[HN Gopher] xPrize in Carbon Removal Goes to Enhanced Rock Weath...
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       xPrize in Carbon Removal Goes to Enhanced Rock Weathering
        
       Author : pseudolus
       Score  : 21 points
       Date   : 2025-04-25 13:59 UTC (9 hours ago)
        
 (HTM) web link (spectrum.ieee.org)
 (TXT) w3m dump (spectrum.ieee.org)
        
       | sightbroke wrote:
       | > The company spreads crushed basalt on small farms in India and
       | Africa. The silica-rich volcanic rock improves the quality of the
       | soil for the crops but also helps remove carbon dioxide from the
       | air. It does this by reacting with dissolved CO2 in the soil's
       | water, turning it into bicarbonate ions and preventing it from
       | returning to the atmosphere
       | 
       | > Carbon dioxide in the air dissolves into rainwater, forming
       | carbonic acid. As rocks are worn away (or weathered) by this
       | slightly acidic water, silicate minerals in the rock dissolve.
       | This releases calcium, magnesium, and other positively charged
       | ions called cations. These cations react with carbonic acid in
       | the water, forming bicarbonate ions.
       | 
       | Here is a dumb question: Would the basalt capture CO2 more
       | effectively if released into the atmosphere or into rain storms?
        
         | moomin wrote:
         | You'd need to, at the very least, make it into a powder or it
         | would just fall to the ground anyway. That, in turn, would
         | require you to crush basalt, which is pretty tough and,
         | importantly, energy intensive. And you wouldn't have any
         | agricultural benefits either.
        
           | sightbroke wrote:
           | They're already crushing it here though?
           | 
           | You can still do both things but if the primary goal is to
           | capture carbon my question is if it would capture more if
           | released in the atmosphere (by planes or similar).
        
             | zdragnar wrote:
             | You'd want to crush it much more finely for it to have a
             | chance to actually capture anything while in the air,
             | requiring more energy input and causing breathing hazards
             | due to the fine particulates, not to mention staining
             | everything it rains on with the fine basalt.
             | 
             | You could release it extremely high such that it stays
             | suspended a bit longer, but then you'd waste even more
             | energy getting it up there.
        
         | Teever wrote:
         | I've been wondering for a while now about the viability of
         | asteroid/lunar mining that involves returning the payload of
         | rare earth minerals or titanium in flying wing shaped return
         | vehicles that are wrapped in some sort of mineral that ablates
         | in the atmosphere while absorbing CO2 like this stuff does.
         | 
         | The idea is that we could both eliminate the Earth based
         | pollution associated with mining while sequestering co2
         | previously emitted by terrestrial mining at the same time.
        
         | JumpCrisscross wrote:
         | > _Would the basalt capture CO2 more effectively if released
         | into the atmosphere or into rain storms?_
         | 
         | Guess: it would do so more quickly, but not necessarily more
         | effectively in the long run to the extent it balances the
         | energy required to loft it. (Even if it's all green. You could
         | just that energy to grind and distribute more basalt to the
         | ground.)
        
         | jrapdx3 wrote:
         | AFAIK cationic calcium, et. al., combine with dissolved CO2
         | forming carbonates which having low water solubility eventually
         | precipitate out of solution. Area with "hard water" often have
         | issues with buildup of scale in water pipes. The scale is
         | mainly calcium carbonate and sulfate.
         | 
         | This is normally a gradual process requiring ample moisture.
         | Releasing finely ground rock into the air wouldn't likely be
         | effective. For one thing, such dispersal would be rather
         | dilute. IOW the dispersion wouldn't reliably react with CO3
         | ions before settling out of the air. Another consideration is
         | the salicaceous content of the rock being a potential health
         | hazard.
         | 
         | The original idea of adding crushed rock to water-containing
         | soil is logically the best way for the project to accomplish
         | its goals.
        
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       (page generated 2025-04-25 23:01 UTC)