Interesting project although the journalists seem to have moved Weymouth some 300 miles west.

Also someone seems to have moved the quote function in the input editor as I can't find it anymore

I also wonder if there are enough coconut trees in the world to make this a viable large scale project.

Sorry I can't post a longer summary , without the quotes.

BBC News

Could taking carbon out of the sea cool down the planet?

A pilot project will test whether it is a useful way of fighting climate change.

Aside from the energy equation (if you have sufficient renewable energy to actually do this at a significant rate....why not just use that RE to replace fossil fuel, thus solving the larger problem with fewer steps?), I have to wonder what processing seawater like this in high volumes would do to the plankton population. Phytoplankton in particular, since it's a key player in the carbon cycle. Oh the face of it, this project looks to be the same sort of greenwashing that big polluters are already doing with air scrubber projects. I. e. they simply won't scale up in an affordable way.

1 hour ago, TheVat said:

Aside from the energy equation (if you have sufficient renewable energy to actually do this at a significant rate....why not just use that RE to replace fossil fuel, thus solving the larger problem with fewer steps?), I have to wonder what processing seawater like this in high volumes would do to the plankton population. Phytoplankton in particular, since it's a key player in the carbon cycle. Oh the face of it, this project looks to be the same sort of greenwashing that big polluters are already doing with air scrubber projects. I. e. they simply won't scale up in an affordable way.

I suppose raising the pH might help coral reefs survive. But I agree it seems like locking the stable door and needlessly complex.

Unfortunately they don’t give any numbers. How much does the pH and CO2 concentration drop? They suggest it’s significant if they purport to be worried about the pH change having an effect on ocean life, but how can a small-scale project do that?

And how much does that affect the absorption rate? That’s the key metric.

I don't see how they can be serious. I think it is unrealistic enough to expect much from Carbon Capture and Storage even in more familiar forms - it would have to become the world's single biggest industry, without any profitability, ie paid for by taxes or levies, which will be opposed and evaded.

Oceans are so enormous I can't see how useful amount of sea water could be processed at all, let alone cost effectively - or even do it in a way that is easier and cheaper than (not economically viable) Direct Air Capture.

The top 1mm of Earth's oceans is 360 Gigatonnes and I doubt treating even that much (that little) would be sufficient. Having localised, probably coastal processing and expecting mixing by currents seems to require taking more CO2 out of some water, to well below an ideal concentration, to dilute the concentrations elsewhere, with ecological impacts of that. Then there is all that CO2 to temporarily store and transport and then permanently store somewhere. Utilisation? There are few ways it can be used that won't ultimately release the CO2 back to the atmosphere again and those uses that could permanently lock up the carbon are not going to have markets big enough.

I think low emissions energy to displace fossil fuel burning is both the most directly effective and the least cost action we can take. Studies to explore the novel 'solutions' are worthwhile but committing to schemes like this is not.

Edited April 19Apr 19 by Ken Fabian

9 hours ago, Ken Fabian said:

don't see how they can be serious. I think it is unrealistic enough to expect much from Carbon Capture and Storage even in more familiar forms - it would have to become the world's single biggest industry, without any profitability, ie paid for by taxes or levies, which will be opposed and evaded.

Appreciate your post exploring more thoroughly the absurdity of this than mine did.

One wonders what the company mottos would be...marginally raising marine pH while we carbonate slaked lime by the gigaton instead of just making you an affordable electric car and an actual profit!

On 4/18/2025 at 7:26 AM, studiot said:

Interesting project although the journalists seem to have moved Weymouth some 300 miles west.

Also someone seems to have moved the quote function in the input editor as I can't find it anymore

I also wonder if there are enough coconut trees in the world to make this a viable large scale project.

Sorry I can't post a longer summary , without the quotes.

BBC News

Could taking carbon out of the sea cool down the planet?

A pilot project will test whether it is a useful way of fighting climate change.

