Brines for carbon capture

[Seth Miller]

I am looking to ask a couple quick questions of someone with knowledge of the behavior of brines, for example from reverse osmosis or produced water.

I am advising a professor of chemistry who has developed a polymer that will rapidly catalyze the precipitation of calcium carbonates from supersaturated solutions (a process that is usually frustratingly slow). We are interested whether there is use for this to treat brines, either to co-inject base and CO2 in order to capture CO2 as the carbonate for storage, or simply to up-value the brine by selectively separating out calcium.

We are looking for appropriate industry insights to see whether there is value in investigating this space further. If you have comments, please PM me!

Best,

Seth

-------

Seth Miller, Ph.D.

www.linkedin.com/in/sethmiller2

Check my blog at: perspicacity.xyz

[Roger Arnold]

Dr. Miller,

You need a chemical process engineer -- which I'm not -- for estimating economics. But I'd like to clear the air on a couple of points that may cause some confusion among readers here.

I presume you're well aware that precipitation of calcium carbonate consumes alkalinity and leads to evolution of CO2 from the precipitate solution. The normal state of ocean surface waters is mildly supersaturated with calcium carbonate. That supersaturation enables a range of marine organisms, from calcareous phytoplankton to shellfish, to grow shells. I believe they employ enzymes, perhaps similar to what your colleague has developed, to catalyze the precipitation. The supersaturation is maintained by upwelling of cold deep waters. The solubility of all forms of calcium carbonate increase with lower temperatures and higher pressures. Deep ocean waters are generally in near equilibrium with calcium carbonate. As they rise and are warmed by mixing with surface waters, equilibrium becomes supersaturation. From the perspective of both CDR and the health of marine ecosystems, the LAST thing we want to do is to release enzymes into the ocean that will catalyze carbonate precipitation. But that, I presume, is not the intent. It would be why you're asking about treatment of brines, not ocean water.

In a semi-closed and appropriately designed process, precipitation of calcium carbonate CAN be used to sequester both calcium and CO2. That could reduce the dilution requirements for safe return to the ocean of desalination brines, for example, or to increase the desalination fraction. It would be a pH swing process. I won't attempt to lay out the details here, but I'm pretty certain of its technical feasibility. Its economic feasibility and scalability are matters that I'm not truly qualified to address.

If you're interested in exploring the process further, you're welcome to contact me offline.

Roger Arnold

Silverthorn Consulting

silverthorn44 at gmail

leave voicemail at (408) 802-3060

[Tom Goreau]

Deep ocean waters are  NOT “generally in near equilibrium with calcium carbonate.” as stated below!

 

They are markedly undersaturated, so limestone rapidly dissolves in deep waters and sediments.

 

This is in part due to low temperature and high pressure, but the acidifying nature of deep waters is largely due to the CO2 released into the deep ocean by organic matter decomposition on the bottom and in deep waters, decomposition that most deep ocean carbon sequestration schemes systematically ignore, and which falsifies their predictions.

 

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

 

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[Seth Miller]

Roger,

Thanks for responding (and to others who have responded privately).

Yes, as has been discussed here, taking calcium carbonate out of the ocean net releases carbon! Hence my interest in less natural systems, where it is of benefit to remove calcium for other reasons (scaling, purity, etc). In these applications, a process (including the addition of base) that results in carbon capture adds value, and might be preferred to other chemical treatments that produce no value-add. In principle, the notion of stripping the calcium out of brine is therefore interesting, and it’s been discussed in academia under this logical framework.

Does stripping the calcium in this way make sense in industry, in practice? That is a more exacting question, and it’s these details that are really the driving me. I can’t tell if this is something industry would value, or if it is something that looks good in the introduction section of a paper, but for which there are obvious practical impediments.

