making your own pure ethanol cheap

Everclear is maybe $15 for 750 mL = $75 per gallon

Gasoline is maybe $4 per gallon. Since you can put back the non-alcohol portion back in your car, the alcohol would be about the same, $4 per gallon, about 1/20th the cost of Everclear. And if you only remove the alcohol from, for example, 1 gallon of fuel in your tank it won't significantly effect performance.

Not bad…

Points for creativity, but it wouldn't work that way. Gasoline is a complex mixture of many compounds, some of which are more soluble in water than others. Modern gasolines contain detergents that make them even less likely to separate when you add water. The ethanol further helps the water dissolve in the gasoline, rather than pulling the ethanol out of solution with it. This is what Heet is marketed for—you add methanol or isopropanol to your gas tank and it helps any water that's condensed in the tank and settled to the bottom dissolve in the gasoline.

Even if it were practical to separate the ethanol from gasoline at home, some of the aromatic contaminants you mention are more toxic than methanol, which kind of defeats the purpose.

Why not just distill moonshine. It is basically ethanol with hopefully not too much methanol etc in it. Potatoes are cheap. Just watch out for the FDA.

I agree with Fog. All sorts of stuff in car gasoline. Additives, besides other residuals from fractionating, are generally highly toxic. Many are like alcohols in that they can disolve both. You WOULD get a high concentration of these toxic additives.

EVERYTHING disolves in water to some degree. Or, everything will disolve water into it, if you want to look at it that way. Some stuff, according to simple high school chemistry, will disolve in water but not gasoline. This is not really what happens. There is a balance between molecules that allow small ammounts of one to dissolve in another. A simple example is the eutectic mixtures of water/ethanol at ~95% ethanol. Vapor pressure vs temperature means you will not get more ethanol by double distilling, it all just boils off. Generally, water is present in gasoline in fairly large ammounts. Changes in temperature can often cause it to come out of solution, and, freezing. Hence the need for alcohol. You can *think* of alcohols as "one end will disolve in water, one end in gasoline." This is not correct, but a usefull model. Soo, this is why alcohol disolves in both. (The reality is much more complex.)

Modern fuel, with ~9-10% alcohol added, never needs dry-gas, BTW. But, I worry that the companies selling it are actually adding some water, too…Not Good for gas milage.

Why not distill your own? One reason is that it is illegal…

Actually, it is not illegal. You can get a fuel distillers permit from the government. There is quite a few enthusiasts that make their own ethanol fuel. The catch is they have to denature it, often done by addition of gasoline, which is what the commercial ethanol producers do too today too.

Gasoline as a denaturant? Lol. I see what you mean, but it sounds funny.

All of this sounds like a huge amount of faffing about for not that much reward. You can get fairly high ethanol content alcohols by buying Klean Strip “Green” denatured alcohol at Home Depot, or you can buy Sunnyside brand denatured alcohol which has a pretty high ethanol content (way more than SLX). I don’t have the MSDS numbers at my finger tips, but from memory those two (Green and Sunnyside) have good ethanol content.

I guess the ultimate question is: Does it really matter? In other words, what practical difference does it make to get something like 190 proof vs. something like SLX denatured? Again, I don’t have exact numbers at my finger tips, but my memory is that you can save a gram or two of fuel per 500ml of water heated if you use higher ethanol content alcohol.

How much effort and expense does 2g per boil justify? That’s a rhetorical question and can only be answered by the individual, but I just throw that out there as a “put it into perspective question.” I haven’t completely answered that question for myself, so I am very interested in the comments of others.

HJ
Adventures in Stoving

Just go to your local college, take a chemistry class, get in good with the professors and they can hook you up with research ethanol for about $10 to $15 a gallon. Don't ask me how I know this because I will lie like a rug. The above post was right about pure ethanol; the only way to get 100% pure with no water is with a drying agent since you can distill it over and over without removing all the water. To much work though and borderline scary doing all that with gasoline.

…the only way to get 100% pure [alcohol] with no water is with a drying agent since you can distill it over and over without removing all the water. To much work though and borderline scary doing all that with gasoline.

Borderline scary? Way too much work, very questionable results, and to me working with gasoline is way more than “borderline” scary. Just plain sounds like a bad idea to me, BUT I appreciate the creativity of the people here on BPL. Need something? The guys on BPL will figure out a way. :)

HJ
Adventures in Stoving

There is probably no amount of research you could do that would allow you to find out *exactly* what is in your can of gasoline. You'd need to know this before even attempting anything like this with it.

You could do the phase separation like you said, and it will very likely work (there are examples of other people out there doing this) but you'd end up with ethanol plus who-knows-what. That scares me way more than just buying pure methanol and burning that instead.

you’d end up with ethanol plus who-knows-what

And doesn’t that sound like fun to put a match to?

Seems like it would be better to stick with known quantities (plus you’d save a lot of time).

HJ
Adventures in Stoving

Large esbit tablets:

(don't waste time with gasoline)

fire up thine ol' tires.

If you want to dry out some drinking grade ethanol….say if you can only get everclear at 75% or cheap vodka at ~40% you can alway use a molecular sieve to remove the water while leaving the ethanol. You'll need a 3 angstrom sieve to remove water (http://www.deltaadsorbents.com/molecular-sieve-desiccants.html) and they can be regenerated by heating from around 120C to 250C to remove the water from the sieve so they should, in theory, last a long time while still being useful.

It seems to me to be the easiest way (compared to a homemade still etc.) to get a high proof ethanol (~195 proof) but over time water from the atmosphere will enter solution in the "dried" alcohol if storage is lax.

Hope someone finds this info useful. Cheers

A molecular sieve?! Wow. Have you tried it? Is it practical or is it a major PITA.

HJ
Adventures in Stoving