Using mechanical or chemical means, what are the options for capturing CO2 from the surrounding air.

Not necessarily extracting all of it as pure CO2, just enriching the proportion of CO2 in air to something that might be used in intensive greenhouse farming would suffice.

What would be the energy requirements, capital set up etc?

party_pants said:

Using mechanical or chemical means, what are the options for capturing CO2 from the surrounding air.

Not necessarily extracting all of it as pure CO2, just enriching the proportion of CO2 in air to something that might be used in intensive greenhouse farming would suffice.

What would be the energy requirements, capital set up etc?

Um, what? “Enriching the proportion of CO2”. You mean capture followed by release?

It’s easier to do it the other way around. eg. start with CaCO3, limestone, heat to release CO2 for your greenhouse, then over time the CaO captures CO2 again to turn it back into CaCO3. For more, see https://en.wikipedia.org/wiki/Carbon_dioxide_scrubber

Another way to increase CO2 levels in a greenhouse is to grow fungi or animals or bacteria there. eg. put insects into your greenhouse then they produce CO2 as they eat the plants making more CO2 available for the plants to grow.

Neither of those solutions is quite what you’re looking for, but both beat the use of cryogenics to extract CO2 from air.

http://www.climeworks.com/our-technology/

What energy source does the technology require?

The majority of the energy required to run the direct air capture plant comes from low-grade/waste heat.

Does the technology require a source of water?

No, the filter actually removes moisture from the air, so the plants generate their own supply of fresh water.

What is the filter material?

The filter material is made of porous granulates modified with amines, which bind the CO2 in conjunction with the moisture in the air. This bond is dissolved at temperatures of 100 °C

dv said:

http://www.climeworks.com/our-technology/

What energy source does the technology require?

The majority of the energy required to run the direct air capture plant comes from low-grade/waste heat.

Does the technology require a source of water?

No, the filter actually removes moisture from the air, so the plants generate their own supply of fresh water.

What is the filter material?

The filter material is made of porous granulates modified with amines, which bind the CO2 in conjunction with the moisture in the air. This bond is dissolved at temperatures of 100 °C

Surely they need to use some zinc?

dv said:

http://www.climeworks.com/our-technology/

What energy source does the technology require?

The majority of the energy required to run the direct air capture plant comes from low-grade/waste heat.

Does the technology require a source of water?

No, the filter actually removes moisture from the air, so the plants generate their own supply of fresh water.

What is the filter material?

The filter material is made of porous granulates modified with amines, which bind the CO2 in conjunction with the moisture in the air. This bond is dissolved at temperatures of 100 °C

Interesting, thanks.

mollwollfumble said:

start with CaCO3, limestone, heat to release CO2 for your greenhouse, then over time the CaO captures CO2 again to turn it back into CaCO3.

Converting CaCO3 to CaO would be quite energy intensive. A milder reaction would be:

2 NaHCO3 ‹—› Na2CO3 + CO2 + H2O

However, it is not clear to me if sodium carbonate would be an effective absorber of carbon dioxide at atmospheric concentrations (the benefit of a milder reaction comes at the cost of reduced effectiveness as an absorber).

KJW said:

mollwollfumble said:

start with CaCO3, limestone, heat to release CO2 for your greenhouse, then over time the CaO captures CO2 again to turn it back into CaCO3.

Converting CaCO3 to CaO would be quite energy intensive. A milder reaction would be:

2 NaHCO3 ‹—› Na2CO3 + CO2 + H2O

However, it is not clear to me if sodium carbonate would be an effective absorber of carbon dioxide at atmospheric concentrations (the benefit of a milder reaction comes at the cost of reduced effectiveness as an absorber).

Yes, I only mention CaCO3 because mining it puts very little CO2 into the air. The production of the more effective ethanolamine, for example, puts much more CO2 into the air.

To make ethanolamine requires ammonia. To make ammonia requires (more than 1% of all man-made power) as well as CaO. To make CaO requires CaCO3.

Came up the answer to this one a while ago

Yes you do use caco3

wookiemeister said:

Came up the answer to this one a while ago

Yes you do use caco3

Please expand on this notion. Chemical equations would assist.

Michael V said:

wookiemeister said:

Came up the answer to this one a while ago

Yes you do use caco3

Please expand on this notion. Chemical equations would assist.

Earlier in this thread, I suggested an aqueous solution of sodium carbonate. However, I also expressed uncertainty of its ability to absorb atmospheric concentrations of carbon dioxide. In the case of an aqueous suspension of calcium carbonate, I strongly doubt its ability to absorb atmospheric concentrations of carbon dioxide due to the very low concentration of the carbonate ion.

You are only using it to extract it from the air nothing else, its only part of the process.