Toward a consensus framework to evaluate air–sea CO2 equilibration for marine CO2 removal

[chris.vivian2]

https://aslopubs.onlinelibrary.wiley.com/doi/10.1002/lol2.10330

Lennart T. Bach, David T. Ho, Philip W. Boyd, Michael D. Tyka

Deliberately altering atmospheric CO2 to influence the Earth's climate has been debated for decades (Keith 2000), but was generally not considered a key strategy for climate mitigation. This viewpoint has changed since The Paris Agreement in 2015, and with the IPCC's 6th assessment report concluding in April 2022 that atmospheric CO2 removal (CDR) is now “unavoidable” to reach net zero emissions (IPCC 2022).

The ocean has great potential to deliver CDR at scale but marine CDR (mCDR) methods have key constraints that differ critically from terrestrial CDR approaches. One of the most pronounced differences is that most mCDR methods create or enhance a seawater pCO2 (partial pressure of CO2) deficit when deployed in regions where the seawater pCO2 is equal to or below atmospheric pCO2. Or, they reduce a seawater pCO2 surplus in regions where seawater pCO2 is higher than atmospheric pCO2 (e.g., Eastern Boundary Upwelling Systems). However, in stark contrast to terrestrial CDR methods, mCDR methods cannot directly remove CO2 from the atmosphere. Atmospheric CO2 removal is only potentially occurring in a subsequent step, namely when surface seawater pCO2 equilibrates with atmospheric pCO2. Thus, atmospheric CO2 removal depends upon how completely atmospheric CO2 equilibrates with the CO2-deficient surface water following an mCDR deployment. Or, when the mCDR deployment is in a pCO2 surplus region, how much of the surplus CO2 would have outgassed into the atmosphere in the absence of the mCDR deployment. The necessary air–sea CO2 exchange depends on various factors such as the residence time of seawater at the surface, carbonate chemistry, and how rapidly atmospheric CO2 invades the surface ocean (Wanninkhof et al. 2009).

[Jim Baird]

”how much of the surplus CO2 would have outgassed into the atmosphere in the absence of the mCDR deployment”

 

“Direct Climate Cooling (DCC) can dramatically reduce harm, preserve ecosystems, and save lives as we work to reduce greenhouse gas (GHG) emissions and remove GHG from the atmosphere and oceans,” Healthy Planet Action Coalition.

 

This cooling can “Ungas” CO2 from the atmosphere.

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[Jim Baird]

Hi Ye,

 

Isn’t that what Resplandy et al. did in Quantification of ocean heat uptake from changes in atmospheric O2 and CO2 composition?

 

Quantified temperature-dependent fluxes from the various sources and sinks.

 

Jim

 

From: Ye Tao
Sent: May 19, 2023 10:53 AM
To: Jim Baird <jim....@gwmitigation.com>; 'chris.vivian2' <Chris....@btinternet.com>; 'Carbon Dioxide Removal' <CarbonDiox...@googlegroups.com>
Cc: healthy-planet-...@googlegroups.com
Subject: Re: [CDR] Toward a consensus framework to evaluate air–sea CO2 equilibration for marine CO2 removal

 

Hi Jim et al,

Can people suggest sources that have quantified temperature-dependent fluxes from the various sources and sinks?  Obviously we have the methane (uncertain), permafrost, and forest burning (probably secondary importance wrt fossil fuel burning) emissions at higher temperatures.   Can we pool together sources that give the various flux changes vs Del T?

I once believed, simply because many people said it, that the CO2 would outgas from the oceans at higher temperatures.  I am not so sure anymore since the ionizations of carbonic acid and the bicarbonate ion seem to be favored by rising temperatures with a gradient proportionally larger compared to that of CO2(g) water solubility decreasing.

Ye

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[Michael Hayes]

[...] However, in stark contrast to terrestrial CDR methods, mCDR methods cannot directly remove CO2 from the atmosphere. Atmospheric CO2 removal is only potentially occurring in a subsequent step, namely when surface seawater pCO2 equilibrates with atmospheric pCO2. [...]

MH] In the case of OAE using electrolysis where alkiline water is produced, simply spraying the water into the air to gain a greater air/water surface contact area will 'capture' some amount of atmospheric CO2. Lowering the water pCO2 before spraying, by running the water through an enclosed aquatic cultivation system, can likely help lower the transfer of CO2 from the water to the atmosphere. This dual mCDR tech, biotic and abiotic, helps addresses both water/air pCO2 transfer needs and water pH adjustment needs.

