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CO2 to go

Well sure it's cold... but it's a dry cold.
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Intake
Compression
Sublimation
& Exhaust

The expansion properties of frozen Carbon Dioxide, or dry ice, sublimating could be used to power a motor if the pistons were designed to withstand the extreme cold.
Until recently the energy costs of extracting CO2 from the air and compressing it to liquid form far outweighed potential return on investment for such a use.

A new invention can extract CO2 directly from the air as a bi-product of charging a battery. The following is an excerpt from the [link].

"The device is essentially a large, specialized battery that absorbs carbon dioxide from the air (or other gas stream) passing over its electrodes as it is being charged up, and then releases the gas as it is being discharged. In operation, the device would simply alternate between charging and discharging, with fresh air or feed gas being blown through the system during the charging cycle, and then the pure, concentrated carbon dioxide being blown out during the discharging.
As the battery charges, an electrochemical reaction takes place at the surface of each of a stack of electrodes. These are coated with a compound called polyanthraquinone, which is composited with carbon nanotubes. The electrodes have a natural affinity for carbon dioxide and readily react with its molecules in the airstream or feed gas, even when it is present at very low concentrations. The reverse reaction takes place when the battery is discharged -- during which the device can provide part of the power needed for the whole system -- and in the process ejects a stream of pure carbon dioxide. The whole system operates at room temperature and normal air pressure."

Okay, so now we use the discharging battery to compress the CO2 emitted and store it in a liquid state.
The pressure when released could begin the process of driving the pistons and be recollected in its gaseous form to be reabsorbed during the next battery charge.
Any CO2 left in the storage tank will now be in solid snow-like form which can be blasted into the piston chamber on the intake cycle.

All emissions are stored to maximize the extraction potential of the battery system.


Ambient pressure and temperature CO2 extraction. https://www.science...10/191025170815.htm
[2 fries shy of a happy meal, May 31 2020]

Sublimation heat engine https://theconversa...onies-on-mars-38250
[kdf, May 31 2020]

Supercritical CO2 https://en.wikipedi...ical_carbon_dioxide
Other fun things to do with CO2 [kdf, May 31 2020]

[link]






       See also sublimation heat engine (link) proposed for powering colonies on Mars.   

       Whereas Mars already has a ready supply of dry ice, I wonder if the energy cost of this Earth- bound extraction method would outweigh the power you could get from your engine design.   

       Even so, more energy efficient CO2 extraction will benefits a lot of industries. Thanks for pointing out the MIT research.
kdf, May 31 2020
  

       //A new invention can extract CO2 directly from the air as a bi-product of charging a battery. //   

       In this house we obey the laws of physics! You can charge a battery or extract CO2 from the air, or transfer heat from the CO2 until it becomes ice but you can't do any of those things without putting in energy.
Voice, May 31 2020
  

       Solar charging.
No free lunch.
The battery collects Co2 while charging, compresses this CO2 while discharging and the star we orbit does all of the work. Exhaust gas goes right back into the system.
It is both simple and elegant.
How does this in any way bend the laws of thermodynamics even a little bit?
  

       Cool links [kdf].   

       According to the MIT paper, you'll need about "one gigajoule of energy per ton of carbon dioxide captured..." (which is very good) but says nothing about making dry ice. As the whole pricess runs at ambient temp & pressure I assume the output stream is gaseous.
kdf, Jun 01 2020
  

       I assumed the output would be a gas as well.
Compressing CO2 gas turns it liquid. Releasing the pressure causes rapid cooling on its own as the liquid evaporates and you're left with CO2 snow to be fed into the pistons.
  

       It's a simple steam engine at that point... just using cold instead of heat is all.   

       Yes, but ... compressing it takes energy, and you’re gonna get less energy back out on the expansion stroke. You may as well be using air at that point, there’s nothing magical about CO2.
kdf, Jun 01 2020
  

       The rates of CO2 in the energy steps have to be calculated.   

       I am thinking the battery output probably won't be enough to restate the CO2 for the heat engine.   

       Ultimately it's the solar panels changing the state of the C02 with an added function of CO2 collection and concentration.
wjt, Jun 01 2020
  

       //You may as well be using air at that point, there’s nothing magical about CO2.//   

       Compressed air does not turn into a sublimating solid upon release of pressure, so yes there is something magical about dry ice compared to snow in my opinion.   

       //where’s the borg?//   

       If I don't miss my bet, I imagine they are in one of the various stages of grief having lost one of their closest, if not the closest, of on-line friends and their wits are not being matched at the rate they have become accustomed to. Just a guess.   

       //The rates of CO2 in the energy steps have to be calculated.
I am thinking the battery output probably won't be enough to restate the CO2 for the heat engine.//
  

       <shrugs> Could be, but once the system contains no other gasses then the recoup should be about as optimal as it gets. Sublimating CO2 is just like steam though, as in; if you don't give it an outlet it will explode unless kept cold.   

       Should be very easily tested on a small scale I would think.   

       Honestly, I just sat down at the computer, thought to myself; 'I haven't contributed anything in a while, I should see if I can whip up an idea', blanked my mind, dipped into the ol' stream of consciousness thingy, and this is what I surfaced with.   

       Might work. Might not.
<shrugs>
  

       Do or do not do with it what you will. I'm off to kick my daughter and her boyfriends ass at Halo.   

       Ta.   

       I like the multi-faceted aspect , processes that do other asides as well. Seems the natural way. And, err... I don't think it's a competition.
wjt, Jun 01 2020
  

       Me too... and it is if you're not in Campaign mode and just running around shooting each other.
Turns out her boyfriend is a gamer and we got slaughtered.
  

       [+]
FlyingToaster, Jun 01 2020
  

       ^ you say you [+]... but you no [+], not that I give much of a crap about [+]'s, but still...   

       lol, oops, sorted. I like the discharge being used to compress.
FlyingToaster, Jun 03 2020
  
      
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