Next week on OpenAir's This Is CDR - Gaurav Sant and Dante Simonetti from SeaChange - Tues Dec 7 12p ET

[Toby Bryce]

https://www.eventbrite.com/e/190028088127

SeaChange: Electrochemical Ocean CDR - Dante Simonetti and Gaurav N. Sant

OpenAir is excited to present This Is CDR, an online event series that explores the wide range of carbon dioxide removal (CDR) solutions currently being researched, developed, and deployed, and discusses them in the context of policy proposals under development for New York, and other states and localities.

This week we are pleased to welcome Dante Simonetti and Gaurav Sant from SeaChange to tell us about the company's novel electrochemical CDR process that leverages the ocean's natural carbonate cycle to sequester CO2 at scale.

[Toby Bryce]

ICYMI here is a recording of the episode (excellent and lots of technical detail) https://www.youtube.com/watch?v=9XJ4A9yjeS8

[Tom Goreau]

This “newly invented” process is another well-known variant of the 45 year old Biorock mineral production method (Hilbertz, 1979), and based on those results, it will work.

 

Congratulations to the UCLA team for independently re-discovering it!

 

They repeatedly claim to produce calcite, a mineral that in fact does NOT grow by sea water electrolysis.

 

A more complete discussion of the process, based on decades of field results, will soon be posted here.

 

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

 

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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[Andrew Lockley]

I watched this video twice and was still confused by their claims not to evolve CO2 at the electrode. I would have thought evolving CO2 would allow efficient geological disposal, a la carbfix.

From what I recall (and I appreciate I might be misquoting him), Ken raised questions about whether this precipitation reaction affects the bicarbonate buffer system, resulting in displaced CO2 emissions from the ambient environment. 

Apologies for my general inability to electrochemistry properly. It is not a strong point, for me. 

I'm naturally keen to get these guys on the Reviewer 2 podcast, but (from my hazy memory) I think they didn't respond. 

Andrew 

To view this discussion on the web visit https://groups.google.com/d/msgid/CarbonDioxideRemoval/1B6DA001-3C72-4DDC-A439-041C7DE701B9%40globalcoral.org.

[Tom Goreau]

In general, since CO2 is the major acid in the ocean system, increased pH results from CO2 removal by photosynthesis or de-gassing, so there is normally a near one to one correspondence between CO2 removal, alkalinity generation, and limestone precipitation, in that sequential order.

 

But in the case of electrolysis, hydroxyl ions are provided directly from electrolysis of water, so CO2 is not released, instead locally higher pH encourages CO2 dissolution and ionization to carbonate anions to replace that precipitating out.

 

They talk primarily about reactions at one electrode, but one must consider BOTH electrodes, and there is an equivalent generation of acidity at the other.

To view this discussion on the web visit https://groups.google.com/d/msgid/CarbonDioxideRemoval/CAJ3C-04XEtSZPOHig7jj%2BGsS0B1ZYUHCuHVKcAhFfSDrKMyKLQ%40mail.gmail.com.

[steve.rackley]

Hi Andrew,

I also watched it twice and think I finally figured it out. I'm no electrochemist but here's my understanding ...

No CO2 is evolved at the cathode where the Mg(OH)2 and (Mg)CaCO3 are deposited because instead of the usual precipitation reaction (Ca++ + 2HCO3- > CaCO3 + CO2 + H2O), we will have Ca++ + HCO3- + OH- > CaCO3 + H2O, or simply Ca++ + CO3- - > CaCO3! Essentially in the alkaline environment at the cathode surface, all CO2 is immediately deprotonated to HCO3- and CO3- -. At the anode the remaining DIC will be protonated to CO2 and evolved (all ~2000umol/kg) with no attempt to capture it. The presenter "justified" this as a small amount compared to the 3.9 kg of CDR per m3 of seawater processed, which it is. The 3.9 kg seems to correspond to the precipitation of pretty much all the Mg in seawater as Mg(OH)2 with subsequent OAE and CDR. 

The presenter's assumption that air-sea pCO2 equilibrium would be restored within days was worrying - presumably this is "required" in their analysis to prevent recirculation of unequilibrated discharge streams into the seawater intake. Equally worrying were the idea of discharging all of the dissolution products from the mineral or waste material that is used to neutralize the anode stream, and the nonchalant way the presenter passed off any ecological concerns to those other disciplines that deal with these tricky problems that cannot be solved with thermodynamic simulations. The particle size distribution of precipitates scraped off the cathode is another concern; these will either end up as heap downstream of the discharge point or result in a high turbidity plume which will be an EQS challenge. Oh yes, and the chlorine?

Not one I'll be queueing up to invest in!

Steve