Lessons from commercial fuel ethanol producers

[Pierrot Lunaire 55]

I sat through a presentation by an engineer from a commercial corn-to-ethanol producer that proved to be very interesting. I won't name the company or individual, but here's the interesting statement:
3 pounds of corn becomes 1 pound of ethanol, 1 pound of carbon dioxide and 1 pound of distiller's grain (for animal feed).

The fact that fermentation produces an equal amount of ethanol and carbon dioxide (by weight) was something I had never realized, but it makes sense if you look at the chemistry involved.

The yield per pound of corn is particularly instructive. Ethanol is about 6.5 lbs per gallon, so that says it takes about 19.5 lbs of corn to produce 1 gallon of ethanol. (Sorry, I don't know how much water is involved.) Obviously this is a highly optimized process and probably uses enzymes that might make it taste bad, but doesn't seem all that different from someone able to produce mash with 10% ABV. On a good day, most of us could probably come pretty close to that.

We might have a harder time recovering it. Their distillation is different with a much larger and more sophisticated still, but they are subject to the same ABV limitations we are. The final de-watering process is done with a "chemical sieve."

Something to think about.

[Pikey]

............The fact that fermentation produces an equal amount of ethanol and carbon dioxide (by weight) was something I had never realized, but it makes sense if you look at the chemistry involved....................

The old (1960's ) winemaking books will tell you that

2lb sugar will give you 50% alcohol - 50% CO2

If you can get 2 lb sugar from 3 lb maize - then yes what you say is true

[cuginosgrizzo]

well, it sounds almost right. 3kg of flaked maize in 10 liters water, with 100% efficiency virtually produce a 10%ABV wash, with a little less than 1kg alcohol.

So the ratio 3-1 is theoretically feasible. Not in my house, though, not with 100% efficiency.

[Kareltje]

2 kg of sugar in 10 liters wash makes 1 kg of alcohol and 1 kg CO2. 1 kg of alcohol is about 1.2 liters. 2 kg of sugar is also about 1.2 liters, CO2 vanishes into thin air.
So 2 kg of sugar in 10 liters of wash results, if everything goes well, in 12 %ABV of alcohol. And in 1 kg of CO2, being about 555 liter.