Big Decisions from Small Experiments: Observational strategies for biomass-based marine CO2 removal (13 emails 9/26/2024 to 9/28/2024)
CDR
Big Decisions from Small Experiments: Observational strategies for biomass-based marine CO2 removalSep 26 2024 12:42PM - Michael Hayes
Abstract
Biomass-based marine CO2 removal (mCDR) aims to harness photosynthetic organisms to remove excess CO2 from the atmosphere and sequester that fixed carbon in a long-lived marine reservoir. This strategy would contribute to a portfolio of climate mitigation efforts. To guide decision-making around testing, deploying, and regulating mCDR, we need to better understand how the deep sea and the broader Earth system would respond to increased biomass addition. The central processes driving this response are
sensitive to choices about biomass type and storage site, and they stretch across spatial and temporal scales
from microns to kilometers and from minutes to millenia. To organize this immense interdisciplinary challenge, we define five generalizable phases of a biomass-based mCDR project: inputs, placement, short-term response, long-term response, and functional stability. Each phase is associated with high-priority research objectives that could be achieved through thoughtful integration of direct field measurements, investigations of analog sites, experiments, and/or models. In-situ and laboratory experiments can be
particularly powerful for isolating key processes; for example, in-situ “closed-system” bottle incubations can amplify small signals and reduce uncertainties created by complex physical flows. Regardless of approach, the overarching goal of biomass-based mCDR research is to develop a process-based understanding of biomass sequestration that is robust enough to project the likely outcomes of alternative choices related to mCDR. Beyond assessing carbon storage and ensuring regulatory compliance, future
field experiments should prioritize generating the data required to improve models for impacts of biomass-
based mCDR on the deep ocean at climatically-relevant scales."
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Sep 27 2024 3:48AM - Sev Clarke
To answer your first question: both because the deep sea is one of the safest places for excess carbon and because we know with fairly high probability that increasing the ocean’s biomass, biodiversity and biological pump are all good things to do.
We also know that the amount of living marine biomass (at least that in surface waters) has been roughly halved over the past few centuries and that regenerating it would have many benefits, including increasing oceanic albedo, fish stocks, nutrient recycling by way of the marine food chain (whales, etc.), and carbon sequestration.
Most of the other plans you suggest are likely to fail the KISS test, as well as taking far too long to implement at the required scale.
Supplementing surface ocean nutrients with slow-release, FePSi ones from mining wastes would allow diazotrophs to provide the necessary, reactive nitrogenous ones, whilst the intransigent, carbon-rich lignin ‘glue’ binding the FePSi nutrients to opaline, silica-rich rice husks would sink unaffected by bacterial action to the seabed. Furthermore, much of the biomass of phytoplankton consumed by diel vertically migrating species would be excreted and respired at depth, thereby avoiding the intense bacterial action of the euphotic zone.
Deoxygenation of the deep ocean might be partly offset by some methods of ice thickening and by the reaction of seabed carbonates with dissolved carbon dioxide to produce benign bicarbonate.
Sev
Sep 27 2024 2:23PM - Greg Rau
Why does bio mCDR have to involve the deep sea and why does it have to involve storing raw biomass? Harvest the biomass from the surface ocean, extract and separate the carbon from the N, P, Si, etc and recycle the latter element to the surface ocean. Convert the C to an inert form for storage on land or in the ocean (inert means it cannot generate CO2. Making diamonds would be the perfect solution in terms of permance, but let's not let perfect/impractical be the enemy of the good enough). Plan B - marine biochar. Plan C - marine BECCS with N, P, Si etc recycling. Plan D - bioengineer marine microorganisms to produce and excrete very long lived, dissolved organic compounds, without sequestering nutrients (to some extent they already do this. Let's just up their game.) Etc? Otherwise, enhancing marine biomass sinking strips and sequesters valuable nutrients from the surface ocean and acidifies and deoxygenates the deep ocean(?)
Greg
Sep 27 2024 4:35AM - Clive Elsworth
Hi Sev
I was right there with you until the last half of your last sentence. Once you have got dissolved carbon dioxide, haven’t you already taken oxygen out of the water?
