using compressed co2).

Stage 2: Exploit Henry's Law, varying temperature and pressure in such a way that the various components of the air outgas in a predictable way. This is the part where I need you to tell me it is stupid and won't work.

The other aspect is energy - even if the idea is feasible it needs to be efficient.

I apologize for coming off as a complete amateur!

[T3sl4co1l]

You don't even need a compressor, water dissolves CO2 pretty well at STP.  A bubbler will do, at least if you don't need much concentration.

But that really is the rub, isn't it?  If you have low concentration, then a lot of water will evaporate in the process (indeed, more than the CO2 absorbed, I think, in most places on Earth!) while recovering not very much CO2; and its purity will be low (because O2 also dissolves in water, and to a small extent, Ar and N2).

And how much power are you going to spend, doing all of this?  Water isn't free, you'll need a lot of it to capture much CO2.  Or spend even more power condensing it.  Every opportunity you have, to turbo-expand gas that's been compressed, or heat exchangers for fluids you're thermally cycling, must be taken.  CO2 is a waste product as-is, so it better be minimal!

And indeed, as it happens, cleverer minds than mine have pondered this task.  The choice of solvent is one with a fairly high boiling point (low vapor pressure: little lost to evaporation), and with a high affinity for CO2.  Thus the concentration is fairly high, and the yield on extracting it is also high (say by thermal cycling).  Ethanolamine seems to be a typical choice.

And, obviously it helps to start with a high CO2 source, like a coal plant; this can pretty much be compressed directly, and whatever doesn't liquefy as CO2 (which does need to be chilled enough to condense; CO2 is supercritical* very near room temperature) can just be vented (mostly N2 and Ar?).  Liquid CO2 is a fantastic solvent, so some purification is probably a good idea (sheesh, does anyone distill liquid CO2? that's one high-pressure column..), but a typical proposal is to just pump the stuff to the bottom of the ocean, where the pressure keeps it in liquid phase, and being denser than water, just kinda... sits there, eventually diffusing into the water column, or the sea floor, or "freezing" as clathrates, for indeterminate consequences... well, someone's thought about it I'm sure, I just haven't read about it.

*Supercritical gasses mix the properties of liquids and gasses.  They cannot be condensed by reducing temperature (at constant pressure), or by increasing pressure (at constant temperature).  Basically the density of liquid and gas phases coincide at the supercritical point; the vapor is as dense as the liquid.  So, uh, clearly this takes pretty high pressures, eh?


This looks like a pretty good overview for further reading:
https://www.cmu.edu/epp/iecm/documentation/2019Jan_IECM%20Amine-based%20CO2%20Capture.pdf

Tim

[RJSV]

Politically speaking (lightly), it's potentially good idea, as there appears to be a perfect storm combination, socially:
   Ignorance, with gobs of near-panic, can incubate some potent STUPID, this allowing you ample room to perpetuate clever FRAUDS.
   Even worse, various REAL threats loom, right in there with bogus ones. A virus kills, while I've heard about some virus prevention measures themselves being harmful!

   My opinion, given from oldster's 'daybed', is the better tack would be a 'Tree Preservation Ordinance', done correctly. (Good luck: Gird Your Loins, as they say). That would act to avoid carbon loss, to atmosphere.

   Chemically, perhaps a water bath, with fast growing water 'lilies' and such, can be used, in a carbon production system.
   Sorry, that isn't such an impossible innovation...Now go build it!

[Haenk]

IMHO CCS is the very wrong way to do this. Let nature do the work; that requires hardly any additional energy (higher temperatures and higher levels of CO2 will make plants grow faster, temperature within a certain range). However this is a rather slow feedback loop.
Of course this also requires massively reducing emissions at the same time, which hardly any nation is willing to do.

Edit: IMHO the CO2 level is probably the smallest of our air pollution problems...

[MazeFrame]

There is a company that built a "CO2 Harvester"

Not sure how well this article will make it trough the translator of your choice:
https://www.forschung-und-wissen.de/nachrichten/oekonomie/erste-kommerzielle-anlage-filtert-co2-aus-der-atmosphaere-13372431

Alternatively, you can plant a tree   

[Just_another_Dave]

IMHO CCS is the very wrong way to do this. Let nature do the work; that requires hardly any additional energy (higher temperatures and higher levels of CO2 will make plants grow faster, temperature within a certain range). However this is a rather slow feedback loop.
Of course this also requires massively reducing emissions at the same time, which hardly any nation is willing to do.

