Geoengineering Info Profile picture
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

Oct 16
🚨French Academy of Sciences has released a new report on #SolarGeoengineering, stressing that the absolute priority must remain reducing GHG emissions via structural changes & accelerating adaptation to climate impacts.

On #SRM, the report offers several recommendations:🧡1/6 Image
2/ SRM Recommendation 1️⃣

Promote an international agreement aimed at prohibit any initiative, public or private, to deploy SRM, regardless of the framework or scale.

To do this, the entire scientific community will have to be involved.
3/ SRM Recommendation 2️⃣

Support & deepen research on climate, atmospheric physicochemical processes and biodiversity in order to be able to rigorously assess the potential & risks of SRM.
Read 7 tweets
Oct 11
🚨An analysis of forest-based projects funded through the sale of #CarbonCredits shows that 10% of them may have a net warming effect on the climate because of the way they alter the Earth’s #albedo, or how much sunlight is reflected back into space.

DETAILS🧡1/12 Image
2/ Albedo is how much sunlight Earth’s surface reflects vs. absorbs

Forests are darker than grass or snow, meaning they absorb more heat

So when grasslands or snowy areas are turned into forests, Earth’s surface can absorb more heat, partly cancelling out cooling effect of #CDR Image
3/ So, this study analyzed 172 Afforestation, Reforestation & Revegetation projects in the Voluntary Carbon Market - projects that collectively aim to deliver nearly 800 million tons of CDR over the next century.

But none of these projects’ standards account for albedo change. Image
Read 13 tweets
Oct 8
🚨New paper argues that rejecting Carbon Dioxide Removal (#CDR) on moral hazard grounds may itself be unjust.

Using a framework of transitional justice, they propose that CDRs can, if carefully governed, form part of a just transition to a livable climate.

🧡1/9 Image
2/ The authors note that with climate overshoot increasingly inevitable, the IPCC and Climate Overshoot Commission both view CDRs as unavoidable.

The question shifts from whether to use CDRs to how to deploy them justly.
3/ The authors apply transitional justice - a framework for navigating imperfect choices to reach fairer outcomes.

It asks: when can seemingly unjust actions (like risky technologies) be justified to achieve a more just, sustainable future?
Read 10 tweets
Oct 1
🚨The Earth is reflecting less & less sunlight, new study reveals🚨

Satellite data show the planet is reflecting less sunlight than it used to, with the Northern Hemisphere darkening fastest.

This imbalance has big implications for climate and rainfall.🧡1/8 Image
2/ Using 24 years of NASA’s CERES satellite data, scientists found both hemispheres now absorb more solar energy than before.

But the Northern Hemisphere has pulled ahead, darkening faster than the South. Image
3/ This breaks a long-standing balance: for decades, Earth’s hemispheres reflected nearly the same amount of sunlight.

That symmetry was thought to be maintained by clouds. But the new data shows the NH is diverging.
Read 9 tweets
Sep 25
🚨Can buildings remove COβ‚‚ while cooling indoor air?

A new study shows that adding COβ‚‚ capture units (#DAC) to building cooling systems can cut energy use by over 50% & remove atmospheric carbon, even in hot, humid places.

Details🧡1/10 Image
2/ Buildings use a lot of energy. About 37% of global energy & 40% of COβ‚‚ emissions.

Cooling is the biggest part, taking almost 40% of building electricity.

As the planet warms, cooling demand rises, creating a vicious cycle.
3/ Direct Air Capture extracts COβ‚‚ directly from ambient air, unlike point-source capture.

But adsorption-based DAC struggles in humid environments: water competes with COβ‚‚ for sorbent sites, making it very energy-hungry.
Read 12 tweets
Sep 19
🚨A new study presents the 1st structural prototype of a planetary sunshade - a large space-based system at L1 designed to block some sunlight & cool Earth.

Using solar sails, deployable booms & CubeSat-based frames, it outlines a pathway for space-based #geoengineering.🧡1/11 Image
2/ The planetary sunshade would function as a vast array of satellites at the Sun–Earth L1 point, collectively blocking ~1.8% of incoming photons - enough to reduce global temperatures by ~2 Β°C.

"Unlike #SAI or orbital dust, it promises uniform, reversible cooling."
3/ The team followed European spacecraft design standards, testing different ideas with decision matrices & computer simulations (finite element analysis) to choose materials & structures that could actually survive launch.
Read 12 tweets

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