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CO2-enriched Greenhouse

Improve hydroponic crop yeilds with CO2 enrichment
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Using an aqueous solution of monoethanolamine, you can remove CO2 and other weakly acidic gasses from the air. When heated, the MEA is 'regenerated', the CO2 bubbling out.

This is often used in submarine scrubbers, but I had a thought: what if you were to use an MEA scrubber to increase the CO2 a small (say, 6' tall x 2' wide by 20' long) hydroponic greenhouse with CO2. From what I can determine, most plants will thrive in an increased CO2 atmosphere. With current modern hydroponic techniques, such a technology could increase crop yeilds dramatically.

The system would be a continuous one, where air is bubbled through an MEA resevior, both cooling the system and adding CO2 to the MEA. The MEA is continuously cycled into a narrow pipe, and into a flattened smaller resevior where it is heated, letting the CO2 bubble out. It then flows back into the main resevior.

Fordi, Jun 27 2006

Carbon Dioxide Enrichment http://homeharvest....chmentgenerator.htm
[ldischler, Jun 28 2006]

Safe levels of CO2 http://www.health.s...ndex.html#workplace
(It's 5,000 ppm for an 8-hour exposure) [ldischler, Jun 28 2006]

Monoethanolamine http://en.wikipedia...wiki/2-aminoethanol
Nasty stuff [ldischler, Jun 28 2006]

A similar concept http://www.csmonito...11/p01s03-sten.html
They're using this idea as a CO2 scrubber for a power plant (pilot only, as far as I know). [NoOneYouKnow, Jun 28 2006]

Adding CO2 to greenhouses http://www.omafra.g...ps/facts/00-077.htm
[Loris, Nov 12 2016]

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       this greenhouse wouldn't be safe for people to enter while this thing was on.
tcarson, Jun 27 2006
  

       I was thinking about this a while ago, and on googling it, found it to be widely baked. Try googling it yourself. Mostly it looks like these systems use small propane heaters, which is no doubt simpler than your interesting MEA idea.   

       My question is: why is there a maximum CO2 for greenhouse plants? Shouldn't they thrive at high (50%) CO2? Or does this start to alter the pH of water to the point where it becomes harmfull to plants?
bungston, Jun 27 2006
  

       Retrofit them to coal fired power plants and "sequester" that CO2 straight into high value food crops.
BunsenHoneydew, Jun 28 2006
  

       That is pretty clever, [Bunsen]. I bet that some experimentation might discover a crop for which CO2 was the limiting factor on growth, and which would grow like mad given a big supply. Maybe Reed Canarygrass? You can always do something with biomass, and it would lock up that CO2.
bungston, Jun 28 2006
  

       [bungston], doesn't the 'doing something with biomass' (eating it? burning it?) usually let the CO2 out again? Or am I just being unimaginative here?
pertinax, Jun 28 2006
  

       Build a house with it.
david_scothern, Jun 28 2006
  

       //That is pretty clever, [Bunsen]. I bet that some experimentation might discover a crop for which CO2 was the limiting factor on growth, and which would grow like mad given a big supply. Maybe Reed Canarygrass? You can always do something with biomass, and it would lock up that CO2.//   

       Hemp is a perfect candidate for this.   

       With regards to CO2, there is a point where too much CO2 puts a plants system into an imbalance and kills the plant. Plants also need O2, most notably at night.   

       This is the same with all life, we need oxygen but prolonged exposure to pure oxygen and nothing else could be harmful. There is always an optimum level.
webfishrune, Jun 28 2006
  

       There has already been work done in a similar vein. They're basically bubbling smokestack emissions from a power plant through vats of algae laden water (see link). The resulting algae can be used to produce biodiesel and ethanol for fuel.
NoOneYouKnow, Jun 28 2006
  

       You can also bury or sink the biomass in an anaerobic environment. Basically you are starting some new coal and oil. (Just wait a while.)   

