John Nowatzki NDSU Extension Service Ethanol Production John Nowatzki NDSU Extension Service 2/21/2019

Introduction What is Ethanol? Ethanol Production From Biomass Ethanol Production From Grains Ethanol Engine Fuel Characteristics Ethanol Strengths & Weaknesses 2/21/2019

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 2/21/2019

Cellulosic Ethanol Production 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 Hydrolysis Hydrolysis is a chemical decomposition process that uses water to split chemical bonds of substances. There are two types of hydrolysis, acid and enzymatic. Feedstocks that may be appropriate for acid or enzymatic hydrolysis typically are plant-based materials containing cellulose. These include forest material and sawmill residue, agricultural residue, urban waste, and waste paper. All plants have structural components composed of lignocellulosic fibers, which in turn are comprised of three major fractions: cellulose, hemicellulose, and lignin. Cellulose and hemicellulose are chains of sugar molecules that can be broken down chemically or biologically into the component sugars. The sugars are then fermented using yeast or bacteria to produce ethanol, which is then distilled to a higher concentration for final use. Sugars can also be converted to levulinic acid and citric acid. Levulinic acid is a versatile chemical that is a precursor to other specialty chemicals, fuels and fuels additives, herbicides, and pesticides. The largest application for citric acid is in the beverage industry, which accounts for about 45 percent of the market for this product. Citric acid is also used in a wide variety of candies, frozen foods, and processed cheeses and as a preservative in canned goods, meats, jellies, and preserves.Lignin binds cellulose and hemicellulose together and cannot be broken down to form sugars. At this point, the most cost-effective use for lignins is as a fuel for biomass-to-energy facilities. Reference: http://www.ciwmb.ca.gov/Organics/Conversion/Hydrolysis/ (California Integrated Waste Management Board ) Fermentation of xylose and other simple sugars from hemi-cellulose 2/21/2019

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: http://genomicsgtl.energy.gov/biofuels/placemat1.shtml 2/21/2019

Cellulosic Ethanol Production 2nd Pretreatment Convert cellulose into hexoses (6 carbon sugars) The cellulose fraction is hydrolyzed by acids or enzymes to produce glucose Enzymatic hydrolysis – biological conversion of cellulose to sugars Acid hydrolysis – acid concentrations to convert cellulose to sugars http://www.energy.ca.gov/pier/index.html Enzymatic Hydrolysis Enzymatic hydrolysis; simultaneous saccharification and co-fermentation (SSCF): The steps in the conversion of cellulosic materials to ethanol in processes featuring enzymatic hydrolysis includes pretreatment, biological conversion, product recovery, and utilities and waste treatment. SSCF is an adaptation to the process, which combines hydrolysis and fermentation in one vessel. Sugars produced during hydrolysis are immediately fermented into ethanol. By fermenting the sugars as soon as they form, eliminates problems associated with sugar accumulation and enzyme inhibition.  Dilute Acid Hydrolysis  Dilute acid hydrolysis: This process uses low concentration acids and high temperatures to process the cellulosic biomass. Lignocellulose biomass is pretreated with approximately 0.5% acid in liquid at up to 200ºC to hydrolyze the hemicellulose and expose the cellulose for hydrolysis. The hemicellulose hydrolysis yields most pentose (C5) sugars, principally xylose and arabinose, which are fermented to ethanol and distilled. The remaining solids, cellulose and lignin, enter the second stage hydrolyzer where cellulose is converted to glucose with approximately 2% acid in liquid at up to 240º C. The resulting sugars are then fermented to ethanol and distilled.  Concentrated Acid Hydrolysis  Concentrated acid hydrolysis: This process uses high concentration halogen acids and near ambient temperatures to convert cellulosic biomass to sugars. The decrystalization and hydrolysis of cellulose with nearly 100% yields may be accomplished with 40 wt% hydrochloric acid, 60 wt% sulfuric acid, or 90 wt% hydrofluoric acid. The liquid phase hydrochloric acid process is the only halogen process to have reached commercial development.  2/21/2019

