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Ethanol Does NOT Suck Water Out Of The Air


By Marc J. Rauch
Exec. Vice President/Co-Publisher

Among the many ignorant and insidious claims spread by the oil industry to denigrate ethanol is that ethanol sucks water right out of the air. Sometimes it's phrased as "it absorbs water right out of the atmosphere." You see this claim on lots of websites (often on the websites that are trying to sell some kind of whizzbang engine treatment product); you hear it on radio and TV; and you see it all over the place in the comment sections of anti-ethanol news stories and blogs. Even comedian-auto enthusiast Jay Leno made this claim last year in a story he wrote for AutoWeek magazine.

Well, it's a lie: ethanol does not suck or absorb water right out of the air. The only thing that sucks is that the oil industry has been allowed to propagate lies like this for so long.

The origin of the claim is that ethanol is classified as a "hygroscopic" substance. Please note the spelling: hygroscopic (we've had people send us emails that say "ethanol is hydroscopic..."). It is HYGRO, with the letter "G." It seems that many years ago some clever oil industry person must have learned that ethanol (alcohol) is a hygroscopic substance, and that the general dictionary definition for a hygroscopic substance is that it can attract moisture from its environment.

What the oil industry wag then did was to play a semantic word game by substituting the word "attract" with "absorb," and "air" for "environment." The words attract and absorb are two different things, with two different meanings:

        Attract - to pull to or draw toward oneself or itself (as a magnet attracts iron).
        Absorb - to take in and make part of an existent whole (as a sponge absorbs water).

And the words environment and air have different contexts:

        Environment - the immediate adjacent surroundings (as in the type of environment in which you live).
        Air - the mixture of invisible odorless tasteless gases that surrounds the Earth.

How do we know that a semantic word game was played and that alcohol will not absorb water right out of the thin or ambient air, simple: fill any open container halfway with alcohol and place it on your kitchen counter. Allow it to sit for one or more days. If alcohol absorbs water right out of the air, then when you check the level of liquid in the ensuing days you would find that the volume of liquid has increased. Try it and see what happens.

Incidentally, cotton is also a hygroscopic substance. So just as additional proof that being a hygroscopic substance doesn't mean that it absorbs water right out of the air, place a ball of cotton on the other side of your kitchen counter and see if it gets saturated with water from just sitting out in the open. SPOILER ALERT, the cotton ball will not get saturated with moisture. However, if you want to see a hygroscopic substance in action, then place the cotton ball immediately adjacent to some water, so that the cotton ball is in an environment that includes liquid water. The cotton ball "wicks" up the water. If you place a piece of glass next to the water, instead of the cotton ball, the glass does not wick up the water because glass is not a hygroscopic substance.

Other than by a dumb accident, water will form in your fuel system because of condensation, but condensation has nothing to do with hygroscopic action. For example, if you have a glass-top outdoor table you have probably noticed that moisture formed on the glass after a cool night. This happens to your car windows. Since glass is not a hygroscopic substance, how does this occur? The moisture forms because of condensation.

So what do you do if you have some water in your fuel system? Do you stick a straw in and suck it out? No, you add a product like Dry Gas. Dry Gas is one or more type of alcohol, and ethanol is alcohol, meaning that you use ethanol to solve the problem of water in your gasoline tank. That's right, to solve the problem! In the years since E10 has been in regular use the overall incidence of car owners needing to use Dry Gas has declined dramatically. In April 2003, NPR Radio's Tom and Ray Magliozzi (CAR TALK Click & Clack) responded to a question on this issue:

"Dear Tom and Ray: Every time I fill my gas tank, I buy half a quart of dry gas. My father says it really helps with the fuel line and keeps things clean. Is this stuff legit, or am I wasting my cash? -- Chris

RAY: Well, we think you're wasting your cash, Chris. This stuff is mostly alcohol, which absorbs any moisture that is in your gas tank.

TOM: The idea is that by getting rid of any water in the tank, you eliminate the chance of the water freezing in the fuel line and preventing the car from running.

RAY: But to be honest, we haven't seen a frozen fuel line in our garage in a decade or more. Why? It could be because gasolines are better-formulated now. All gasolines have alcohol already mixed into them."

Ethanol doesn't actually absorb the water, it breaks the water down so that ignition and combustion of the gasoline can take place. The water molecules are then expelled in the exhaust. In other words, ethanol aids combustion, not inhibits combustion. Gasoline, on the other hand, doesn't have the ability to break down the water molecules, so the water separates from the gasoline and freezes, if it's cold enough, or gets sucked into the piston chambers where it cannot combust.

Does this mean that you could pour five gallons of water into your gasoline tank and the available ethanol will break down all this water? No, don't be silly; too much of anything can be bad...even ice cream.

Want to know what one of America's leading auto mechanics says about ethanol? Read this article from Bobby Likis: Can’t We Just Get Rid of Ethanol Ignorance?.

And for those among you who are boat owners and have been swayed by the ethanol-hygroscopic lies related to boats, you should be aware of the Mercury Marine Ethanol Webinar conducted in August 2011 - you will be shocked at their study findings, a position they've continued to support through two subsequent updated Power Point presentations (one in 2016 and another in 2018). The 2016 presentation can be found by CLICKING HERE. And you can watch the 2011 webinar in the video below.

For those of you who are too impatient to see the entire presentations, this is Mercury Marine's finding:

"There is no active transfer mechanism for ethanol molecules to reach out and grab water molecules out of the air. Under normal storage conditions, even in a vented fuel tank it just does not happen...The primary cause of water collecting in fuel tanks is condensation from humid air..."

From this point forward, let there be no more discussion about ethanol sucking the water right out of the air. Those who do, suck.

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TRUTH ABOUT ETHANOL - Review and Reply to Robert Bryce's GUSHER OF LIES