Ethanol Information

The production of ethanol or ethyl alcohol from starch or sugar-based feedstocks is among man's earliest ventures into value-added processing. While the basic steps remain the same, the process has been considerably refined in recent years, leading to a very efficient process. There are two production processes: wet milling and dry milling. The main difference between the two is in the initial treatment of the grain.

Importantly, companies today are involved in technological innovations such as cold starch fermentation, corn fractionation and corn oil extraction. Companies are also utilizing biomass gasification and methane digesters to reduce natural gas consumption. Additional work is being done to reduce energy consumption and production costs, increase efficiency and reduce emissions using the best available control technologies.

Watch a flash video on how ethanol is made Here

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Dry Milling Process

In dry milling, the entire corn kernel or other starchy grain is first ground into flour, which is referred to in the industry as "meal" and processed without separating out the various component parts of the grain. The meal is slurried with water to form a "mash." Enzymes are added to the mash to convert the starch to dextrose, a simple sugar. Ammonia is added for pH control and as a nutrient to the yeast.

The mash is processed in a high-temperature cooker to reduce bacteria levels ahead of fermentation. The mash is cooled and transferred to fermenters where yeast is added and the conversion of sugar to ethanol and carbon dioxide (CO2) begins.

The fermentation process generally takes about 40 to 50 hours. During this part of the process, the mash is agitated and kept cool to facilitate the activity of the yeast. After fermentation, the resulting "beer" is transferred to distillation columns where the ethanol is separated from the remaining "stillage." The ethanol is concentrated to 190 proof using conventional distillation and then is dehydrated to approximately 200 proof in a molecular sieve system.

The anhydrous ethanol is then blended with about 5% denaturant (such as natural gasoline) to render it undrinkable and thus not subject to beverage alcohol tax. It is then ready for shipment to gasoline terminals or retailers.

The stillage is sent through a centrifuge that separates the coarse grain from the solubles. The solubles are then concentrated to about 30% solids by evaporation, resulting in Condensed Distillers Solubles (CDS) or "syrup." The coarse grain and the syrup are then dried together to produce dried distillers grains with solubles (DDGS), a high quality, nutritious livestock feed. The CO2 released during fermentation is captured and sold for use in carbonating soft drinks and beverages and the manufacture of dry ice.

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Wet Milling Process

In wet milling, the grain is soaked or "steeped" in water and dilute sulfurous acid for 24 to 48 hours. This steeping facilitates the separation of the grain into its many component parts.

After steeping, the corn slurry is processed through a series of grinders to separate the corn germ. The corn oil from the germ is either extracted on-site or sold to crushers who extract the corn oil. The remaining fiber, gluten and starch components are further segregated using centrifugal, screen and hydroclonic separators.

The steeping liquor is concentrated in an evaporator. This concentrated product, heavy steep water, is co-dried with the fiber component and is then sold as corn gluten feed to the livestock industry. Heavy steep water is also sold by itself as a feed ingredient and is used as a component in Ice Ban, an environmentally friendly alternative to salt for removing ice from roads.

The gluten component (protein) is filtered and dried to produce the corn gluten meal co-product. This product is highly sought after as a feed ingredient in poultry broiler operations.

The starch and any remaining water from the mash can then be processed in one of three ways: fermented into ethanol, dried and sold as dried or modified corn starch, or processed into corn syrup. The fermentation process for ethanol is very similar to the dry mill process described above.

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Cellulosic Ethanol

While ethanol is typically produced from the starch contained in grains such as corn and grain sorghum, it can also be produced from cellulose. Cellulose is the main component of plant cell walls and is the most common organic compound on earth. It is more difficult to break down cellulose to convert it into usable sugars for ethanol production. Yet, making ethanol from cellulose dramatically expands the types and amount of available material for ethanol production. This includes many materials now regarded as wastes requiring disposal, as well as corn stalks, rice straw and wood chips or "energy crops" of fast-growing trees and grasses.


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Ethanol yields more energy than it takes to produce it, which means it has a positive energy balance. Not only is ethanol an efficient fuel, but it is made through an efficient process; it requires less than 35,000 BTUs of energy to turn corn into ethanol, while the ethanol offers at least 77,000 BTUs of energy. Studies show that ethanol has a positive net energy balance. The most recent study, conducted by the U.S. Department of Agriculture, shows that ethanol provides an average net energy gain of at least 77%.


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E85 is the term for motor fuel blends of 85 percent ethanol and just 15 percent gasoline. E85 is an alternative fuel as defined by the U.S. Department of Energy. Besides its superior performance characteristics, ethanol burns cleaner than gasoline; it is a completely renewable, domestic, environmentally friendly fuel that enhances the nation's economy and energy independence.

The horsepower a given engine has when using E85 is comparable or slightly higher than gasoline. Depending on composition and source, E85 has an octane rating of 100 to 105 compared to regular gasoline's typical rating of 87 for regular and 93 for premium. This allows it to be used in higher compression engines, which can lower emissions.


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Ethanol, also called ethyl alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is best known as the type of alcohol found in alcoholic beverages and in thermometers. In common usage, it is often referred to simply as alcohol.

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E85 has the highest oxygen content of any transportation fuel available today, making it burn cleaner than gasoline. Fewer exhaust emissions result in reduced production of smog and a decline in respiratory illness associated with poor air quality. E85 also reduces greenhouse gas emissions such as carbon dioxide, the main contributor to global warming, as much as 39 to 46 percent compared to gasoline.

Since E85's main ingredient is ethanol, which is non-toxic, water soluble and biodegradable, E85 is simply a better fuel for the world around us.

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Energy independence was forefront in the minds of Americans during the 1970s when gas prices soared and lines formed at every gas station. Consumers responded with energy saving practices and smaller cars...and then quickly forgot. We forgot that using less oil is only one part of the solution. Ultimately we need to be more energy independent.

Twenty years later, prices are again soaring and consumers are demanding answers. Well, this time E85 offers an alternative. E85 is a home-grown alternative fuel produced from crops and waste products. It is environmentally good for us -- think of it...turning waste into fuel! It is economically good for us, stabilizing commodity prices and increasing U.S. jobs. It is good for our transportation needs, with more than 750,000 flexible fuel vehicles on the market this year.

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As was the case in the early 1970s, the American motorist has recently experienced a new run-up in the price of motor gasoline. The oil shortages of 1973-74 were the result of an embargo; the oil charges of 1991 were the result of the Gulf War; while the price spike of early 2000 was the result of planned supply reductions which increased the price of crude oil from $11 to $32 per barrel. This increased price of imported oil has also been the primary cause of the U.S. balance of trade deficit setting record after record, month after month.

The United States imports over 53 percent of its total energy and uses more energy than any other nation in the world. The use of alternative fuels, including propane, natural gas, methanol, electricity, and ethanol, will all contribute to a reduction in the amount of crude oil used in vehicle operations.

Not only does using E85 help reduce American dependence on foreign oil, but because Ethanol is produced from crops grown in the U.S., it can also help stabilize commodity prices. And because E85 is a viable, home-grown alternative to gasoline, E85 provides competition, which is good for consumers.

In the near future, a wide range of waste products will be used to produce ethanol, further developing our national energy independence.Ethanol production is estimated to increase net farm income more than $4.5 billion. It boosts employment by 200,000 jobs and improves the balance of trade by over $2 billion.The pricing for E85 is comparable to traditional gasoline.

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