Some have discussed using massive fields of spray, or misting, as a direct means of cooling the water surface, however, misting without first lowering the pCO2 of the water would likely result in a more acidic surface water due to the mechanical capture of atmospheric CO2. 

(Jim, misting with cold deep water that has been degassed and pH adjusted is an ideal tech combination, IMO, can your TG tech supply the cold water?)

Moreover, misting with low pCO2/strong alkiline water can likely be rightfully viewed as a cheap form of DAC, and the 45Q/C credits should reflect that once the full system, biotic and abiotic methods working together, is properly evaluated. Adding the biofuel produced in the biotic side and H2 fuel produced in the abiotic side to the equation should produce a rather high overall CDR/emissions avoidance value rating. 

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[Josh Perfetto]

Hi Michael,

That is an interesting idea. However what happens to the CO2 in the mist droplet if/when the mist droplet evaporates? Would you need to ensure it falls back into the water first?

Or is the idea that it transforms into bicarbonate while in the droplet, which falls into the ocean as a solid? And then the CO2 that remained in the droplet degasses and is an inefficiency of the system? (or the remaining behind alkalinity treated as traditional OAE subject to the MRV this thread was about)

Also doesn't 45Q tax credit also require storing it in an underground geological formation (or EOR or products), and so might not work here even if this system is construed as a DAC?

I think this is an interesting idea though and could make OAE work in regions otherwise deemed unsuitable for equilibration.

-Josh

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[Michael Hayes]

Thanks for the interesting questions, Joshs. What I wrote is an early stage idea and questions help me work out the details. The broader concept that I'm working on, beyond misting alkiline water, involves a rather large basket of technical systems being coupled together for both mCDR and oceanic farming, possibly resulting in C negative self sustaining offshore human colonies.

1) "However what happens to the CO2 in the mist droplet if/when the mist droplet evaporates? Would you need to ensure it falls back into the water first?" 

MH] Spraying low to no pCO2 content water would be needed as, if the CO2 outgasses from the mist, that would be an emission that would count against the overall positive MRV math, just as you indicated. As a side note on degassing surface water, there are mechanical means to do so as well as biological means, no reason not to use both if needed. Using low to no pCO2 content water is critical to a misted discharge system.

2) "Or is the idea that it transforms into bicarbonate while in the droplet, which falls into the ocean as a solid? And then the CO2 that remained in the droplet degasses and is an inefficiency of the system? (or the remaining behind alkalinity treated as traditional OAE subject to the MRV this thread was about)"

MH] The idea of spraying alkiline water is to increase the contact area between the air and water for rapid conversion of atmospheric CO2 into carbonic acid, and some capture of atmospheric CO2 can also be expected. This potential capture of CO2 would seem to be a form of DAC that drops the captured atmospheric CO2 into the water surface if it is not immediately converted by the alkiline water being misted.

The open air release of H+ into during misting operations might be limited by using some form of containment system. If sprayed within a tower, the lower tower would need to be open to the air, and the bulk of the misting would happen just above the opening in the lower tower. An enclosed tower top can collect the H for further use, the released H should displace all other gasses at the top of the tower.

A further benefit of such a misting tower would be that most of the water can possibly be captured and recycled through the pCO2 reduction/alkilinty enhancment process and resprayed in the tower to take down more atmospheric CO2. This would eliminate the need for using large surface alkalinity enhancement. Sea/air pCO2 equilibrium over large surface areas, the subject of this thread, would become moot. 

3) On the issue of 45Q qualifications:

https://www.law.cornell.edu/uscode/text/26/45Q

[...] (5)Utilization of qualified carbon oxide

(A)In generalFor purposes of this section, utilization of qualified carbon oxide means—

(i)

the fixation of such qualified carbon oxide through photosynthesis or chemosynthesis, such as through the growing of algae or bacteria,

(ii)

the chemical conversion of such qualified carbon oxide to a material or chemical compound in which such qualified carbon oxide is securely stored, or

(iii)

the use of such qualified carbon oxide for any other purpose for which a commercial market exists (with the exception of use as a tertiary injectant in a qualified enhanced oil or natural gas recovery project), as determined by the Secretary. [...]

MH] 

a) A vast scale oceanic cultivation infrastructure that can release CO2 would be generating an 'industrial source' of CO2. Plant outgas CO2 at night. As such, any captured CO2 from such an offshore operation can possibly be discribed as a 'qualified carbon oxide'.