If suck in more co2 storage, could that mean we need more green stuff (i.e. trees etc) planted in order for the extra co2 storage to be converted into healthy air for us to breathe?

I made that question because of proportional ratio, which I think possibly exist in some way, within the Goldilocks zone of habitable on mostly surface of this planet. Whereas zones or areas outside of that Goldilocks zone, are possibly not (e.g. uneven etc)?

That visual or diagram picture of the sucking in co2 process seemingly make sense but that co2 storage got my attention.

I was disappointed with the smart arse responses to my topic as few seem to have read the article properly.

In my summary I indicated some of my own reservations about the idea, as the article clearly sufferd journalistic mangling.

An important unclear point was the statement

QUOTE

"Seawater has got loads of carbon in it compared to the air, about 150 times more," says Dr Halloran.

ENDQUOTE

What does this mean ? how was the figure of 150 arrived at ?

It is crucial to the idea, even if other (im) practicalities mitigate against it.

3 hours ago, studiot said:

What does this mean ? how was the figure of 150 arrived at ?

I have a different value from here (but it is from 2000. Maybe current estimates are different):

https://en.wikipedia.org/wiki/Carbon_cycle#Ocean

"the deep ocean contains far more carbon—it is the largest pool of actively cycled carbon in the world, containing 50 times more than the atmosphere"

Maybe it’s concentration? 400+ ppm is around 1 mg/L and the most you can dissolve in water is around 1g/L (at STP) and we’re not at that maximum.

Thank you both, but it is not as simple as that since the oceanic and atmouspheric mechanisms are different.

The carbon dioxide molecule has a molecular weight well above the atmouspheric average so the concentration will be greater at lower levels.

Oceanic carbon dioxide on the other hand is not part of a gaseous mixture and subject to those laws, it is a dissolved ion, subject to oceanic mixing processes and removal processes.

But the fact remains that the question how much seawater (preferably weight) v how much air (weight again) would you have to process to remove x amount of carbon dioxide ?

The comparisons of how difficult/costly each would be can be fairly made.

I wonder how difficult can to make co2 'filter' sponge(s) for both air and ocean / seawater and then feed it to plants?

9 hours ago, studiot said:

QUOTE

"Seawater has got loads of carbon in it compared to the air, about 150 times more," says Dr Halloran.

ENDQUOTE

What does this mean ? how was the figure of 150 arrived at ?

It is crucial to the idea, even if other (im) practicalities mitigate against it.

Surface seawater CO₂ concentration is typically <10 ppm or <10 g/m³

Average sea level air concentration is 428 ppm or ~0.5 g/m³

So I make it 20:1 max

On 4/21/2025 at 2:58 PM, swansont said:

Maybe it’s concentration? 400+ ppm is around 1 mg/L and the most you can dissolve in water is around 1g/L (at STP) and we’re not at that maximum.

However, the acidification process will protonate some of the ~1,500 ppm of bicarbonate releasing more CO₂ so I assume that's where the extra boost is coming from.

The thinking appears to be that CO₂ extraction from a source with 150 × the volumetric concentration will save ~ RTln(150) J/mol on the entropy reversal cost. A major consideration for carbon capture from low concentration sources.

On 4/22/2025 at 12:09 AM, studiot said:

The carbon dioxide molecule has a molecular weight well above the atmouspheric average so the concentration will be greater at lower levels.

This is incorrect. There is higher than average concentration because the sources of CO2 are at the surface and it takes mixing to disperse and homogenize them in the air. Those sources are higher concentration than the air, not from any stratification. Total gross amounts are mostly greater because lower atmosphere is higher density.

At larger scales bulk air movements mix atmospheric gases - convection and wind. A big thunderstorm will carry air from ground level to the stratosphere with vigorous mixing all the way. At small scales diffusion mixes them and prevents any stratification, even in enclosed spaces with still air. Without a source at higher concentration it won't pool in the bottom - and is maintained by the source. Take the source away and diffusion will mix them to very close to homogeneous.

