How much CO2 is produced during fermentation?

[jseyfert3]

ABV f*cking does

Yeah there's absolutely no other way to determine the concentration of ethanol in a solution except a mass spectrometer.

https://www.canterbury.ac.nz/media/documents/science-outreach/ethanol.pdf

 

[micraftbeer]

Wow, this thread has turned into something great. What keeps making me laugh is that the OP's question of "will it make enough CO2 to do this?", has been agreed to by everybody that the answer is "yes"...

 

[Wables]

OP here. The new all-rounders have been great. My 10 year old checks them every couple hours and reports on the yeast progress. I’m going to have to buy him a couple of Tilts for Christmas and pair them to his iPad. To settle this ABV measurement discussion, I suggest we agree on a new measurement, such as PTS (pints to shitfaced).

 

[micraftbeer]

But what I'm really hoping for more than anything, is someone to come in and post something that contradicts both the "equation science camp" and the "esoteric science camp" and definitely claims the OP won't make enough CO2!

 

[Wables]

I can definitely say that I made so much CO2 I’m thinking of ways to harvest it.

 

[McMullan]

I suggest we agree on a new measurement, such as PTS (pints to shitfaced).

Sounds like a perfectly acceptable measure to me. Probably more accurate than my p*ssed hydrometer.

 

[McMullan]

I can definitely say that I made so much CO2 I’m thinking of ways to harvest it.

Daisy chain as many empty kegs as you can. I cranked up the spunding pressure to about 30psi to get a good carbonation level towards the end of fermentation.

 

[Knightshade]

 

[Gnomebrewer]

Well I do like a maths question! Yes, I'm aware that the question is already answered (there is enough CO2), but to put a rough figure on the amount (there are some simplifications and I've made some assumptions, but should be in the ballpark).......

A 1.060 beer, fermented to 1.010 uses 50 points of gravity. That equates to about 1.25Kg of fermented sugar per 10L.
5.5 gallons is about 22L or 2.2cl.
2.2cl x 1.25Kg/cl = 2.75Kg of fermented sugar (glucose).
Glucose has a mass of about 180g/mol.
2.75Kg/0.18Kg = about 15 moles of fermented glucose.
Each mole of glucose gives 2 moles of CO2, so that's about 30 moles of CO2.
CO2 has a mass of about 44g/mol, so 30 moles has a mass of about 30mol x 44g/mol = about 1300g, or 1.3Kg (2.86lbs). So a bit over half a 5lb CO2 cylinder!
In volume terms, 1 mole of gas at stp has a volume of 22.4L, so 30 moles of CO2 is between 600 and 700L!!!
Assuming my maths is correct. Which it probably isn't. Let me know if I've made a mistake and I'll be suitably embarrassed!

TLDR: 5.5 gallons of1.060 beer fermented to 1.010 produces about 1.3Kg/2.86lbs or 600-700L (150 to 170 gallons) of CO2.

 

[Terpene]

TLDR: 5.5 gallons of1.060 beer fermented to 1.010 produces about 1.3Kg/2.86lbs or 600-700L (150 to 170 gallons) of CO2.

Yup, sounds about right.

My numbers were a bit different, but it's in the ballpark. Remember, for gases, STP is 0 Celsius -- at room temp, volume will be greater than 22.4 L.

I came up with 22.3 moles of CO2 for a 20 L batch, with slightly different assumptions than yours. Both ways get a decent ballpark number.

 

[Gnomebrewer]

I came up with 22.3 moles of CO2 for a 20 L batch, with slightly different assumptions than yours. Both ways get a decent ballpark number.

So that's about 25 moles of CO2 for a 22L batch. +/- 20% of each other is close. A fair chunk of that would be taken up by me assuming a 1.010FG, when in reality it was probably more like 1.015. That's 10% of my calculation straight up.

 

[McMullan]

It would have been even funnier had the text read "I accept mathematics as a science". But the phrase 'believe' made me laugh

 

[hottpeper13]

Too bad we can't go to the hardware store and purchase a MOLE trap to store the extra CO2 in!

 

[McMullan]

Too bad we can't go to the hardware store and purchase a MOLE trap to store the extra CO2 in!

Get at least a couple to store all the carbon based biomass produced during a good fermentation.

 

[Wables]

If you strung together 2 or 3 kegs on a 30 psi fermentation, you would have plenty of CO2 to run your keggerator, and the beer would already be carbonated.

 

[renstyle]

While I am resurrecting an old thread, it's to give thanks.

I just started a dark mild fermenting in a keg, and have a serving keg freshly cleaned and sanitized, but used the sanitizer during the mild brew day.

Armed with the knowledge of this thread and the quoted "Keg Purging..." I am confident that my current batch could easily purge my eventual serving keg to O2 levels in the low PPB range over the course of a normal (non-spunded) fermentation.

It saved me from a wee bit of work, as well as some tank CO2 once I realized if I hooked this up right away my serving keg we would be ready to roll once we hit FG.

I ran a line from the gas OUT on the serving keg to a bubbler on my workbench. It's nice to see things working.. remotely LOL.