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Supercritical CO2 is heavy like a liquid, with weird and useful properties

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Re: Supercritical CO2 is heavy like a liquid, with weird and useful properties

#31

Post by londons_explore »

jackfoxy wrote: post #29
londons_explore wrote: post #21

Earlier quoted context omitted.

It's also a very convenient way for oil and gas companies to suck all the renewable subsidy money in the name of "carbon sequestration", when the reality is they're developing new ways to get even more oil and gas out...

I assure you, the decision is entirely economic on the production side. CO2 is fungible, no? (in regards to sequestration subsidies)

CO2 is indeed fungible. I simply suspect that a lot of companies are requesting government money to research and develop something that they would choose to research anyway even without government money. (because it increases oil production).

They get away with that because many governments don't have good tech advisers.

Re: Supercritical CO2 is heavy like a liquid, with weird and useful properties

#32

Post by lightedman »

ajbeach22 wrote: post #9
mikeyouse wrote: post #6

It's amazing how wide the applications of supercitical CO2 can be -- we used it as a solvent to extract high-value lipids from algal biomass at a biofuel company I worked for: https://en.wikipedia.org/wiki/Supercritical_fluid_extraction But it can also be used as a 'solvent' in non-toxic and low/no-water laundry systems: http://e3tnw.org/ItemDetail.aspx?id=512 In addition to all of the benefits it can provide for ene…

Super critical co2 is also used for caffeine extraction in coffee, and its safer solvent for cannabis extracts and concentrates. I would never buy cbd products unless they are lab tested with a GC for contaminates and extracted with co2.

Look into USP-grade acetone-extracted cannabinoids. Acetone is 100% VOC so it will evaporate away cleanly without needing a vacuum purge (I'd still heat it to 135F to boil off the acetone which boils at ~133F) and your body naturally produces it in small amounts, so a tiny bit of contamination isn't going to be likely to cause damage. It is cheap to obtain vs. compressed CO2 (the cost of the equipment required for CO2 extraction represents the bulk of the cost of the extract) so you'll also save money.

Many places that do CO2 extraction also don't use a closed-loop system, so many are just venting the CO2 directly into the atmosphere.

Re: Supercritical CO2 is heavy like a liquid, with weird and useful properties

#33

Post by cperciva »

Supercritical liquids are generally weird. H2O, for example, changes from being a polar solvent to a nonpolar solvent -- you can dissolve oil in supercritical water, and even burn it if you have a source of oxygen. It's also more corrosive -- which is relevant if you're considering using supercritical water in a nuclear reactor.

Re: Supercritical CO2 is heavy like a liquid, with weird and useful properties

#34

Post by jackfoxy »

londons_explore wrote: post #31
jackfoxy wrote: post #29

Earlier quoted context omitted.

I assure you, the decision is entirely economic on the production side. CO2 is fungible, no? (in regards to sequestration subsidies)

CO2 is indeed fungible. I simply suspect that a lot of companies are requesting government money to research and develop something that they would choose to research anyway even without government money. (because it increases oil production). They get away with that because many governments don't have good tech advisers.

CO2 injection is not R&D, but established operating procedure. Its use can count to what determines recoverable reserves.

Re: Supercritical CO2 is heavy like a liquid, with weird and useful properties

#35

Post by dv_dt »

The other interesting thing is it can be used within a 100% carbon capture power plant that happens to generate more liquid CO2 which is inherently trapped within circuit of the plant. (and is presumably tapped off to sequester in places - this is said to be better than trying post collect and sequester the gas in a regular system).

https://en.wikipedia.org/wiki/Allam_power_cycle

Re: Supercritical CO2 is heavy like a liquid, with weird and useful properties

#37

Post by egdod »

neltnerb wrote: post #25
jcims wrote: post #23

Earlier quoted context omitted.

Let's guess. I'm going to say they are dissolving the 'precursors' into the co2, pumping it through the bed of particles with sufficient vigor to achieve 'fluidized' [1] state. As the supercritical co2 rises through the bed, the particles are dumping heat into it, ultimately flashing to vapor and leaving the solute (or at least the metallic part of it) behind as a thin film on the particle that did the trick. This of…

Almost! Except for the flashing CO2 to vapor, I actually just had a filter at the top to keep particles from flying out but the reactor itself was at 5000PSI and I just used a backpressure regulator for the exhaust stream which was very little since basically every byproduct was a gas. But in backstory, I invented a process, particle supercricial fluid deposition (UMass Amherst previously demonstrated deposition onto…

Super interesting. Comments like this are what keep me coming back to HN.

Re: Supercritical CO2 is heavy like a liquid, with weird and useful properties

#38

Post by jeremyspurz »

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Re: Supercritical CO2 is heavy like a liquid, with weird and useful properties

#39

Post by jcims »

neltnerb wrote: post #25
jcims wrote: post #23

Earlier quoted context omitted.

Let's guess. I'm going to say they are dissolving the 'precursors' into the co2, pumping it through the bed of particles with sufficient vigor to achieve 'fluidized' [1] state. As the supercritical co2 rises through the bed, the particles are dumping heat into it, ultimately flashing to vapor and leaving the solute (or at least the metallic part of it) behind as a thin film on the particle that did the trick. This of…

Almost! Except for the flashing CO2 to vapor, I actually just had a filter at the top to keep particles from flying out but the reactor itself was at 5000PSI and I just used a backpressure regulator for the exhaust stream which was very little since basically every byproduct was a gas. But in backstory, I invented a process, particle supercricial fluid deposition (UMass Amherst previously demonstrated deposition onto…

Holy moly this is cool! Thanks for all the detail and the link to your blog post. The process sounds really cool, i bet it was awesome seeing it work the first time!

Also:

>Almost!

You’re quite generous with your knowledge and compliments haha!

Re: Supercritical CO2 is heavy like a liquid, with weird and useful properties

#40

Post by DuskStar »

Gravityloss wrote: post #5

Some molten salt reactor designs were planned first with helium turbomachinery and later with supercritical CO2. Also GE tried to sell gas turbines for ship propulsion. You get back some efficiency with a CO2 turbine running with the waste heat. Ship owners still like their diesels. Really long time between overhauls.

> Also GE tried to sell gas turbines for ship propulsion.

Pretty common for warships though, or at least that's my understanding. The Arleigh Burke class [0] is powered by GE gas turbines, for instance.

Though the requirements list for "large surface combatant engine" and "huge cargo vessel engine" are probably more than a bit different.

0: https://en.wikipedia.org/wiki/Arleigh_Burke-class_destroyer

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