Another example, upwelling water for use of the nutrients in confined cultivation operations would be an industrial process, the same industrial biotic process that helped provide low to no pCO2 water for the spray. The decompressed CO2 released during upwelling should fit the definition of an 'industrial source'. Contrary to my first post, I don't see the spraying of alkiline water itself as being 45Q qualified as the language now reads. The captured outgassed CO2 from the upwelled water, from nightly plant outgassing, and use of the captured CO2, however, may qualify.

b) The overall C math, including biotic and abiotic processes, should generate C credits.

c) I would argue that simply generating C credits while capturing and using the oceanic infrastructure generated CO2 fits the below utilization definition:

[...] for any other purpose for which a commercial market exists. [...] 

Adjustments to 45Q, based upon new tech developments, may happen in the future as it already has happened in the past. It is up to the Secretary to interpret the existing language. 

As a final technical note, the cost of a vast scale mCDR/farming infrastructure can be a seperate write up, this response is likely already too long.

I hope this helped sort things out for you, my first post was not that well crafted. Your questions helped me think through important details.

Best regards

[Tom Goreau]

Doesn’t the very slow kinetics of CO2 hydration limit the effectiveness of spraying alkaline seawater to absorb CO2?

 

You may need to add carbonic anhydrase.

 

Thomas J. F. Goreau, PhD
President, Global Coral Reef Alliance

Chief Scientist, Blue Regeneration SL
President, Biorock Technology Inc.

Technical Advisor, Blue Guardians Programme, SIDS DOCK

37 Pleasant Street, Cambridge, MA 02139

gor...@globalcoral.org
www.globalcoral.org
Skype: tomgoreau
Tel: (1) 617-864-4226 (leave message)

 

Books:

Geotherapy: Innovative Methods of Soil Fertility Restoration, Carbon Sequestration, and Reversing CO2 Increase

http://www.crcpress.com/product/isbn/9781466595392

 

Innovative Methods of Marine Ecosystem Restoration

http://www.crcpress.com/product/isbn/9781466557734

 

No one can change the past, everybody can change the future

 

It’s much later than we think, especially if we don’t think

 

Those with their heads in the sand will see the light when global warming and sea level rise wash the beach away

 

Geotherapy: Regenerating ecosystem services to reverse climate change

 

 

 

From: <carbondiox...@googlegroups.com> on behalf of Michael Hayes <electro...@gmail.com>
Date: Saturday, May 20, 2023 at 3:58 AM
To: Josh Perfetto <jo...@snowrise.com>
Cc: Carbon Dioxide Removal <carbondiox...@googlegroups.com>
Subject: Re: [CDR] Toward a consensus framework to evaluate air–sea CO2 equilibration for marine CO2 removal

 

Thanks for the interesting questions, Joshs. What I wrote is an early stage idea and questions help me work out the details. The broader concept that I'm working on, beyond misting alkiline water, involves a rather large basket of technical systems being coupled together for both mCDR and oceanic farming, possibly resulting in C negative self sustaining offshore human colonies.

To view this discussion on the web visit https://groups.google.com/d/msgid/CarbonDioxideRemoval/CABjtO1fi%3D2gUKkVGFyNX%3Dcn0P2m5Q24fTFBV1WxXyQ8doaC%2BZQ%40mail.gmail.com.

[Michael Hayes]

Thanks, Tom

I looked for commercial availability of CA and realized that CA can be derived from both algae and bacteria, both being candidates for on-board crops for food/fuel/CDR.

I've been reluctant to call for any additives to the spray water as that would represent a seperate system for production, and the use of additives can increase uncertainties about environmental impacts. However, as external CA is found in microalgae/bacteria there may be the possibility of using crushed microalgae/bacteria as a CA source. Putting either through a high pressure spray system will crush them. 

So, the crop can drawdown aquatic pCO2 as it grows, and then spraying the crushed biota can possibly, maybe, hypothetically speaking convert atmospheric pCO2 due to the exposed eCA. Moreover, by limiting the CO2 availability to the culture just before spraying, the amount of eCA can likely be increased:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3668045/

That was a fun morning read...

Best regards 

[Jim Baird]

Ye, this is how I tried suss  out C fluxes as a function of T from this paper. 

They determined about 1.11 ± 0.68 per meg or parts per million (ppm) of O2 and CO2 is going into the atmosphere on account of warming of the tropical surface, with the concentrations of these gases being 1 part O₂ to 1.05 parts CO₂.