Best to all,

Seth

-------

Seth Miller, Ph.D.

www.linkedin.com/in/sethmiller2

Check my blog at: perspicacity.xyz

[Douglas MacMartin]

Hi Tom – a question more relevant to a previous thread, but what is the equivalent atmospheric CO2 (or range) that deep waters would be roughly equilibrated to if they were brought to the surface?  Higher than pre-industrial, for sure, but as atmospheric CO2 keeps going up, eventually even those waters would be undersaturated relative to the atmosphere…

 

Thanks,

doug

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[Tom Goreau]

I can’t give a good answer to your great question now, because I’m in a small fishing village on a fjord in southern Patagonia, and my copy of Broecker and Peng, the best place to answer your question, is out of reach for several weeks at home in Cambridge. But I’m sure Eelco Rohling has his handy and can respond!

 

Best wishes,

Tom

[Chris Van Arsdale]

You can an image search for "DIC vertical profile". It's high.

- Chris

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[Jim Baird]

I have a similar question.

 

In Greg Rau and my paper Negative-CO2-emissions ocean thermal energy conversion we calculate  each gigawatt (GW) of continuous electric power generated by negative emissions OTEC could consume and store (as dissolved mineral bicarbonate) approximately 5 × 10⁶ tonnes of CO2/yr.

 

I calculate the electrical generation potential of Thermodynamic Geoengineering is 31 TW, which would total an annual consumption and storage of  155 Gt of CO2.

 

The current atmospheric concentration is 416.45 ppm which is  3252 Gt which theoretically could be eliminated in as little as 21 years. Which would collapse the greenhouse effect leading to the cooling of the surface and atmosphere by 33°C, all else being equal. But the ocean contains about 60 times the preindustrial ocean concentration of the atmosphere and entropy detests a void so as soon as you reduce the atmospheric concentration doesn’t the void simply  get immediately backfilled with CO2 from the ocean?

 

So does cooling the surface actually provide any CDR benefit?

 

Best

Jim

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[Jim Baird]

 

This from Modelling the ocean carbon cycle suggests the following isn’t correct.

 

Jim

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[Greg Rau]

Seth,

Produced waters typically are supersaturted in CO2 (rel to air), so adding a chem base to these solutions will convert (some of) this C to bicarbonate and carbonate ions and prevent (some) degassing to the atmosphere. However, you seem to want to go to the extreme and add so much base and elevate pH so much that CaCO3 and other metal carbonates/hydroxides are spontaneously precipitated. But from a C credit POV this would be about 40% less efficient (per mol of base added) than keeping the the C in solution as bicarbonate/carbonate ions by adding less base. Most produced water is simply pumped back underground, so any alkaline, dissolved C produced would go back with it and be stored.  A scheme for doing this by adding CaCO3 (limestone; rather than removing CaCO3) is discussed (along with other stuff) in the attached. 

You can also degas and store the excess CO2 from PW without adding base, possibling elevating pH enough to spontaneously precip Ca/metalCO3.

As for a CaCO3 precip catalyst, I've an idea (nightmare) for a science fiction novel where a graduate student at a marine bio lab (unnamed, but E Coast ;-) ) bioengineers such a catalyst using a common marine microbe. Some of these microbes get accidentally flushed done the drain and rapidly populate the ocean, causing massive CaCO3 precipitation and CO2 release from the naturally CaCO3-supersaturated surface ocean, repartioning C from the ocean to the atmosphere and starting a runaway planetary greenhouse. I haven't figured out a happy ending yet (ocean vacination?), but the moral of the story is ignore/undervalue the importance of seawater inorganic carbon chemistry at your own and Earth's peril (and be careful with bioengineering). 

Greg

https://groups.google.com/d/msgid/CarbonDioxideRemoval/C82C5D49-D559-4172-BF7A-CF05E50C6E67%40globalcoral.org

.

[Eelco Rohling]

All,

In the deep sea, dissolved inorganic carbon (DIC) is determined by preformed carbon (Cpre; the DIC of the water parcel at the time of sinking into the deep sea) and the regenerated carbon (Creg; the carbon accumulated due to biologically mediated processes). Cpre is a function of the pre-industrial saturation (ocean temperature dominated) plus a component of anthropogenic carbon that has made it into the deep sea. The various components are  teased apart in a very nice manner in Chapters 11 and 13 of Williams and Follows (2011, Ocean Dynamics and the Carbon Cycle; Cambridge Uni Press). 