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.  http://www.energy.ca.gov/pier/index.html Enzymatic Hydrolysis Enzymatic hydrolysis; simultaneous saccharification and co-fermentation (SSCF): The steps in the conversion of cellulosic materials to ethanol in processes featuring enzymatic hydrolysis includes pretreatment, biological conversion, product recovery, and utilities and waste treatment. SSCF is an adaptation to the process, which combines hydrolysis and fermentation in one vessel. Sugars produced during hydrolysis are immediately fermented into ethanol. By fermenting the sugars as soon as they form, eliminates problems associated with sugar accumulation and enzyme inhibition.  Dilute Acid Hydrolysis  Dilute acid hydrolysis: This process uses low concentration acids and high temperatures to process the cellulosic biomass. Lignocellulose biomass is pretreated with approximately 0.5% acid in liquid at up to 200ºC to hydrolyze the hemicellulose and expose the cellulose for hydrolysis. The hemicellulose hydrolysis yields most pentose (C5) sugars, principally xylose and arabinose, which are fermented to ethanol and distilled. The remaining solids, cellulose and lignin, enter the second stage hydrolyzer where cellulose is converted to glucose with approximately 2% acid in liquid at up to 240º C. The resulting sugars are then fermented to ethanol and distilled.  Concentrated Acid Hydrolysis  Concentrated acid hydrolysis: This process uses high concentration halogen acids and near ambient temperatures to convert cellulosic biomass to sugars. The decrystalization and hydrolysis of cellulose with nearly 100% yields may be accomplished with 40 wt% hydrochloric acid, 60 wt% sulfuric acid, or 90 wt% hydrofluoric acid. The liquid phase hydrochloric acid process is the only halogen process to have reached commercial development.  2/21/2019

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) The catalyst is dissolved in the alcohol using a standard agitator or mixer. After the addition of alcoloh the reaction is closed to prevent the loss of alcohol. Some processors use more heat to speed up the process. 2/21/2019

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.) The catalyst is dissolved in the alcohol using a standard agitator or mixer. After the addition of alcoloh the reaction is closed to prevent the loss of alcohol. Some processors use more heat to speed up the process. 2/21/2019

Grain Ethanol Production Dry Milling Process Hydrolysis Hydrolysis is a chemical decomposition process that uses water to split chemical bonds of substances. There are two types of hydrolysis, acid and enzymatic. Feedstocks that may be appropriate for acid or enzymatic hydrolysis typically are plant-based materials containing cellulose. These include forest material and sawmill residue, agricultural residue, urban waste, and waste paper. All plants have structural components composed of lignocellulosic fibers, which in turn are comprised of three major fractions: cellulose, hemicellulose, and lignin. Cellulose and hemicellulose are chains of sugar molecules that can be broken down chemically or biologically into the component sugars. The sugars are then fermented using yeast or bacteria to produce ethanol, which is then distilled to a higher concentration for final use. Sugars can also be converted to levulinic acid and citric acid. Levulinic acid is a versatile chemical that is a precursor to other specialty chemicals, fuels and fuels additives, herbicides, and pesticides. The largest application for citric acid is in the beverage industry, which accounts for about 45 percent of the market for this product. Citric acid is also used in a wide variety of candies, frozen foods, and processed cheeses and as a preservative in canned goods, meats, jellies, and preserves.Lignin binds cellulose and hemicellulose together and cannot be broken down to form sugars. At this point, the most cost-effective use for lignins is as a fuel for biomass-to-energy facilities. Reference: http://www.ciwmb.ca.gov/Organics/Conversion/Hydrolysis/ (California Integrated Waste Management Board ) 2/21/2019

Grain Ethanol Production Grinding The grain passes through a hammer mill which grinds it into a fine powder called meal. 2/21/2019

Grain Ethanol Production Liquify 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 Liquefaction. The meal is mixed with water and alpha-amylase, then passed through cookers where the starch is liquefied. Heat is applied at this stage to enable liquefaction. Cookers with a high temperature stage (120-150 degrees Celsius) and a lower temperature holding period (95 degrees Celsius) are used. High temperatures reduce bacteria levels in the mash. 2/21/2019

