The process in question is that of a company called Equatic. The were in the news because they made a deal with Boeing.
As I understand their process, they apply some kind of electrolysis to sea water which causes the dissolved CO2 to combine with either magnesium or calcium ions already in the water to form carbonates. The water, minus the CO2, is returned to the ocean where it will absorb more CO2 from the air. As a side effect, it also generates some hydrogen. Not sure what happens to the carbonates.
I’m going to guess that one negative effect is that the sea is now deficient in calcium ions. I expect that shellfish depend on a certain density of calcium ions to make their shells, so they will have difficulty doing that. Perhaps there’s something similar for magnesium. Any other possible negative effects?
OTOH, CO2 acidifies the ocean which interferes with shellfish uptake of Ca. It may be that by performing this reaction and reducing the ocean’s acidity, the net effect improves shell formation. I know that I don’t know.
Almost any ecological tradeoff involves many many 2nd through 10th order effects and a naïve off-top-of-head analysis (like mine) misses more than it catches.
This is a highly discussed matter in general for hydrogen productio, to the point that hydrogen comes in a whole rainbow of colours
There is a lot of debate about what is classed as “renewable sources” for example biomass, (what would happen to the biomass material if it wasn’t burnt to create electricity, what are the emissions getting the biomass to the power station?), but even for wind, if an electrolyser has a contract to take all the output of a wind farm, but if that contract wasn’t there the wind farms out put would go onto the grid displacing a coal plant is that really green?
The aim of those working towards a net zero future is all electricity production is renewable (and possibly nuclear) and almost everything is powered either by electricity or hydrogen produced from renewable electricity.
They’re neutralizing the anolyte with mafic/ultramafic or other basic rocks. Albeit not all those have much calcium. And I didn’t see in the paper they link to any analysis of the energy required for mining, comminution, or transportation of that rock.
The ocean is mighty big (352 quintillion gallons). I’d be surprised if this process could meaningfully affect that balance (maybe in a very local area).
If we processed 1 billion gallons of water a day like this (which would be nuts…over 1500 Olympic sized swimming pools…about one per minute) it would take over 960,000 years to clear the whole ocean.
Not to mention I would assume calcium is being replaced via natural processes (e.g. smoker vents in the Atlantic…just guessing).
I get we do not need to clear the whole ocean of all calcium to have an effect on wildlife but I don’t think we can make a meaningful dent in it for ages.
I meant locally, although now I see I failed to say that. Another thing I failed to say is that not all the calcium needs to be removed for it to be deficient. Shellfish may require a certain density of ions to be able to use them. However, I’m just guessing on that.
I’ll admit that I didn’t read that paper. I didn’t see any mention of adding pulverized rock to the water on the web page. Perhaps I missed it.
That kind of info is not likely to be in a scientific paper on a chemical process. I would hope it would be in the EIS for building a reactor.
Don’t tell the clients who have been paying me to read just that kind of info in scientific papers from authors trying to convince the world that their technology is better than other solutions.
