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A while ago in a post about making ethanol from orange pulp Mr Clint asked:

Tell us how to make it..please?

A lot of people ask me things like “just how is ethanol made anyway?” So lets talk a little about ethanol, how its made, and how you would go about making it at home if you wanted to. First what is ethanol anyway?

What is ethanol?



The chemical compound ethanol. Ethanol's chemical formula is C2H5OH

Ethanol also known as grain alcohol or ethyl alcohol, can be produced chemically from ethylene or biologically from the fermentation of various sugars from carbohydrates found in agricultural crops and cellulosic residues from crops or wood. When non-chemists refer to “alcohol”, they almost always mean ethanol.

You take something with a carbohydrate (sugar usually) and let various microorganisms go to town on it, the little beasties eat up the carbs and poop out alcohol. Most current methods of creating ethanol also require distilation to remove impurities from the alcohol. This is a similar process to the one that makes beer, wine, whiskey, hard cider, and some acids.

Pure ethanol is a flammable, colorless liquid with a boiling point of 78.5Â° C. Its low melting point of -114.5Â° C allows it to be used in antifreeze products. It has a pleasant odor reminiscent of whiskey.

Its density is 789 g/L, about 20% less than that of water. It is easily soluble in water and is itself a good solvent.

Ethanol can lose a proton from the hydroxyl group and is a very weak acid, weaker than water.

The CAS number of ethanol is 64-17-5 and its UN number is UN 1170.

If you were interested here is the equation for glucose (the simplest sugar) to ethanol.

Chemical Equation

C6H12O6 â†’ 2C2H5OH + 2CO2 + 2 ATP (Energy Released:118 kJ mol^âˆ’1)

Word Equation

Sugar (glucose, fructose, or sucrose) â†’ Alcohol (ethanol) + Carbon Dioxide + Energy (ATP)

As you can see when ethanol is made it releases co2. However this is the same co2 that future plants will be taking in to grow. So in a perfect world ethanol is carbon neutral (it doesn’t add more carbon to the atmosphere). There is however a large debate over weather or not the entire process of creating ethanol (growing the plants, shipping, fermenting, distilling etc) is carbon neutral.

What can you use ethanol for?

So now we know what ethanol is, lets talk a bit about what it is used for. Ethanol can be used as a solvent in perfumes, paints and tinctures. The use most people are familiar with is when they kick back a bear or a shot at the bar. The various tastes of different drinks are because the ethanol absorbs different amounts of various impurities giving the drink its special flavor and kick.

A solution of 70-85% of ethanol is commonly used as a disinfectant; it kills organisms by denaturing their proteins and dissolving their lipids: it is effective against most bacteria and fungi, and many viruses, but is ineffective against bacterial spores. This disinfectant property of ethanol is one of the reasons that alcoholic beverages can be stored for a long time. Ethanol is also used to preserve tissue and specimens due to its protection against bacteria and fungi.

Ethanol has also been gaining a lot of attention lately as a fuel source.

Ethanol as a fuel:

Most cars since the late 80’s have been manufactured to use some amount of ethanol. Due to its solvent nature special hoses and gaskets must be installed in a car to allow it to use ethanol. Almost all cars will run on a 10% blend (90% gasoline and 10% ethanol sometimes called gasohol) of ethanol and many new cars are “E85” ready. Meaning they can run on an 85% ethanol and 15% gasoline. These cars are often called duel fuel, flex fuel, or biofuel ready cars. Due to the higher octane content of ethanol you will also need a car that can adjust its spark plug timing. Flex fuel cars and trucks are able to detect what fuel is put into them and adjust the timing as needed.

What are the environmental benefits of using ethanol?

It is a renewable fuel made from plants

It is not a fossil-fuel: manufacturing it and burning it does not increase the greenhouse effect

It provides high octane at low cost as an alternative to harmful fuel additives

Ethanol blends can be used in all petrol engines without modifications

Ethanol is biodegradable without harmful effects on the environment

It significantly reduces harmful exhaust emissions

Ethanol’s high oxygen content reduces carbon monoxide levels more than any other oxygenate: by 25-30%, according to the US EPA

Ethanol blends dramatically reduce emissions of hydrocarbons, a major contributor to the depletion of the ozone layer

High-level ethanol blends reduce nitrogen oxide emissions by up to 20%

Ethanol can reduce net carbon dioxide emissions by up to 100% on a full life-cycle basis

High-level ethanol blends can reduce emissions of Volatile Organic Compounds (VOCs) by 30% or more (VOCs are major sources of ground-level ozone formation)

As an octane enhancer, ethanol can cut emissions of cancer-causing benzene and butadiene by more than 50%

Sulphur dioxide and Particulate Matter (PM) emissions are significantly decreased with ethanol. (via)

So now that we know what ethanol is and how we use it how would we go about making it at home.

How to make ethanol at home:

Ever hear of moonshine? How about back yard stills? The technology to make ethanol has been around for a long, long time. The only difference between a moonshine still and an ethanol still is the proof of the resulting ethanol. Ethanol needs to have a very high proof (180+) in order to function as a fuel. This means that you will need to distill almost all of the impurities out of the ethanol to use it as a fuel.

The easiest way to start making ethanol is to buy or make your own still. A still is a device that allows you to ferment and distill ethanol from a feed stock. The feed stock can be sugar, corn, or anything else that has a carbohydrate in it. Some newer forms of ethanol are made using cellulose feed stocks. They use special bacteria that can break down cellulose into sugars and then they ferment these sugars into alcohol. Some have even figured out bacteria that will break the cellulose down into alcohol taking out the fermenting stage and saving a lot of energy.

This is a diagram of a moonshine still, an ethanol still works in much the same way. In essence you heat up the “mash” (fermented corn, sugar, whatever) and that begins producing alcohol vapor(it boils the alcohol out of the mash), the vapor is captured and cooled and forced to condense into liquid alcohol. You would then remove impurities and water from this alcohol to create fuel grade ethanol. Read more about ethanol creation here (pdf)

Here are some places you can buy sell contained ethanol stills (I make no guarantee any of these places are legit, but some look better than others).

You can also find DIY instructions here Also Journey To Forever has an amazing ethanol (and other biofuel) resources, from DIY stills, to instructions on how to make your own mash to how to distill the final product. They are really a great resource check them out here. You can also read about some others experience with home made ethanol here.

I hope this helps you on your way to making your own ethanol at home. Good luck.

Edit: Thanks Joel for help with the fermenting stage.