Grain Ethanol Production Saccharify An enzyme is added to the mash to convert the liquefied starch to fermentable sugars 2/21/2019

Grain Ethanol Production Fermentation 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. Fermentation. Yeast is added to the mash to ferment the sugars to ethanol and carbon dioxide. Using a continuous process, the fermenting mash is allowed to flow through several fermenters until it is fully fermented and leaves the final tank. In a batch process, the mash stays in one fermenter for about 48 hours before the distillation process is started. 2/21/2019

Distillation (Cellulosic or Grain) 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. Fractional Distillation Process The ethanol, which is produced from the fermentation process, still contains a significant quantity of water, which must be removed. This is achieved by using the fractional distillation process. The distillation process works by boiling the water and ethanol mixture. Since ethanol has a lower boiling point (78.3C) compared to that of water (100C), the ethanol turns into the vapour state before the water and can be condensed and separated. Dehydration. The alcohol from the top of the column passes through a dehydration system where the remaining water will be removed. Most ethanol plants use a molecular sieve to capture the last bit of water in the ethanol. The alcohol product at this stage is called anhydrous ethanol (pure, without water) and is approximately 200 proof. 2/21/2019

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%) Fractional Distillation Process The ethanol, which is produced from the fermentation process, still contains a significant quantity of water, which must be removed. This is achieved by using the fractional distillation process. The distillation process works by boiling the water and ethanol mixture. Since ethanol has a lower boiling point (78.3C) compared to that of water (100C), the ethanol turns into the vapour state before the water and can be condensed and separated. Dehydration. The alcohol from the top of the column passes through a dehydration system where the remaining water will be removed. Most ethanol plants use a molecular sieve to capture the last bit of water in the ethanol. The alcohol product at this stage is called anhydrous ethanol (pure, without water) and is approximately 200 proof. 7. Denaturing. Ethanol that will be used for fuel must be denatured, or made unfit for human consumption, with a small amount of gasoline (2-5%). This is done at the ethanol plant. 2/21/2019

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 2/21/2019

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 2/21/2019

(Cellulosic or Grain) Carbon Dioxide (CO2) Ethanol Production (Cellulosic or Grain) Carbon Dioxide (CO2) CO2 is given off during fermentation Ethanol production plants collect, compress, and sell it for use in other industries 2/21/2019

Ethanol Fuel Characteristics Ethanol E100 E85 85 % Ethanol – 15 % Gasoline Gasohol 10 % Ethanol – 90 % Gasoline Gasoline BTU,s/Gal 84,400 90,000 120,900 125,000 Octane Number 100 98 94 87 - 93 Equitable Value (BTU) $2.02/gal $2.16/gal $2.90/gal $3.00/gal http://www.popularmechanics.com/science/earth/2690341.html?page=2&c=y 2/21/2019

Ethanol Strengths & Weaknesses Potential Strengths Fewer air pollutants Renewable sources Potential Weaknesses Fewer BTU’s per gallon Higher ethanol blends require engine modification Fuel line heaters 2/21/2019

More Information http://www.ag.ndsu.nodak.edu/abeng John Nowatzki, NDSU Extension State Specialist Telephone: 701-231-8213 Email: John.Nowatzki@ndsu.edu References http://www.harvestcleanenergy.org/enews/enews_0505/enews_0505_Cellulosic_Ethanol.htm http://en.wikipedia.org/wiki/Gasoline#Octane_rating http://genomicsgtl.energy.gov/biofuels/placemat1.shtml The Institute for Energy and Environment, within the RAE '5' rated Electronic and Electrical Engineering Department at Strathclyde University, has established itself as one of the leading centres of its kind internationally. http://www.esru.strath.ac.uk/EandE/Web_sites/02-03/biofuels/ http://www.ethanol.org/howethanol.html 2/21/2019