ETHANOL PRODUCER'S DATA BASE

Harry form the alcohol fuel group, clarifies some possible differences in the way the potential yield in alcohol per ton of molasses is expressed.

SEE Posting: http://tech.groups.yahoo.com/group/alcoholfuel/message/7737 

Hi Katt,There is indeed about 170 gallons (of molasses) to a ton.

• It must be remembered that the Brix scale measures on a
• Weight % basis, and all calculations must be based on weight 
• Not on Volume 80° Brix Molasses have a specific gravity of 
• 1.416, therefore, a gallon weighs about 11.8 Lbs
• And a Ton contains about 169.5 Gallons
   

Gilles' chart refers to theoretical potential yield of ethanol per ton of molasses. 

He quotes molasses as 70 gallons per ton.  But Murtagh in "The Alcohol Textbook" puts it a bit lower than that for practical purposes...

Economics of using  blackstrap molasses for alcohol production.

Based on the Gay-Lussac equation for ethanol production from glucose by fermentation (Figure5)* we should obtain 48.89 lbs of carbon dioxide(CO2) and 51.11 lbs of ethanol if we ferment 100 lbs of glucose. This is the maximum theoretical output; however Pasteur concluded that it was virtually impossible to obtain more than 95% of the maximum theoretical yield as the reaction is not as simple as the Gay-Lussac equation implies. In addition to ethanol, yeast also produce other substances such as glycerol and succinic acid. Many distillers, therefore, use 95% of the 51.11% w/w figure as a realistic basis for calculating expected ethanol yields. (When comparing yields from different plants (refineries), one should know exactly how each plant calculates theoretical yields.)

For costing purposes, one can expect to obtain about 58 gallons of ethanol from a ton of molasses at 46% sugars (TSAI).  (Molasses prices are generally quoted f.o.b. New Orleans on the basis of 79.50 Brix and about 46% w/w "Total Sugars as Invert" (TSAI).

This is calculated as follows:

A) 1 ton molasses at 46% sugars contains 920 lbs sugar.
B)  920 x 51.11% (Gay-Lussac yield) = 470.21 lbs ethanol.
C)  470.21 @ 6.58 lbs ethanol/gallon = 71.46 gallons  ethanol.
D) 71.46 gallons x 95% (Pasteur yield) = 67.89 gallons.
E) 67.89 gallons x 85% (low-average plant efficiency) = 57.71 gallons/ton of molasses.

 *   C₆ H₁₂ O₆   +  YEAST    -->   2CO₂    +    2C₂ H₅ OH

100 Lbs Glucose = 48.89 Carbon dioxide and 51.11 Lbs Ethanol

Fig. 5 The Gay-Lussac equation for ethanol production from glucose by fermentation.

 Source: "The Alcohol Textbook" by J.E.Murtagh et al; Ch 6 'Molasses as a Feedstock'.

Slainte! regards Harry

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• Dissolve 100kg molasses in 50 litres of water.
• Bring to a full boil
  • ( Optionnal to kill any unwanted bacterias )
• Add yeast
• Cover and stand at 25-30 deg C (77-86 deg F).
• Reaction time is 2-3 days 
  • Fermentation is  over when bubbling of CO2 ceases.

Based on 50% Sugar content Molasses

Note : This is a recipe from the 1980's, and although it should work well,

I suggest a scalled down test like: 1kg molasses  in 4 litres of water.