Anaerobic Digestion of Thin Stillage for Biogas

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Anaerobic Digestion of Thin Stillage for Biogas

Patrick J. Hirl, P.E. Ph.D.


Whole Stillage 7 gallons @ 12% Wet Cake 10 lbs @ 36% Centrifuge Thin Stillage 4 gallons @ 5% Evaporator •Values per gallon of ethanol produced •Concentrations are % solids by weight Dryer Syrup 0.4 gallons @ 33% 2,000 btu 10,800 btu DDGS 6 lbs @ 90%


Whole Stillage 7 gallons @ 12% Wet Cake 10 lbs @ 36% Centrifuge Thin Stillage 4 gallons @ 7% Anaerobic Digester •Values per gallon of ethanol produced •Concentrations are % solids by weight Dryer 20,000 btu 5,400 btu DDG 5.4 lbs @ 90%


Whole Stillage 6.2 gallons @ 12% Anaerobic Digester 30,000 btu •Values per gallon of ethanol produced •Concentrations are % solids by weight


(US Patent 7,524,418)


Energy Use to Produce a Gallon of Ethanol (BTU) 90000 80000 70000 60000 50000 40000 30000 20000 10000 0 Green Energy Production Transportation Corn Growing Energy Value of a Gallon of Ethanol Green Energy Production Transportation Corn Growing Dry Mill Thin Stillage AD


Carbon Emission (gCO 2e/MJ) 120 100 80 60 40 20 0 CaRFG Ethanol Thin Stillage AD WTW Indirect Land Use


Value of Stillage ($ US/10 3 gallons ethanol produced) 590 540 490 440 390 340 290 240 190 140 90 Value of Stillage = value of biogas + value of DDGS – energy input 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 Average Natural Gas Price $6 US/mmBTU DDGS Price ($ US/ton) DDGS


Value of Stillage ($ US/10 3 gallons ethanol produced) 590 540 490 440 390 340 290 240 190 140 90 Value of Stillage = value of biogas + value of DDGS – energy input Biogas 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 Average Natural Gas Price $6 US/mmBTU DDGS Price ($ US/ton) DDGS


Value of Stillage ($ US/10 3 gallons ethanol produced) 590 540 490 440 390 340 290 240 190 140 90 Value of Stillage = value of biogas + value of DDGS – energy input Biogas DDG and Biogas 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 Average Natural Gas Price $6 US/mmBTU DDGS Price ($ US/ton) DDGS


Value of Stillage ($ US/10 3 gallons ethanol produced) 590 540 490 440 390 340 290 240 190 140 90 Value of Stillage = value of biogas + value of DDGS – energy input Biogas DDG and Biogas 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 Average Natural Gas Price $8 US/mmBTU DDGS Price ($ US/ton) DDGS


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