       Oh, but I think the best percentage of CO2 for plant life is still pretty low. Maybe as high as 1-2%
Galbinus_Caeli, Jun 28 2006
  

       tcarson: The greenhouses are small enough for the plants only. Come harvest time, they would have to be flushed with normal atmosphere (preferably to the outside, but can simply rely on the 'good ventilation' clause you see on aerosols.) Still, playing paintball doesn't bring about toxicity, so I don't think CO2 enriched air would be too horrible.   

       Galbinus_Caeli: You are correct. The best percentage of CO2 for plant life has to be higher than the atmospheric CO2 (appx 0.035%), so enriching it need only be to about 2%. Research would need to be done to determine CO2% v. Average crop yield.   

       webfishrune: Plants will have O2; both what they produce and atmospheric. I'm not talking about filling the greenhouse with pure CO2, just enriching its CO2 concentration.   

       pertinax: You are correct. The act of eating plant biomass eventually releases the carbon in the form of human respiration. Burning it or converting it to biofuel (ethanol, biodiesel, TCP diesel) releases the carbon immediately. However, I never suggested this was a form of carbon sequestration, just a way of increasing crop yields in controlled farming environments (hydroponics)   

       bungston: CO2 is a weak acid, and would, in fact, help those plants that desire an acidic environment to thrive. However, by sheilding the water system or making it compensatorily basic, one could probably grow almost anything in a high-CO2 environment. Meanwhile, CO2 concentrations in excess of 2% have been shown to increase a given plant's optimal temperature (offering a more effective means to cool the resevior).   

       ldischer: Nasty yes, but only to handle. Its use in submarine air scrubbers shows that it is possible to construct a 'clean' system to aid in CO2 selection. Meanwhile, your first link is to a CO2 'generator' that's little more than a combustion chamber. The idea here is to use a nonconsumable.
Fordi, Jun 28 2006
  

       The MEA system could be routed through a chamber containing the exhaust from, say, a nextdoor diesel generator or propane water heater serving some other function. As [tcarson] noted, toxicity to greenhouse workers is a real threat using combustion enrichment systems - toxicity both from CO2 and CO. The small amounts of CO2 released by the MEA should make the threat less. I am not sure if MEA will trap and release the CO as well.
bungston, Jun 28 2006
  

       My take on this was to produce alcohol by fermentation, and release the CO2 into the greenhouse. In common with the present Idea, and in contrast with propane (etc) burners, this would not consume oxygen inside the greenhouse (although a lesser amount of oxygen would be lost by displacement). If the alcohol is burned outside the greenhouse and the feedstock for the fermentation likewise grown outside, the net effect is to shunt CO2 in.
spidermother, Jun 29 2006
  

       Spider's plan only suffers one minor flaw--it's insane.
ldischler, Jun 29 2006
  

       Of course, I use the term 'burn' in the broader sense, and note the intoxicating effect of alcohol on certain carbon based halfbakers. Balance the equations - it's rather elegant. //insane// If so then the fact that I've baked this would imply that I, that is we, are, or is that is, err... As you were.
spidermother, Jun 29 2006
  

       I'm sorry...actually, I misread your annotation. The CO2 is a byproduct, so it isn't insane. And you can quote me on that.
ldischler, Jun 29 2006
  

       Let's call the alcohol and CO2 co-products and be done with it. I simply adore combining the solving of two problems in a synergistic way like this. (Reminds me of the cartoon: (A) I have soy sauce! (B) And I have needles! (Both) Let's inject our eyes!)
spidermother, Jun 30 2006
  

       The MEA could probably be regenerated using solar thermal energy (concentrated, if necessary), eliminating the need to burn fossil fuels.
goldbb, Mar 03 2010
  

       nice [goldbb] and, being solar-powered, wouldn't operate when the plants were sleeping (ie: not absorbing CO2)
FlyingToaster, Mar 04 2010
  


 

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