 

About .56 ppm of CO₂ was therefore added to the atmosphere each year of the study due to warming. 

The atmospheric CO₂ level as of Aug. 22, 2021 was 414.68 ppm and Aug. 22, 2020 it was 412.68 ppm so, the annual accumulation was 2 ppm. Since 1 ppm  CO₂ = 7.81 gigatonnes (Gt), about 15.6 Gt of the greenhouse gas went into the atmosphere over the course of the year, with the 28% of this due to surface warming, which amounts to 4.4  Gt.

 

 

They said the oceans gained 1.29 ± 0.79 × 10²² Joules of heat per year between 1991 and 2016 doesn’t this give you the same result as Temperature?

 

 

 

From: Ye Tao
Sent: May 21, 2023 12:37 PM
To: Jim Baird <jim....@gwmitigation.com>; 'chris.vivian2' <Chris....@btinternet.com>; 'Carbon Dioxide Removal' <CarbonDiox...@googlegroups.com>
Cc: healthy-planet-...@googlegroups.com
Subject: Re: [CDR] Toward a consensus framework to evaluate air–sea CO2 equilibration for marine CO2 removal

 

Hi Jim,

Thanks for the paper.  I think not quite what I was looking for.  I am looking for changes to C fluxes as a function of T as the independent variable.  The paper you suggest is looking the otherway, and aggregates all sources and sinks wrt the atmosphere.

Ye

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[Jim Baird]

Hi Ye,

 

I agree. Attached is a link to a proposed closed experiment that could test if carbon dioxide moves from the atmosphere into the ocean as the atmosphere is cooled  http://gwmitigation.com/Videos/TG5minladderpiitch.m4v.

 

The video is dated because I would now use 3D printed, thin film, heat exchangers.

 

According to CleanTechnica there are .75 grams of CO2 in a cubic meter of atmosphere.

 

The atmosphere in the experiment is 14 cubic meters so there would be 10.5 grams of CO2 and the atmosphere would be additionally at 30C.

 

The system should be able to power 3 - 100 watt light bulbs. Obviously it couldn’t do this without an external source of power but the point is, producing this energy causes surface heat to move into the cold water sink. So, the experiment would run at a surface temperature of 30C for 6 months and then drop the surface temp by 1.8C – about how much the surface will have reached in about 30 years, and see how much efficiency you lose by cooling the surface and cooling the deep water. In real world conditions a 1000 meter long column of water should be warmed by less than .2C. After 6 months at the cooler surface there should be a migration of CO2 from the atmosphere into the water. According to Resplandy this should be 28% of the 10.5 grams.

 

Completing my original thought, the ocean contains 1.347e18 cubic meters of water.

The specific heat of water is 4,184 Joules per kilogram.

It would take 4,184 * 1.347e18 cubic meters =  5.57e22 joules to warm the ocean 1 degree.

Resplandy calculated the ocean warmed by 1.29 ± 0.79e22 each year between 1991 and 2016, which would be .23 degrees?

 

Since this can never be tested at a global scale, this small closed system experiment could give us a clue?

 

Jim

 

From: Ye Tao
Sent: May 22, 2023 7:09 AM
To: Jim Baird <jim....@gwmitigation.com>; 'chris.vivian2' <Chris....@btinternet.com>; 'Carbon Dioxide Removal' <CarbonDiox...@googlegroups.com>
Cc: healthy-planet-...@googlegroups.com
Subject: Re: [CDR] Toward a consensus framework to evaluate air–sea CO2 equilibration for marine CO2 removal

 

Hi Jim,

I don't think one can get at the fluxes by involking historical CO2(atm) changes, with historical temperature changes and heat accumulation.

These carbon fluxes should be "measured" with anthropogenic fluxes turned down to zero, while temperature is changed by an extraterrestrial source that is not connected to the various forcings involving carbon based gases.  Obviously, it is not possible to do such measurements from a top-down approach, so results necessarily need to emerge from small scale mechanistic experiments extrapolated to the global scale.

Ye

[Jim Baird]

Correction

 

4,184 * 1.347e18 cubic meters =  5.57e21 joules so the ocean would have warmed by 2.3 degrees which is certainly not the case.

To view this discussion on the web visit https://groups.google.com/d/msgid/CarbonDioxideRemoval/004701d98cc8%24a91a9620%24fb4fc260%24%40gwmitigation.com.