Comparing Kelp Conveyance Strategies for Marine Carbon Dioxide Removal with Farmed Macroalgae

[Geoengineering News]

https://eartharxiv.org/repository/view/5582/

Authors

Sebastian Jian Ernst Krause, Daniel Patrick Dauhajre, Tom Bell, Robert Miller, David Valentine, David Siegel

Published: 2023-06-23 

Abstract

Sequestration of carbon dioxide via sinking of farmed seaweed into the ocean is a promising strategy to the ever-growing need to achieve negative emissions of carbon dioxide. A key component to the durability of the strategy is the method to which seaweed biomass is conveyed to the seafloor. The purpose of this white paper is to introduce four different conveyance techniques, plans for how each technique will be implemented at smaller scales, and describe how each conveyance method will be modeled. The development of each conveyance technique is guided by the balance between overcoming the positively buoyant kelp biomass, overall feasibility given resources and technology, and the ability to monitor, validate and record the environmental impact of sinking Giant Kelp biomass. We plan to use a combination of laboratory and field-based experiments at a smaller scale, to acquire information about sinking rates, dissolved organic carbon release rates, and kelp decomposition rates for each conveyance method. Lastly, the white paper will describe how the data acquired from the laboratory and field-based experiments will inform a series of models, that when combined together, will simulate the durability and the environmental impact of each conveyance method if adopted to scale.

DOI

https://doi.org/10.31223/X5M66B

Keywords

Giant kelp, Conveyance, carbon dioxide removal

Source: Earth R Xiv

[Ronal Larson]

List, cc Andrew and lead author Krause (apparently asking here for comments prior to additional research.)

I like the topic and think it important.  But I hope there should be a few paragraphs on two additional kelp stopics: 

a.   Likelihood of quick attack by bottom dwelling organisms - a regular list concern from Dr. Tom Goreau.   

b.   Possibility of greater societal benefit if the giant kelp is used for both carbon neutral energy and carbon negative biochar placed in soils.

Ron

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[Tom Goreau]

I can’t imagine why people think dead kelp will sit around forever unless they understand nothing about marine biology!

 

There are abundant bacteria in the ocean that specialize in decomposing alginates, and other chemicals found in kelp, that will probably consume almost all of it, they are found in guts of marine organisms that eat kelp, in the water and sea floor.

 

There are other bacteria specializing in decomposing the distinctive carbohydrates that other species of algae make for structural purposes.

 

This is windfall FOOD for hungry organisms, not inert waste that will last forever, as people touting seaweed carbon sinks seem to think.

 

Ron’s right, sinking it is a waste.

 

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

 

[Chris Vivian]

Tom,

 

I think you mis-characterise the sinking kelp proponents understanding of what happens to the kelp on the deep seabed. I don’t think that they believe that dead kelp will sit around forever, just that it and its decomposition products will be out of contact with the atmosphere for some hundreds to a thousand years or so.

 

Ron may have a point about it being considered a waste to sink the seaweed and this was raised in one of the early Ocean Visions workshops that I was involved with some years ago. However, I think that some proponents are considering extracting beneficial products from the seaweed before sinking the residue.

 

Chris.

To view this discussion on the web visit https://groups.google.com/d/msgid/CarbonDioxideRemoval/985E8AEC-3FF0-437A-B587-817CFAAC72EF%40globalcoral.org.

[Michael Hayes]

I've been an aquacultulturist for over 30 years, sinking raw biomass to the seabed seems to be a waste of valuable resources.

Economically speaking, using seaweed just for C credits negates the downstream socioeconomic value of the biomass. Aquaculture-based CDR likely has the most complex C math, yet the socioeconomic value of any CDR method is an established priority in the CDR field and aquaculture CDR likely has the greatest socioeconomic CDR value.

Below is a list of higher trophs that can use seaweed as a feed:

https://www.americanoceans.org/facts/what-eats-seaweed/#:~:text=Some%20of%20the%20most%20common,bird%20species%20like%20the%20albatross.

A new form of offshore farming containment infrastructure, or regenerative 'fish farm', is needed. The basic tech components needed for advanced aquaculture are currently available to create such an infrastructure. 

To view this discussion on the web visit https://groups.google.com/d/msgid/CarbonDioxideRemoval/01a001d9b4c9%2444820c60%24cd862520%24%40btinternet.com.

[Tom Goreau]

This only lists the vertebrates eating seaweeds, but ignores the far more numerous invertebrates who eat seaweed, such as snails and nudibranchs and the microbial decomposers that specialize in seaweeds.

 

Some algae are chemically defended with toxic compounds and nobody eats them except by accident, and that includes the harmful algae bloom (HAB) dinoflagellates and cyanobacteria.

 

However when you collect the cyanobacteria growing at the end of Florida sewage pipes and all over the dead reefs you find it full of tiny nematodes!

 

Michael is right, the real value of carbon comes from downstream recycling, not from throwing it away.

[Michael Hayes]

Cultivation of copepods is a substitute for wild catch krill. The one eyed copepod needs minimal light to see it's fiber meal and they like calm water. Below is a book that describes a regenerative multi-trophic aquacultural method that many of the large seafood companies have invested in:

https://books.google.com/books/about/Copepods_in_Aquaculture.html?id=erciJ8P5xS8C&source=kp_book_description