For billions of years, the oceans have been absorbing CO2 from the atmosphere. Now, to boost that drawdown, startup companies and researchers are experimenting with ‘marine carbon dioxide removal’ by altering the chemistry of the ocean and sinking biomass to the seafloor.
  • ganksy@lemmy.worldEnglish
    7·
    8 months ago

    I think the alkaline rocks create a way to absorb the carbonic acid that comes from CO2 diluted in water.

    • LvxferreEnglish
      27·
      8 months ago

      That’s correct. And my point is that they aren’t “further acidifying” the ocean, like Icalasari said; they’re doing the exact opposite.

      I’ll use the opportunity for an info dump. You potentially know what I’m going to say, but it’s for the sake of users in general.

      Carbon dioxide dissolution in water can be simplified through the equation

      CO₂(g) + 2H₂O(l) ⇌ H₃O⁺(aq) + HCO₃⁻(aq)
      gaseous carbon dioxide + water generates (→) hydronium (“acidity”) + bicarbonate, and vice versa (←).

      It’s a reversible reaction, as anyone opening a soda can knows (wait a bit and the gas GTFO and you’re left with flat soda). However, you can “force” a reversible reaction to go more into one or another direction, by messing with the amounts of substances in each side of the equation:

      • if you add more of the junk to one side, the reaction will go more towards the other side - to consume the stuff that you added
      • if you remove junk from one side, the reaction will go more towards that side - to regenerate the junk that you removed

      So it’s like reactions go against whatever change you do. This is known as Le Chatelier’s principle. In a simplified way, “if you change shit the reaction tries to revert your change”.

      Now. The main concern is CO₂ in the atmosphere. We don’t want it. To consume it through this reaction, we could remove acidity from the ocean. That’s actually doable by dumping some alkaline substances there, because of another equilibrium:

      H₃O⁺(aq) + OH⁻(aq) ⇌ 2H₂O(l)
      hydronium (“acidity”) + hydroxide (“alkalinity”) generates water, and vice versa.

      So by adding alkaline substances to the sea you could remove hydronium, and by removing hydronium you’re encouraging the sea to gorge on even more carbon dioxide.

      It sounds like an extremely bad idea though. Just like the two reactions that I mentioned interact with each other, there’s a bazillion other reactions doing the same. Specially when we’re talking about acidity/alkalinity (pH), it’s hard to find something where pH does not influence the outcome!

      So the consequences of “let’s dump alkaline substances in the sea! What could go wrong?” might be extremely messy, and not so obvious from a first moment. Instead we’re simply better off by avoiding to add even more CO₂ to the atmosphere.