Into The Outdoors

Advanced Overview

History — Although ethanol is in the news today as a renewable bio-fuel, it has actually existed for a very long time. Ever since early humans made grape juice that fermented into wine, we’ve been producing ethanol. But it wasn’t used as a fuel source in combustible engines until the age of discovery. Ethanol’s first experimental use in an engine was in 1826, and again, in 1876. Nicolaus Otto, the inventor of the modern four-cycle internal combustion engine, was the first to try ethanol to power an early automobile’s engine. Way to go Mr. Otto! (sounds like “Mr. Auto”;). Ethanol also was used as a lighting fuel in the 1850s, but became a limited resource once it was taxed as a liquor, to help pay for the nation’s Civil War expenses. Ethanol was later used as a fuel in Henry Ford’s Model T automobile models, in 1908. The first ethanol blended with gasoline, for use as a chemical octane booster, occurred in the 1920s and 1930s. Ethanol’s high demand grew during World War II, because of American fuel shortages. How’s it made? — Unlike petroleum-based gasoline that’s refined from crude oil (which is a prehistoric “fossil fuel”), ethanol is made from present-day renewable resources, such as corn. If you have ever (okay, we know you have) consumed something sweetened with corn sugar, or eaten something made with cornstarch, then you know that corn contains starch that can be broken down into sugar. Turning those starch and sugar molecules within corn into ethanol involves the production processes of either “wet milling” or “dry milling”. The major difference between the two is in the ways they initially treat the corn. Because the primer video here shows ethanol’s dry milling, we will focus on that method. In dry milling, the entire corn kernel is first ground into flour. This powdery stuff is referred to in the industry as “meal” and is processed without separating out the various component parts of the grain. The meal is “slurried” with water, to form a “mash.” Now comes the setup and not-so-secret ingredients for some “bio-chemical” reactions. Enzymes are then added to the mash to convert the starch to dextrose, a simple sugar. Next, ammonia is added to the mixture for pH control and as a nutrient to the yeast. The mash is then processed inside a high-temperature cooker to reduce bacteria levels, before the fermentation starts. Afterward, the mash is cooled and transferred to fermenters where yeast is added and the conversion of sugar to ethanol and carbon dioxide (CO₂) takes place. Those little yeast dudes perform the real work of turning the sugars into ethanol and are actually living organisms. This ethanol fermentation, is a biological process where sugar molecules are converted by the yeast organisms into cellular energy and they produce ethanol and carbon dioxide as metabolic waste products. Because the yeast perform this conversion in the absence of oxygen, ethanol fermentation is considered an anaerobic process. This fermentation process generally takes about 40 to 50 hours to complete. During this part of the process, the mash is agitated and kept cool to maximize 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 mixture’s resulting 15%, that is ethanol, is concentrated to 190 proof using conventional distillation, then is dehydrated to approximately 200 proof, in a molecular sieve or sifting system. Now, we’ve got some technology humming. Lastly, anhydrous ethanol is then blended with about 5% denaturant (such as natural gasoline) to render it undrinkable, so it will not be subject to beverage alcohol taxation. The finished ethanol product is then ready for shipment to gasoline terminals or retailers. Ta-da! We have just completed what early humans did with fermenting their wine – along with some serious science and technology of course. And the big difference is that we now understand the complex biology, chemistry, bio-chemical reactions, and various technologies involved in the production process. What’s left over? — Hey, what about all the stuff that’s left over? Waste not, want not. The stillage is then sent through a centrifuge that separates the coarse grain from the solubles; you know, the wet stuff. The extracted solubles are 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), providing a nutritious, high quality livestock feed. The CO₂ released during fermentation is captured and sold for use in carbonating soft drinks and beverages, as well as, utilized in the manufacturing of dry ice. So in the end, ethanol production requires only the starchy portion of a corn kernel. The remaining kernel protein, fat, fiber and other nutrients are eventually recycled and returned to the global livestock and poultry feed markets.  Every bushel of corn that’s processed by an ethanol plant produces approximately 17 pounds of animal feed. Oh no, Chemistry! — Okay, we admit that chemistry may sound scary, especially considering we can’t actually watch what’s happening at the molecular level. However, as you learn more about science and these bio-chemical reactions, you’ll begin to understand that chemistry is the foundational key to just about everything that happens in science. So, let’s explore some of the chemical reactions that take place in the ethanol production and combustion process. During fermentation, glucose and other sugars in the corn, are converted by the yeast into ethanol and carbon dioxide. Here’s the chemistry formula:             C₆H₁₂O₆ → 2 C₂H₅OH+ 2 CO₂ + heat Then, when it is used in your car’s engine, it goes through the thermal chemical reaction of “combustion,” where ethanol reacts with oxygen to produce carbon dioxide, water, and heat. Here’s that chemistry’s formula:       C₂H₅OH + 3 O₂ → 2 CO₂ + 3 H₂O + heat And that’s all for today. We suppose by now your brain has done enough of its own biochemical reactions. Ah, but that’s a whole other story of energy conversions …