Carbon sequestration via large scale algae farming and continuous pumping of the biomass underground
Image credit: Seambiotic open-pond test facility
Darko SavicJul 19, 2021
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Necessity
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Bounty for the best solution
Provide a bounty for the best solution
Bounties attract serious brainpower to the challenge.
The idea is to sequester carbon from the atmosphere via automated cultivation of a fast-growing species of algae or cyanobacteria on a large scale. The continuous harvest of biomass would be drained and pumped via a pipeline to backfill abandoned quarries, mines, small valleys - any holding area that can accept billions of tons of biomass and store it indefinitely.
This is like oil extraction but in reverse. The fastest possible growth of biomass and pumping it underground with the least amount of energy and the least damage to the environment.
The excess water in the holding area would be drained, filtered, and returned to nature. Leaving the carbon-rich biomass in the holding area as dry and compact as possible.
Finally, the biomass holding area would be layered with several meters of soil and a forest planted on top. The topsoil could be made fertile by mixing the algal biomass into it. The same would be repeated again and again around the world, where ever the conditions are suitable.
Design principles:
minimal use of energy
minimal requirement for human labor
proximity to final storage area
no or minimal processing
fastest growth of biomass
no or minimal requirement for fertilizers
Here is an overview of current best practices for algae farm design.
Image credit: A. Ben‐Amotz, M. R. Tredici, Ying Shen
Affordable pond liner for easy scaling
Why do it, and who pays for it?
To stop and reverse global warming and save life on Earth as we know it. Basically to survive.
The initial implementation of this idea could compete for the carbon capture Xprize. After the proof of concept and if this turns out to be an efficient way to sequester carbon from the atmosphere, countries could finance such operations via carbon taxes.
Piggybacking off of rivers
In addition to solar power, rivers could be used to supply the fertilizer and energy to run the pumps that circulate the water within the algae growing tanks.
Re-release of CO2 and methane
The biomass that is stored underground would re-release some of the greenhouse gasses CO2 and methane into the atmosphere. Vents could be left out so that the gasses get captured. The methane could be used as rocket fuel. That way some of it would be jettisoned out of the Earth's atmosphere.
Proof of concept
The initial proof of concept could be done in cooperation with an existing large-scale alagae-to-biofuel farm. For a test period of time we could buy the entire output, pump it unprocessed into a holding area and measure the actual impact.
Image credit: Cyanotech Algal production facility in Hawaii
Moving forward
Scout for appropriate locations. Outskirts of deserts, barren lands in proximity of rivers , etc
Get local permissions for demo plants
Establish demo plants
With each new installation, iterate on the design to make it cheaper and more efficient
Repeat
Open source everything and have other teams around the world copy the concept in their localities
Scaling vs Efficiency
The production efficiency doesn't need to be as high compared to algal production of biofuel. It just needs to be persistent and use purely non-carbon emmiting energy. Then the entire concept should be multiplied where ever the conditions are suitable and it doesn't bother anyone. That's how we scale it. Every country and county could be required to offset own carbon emissions.
Picochlorum renovo - a fast growing species of micro algae
Darko SavicSep 23, 2021
Picochlorum Renovo grows 5 to 10 times faster than other industrially useful species of algae. It has a doubling time of about 2.2 hours.
Until we find a faster-growing species Picochlorum sounds like a great candidate.
[1]Dahlin, L.R., Gerritsen, A.T., Henard, C.A. et al. Development of a high-productivity, halophilic, thermotolerant microalga Picochlorum renovo. Commun Biol 2, 388 (2019). https://doi.org/10.1038/s42003-019-0620-2
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The biomass should be polymerized so as to prevent degradation by microorganisms
Darko SavicOct 17, 2021
The biomass that gets pumped underground should be polymerized in a way that isn't likely to be depolymerized by future microorganisms and thereby turning it back into CO2.
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Turning microalgae into energy and concrete instead of pumping them underground
jnikolaJul 23, 2022
Although microalgae can help CO2 sequestration, I think I found a way how to, directly and indirectly, make it much more efficient!
Why?
concrete is the most produced material on Earth and is responsible for a massive percentage of CO2 emissions due to its production (extracted from large quarries and burned at high temperatures, releasing large amounts of carbon dioxide)
"If all cement-based construction around the world was replaced with biogenic limestone cement, each year, a whopping 2 gigatons of carbon dioxide would no longer be pumped into the atmosphere and more than 250 million additional tons of carbon dioxide would be pulled out of the atmosphere and stored in these materials."
microalgae perform photosynthesis and capture CO2
why use microalgae just for carbon sequestration when you can get energy and the most used material, while still sequestering carbon?
How would it work?
The concept exists and was developed and described by a team of scientists from the University of Colorado . In short, they use coccolithophores microalgae which have an amazingly fast capability of capturing CO2 and creating limestone protection structures (for a comparison, limestone in the nature that is being used for the production of concrete needs millions of years to "grow"). They grow them in ponds, where algae produce sugars and O2 through photosynthesis. When biomass grows, they collect it and biochemically translate it to concrete that can be used in building.
They even have a start-up company that is working on this full-speed. Check it out here.
It's the same technique you mentioned in session with filter feeders. This way, you could harvest energy through photosynthesis of microalgae, create concrete and dramatically reduce the CO2 emissions!
Darko Savic Jul 19, 2021