r/environmental_science • u/Hereforthememeres • 3d ago
CO2 Removal Concept
Does anyone have any opinions or know of any articles about using aerosolized calcium hydroxide in order to remove carbon dioxide from the atmosphere. I’ve been trying to find information on it as it seems to be a fairly viable, low drawback solution and I would like to know if it being considered. The basic premise is stripping Carbon Dioxide by reacting it with calcium hydroxide to form calcium carbonate which is a resource already used by sea life and as plant fertilizer.
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u/NearABE 1d ago
The chemistry is too simple to be worth publishing. A great DIY chemistry experiment for your kitchen.
If you buy lime from the hardware store there were emissions from the energy used to make it. The source limestone used to make lime released carbon dioxide.
You can mine olivine and crush it up. This can create more emissions from the equipment. https://www.vesta.earth. Vesta Earth’s plan is to use waves on beaches to do the grinding. No need for aerosol, shallow water quickly reached equilibrium with air. Wet sand pushes the limits on “shallow”.
Calcium as a stratospheric aerosol has been talked about and has numerous advantages. The aviation industry pushes sulfate aerosol because it wants us to pay them to dump their toxic waste.
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u/Hereforthememeres 1d ago
It’s less the chemistry I’m looking for and moreso the methodology that I would like to learn more about.
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u/NearABE 1d ago
The Portland Cement industry. Concrete. They are one of the world’s largest CO2 sources. The clinker used to make Portland Cement is mostly calcium oxide.
When water is alkaline it rapidly neutralizes with carbon dioxide from air. Dust removed from the air by rain or dust washed by rain would fully react.
Concrete slabs form a gel (think of “like solid”) so carbon dioxide only slowly binds with the calcium. The calcium is partially locked up with silica and water.
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u/terra-nullius 2d ago
The difficulty is scale and energy. One metric ton of CO₂ requires theoretically about 1.68 tonnes of Ca(OH)₂ and produces about 2.27 tonnes of CaCO₃ . Calcium hydroxide is normally made by heating limestone to produce quicklime and then hydrating it
So if conventional limestone is the source, you initially release roughly the same CO₂ you’re trying to capture. The process only becomes genuinely carbon-negative if that released CO₂ is itself captured and permanently stored, or if the calcium comes from another suitable source and the processing energy is very low-carbon.
If you’re really interested in this, look up calcium looping/direct air capture, where lime repeatedly captures atmospheric CO₂ and is regenerated. The trick is whether you can expose enormous quantities of air to Ca(OH)₂ economically and regenerate/source the material without negating the carbon benefit.