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'Rock candy' technique offers simpler way to capture carbon directly from air (techxplore.com)
3 points by PaulHoule 14 days ago | hide | past | favorite | 5 comments


From "Passive direct air capture via evaporative carbonate crystallization" (2025) https://www.nature.com/articles/s44286-025-00308-5 :

> Abstract: [...] This passive, single-chemical-loop approach has the potential to reduce capital and levelized costs by approximately 42% and 32%, respectively, compared with conventional liquid-based direct air capture systems.

What is their projected cost per ton?

From 2025-09 https://news.ycombinator.com/item?id=45282882 :

> A techno-economic analysis estimates a levelized cost of capture of ~$70/tonneCO2 [with this membraneless electrochemical approach], compared to $137/tonneCO2 for conventional EMAR

> [ $50 ]

From 2025-11 https://news.ycombinator.com/item?id=46010414 :

> I just saw $26/ton for (non-CO2) carbon capture in 2025. Gravel is like $10-$50/ton.

From 2025-: https://www.nature.com/articles/s41893-025-01696-5 :

> Using uncertainty-aware cost modelling, including membrane cost, electricity prices, contingency factors and learning curves, we show that capture costs can reach US $50–100 per ton CO2 for natural gas power plants and as low as US $25–50 per ton CO2 for coal and cement plants, positioning this technology favourably against state-of-the-art capture processes.

But then the usability of the captured carbon;

What is more reusable than CO2-derived graphene filters caked in CO2?

Given sequestered carbon in a useful form, what products can be made?


In a post fossil fuel world carbon capture with either plants or something mechanical would be necessary to make the things we make now with fossil fuels. We would still need fuels compatible with gas, diesel, and jet fuel, still need plastic monomers, feedstocks for pharmaceuticals, etc.


Which plants absorb the most carbon?

Phytoplankton, Seagrass meadows; Redwoods, Mangroves, Peat bogs (Sphagnum peat moss)

Algae absorbs more CO2 than plants, but it's only sequestered if harvested and used to produce long lasting products.

Algae store solar energy as triglyceride lipids; triacylglycerols (TAGs). Fuel, cooking oils, and Omega-3 dietary supplements can be made from algae.

Is low-pressure liquid processing of [carbon] the least risky option?

Which plastics can't be functionally replaced with a bio substitute composed of materials like: lignin, cellulose, lignin vitrimer, algae, cornstarch/tapioca, gelatin, fractionated biofeedstock, carbonized lignin (carbon ceramics), graphene, vinegar, water, nitrogen, and co2 ?

> You cannot use the listed materials to replace plastics whose function relies on Fluorine (F), Silicon (Si), or Benzene-ring transparency.

A challenge: It says there's no sustainable alternative to C-F bonds, transparent high impact plastics, o durable rubber that withstands thermal ranges -50C to 250C and oil exposure.

TIL about fluorinase and tea (and simple C-F bonds in nature)

TIL about a new process for bio- silica-based optics; Rice Husk Ash into optical-grade Silica with acid leaching: "Soak [rice] husks in hot, dilute acid (Hydrochloric or Citric acid) for 1–2 hours" before pyrolysis at 600-700C, then add NaOH to make water glass (Na2SiO3) and water and then add Sulfuric or Carbonic acid to extract the refined SiO2.

That's funny; water glass is used for (ancient) geopolymers fwiu


Coral, diatoms

Brilliant take that oughta have come to me instead!



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