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Ethanol Production

Ethanol Production. John Nowatzki NDSU Extension Service. Introduction. What is Ethanol? Ethanol Production From Biomass Ethanol Production From Grains Ethanol Engine Fuel Characteristics Ethanol Strengths & Weaknesses. What is Ethanol?.

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Ethanol Production

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  1. Ethanol Production John Nowatzki NDSU Extension Service

  2. Introduction What is Ethanol? Ethanol Production From Biomass Ethanol Production From Grains Ethanol Engine Fuel Characteristics Ethanol Strengths & Weaknesses

  3. What is Ethanol? • Ethanol is a clear liquid made from fermenting sugars from: • Grains – grain ethanol • Biomass – cellulosic ethanol • Ethanol is an engine fuel that burns to produce carbon dioxide and water

  4. Cellulosic Ethanol Production Cellulosic Feedstock 2nd Pretreatment (convert cellulose into Glucose) Glucose fermentation Lignin 1st Pretreatment (convert hemi-cellulose into xylose and reduce size and open up structure of cellulose) Simultaneous saccharification & fermentation Distillation to recover ethanol Ethanol Fuel for heat and electricity Lignin Fermentation of xylose and other simple sugars from hemi-cellulose

  5. Cellulosic Ethanol Production 1st Pretreatment • Convert hemi-cellulose into pentoses (5 carbon sugars) and partial breakdown of cellulose • Each type of cellulosic feedstock requires a unique combination of pretreatments. • Physical methods: • steam explosion • Chemical methods: • dilute acid, alkaline, organic solvent, ammonia, sulfur dioxide, carbon dioxide • Biological methods:

  6. Cellulosic Ethanol Production 2nd Pretreatment • Convert cellulose into hexoses (6 carbon sugars) • The cellulose fraction is hydrolyzed byacids or enzymes to produce glucose • Enzymatic hydrolysis – biological conversion of cellulose to sugars • Acid hydrolysis – acid concentrations to convert cellulose to sugars

  7. Cellulosic Ethanol Production Lignin (By-product) • The solids remaining after the hemi-cellulose and cellulose are converted to sugars are washed, dried and used as fuel source for power production. 

  8. Cellulosic Ethanol Production Hydrolysis (saccharification) • Hydrolysis breaks down the hydrogen bonds in the hemi-cellulose and cellulose fractions into their sugar components: pentoses and hexoses. • The yeast contains an enzyme called invertase, which acts as a catalyst and helps to convert the sucrose sugars into glucose and fructose (both C6H12O6)

  9. Cellulosic Ethanol Production Fermentation • The fructose and glucose sugars reacts with an enzyme called zymase, which is also contained in the yeast, to produce ethanol and carbon dioxide. • The fermented mash, called beer, contains about 10% alcohol plus all the non-fermentable solids from the corn and yeast cells. • The mash and solids are separated (After fermentation the cellulosic and grain ethanol production processes are similar and will be explained together.)

  10. Grain Ethanol ProductionDry Milling Process

  11. Grain Ethanol ProductionGrinding • The grain passes through a hammer mill which grinds it into a fine powder called meal.

  12. Grain Ethanol ProductionLiquify and Cooking • The meal is mixed with water and cooked to liquify the starch. Heat is applied to enhance liquefaction resulting in a mash. • Enzymes are added to facilitate starch breakdown

  13. Grain Ethanol ProductionSaccharify • An enzyme is added to the mash to convert the liquefied starch to fermentable sugars

  14. Grain Ethanol ProductionFermentation • Yeast is added to the mash to ferment the sugars to ethanol and carbon dioxide. • In a batch process, the mash stays in one fermenter for about 48 hours before the distillation process is started.

  15. Ethanol Production Distillation (Cellulosic or Grain) • The distillation involves boiling the water and ethanol mixture. Since ethanol has a lower boiling point (78.3C) than water (100C), ethanol vaporizes before water and can be condensed and separated • The distilled alcohol is about 96% strength.

  16. Ethanol Production Drying & Denaturing (Cellulosic or Grain) • Most ethanol plants use a molecular sieve to water from the distilled ethanol. • Fuel ethanol must be denatured, or made unfit for human consumption, with a small amount of gasoline (2-5%)

  17. Grain Ethanol Production Dried Distillers Grains (DDG) • DDG is a by-product of grain ethanol production. • Drying the distillers grain increases its shelf life and reduces transportation costs • A bushel of corn (56 lbs) yields about 2.8 gallons of ethanol and 17 pounds of distillers grain

  18. Grain Ethanol Production Dried Distillers Grains with Solubles (DDGS) • DDGS is a by-product of grain ethanol production. • The liquid that is separated from the mash during the distilling process is partially dehydrated into a syrup, then added back onto the dried distillers grain to create DDGS

  19. Ethanol Production (Cellulosic or Grain)Carbon Dioxide (CO2) • CO2is given off during fermentation • Ethanol production plants collect, compress, and sell it for use in other industries

  20. Ethanol Fuel Characteristics

  21. Ethanol Strengths & Weaknesses • Potential Strengths • Fewer air pollutants • Renewable sources • Potential Weaknesses • Fewer BTU’s per gallon • Higher ethanol blends require engine modification

  22. More Information http://www.ag.ndsu.nodak.edu/abeng John Nowatzki, NDSU Extension State Specialist Telephone: 701-231-8213 Email: John.Nowatzki@ndsu.edu

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