Clive
Sep 27 2024 10:50AM - goreau
Not only that, you’re recycling biologically chelated iron from deep water, which is far more effective for phytoplankton than minerals dumped from above!
Sep 27 2024 11:11AM - BST Sev Clarke
Hi Clive,
Not necessarily. Respiration and bacterial action do generate dissolved CO2, as does air to ocean CO2 movement, but CO2 reaction with the carbonate in shells and bones can convert the CO2 to alkaline bicarbonate, whilst photosynthesis, turbulent mixing, downwelling, and the oxygenated brine from Ice Shield ice formation can replace the oxygen lost by respiration etc..
Sev
Sep 27 2024 11:23AM - Philip Kithil
Even better, just do continuous wave-driven upwelling from ~300m to 5m and let mother nature do her thing. Step back and enjoy the data. With many 3m diameter upwelling pumps free-drifting in the open ocean, spaced at 2.5km, the upwelled colder nutrient-enriched plumes create local phytoplankton blooms that support the entire biological cycle, even feeding those voracious microbes which recycle endlessly. You don't need to predict anything, don't need to quantify the "CDR" which will vary by day/season/location. Just do it and then do your science based on real data not hypotheticals. IMHO!
Sep 27 2024 12:35PM - Michael Hayes
Greg, et al.,
1) Marine Biochar would shift excess marine C over to C depleted soils. This likely would provide a very robust C drawdown with the environmental benefits going beyond just CDR for both land and sea.
2) Sequestration of harvested C in a form that allows for further C drawdown, much like Biochar, can also be realized via the production and use of long lasting high density polyethylene marine-grade CDR bioreactor infrastructures. Bio-Ethylene production methods can be used prior to Biochar production using the same biomass.
3) Addressing both CO2 drawdown needs and renewable fuel production needs with the same system of systems is more than likely possible at the Biochar production level via 'emerald H2' production derived from the syngas.
Carbon-negative “emerald hydrogen” from electrified steam methane reforming of biogas: System integration and optimization
https://www.sciencedirect.com/science/article/pii/S0360319924038801
Best regards
Sep 27 2024 1:22PM - Michael Hayes
Apologies, yet please allow me to rectify, or clearify, my statement concerning 'emerald H2' production. Fermentation of the biomass before Biochar production is needed. Biochar production using the spent biomass derived from fermentation would be the processing steps.
Sep 27 2024 7:04PM - Amal Bhattarai
Why deep sea and why raw biomass?
......Deep Sea because of long duration, likely low impact, large area available
.....Raw Biomass because it is the low-hanging-fruit of CDR:
- large availability of terrestrial waste (at least a gigaton CO2e per year, maybe even ~1PPM per year!)
- immediate implementation using existing transport logistics
- rapidity of operations - 100% raw biomass loses buoyancy in minutes via hydrostatic pressure water-logging, no need for accompanying ballast.
- London Protocol makes allowance for deposition of "organic materials of natural origin"
-.........
Sep 28 2024 2:23AM - Clive Elsworth
Sev
Dissolved carbon dioxide is in equilibrium with hydrogen carbonate, which is in equilibrium with carbonate, as we know from the carbonate system. But I don’t see how any change of those equilibria can offset deoxygenation.
Clive
Sep 28 2024 4:14AM - Sev Clarke
Clive,
See H2CO3 + CaCO3 -> Ca(HCO3)2 or dissolved CO2 plus calcium carbonate from shell, bone or limestone gives benign, dissolved and slightly alkaline calcium bicarbonate (the main form of oceanic carbon). However, this reaction does not provide oxygenation.
That’s all I was saying – about the last half of your last sentence below.
That is supplied by photosynthesis; and also from atmospheric oxygen dissolving in rain, spume, and seawater. When some of that seawater is frozen by pumping it thinly onto sea ice (as in my Ice Shields method), its dissolved gases (including oxygen) and salts are concentrated in the leftover brine which tends to sink and increase the overturning currents (such as AMOC) when it falls in rivulets off the perimeter of each lenticular ice shield.
Yes, agreed.
Sev
Sep 28 2024 4:56AM - Clive Elsworth
Sev, see blue below.
Thanks for your clarification.
Clive
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