Ethanol is basic biofuel that can be made by just about anyone. The issues in making ethanol, however, create problems even for pros! The whole trick is quality of the finished product, or how much water is contained in the final output. Getting the water out involves different “tricks” for separating the ethanol, which loves water. On top of that, ethanol can be corrosive to certain metals, and can eat plastics and certain rubbers. So, modifying your vehicle or engine to use ethanol is a must.

Ethanol is basically alcohol from sugar. We won't go into details on what ethanol actually is, but for now, just think of it as really strong liquor, like everclear. Actually, most of the time, ethanol needs to be 80% pure or better to run in your vehicle. If you are mixing it with gasoline, like in E85 mixes, it needs to be 98% pure or better.

Ethanol can be made from anything that contains sugar. Of course, it's easier to make it from something that has a lot of sugar. Forget about making it from corn, as corn doesn't contain as much starch (complex sugar) as other, easier to grow crops. Jerusalem Artichokes are considered the most productive per acre, and the nice thing about them is that you get a lot of extra biomass to feed your methane system! Once you have your feedstock, you mix it with water and yeast to ferment it for a few days. It is best to boil this “mash” before adding the yeast to kill off any wild bacteria, fungi or yeast that might be in there. Everything loves sugar, and you don't want them to compete with your alcohol-producing yeast. If you have a decent amount of sugar in the feedstock (20-25%) you can get up to 14% ethanol content, but most beginners are doing good to get up to 8% ethanol. Filter your mash to clean any solids, and you are ready to purify your mash.

Ethanol loves water, and this creates problems for us, because water doesn't burn so well. A little water is ok, if you are using the ethanol directly, but more than 20% water is probably not going to run too well. There are several ways to take water out of something. The most common is distillation, which involves heating the fermented mixture just beyond the boiling point of alcohol (lower than boiling point of water), and then condensing the vapor back into a highly concentrated liquid. This isn't as hard as it seems, but efficiency is low, and you have to generate heat to make it work.

Another method of separating water and ethanol is to use a chemical or material to absorb the ethanol from the water. Then, you will need to separate the said material from the ethanol, which may be easier than distillation, if it has a substantially higher boiling point than water. Sulfur and oils are usually used in this process, but you can also use special membranes and water absorbent materials.

So, once you get your ethanol to a relatively pure state, you need to be able to use it. This is the rub with ethanol. It has a lower energy content than gasoline (70 kBtu vs 125 kBtu per gallon) so, you have to burn more of it to get the same power out of an engine. This involves modifying the engine, increasing the injector or port sizes, modifying the timing, and possibly even modifying the compression ratio. Of course, once you do all of this to your engine, it won't run as well on gasoline. Computer controlled fuel-injection engines seem to fair better in this respect, as the computer can modify the way to engine components behave, and then return them to gasoline standards when you fill up at the pump.

To top it all off, ethanol can eat some plastics and rubber, so you will need to change those components as well. This is why ethanol is most often mixed with gasoline. With the mix, the ethanol doesn't get to eat things, and the engine mods are not as extensive. This can definitely decrease your dependence on fossil fuels, but it won't replace it completely.

As you can see, making ethanol is not very complicated, but using it requires finesse, to say the least. And this is true for most biofuels, you either spend time and money making them or you spend time and money making them work.