Enrichment of CO2 in greenhouses

[farmerben]

Tripling the CO2 concentration in greenhouses can double plant growth rates.  Greenhouses that button up tightly fall below standard atmospheric CO2 and reduce plant growth.  

We need an affordable machine to suck atmospheric air and increase the CO2 in greenhouses.  Currently most commercial operation use natural gas burners, some bring in bottled gas or dry ice.  Small growers know that keeping rabbits or chickens in the same greenhouse could be optimal in some sense but impractical in others.  Spacecraft have electrochemical separators.  I wonder if anyone has good links about this technology?  

[darthgently]

50 minutes ago, farmerben said:

Tripling the CO2 concentration in greenhouses can double plant growth rates.  Greenhouses that button up tightly fall below standard atmospheric CO2 and reduce plant growth.  

We need an affordable machine to suck atmospheric air and increase the CO2 in greenhouses.  Currently most commercial operation use natural gas burners, some bring in bottled gas or dry ice.  Small growers know that keeping rabbits or chickens in the same greenhouse could be optimal in some sense but impractical in others.  Spacecraft have electrochemical separators.  I wonder if anyone has good links about this technology?  

I recall that current CO2 atmospheric extraction is chilling ambient air and drawing off the liquid components at their phase change temps. Much like a distillation stack, but  upside down and inside out thermodynamically

[sevenperforce]

Direct Air Capture has been studied for a long time, but I believe the cost remains somewhat prohibitive. In particular, the energy requirements (cycles of heating and cooling in the sorbent used to capture the CO2) make any system carbon-positive unless they can use purely zero-emission energy sources, which in turn reduce the availability (and drive up the cost) of those zero-emission energy sources in the market.

10 hours ago, darthgently said:

I recall that current CO2 atmospheric extraction is chilling ambient air and drawing off the liquid components at their phase change temps. Much like a distillation stack, but  upside down and inside out thermodynamically

That's one way of doing it, but I believe that is vastly more expensive (from an energy standpoint) than using sodium hydroxide or some other sorbent to do the trick.

[FleshJeb]

"Several studies have been conducted in recent decades on the effects of eCO₂ on vegetable quality, including parameters related to taste, flavor, nutritive value, and industrial processing. These studies show that eCO₂ can promote the accumulation of soluble sugar including glucose and fructose, and the accumulation of antioxidants including ascorbic acid, total phenols, and total flavonoids, but reduce the levels of protein, nitrate, Mg, Fe, and Zn in products. In practice, it is advisable to enhance vegetable quality by (1) selecting species or cultivars that respond well to eCO₂; (2) providing optimal environments together with eCO₂; (3) harvesting vegetables earlier than standards set at ambient CO₂; and (4) combining with moderate environmental stresses. The promotion by the increased carbon fixation and thus the precursor, dilution effect, stress induction, and limitation by transpiration or N assimilation can generally explain the shifts of vegetable quality under eCO₂. However, research is still required to reveal the underlying physiological and molecular mechanisms more specifically."

https://www.frontiersin.org/articles/10.3389/fpls.2018.00924/full