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We need to take CO2 out of the sky – an overview of climate tech

orbuch.com

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Re: We need to take CO2 out of the sky – an overview of climate tech

#71

Post by ailideex »

privateSFacct wrote: post #37
ComputerGuru wrote: post #28

What the article leaves to the conclusion is what needs to be stated up front and center: it's virtually impossible to do this efficiently, cheaply, or effectively because there's so little CO2 in the air, meaning a) adding even a little bit more greatly affects the CO2 levels b) with a global ppm of ~400, it basically means that you need to filter 2500 molecules of air to get a single molecule of CO2, and that's ass…

It only has to do it cheaply now because there is NO COST to putting CO2 into the air. Why are people surprised that if something is free (pumping CO2 into air) demand for it is high? You are telling me that doing a charge of let's say $10 - $100/ton of CO2 wouldn't have a DRAMATIC impact on emissions? Is $10 - $100/ton too little for a supposed climate emergency? There is so much funding and lawmaking and finger poi…

Good luck convincing China to impose a carbon tax.

Re: We need to take CO2 out of the sky – an overview of climate tech

#72

Post by orbuch »

avmich wrote: post #63
orbuch wrote: post #57

Earlier quoted context omitted.

I'm not sure what this is? You might be thinking of solar radiation management or other "geoengineering" techniques to try to make the earth shiner and reflect more sunlight, making us cooler at a constant CO2 concentration. Theres a ton of interesting topics within that to write about, I mention it briefly as "things I didn't include"

No, the idea is something similar to this - https://sesinnovation.com/ . You carefully compress incoming air. Separate water vapors (and liquids, and hopefully not solids) from it. Cool this air in thermal exchanger - at this point CO2 falls off. Then you pass that air through turbo detander, which returns you some energy, and get a pre-liquified air, which pass to the thermal exchanger. Clean air of normal temperatu…

Ah, thanks! I haven't seen this before. Will look into it.

Re: We need to take CO2 out of the sky – an overview of climate tech

#73

Post by peteretep »

avmich wrote: post #64
foxhill wrote: post #59

Earlier quoted context omitted.

having not read the article (yet), i the OP is referring to “cooling down air until it liquifies then using fractional distillation to pull out the CO2”?

You don't want to do unnecessary transformations, to preserve as much energy as possible (so the turbine, which is needed for cooling, should work on small pressure difference). So, no air liquification - just let CO2 separate and send cleaned air back to the heat exchanger.

> to preserve as much energy as possible

Aren't there plenty of places where energy is so plentiful that you don't need to care that much?

Re: We need to take CO2 out of the sky – an overview of climate tech

#74

Post by perfunctory »

ailideex wrote: post #71
privateSFacct wrote: post #37

Earlier quoted context omitted.

It only has to do it cheaply now because there is NO COST to putting CO2 into the air. Why are people surprised that if something is free (pumping CO2 into air) demand for it is high? You are telling me that doing a charge of let's say $10 - $100/ton of CO2 wouldn't have a DRAMATIC impact on emissions? Is $10 - $100/ton too little for a supposed climate emergency? There is so much funding and lawmaking and finger poi…

Good luck convincing China to impose a carbon tax.

Given trade imbalance you could impose carbon tax on Chinese imports.

Re: We need to take CO2 out of the sky – an overview of climate tech

#76

Post by rckoepke »

avmich wrote: post #63
orbuch wrote: post #57

Earlier quoted context omitted.

I'm not sure what this is? You might be thinking of solar radiation management or other "geoengineering" techniques to try to make the earth shiner and reflect more sunlight, making us cooler at a constant CO2 concentration. Theres a ton of interesting topics within that to write about, I mention it briefly as "things I didn't include"

No, the idea is something similar to this - https://sesinnovation.com/ . You carefully compress incoming air. Separate water vapors (and liquids, and hopefully not solids) from it. Cool this air in thermal exchanger - at this point CO2 falls off. Then you pass that air through turbo detander, which returns you some energy, and get a pre-liquified air, which pass to the thermal exchanger. Clean air of normal temperatu…

> How much energy will you need?

A lot.

Air compression is not cheap, energetically. Chilling is also energetically expensive. You'll need to do both. This would be pretty much the "brute force" method, like O(n!) in software engineering. The concept would be to bring half the planet's atmosphere down to near its liquid temperature. Currently in most US homes, Air Conditioning (air cooling) contributes the majority of each home's energy use. This would be much greater than that, it requires chilling air to -140 °C to get CO2 to "drop out".

In contrast, seeding the ocean with iron would be fairly close to O(1). However, potential side effects of this process concern some scientists greatly. Googling 'Russ George' may provide more insight.

Side note: The press material for sesinnovation also says the outlet stream is nearly 100% nitrogen...that means they're using a stream which already has oxygen removed from it (likely because the air was just used for combusting fuels). Air is roughly 21% oxygen so you can't take air, only remove CO2, and get 100% nitrogen out. Generally these "Carbon Capture" technologies only work on feed streams with high CO2. So hey're placed at industrial outlets, where fuel/coal is being burned. These streams can be > 10% CO2. Often they don't work as well, or at all, on diffuse streams like 0.04% atmospheric CO2. The technical reasons why this is the case deal with "partial pressures" as well as general entropy.

Re: We need to take CO2 out of the sky – an overview of climate tech

#78

Post by Danieru »

chopin wrote: post #70
quixoticelixer- wrote: post #46

Earlier quoted context omitted.

Except many countries have carbon tax

Which ones would that be? I know of many which have a tax on various forms of energy consumption. And even then, industrial consumers are exempt or have a reduced rate.

Heres a document explaining things from 2017 issues by the Japanese government. I remember reading it a few days ago, interesting for the context: http://www.env.go.jp/en/policy/tax/20170130_greening.pdf

IMHO, the first step is to migrate coal power plants to capture and storage. It is much easier to drop emissions than to pull from the air. I would like to see more tax pressure globally incentivizing carbon release reductions. Instead you get weird stuff like Japan's carbon tax where coal pays the lowest carbon tax of gasoline and diesel.

Re: We need to take CO2 out of the sky – an overview of climate tech

#79

Post by jpfr »

ComputerGuru wrote: post #28

What the article leaves to the conclusion is what needs to be stated up front and center: it's virtually impossible to do this efficiently, cheaply, or effectively because there's so little CO2 in the air, meaning a) adding even a little bit more greatly affects the CO2 levels b) with a global ppm of ~400, it basically means that you need to filter 2500 molecules of air to get a single molecule of CO2, and that's ass…

As you write, plants can do this quite efficiently via photosynthesis. So there is at least one working example where CO2 capture is resource-efficient (even solar-powered). From photosynthesis we get sugar. From sugar we can get to raw (solid) carbon for long-term storage.

Forests are not the only option. Imagine large installations with tanks of algae under a white canopy. I imagine the economies of scale are huge once this is ramped up to industrial levels.

The question is who will pay for it. Nobody wants to indirectly subsidize coal plants on another contintent.

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