3 ms·

The question is, would it be possible to use large scale liquid air storage to speed up removing CO2 from atmosphere? I have no idea if removing CO2 is easier

The question is, would it be possible to use large scale liquid air storage to speed up removing CO2 from atmosphere? I have no idea if removing CO2 is easier in liquid form but if it is feasible then ff we already had huge infrastructure to store energy that requires pumping astronomical amounts of air back and forth, it might make sense make sense to add a bit to it to remove CO2 while in liquid form.

pjc50 6y ago
Hmm. This actually has legs - CO2 can't be present in liquid air, because it freezes at only about -80 rather than the -200ish for air. So at some point CO2 "snow" will collect in the system. Unfortunately it's ~0.04% of the air, so this will take a long time to collect much. But if it's removed anyway, sure. Then you have to work out where to put it.
Tade0 6y ago
The energy required to liquefy air is probably too large. Say we have 400pm CO2 in air - that's ~630mg of CO2 per kilogram of air. Given that the specific heat of air sits at around 1kJ/kg[0], you'd have to spend over 125kJ of heat energy to get just one gram of CO2 - that's 35Wh. If you used wind power(14g CO2/kWh) and a heat pump with a coefficient of performance of 1 (not sure how possible at these gradients) you'd "emit" 0.5g of CO2 in the process. [0] https://www.ohio.edu/mechanical/thermo/property_tables/air/air_Cp_Cv.html https://www.ohio.edu/mechanical/thermo/property_tables/air/a...
- lmilcin 6y ago
  Well, you missed the fact that the plan is already to liquefy the air. So the air will already be in liquid form. Also I don't think they are going to cool it but rather compress it. Cooling would require constant expenditure of energy to keep it cool whereas you can compress it and leave it in the vessel at room temperature. It takes 33 atmospheres to liquefy nitrogen and 50 for oxygen.

3 ms·

The question is, would it be possible to use large scale liquid air storage to speed up removing CO2 from atmosphere? I have no idea if removing CO2 is easier

by lmilcin 6y ago

pjc50 6y ago
Hmm. This actually has legs - CO2 can't be present in liquid air, because it freezes at only about -80 rather than the -200ish for air. So at some point CO2 "snow" will collect in the system. Unfortunately it's ~0.04% of the air, so this will take a long time to collect much. But if it's removed anyway, sure. Then you have to work out where to put it.
Tade0 6y ago
The energy required to liquefy air is probably too large. Say we have 400pm CO2 in air - that's ~630mg of CO2 per kilogram of air. Given that the specific heat of air sits at around 1kJ/kg[0], you'd have to spend over 125kJ of heat energy to get just one gram of CO2 - that's 35Wh. If you used wind power(14g CO2/kWh) and a heat pump with a coefficient of performance of 1 (not sure how possible at these gradients) you'd "emit" 0.5g of CO2 in the process. [0] https://www.ohio.edu/mechanical/thermo/property_tables/air/air_Cp_Cv.html https://www.ohio.edu/mechanical/thermo/property_tables/air/a...
- lmilcin 6y ago
  Well, you missed the fact that the plan is already to liquefy the air. So the air will already be in liquid form. Also I don't think they are going to cool it but rather compress it. Cooling would require constant expenditure of energy to keep it cool whereas you can compress it and leave it in the vessel at room temperature. It takes 33 atmospheres to liquefy nitrogen and 50 for oxygen.