Edit: IMHO the CO2 level is probably the smallest of our air pollution problems...

The problem is that the data about CO2 emissions provided in the news usually refers to CO2eq. That means that it is accounting other greenhouse gasses that might not be easily absorbed by nature like CFC-11 (1 ton of CFC-11 equals 4700 tons of CO2eq: http://large.stanford.edu/courses/2010/ph240/ali1/). In fact, there are gases that have a negative contribution to the total CO2eq emissions generated by a country

The problem of oversimplification and indicators is that don’t always help finding solutions, as they can hide part of the problem

[SiliconWizard]

Haven't done calculations to speak of, but knowing the overall constraints, I'm *extremely* doubtful any machine-based approach is ever going to be of any practical value.
Do you realize the amount of air we'd have to treat to even make a very small difference?
The oceans, AFAIK, capture the most atmospheric CO2, and they already struggle. Do you realize what amount of water that is?

While capturing CO2 out of "thin air" with "machines", is IMHO, a completely lost cause, we may think of a more pragmatic approach of capturing the CO2 we emit - for instance from our industries - instead of releasing it in the atmosphere. But it would require so much energy that it looks, as well, very unpractical. Unless... we find this miracle source of energy that emits no CO2 and that can cover all our needs. In which case, we won't be emitting any CO2 anymore anyway, except from our breathing. Let's hope this part is still OK.

[Just_another_Dave]

Haven't done calculations to speak of, but knowing the overall constraints, I'm *extremely* doubtful any machine-based approach is ever going to be of any practical value.
Do you realize the amount of air we'd have to treat to even make a very small difference?
The oceans, AFAIK, capture the most atmospheric CO2, and they already struggle. Do you realize what amount of water that is?

While capturing CO2 out of "thin air" with "machines", is IMHO, a completely lost cause, we may think of a more pragmatic approach of capturing the CO2 we emit - for instance from our industries - instead of releasing it in the atmosphere. But it would require so much energy that it looks, as well, very unpractical. Unless... we find this miracle source of energy that emits no CO2 and that can cover all our needs. In which case, we won't be emitting any CO2 anymore anyway, except from our breathing. Let's hope this part is still OK.

Some industries already do that, but in general they just capture it. However, combining them with some process that requires CO2 might be a really interesting approach. For example, some greenhouses add CO2 to the air inlet to increase their productivity

[IanB]

I am seeking out someone to crush my dreams and help avoid wasting my time.

The idea which I'd like to spend a few years prototyping essentially boils down to distilling dissolved air into its constituent components. Clearly, with the goal of isolating co2, and doing this in a manner which is more efficient than current methods available.

The idea is simple but unproven:

Stage 1: dissolve air into water or some other solvent, using a compressor (I have some practical experience with this with aquariums and aquatic plants using compressed co2).

Stage 2: Exploit Henry's Law, varying temperature and pressure in such a way that the various components of the air outgas in a predictable way. This is the part where I need you to tell me it is stupid and won't work.

The other aspect is energy - even if the idea is feasible it needs to be efficient.

I apologize for coming off as a complete amateur!

I can speak with some qualification here as I am a chemical engineer--this is my field.

Hence I can tell you that whatever idea you can dream up, has already been thought about by experts who know all about the theory and how to do the calculations, and how to work out the economics and feasibility.

Some questions to ask yourself:
1. Have you researched the current methods available, to see if your idea is already there, or if your idea might be new?
2. If your idea is simple (your words), how could it be original?
3. Why would you spend a few years prototyping something, when (with sufficient knowledge) you could spend a few hours or days doing the design calculations to find out if it would work?
4. Why would you want to capture CO2 from the air, when the goal is typically to capture CO2 from the flue gases produced by fossil fuel combustion?

In closing, yes, dissolving CO2 into some kind of solvent is absolutely a standard way of removing CO2 from a gas stream, and there is a huge amount of knowledge in the industry about how to design such systems.

If you are interested in this kind of thing, and depending on where you are in your career, you could enroll in a chemical engineering program at a university, where you can learn all about the theory and practice of systems like this.