Below 2000 m, the pre-industrial saturation (temperature dominated) component of Cpre is ~2125 micromol/kg

The soft-tissue component of Creg is on average ~125 micromol/kg (between 50 and 75 in Atlantic; between 100 and 200 in Pacific)

The carbonate pump component of Creg adds up to ~30 micromol/kg (60 in Pacific, 20 in Southern Ocean, nearly 0 in Atlantic)

The anthropogenic carbon accumulation below 2000 m is still very close to zero.

So, taking the very rough nature of my “eyeball averages” into account, the pCO2 in equilibrium with deep-water conditions of DIC= ~2280 micromol/kg (relative to 2125 for water excluding the biological effects) can then be estimated from their equation 13.14 (Figure 13.3c) to roughly double. Admittedly, this is a rough approximation because the problem they formulate is really in terms of what equilibrium DIC one would expect for a certain atmospheric CO2 level, and partitioning of CO2 between atmosphere and ocean will be different going from air to sea than going from sea to air (notably because of how buffering works), but this at least gives us a reasonably magnitude to think about. It’ll be roughly double preindustrial atmospheric levels.

An even simpler way to look at this: Typically, a 10% CO2 increase leads to a 1% DIC increase (the factor 1:10 is due to the Revelle Buffer factor, which varies between 8 in warm water and 16 in cold water). So for DIC to go up to 2280 relative to 2125 = a 7.3 % increase, expect CO2 to go up some 70-80%, or even more. 

So, ignoring Alkalinity and pH changes, my guess for letting average modern deep water (>2000 m) equilibrate with the atmosphere will lead to roughly double pre-industrial pCO2, or ~560 ppm. And because remineralisation of biological products is focussed on sub-thermocline waters, tailing off toward greater depths, bringing “shallower” deep water up would risk causing even higher DIC to equilibrated with the atmosphere, causing even higher pCO2.

Hope this helps

Eelco

===

Prof. Eelco J. Rohling
(Ocean & Climate Change)
- 2012 Australian Laureate Fellow
- Editor in Chief, Oxford Open Climate Change
Research School of Earth Sciences
The Australian National University
Canberra, ACT 2601
Australia

Mobile: (+61) 434 667441
Tel. Office: (+61) 2 612 53857
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personal WebURL: http://www.highstand.org/erohling/ejrhome.htm

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[Douglas MacMartin]

Thanks for the detailed answer; that’s super helpful!  

Doug 

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---

From: 'Eelco Rohling' via Carbon Dioxide Removal <CarbonDiox...@googlegroups.com>
Sent: Tuesday, February 28, 2023 2:45:49 PM
To: Tom Goreau <gor...@globalcoral.org>
Cc: Douglas MacMartin <dgm...@cornell.edu>; Roger Arnold <silver...@gmail.com>; carbondiox...@googlegroups.com <carbondiox...@googlegroups.com>
Subject: Re: [CDR] Brines for carbon capture

 

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[Seth Miller]

Greg,

That was a fun paper, thank you! 

I think, for irony’s sake, that your science fiction microbe needs to be engineered to subsist on discarded marine plastic. Giving it a unique source of food would explain how it spreads despite competition from native microbes. And it has a certain (im)moral resonance.

Seth

-------

Seth Miller, Ph.D.

www.linkedin.com/in/sethmiller2

Check my blog at: perspicacity.xyz

To view this discussion on the web visit https://groups.google.com/d/msgid/CarbonDioxideRemoval/854720445.1942145.1677622919403%40mail.yahoo.com.
<Rau_et al 2006 copy.pdf>

[Tom Goreau]

Surface cooling provides a CO2 benefit in increasing the solubility of CO2, and hence partitioning more into the water from the atmosphere.

 

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: Jim Baird <jim....@gwmitigation.com>

Date: Tuesday, February 28, 2023 at 6:48 PM
To: Tom Goreau <gor...@globalcoral.org>, 'Douglas MacMartin' <dgm...@cornell.edu>, 'Roger Arnold' <silver...@gmail.com>, "carbondiox...@googlegroups.com" <carbondiox...@googlegroups.com>
Cc: 'Ron Baiman' <rpba...@gmail.com>