Tuesday, March 17, 2009

knowledge of ethanol for fuel


Principles of Alcohol Production For Fuel

Two types of alcohol will work equally well for fuel. They are ethanol and methanol. we refer to ethanol when we speak of alcohol, unless we specifically say methanol. Alcohol content is measured in proof. The proof is twice the percent. Thus 100 proof alcohol is 50% alcohol and 50% water. 200 proof alcohol is 100% alcohol.


Ethanol is also called ethyl alcohol or grain alcohol. All industrial ethanol was produced from grain fermentation until the industry discovered they could make it cheaper from petroleum. This was in pre-OPEC days. The ethanol industry was geared to producing high-purity industrial alcohol or drinkable alcohol. For this reason, they were locked in to using stainless steel and copper equipment, and also to the process of distillation. Distillation served not only to separate the alcohol from the water, but to separate other impurities from the alcohol - impurities that might make a person sick if he drank it. That is why the fuel alcohol industry started with technology developed for the liquor and industrial alcohol industry. That was all the technology there was. As more people experiment with making alcohol strictly for fuel, ways will quickly be found to do it cheaper when we get away from the traditional thinking of the old distillers. Ethanol can be made from anything containing starch or sugar. The higher the starch or sugar content, the higher is the alcohol potential of the crop. Cellulose in stalks, wood or paper can also be used to make ethanol, but the process is expensive with present technology. Starch is the most important storage form of carbohydrates in the plant kingdom. However, another significant form is inulin. Artichokes, Dahlias and Dandelions all store carbohydrates as inulin. The inulin is made up of fructose molecules instead of glucose, as in starch. It has been found that most of the carbohydrate is stored in the Jerusalem artichoke stem before the bulb starts to form. If it is stored as fructose, and if it does not change to inulin soon after harvesting, the fructose can be fermented as is. But if it is inulin, we know of no commercial, economical enzymes available to break down inulin. (Bitter almonds do contain inulinase.) The carbohydrate can be broken down with high heat and strong acid, but with a lot of energy input and 20% or more destruction of the sugar. If the fructose in the stem is useable, the tops can be cut off and the bulb left in the ground to grow again.


Enzymes break down starch into simple sugars, and yeast ferments sugars into ethanol, giving off carbon dioxide gas as a by product. The process has been used since civilization began. Starch is made up of long chains of glucose molecules coiled together. The starch must be broken down into sugars that are only one or two molecules long for the yeast to feed on. In the process described in this book, the liquefying enzyme breaks the chemical bonds at random inside the chain, producing shorter chains, or dextrins, as they are called. The saccharifying enzyme works on the end of the chain only. It could take off the glucose molecules one by one from the ends of the starch chains and eventually would convert all the starch to sugar. The liquefying enzyme gives the saccharifying enzyme more ends to work on, however, and speeds up the process considerably. There are other monosaccharicles (one molecule only) besides glucose, but glucose is the most common. Disaccharides are two monosaccharicles joined together. Table sugar (sucrose) is one glucose and one fructose molecule. Milk sugar, or lactose, is one galactose and one glucose joined together. Maltose is a disaccharide made up of two glucoses. Yeast can ferment glucose, maltose, and sucrose rapidly, and galactose and lactose slowly. Enzymes are proteins that change a chemical entity, or molecule, of one substance into a molecule of something else. The enzyme acts on the substance, but is not used up. The enzyme changes one molecule, then detaches from it and works on another molecule. A few molecules of enzyme will eventually get around to all the molecules of whatever it works on, but the right amount of enzyme will do the job faster. People have enzymes in their mouths that break down starch. If you hold a piece of soda cracker in your mouth, it will begin to taste sweet. This is exactly the process that takes place in the mash. Enzymes are highly specialized. Each one does only one thing. In this process, one enzyme chops up the long chains of starch into shorter chains. Another enzyme changes the short chains of starch into sugar. Enzymes, like humans, function within a fairly narrow range of physical conditions. They must have a certain temperature and degree of acidity. They can be rendered useless by chemical poisons, heavy metals, high heat, etc. Each enzyme has a certain set of conditions under which it works best. When grain sprouts, enzymes change the starch into sugar that the new plant can use for food. Before enzymes were avail-able for purchase, grain was sprouted, or .malted,. then dried, ground, and mixed with the rest of the grain as a source of enzymes. This method can still be used, but it is quicker to use commercially available enzymes. Starch can be broken down without enzymes with strong acid and high heat. However, the process takes a lot of time and energy, and then the excess acid has to be neutralized with alkali before fermentation can take place. After the starch is changed to sugar by enzymes, yeast changes the sugar to alcohol in the absence of air. The process is called fermentation, and it takes about 21/2 days. Carbon dioxide gas is produced as the yeast changes sugar to Alcohol. A bushel of grain yields by weight about 1/3 carbon dioxide, 1/3 ethanol, and 1/3 highprotein residue. The carbon dioxide gas can be allowed to escape through an air lock or a one-way vent valve, or it can be collected and used. The fermented mash contains about 10% alcohol. At this concentration, the alcohol begins to kill the yeast. The batching should be done so that all the sugar and starch in the mash will have been used up by the time this10%alcohol content is reached. It takes 13 pounds of sugar to yield 1 gallon of 190 proof ethanol. The amount of raw material in the mash will be determined by its starch and sugar content. In order to get fuel alcohol, the alcohol content must be increased from 10% to 90 - 95%. At present, the only workable way to do this is to distill it. In the future, other ways may be discovered which take advantage of the different properties of alcohol and water.


The temperature of the water-alcohol mixture is raised to above the boiling point of ethanol (173 degrees F at sea level) but below the boiling point of water (212 degrees F). The alcohol changes to vapor and rises in the column, but some of the water vaporizes with it. In a simple still, like that used by the moon shiner, the distillate is about half water. If this is re-distilled, a higher concentration of alcohol can be obtained, up to about 195 proof. Further separation cannot be obtained by distillation because of a quirk in the chemistry of the mixture. (Water and alcohol form an azeotrope at this point.) The final fraction of water must be removed by other methods, if this is necessary. Farm alcohol plants can produce 190 to 192 proof alcohol with one pass through a still equipped with a reflux column, which is a device for making the mixture of liquids vaporize, condense, then re-vaporize over and over until the alcohol is nearly free of water. In summary, the starch is changed to sugar by enzymes. The yeast changes the sugar to alcohol during fermentation, giving off carbon dioxide gas and leaving a high-protein residue in the mash. The mash contains about 10% alcohol after fermentation. It is then distilled to make a fuel alcohol that is 160 to 190 proof, or 80 to 95% alcohol. After the mash has been distilled, the protein and the water are left. The water can be reused after the protein is separated, or the entire stillage can be flowed over straw or hay and fed to livestock.


Methanol, also called methyl alcohol or wood alcohol, works just as well as ethanol for fuel, but the process for making it is completely different. Methanol is a highly poisonous liquid. It will kill you if you drink it, and it can kill you if it soaks into the skin. Methanol is made by heating wood wastes, stalks, etc., under relatively low heat and high pressure and then purifying the product by fractionating columns. It can be made from material that is not suited to ethanol production, but if grains, for instance were used to make methanol, all the protein would be destroyed. Methanol can also be made from coal. Both ethanol and methanol have their place in farm fuel plants.

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