7 hours ago, Ken Fabian said:

This is incorrect. There is higher than average concentration because the sources of CO2 are at the surface and it takes mixing to disperse and homogenize them in the air. Those sources are higher concentration than the air, not from any stratification. Total gross amounts are mostly greater because lower atmosphere is higher density.

At larger scales bulk air movements mix atmospheric gases - convection and wind. A big thunderstorm will carry air from ground level to the stratosphere with vigorous mixing all the way. At small scales diffusion mixes them and prevents any stratification, even in enclosed spaces with still air. Without a source at higher concentration it won't pool in the bottom - and is maintained by the source. Take the source away and diffusion will mix them to very close to homogeneous.

Thank you for your thoughts but this source explanation does not hold up since many natural and artificial sources are 'ducted' to conduct the output away from the ground directly into the air (though not usually the stratosphere).

Yes indeed there are mixing processes going on but the natural tendency of gas mixtures in a potential field is for the concentration of the lighter gasses to increase with a graduated field.

That is why gasses like hydrogen and helium and even methane vanish upwards very quickly, whilst gasses like carbon dioxide do not and why Health and Safety executives around the world issue cautionary documents and classify carbon dioxide as hazardous.

https://pmc.ncbi.nlm.nih.gov/articles/PMC5380556/

Carbon dioxide (CO₂) is a product of combustion, fermentation, and respiration. In normal room air, carbon dioxide percentages are very low (around 0.04%). It is a colorless, odorless, and nonflammable gas that accumulates near the ground (CO₂ is 1.5 times heavier than air). These characteristics explain why enclosed environments are vulnerable for CO₂ buildup, displacing oxygen from the area [1]. The term “confined space hypoxic syndrome” has been proposed to describe confined space accidents occurring in water meter pits, tanks, holds of ships, mines, underground storage bins, and so forth, resulting from oxygen-deficient atmospheres [2, 3].

The second reference shows very clearly the different fractions of different gasses that will naturally achieve the speed necessary to climb to any given level in the potential field.

Chemistry LibreTexts

5.9: Molecular Speed Distribution

Edited April 24Apr 24 by studiot

@studiot I'll stand by what I said - 'very close to homogeneous'. Yes there is a slight effect, but too small to be significant.

Gravity will slow the rate of vertical diffusion mixing (slightly) but not actually cause any separation under Earth's atmospheric conditions. Any observed accumulation - the sort that present hazards in enclosed spaces - will be from nearby sources that begin at higher concentration than surrounding air - bulk air - sinking and pooling before getting mixed, not from any separation at the molecular level due to different density - molecular speeds are too high.

More extreme conditions eg gas centrifuges used for nuclear fuel enrichment can overcome that diffusion due to molecular speeds, yes, but the equivalent 'gravity' to do that is extreme. (Lab centrifuges can get up to millions of g's).

7 hours ago, Ken Fabian said:

@studiot I'll stand by what I said - 'very close to homogeneous'. Yes there is a slight effect, but too small to be significant.

Gravity will slow the rate of vertical diffusion mixing (slightly) but not actually cause any separation under Earth's atmospheric conditions. Any observed accumulation - the sort that present hazards in enclosed spaces - will be from nearby sources that begin at higher concentration than surrounding air - bulk air - sinking and pooling before getting mixed, not from any separation at the molecular level due to different density - molecular speeds are too high.

More extreme conditions eg gas centrifuges used for nuclear fuel enrichment can overcome that diffusion due to molecular speeds, yes, but the equivalent 'gravity' to do that is extreme. (Lab centrifuges can get up to millions of g's).

Agreed. Atmospheric gases do not spontaneously stratify by molecular weight, because molecular speeds are far too high.

My understanding is that hydrogen and helium tend to escape from the atmosphere because a higher proportion of their molecules have speeds above escape velocity than heavier molecules. So no doubt there will be mostly these gases in the exosphere, but the mean free path is by then so long that they don’t really behave as if they are in a gas.