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May 14, 2023 β€’ 10 tweets β€’ 7 min read β€’ Read on X
πŸš¨βœοΈππ„π– πƒπŽπ‚π“πŽπ‘π€π‹ π“π‡π„π’πˆπ’βœοΈπŸš¨

"The discussion of energy consumption for cryogenic & combined #DirectAirCapture systems is explored in the newly published thesis."πŸŽ›οΈ

Details are discussed in aπŸ§΅β¬‡οΈ
1/10 ImageImage
In this novel approach, "a thermodynamic model was constructed using psychometric theories to model the #desublimation of CO2 in a #DAC system. The system was modeled
to include a precooling heat exchanger & a deposition chamber where the desublimation
of CO2 occurs."
2/10 Image
3️⃣ base systems studied:
πŸ”Έ NC (no precompression/turbine recovery)
πŸ”ΈPC (precompression only)
πŸ”ΈTR (precompression & turbine recovery)
at 3️⃣ different compression ratios, n=400, 800 & 2000.
Then, a combination #DAC system, PSA, was modeled."
3/10 Image
"A dual-column, 4️⃣-step Skarstrom Cycle PSA (pressure swing adsorption & cryogenic distillation) unit was analyzed using Extended Langmuir Models & the
ideal gas law to simulate a CO2 conc. prior to the deposition chamber. The NC & PSA systems were assessed at Tamb= -50β—¦C."
4/10 Image
This study finds that "while increasing the compression ratio of the system, there is no net energy benefit when capturing CO2 given the current state-of-the-art in commercial compressor & #cryocooler capabilities."
5/10 Image
"The assessment of the efficiency of a precooler versus TR finds that it is more advantageous to utilize a heat exchanger precooler than precompression with turbine recovery in a #DAC system. Combining DAC systems may yield a more efficient system."
6/10 Image
"PSA combined with cryogenic capture is less energy intensive than cryogenic capture alone. In a combined #DAC system with PSA and cryogenic distillation,
the PSA unit has a significantly lower energy consumption than the #cryocooler."
7/10 ImageImage
"Increasing the concentration of CO2 entering the deposition chamber significantly decreases the required energy consumption of the #cryocooler."
8/10 Image
Read the complete #Doctoral #Thesis entitled: "Atmospheric Carbon Capture: A Review on Current Technologies and Analysis of Energy Consumption for Various Direct Air Capture (DAC) Systems" here ⬇️
commons.erau.edu/edt/728/

#DirectAirCapture
#DAC

9/10

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More from @geoengineering1

May 14
🚨Greenhouses can grow food in extreme climates, but they often depend on fossil-derived COβ‚‚ inputs to maximize crop yields.

New study investigates whether Direct Air Capture (#DAC) could replace those emissions-intensive COβ‚‚ sources by capturing C directly from air.🧡1/13 Image
2/ Researchers modeled a 1-ha sealed high-tech greenhouse in Jeddah, Saudi Arabia producing cherry tomatoes & lettuce under hot-arid conditions.

The system maintained ~1000ppm COβ‚‚ conc, which are required to sustain high crop productivity in climate-controlled desert agri. Image
3/ The study evaluated two adsorption-based DAC systems:
β€’ temperature-vacuum swing adsorption (TVSA)
β€’ moisture-swing adsorption (MSA)

Both were benchmarked against conventional trucked liquid COβ‚‚ enrichment currently used in commercial greenhouse operations
Read 15 tweets
May 8
🚨Monthly Solar Geoengineering Updates (April'2026)🚨

From EU calls for an #SRM deployment moratorium & WHO-linked health-centered governance report, to Stardust publishing its own SRM rules, key SRM headlines you need to know from past month:
πŸ”—

🧡0/12 …largeoengineeringupdates.substack.com/p/monthly-sola…Image
Top 10 SRM Updates from April 2026

1️⃣ Stardust releases SRM β€œguiding principles”:

The private SRM company publishes voluntary rules and safety guidelines, but experts raise concerns over transparency, unknown aerosols, and private control of planetary-scale interventions.

1/12 Image
2️⃣ WHO-linked report calls for health-centered SRM governance:

A pre-print urges SRM governance centred on human health, equity, and Global South inclusion, stressing SRM must never replace emissions cuts (β€œnon-substitution” principle).

2/12 Image
Read 14 tweets
May 7
🚨Is direct air capture (#DAC) really worth the investment?

A new Nature Climate Change study shows that investing in wind & solar delivers 2-3Γ— greater combined climate + health benefits than direct air capture across most U.S. regions, under the same budget.

Details🧡1/11 Image
2/ DAC is often promoted as essential for net-zero, removing COβ‚‚ directly from the atm. But most studies assess it in isolation, asking: β€œDoes it work?”

This study asks a policy-relevant question:
β€œWhat are we giving up by funding DAC instead of alternatives?”
3/ Researchers modelled cost-equivalent investments across 22 U.S. regions (2020–2050), comparing:

Direct Air Capture vs Utility-scale wind & solar

Critically, they evaluated COβ‚‚ reductions + air pollution + health impacts. Image
Read 13 tweets
Apr 30
🚨What happens to tropical rainforests as COβ‚‚ rises?

New research shows higher COβ‚‚ boosts tree growth & C uptake by pushing roots to aggressively mine scarce phosphorus.

This strengthens the C sink now, but depletes nutrients, ultimately limiting long-term C storage.🧡1/11 Image
2/ Scientists tested this in the Amazon by exposing forest patches to higher COβ‚‚ (future-like conditions) and tracking how trees, roots, and soils responded over time. Image
3/ Step 1: More COβ‚‚ β†’ faster photosynthesis

Trees produce more sugars, grow faster, and pull more COβ‚‚ out of the air.

This is the short-term β€œcarbon sink boost.”
Read 12 tweets
Apr 22
🚨Green roofs + enhanced rock weathering (#ERW) could turn cities into carbon sinks.

A new assessment finds Europe’s rooftops could remove tens of millions of tonnes of COβ‚‚ by 2060, with global potential reaching hundreds of MtCOβ‚‚/yr under ideal conditions.

Details🧡1/12 Image
2/ The work is a conceptual, literature-based assessment combined with geochemical scaling.

It estimates COβ‚‚ removal using theoretical maximum reactivity (100% mineral conversion) and extrapolates across urban roof availability in Europe and globally.
3/ Roof availability is a key input:

The study uses estimates that roofs cover ~30–32% of urban land area, and up to ~50% of impervious surfaces in dense cities, highlighting a large, currently underused surface for carbon removal deployment. Image
Read 14 tweets
Apr 16
🚨A new study details that the climate value of algae & cyanobacteria lies not in COβ‚‚ uptake alone, but in their capacity to generate long-lived, chemically recalcitrant C compounds, such as algaenan & carbonates that may contribute to durable sequestration pathways.

🧡1/11 Image
2/ The study adopts a conceptual synthesis framework, integrating biochemical & geochemical evidence to examine carbon fate post-photosynthetic fixation, moving beyond uptake rates to study the thermodynamic and structural persistence of biogenic carbon. Image
3/ It constructs a functional distinction between:

1) Labile carbon fractions, which are rapidly cycled through microbial respiration

2) Recalcitrant fractions, which resist degradation & contribute to long-term carbon storage across terrestrial & marine systems.
Read 12 tweets

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