• Quick note - the problem with Youtube videos not embedding on the forum appears to have been fixed, thanks to ZiprHead. If you do still see problems let me know.

How corrosive is ethanol?

anor277

Critical Thinker
A
Joined
Apr 28, 2004
Messages
325
I have just read a series of articles in Chemistry and Engineering News, (Vol. 83, no. 37, 12.9.2005) that questioned the role of ethanol as an alternative fuel. Ethanol is produced from corn, which requires much energy to grow, harvest, and ferment, resulting a serious expenditure of energy (much more so than the energy that the final product will deliver). It was further mentioned that ethanol is extremely corrosive, more so than gas or oil, and it therefore requires shipment by tanker or rail rather than by pipe line. Ethanol’s “corrosive” properties are news to me (I happily splash it round to rinse glassware – it’s softer on the hands than acetone and smells much nicer). Are there chemical engineers on the board who know something about ethanol’s properties in the bulk context?
 
This is by no means an answer that is well researched or anything; please note I'm just having a stab.

By 'corrosive' I assume they are meaning 'reacts with metal'. Water is corrosive due to its polarity; it dissolves ions rather efficiently, a property which causes metal to corrode with time. Ethanol shares this property to a greater degree than other hydrocarbons.

Chemists, please correct me if I'm wrong.

Athon
 
My experience as an auto mechanic tells me that ethanol has a certain amount of water in it, it just degrades all on it's own, so rust is a problem. Even Everclear is not 100% alcohol because of this. But ethanol is also hard on rubber parts... possibly just a solvent effect washing the oils out of the rubber?
 
Back in the 80s, I always used gasahol in my car because I could get higher octane for the same price. After about 6 years, my car began to burn oil like crazy. I was told that the ethanol's corrosive effect degraded various seals in the car. I checked my owners manual and it said do not use gasahol.

I have been told this is not a problem in newer cars but I never intentionally use gasahol.

CBL
 
I am not sure but under certain conditions ethanol will react to loose a H+ ion and become ethoxide. This would result in corrosion I think. Mentioned above that alcohol contains water is not necessarily true as you can have pretty close to 100% alcohol only it will contain benzene. Also for those who don't know combustion of stuff usually results in the production of water including alcohol and gas. However it has been years since I studied chem
 
anor277 said:
I have just read a series of articles in Chemistry and Engineering News, (Vol. 83, no. 37, 12.9.2005) that questioned the role of ethanol as an alternative fuel. Ethanol is produced from corn, which requires much energy to grow, harvest, and ferment, resulting a serious expenditure of energy (much more so than the energy that the final product will deliver). It was further mentioned that ethanol is extremely corrosive, more so than gas or oil, and it therefore requires shipment by tanker or rail rather than by pipe line. Ethanol’s “corrosive” properties are news to me (I happily splash it round to rinse glassware – it’s softer on the hands than acetone and smells much nicer). Are there chemical engineers on the board who know something about ethanol’s properties in the bulk context?
Click to expand...

Lines 3-6 of your post are highly questionable.

Let's comparably look at oil. Gas did not just appear at the gas station, either, you know. We have seismic testing for oil which requires vehicles driving to a site, equipment that they need (which has to be manufactured) workers getting hungry and eating, detonation devices that had to be made, offices that had to be wamed or cooled so that intelligent oil men could discuss what they are discussing, oil rigs had to be built and transported and erected, oil once gotten had to be refined. And...of course FIRST they had to build a costly energy gulping refinery! And then there is the trucking involved. Etc.

So to mention ONLY such related matters when it comes to ethanol production is ludicrous.

As far as studies that say ethanol is 'energy negative'? One of the more prestigous research institutes in this country has claimed that ethanol is something like 167% energy POSITIVE.

So what school is right on all this? I don't really know. But I do know that what you posted in lines 3-6 are slanted with no comparable data comparing it to oil.
 
Re: Re: How corrosive is ethanol?

Sorry, double post, corrected version appears directly.
 
Re: Re: How corrosive is ethanol?

Iamme said:
Lines 3-6 of your post are highly questionable.

Let's comparably look at oil. Gas did not just appear at the gas station, either, you know. We have seismic testing for oil which requires vehicles driving to a site, equipment that they need (which has to be manufactured) workers getting hungry and eating, detonation devices that had to be made, offices that had to be wamed or cooled so that intelligent oil men could discuss what they are discussing, oil rigs had to be built and transported and erected, oil once gotten had to be refined. And...of course FIRST they had to build a costly energy gulping refinery! And then there is the trucking involved. Etc.

So to mention ONLY such related matters when it comes to ethanol production is ludicrous.

As far as studies that say ethanol is 'energy negative'? One of the more prestigous research institutes in this country has claimed that ethanol is something like 167% energy POSITIVE.

So what school is right on all this? I don't really know. But I do know that what you posted in lines 3-6 are slanted with no comparable data comparing it to oil.
Click to expand...

The energy efficiency of ethanol, good or bad, is not the subject of my enquiry. Personally, I think it is questionable to allocate large areas of arable land to the production of an oil crop rather than a food crop. I suggest you read the articles first before shooting your mouth off.
 
From long ago, I recall a passage from a book by Wilbur Shaw about race cars of the 30's and 40's...they ran on ethanol. Indeed, to this day, they run on methanol -- not being a chemist, I am not quite sure of the difference, although they're both alcohol, which is a problem, because it burns with an invisible flame...and that's the subject of numerous stories in the Champ car ranks. One of the most memorable pictures I remember from Indy is of (IIRC) Mike Mosley just after he's put it into the wall off of Turn 4 at Indy. He's sitting on the track with his back to cars at speed taking off his shoes. Why? They were on fire invisibly, soaked with burning alcohol.
Anyway, back then, (60+ years ago), Shaw's Maserati had a small 1 gallon tank of gasoline on board, to start and shut down on. It was much easier to start on gas, and would flush the fuel system of ethanol on shutdown, eliminating the corrosive effects on the fuel system and spark plugs. And if the car was not to be run for a few days, the main fuel tank was drained.
Alcohol fuels were recognized as extremely corrosive away back then...
 
Methanol has a single carbon atom (as opposed to ethanol has 2 carbon atoms) and should have quite similar reactions to ethanol resulting in mehtoxide production and a loss of H+. Isopropyl alcohol (rubbing alcohol) has 3 carbon atoms and likewise should have similar reactions (propoxide?) however as you might know in our bodies they have different effects because of the byproducts of metabolizing them. Don't drink rubbing alcohol or methanol since they have a higher toxicity. Wino's seem to handle it because they get drunk on regular alcohol first and that ties up the metabolic pathway to metabolize alcohol and stops the methanol from being metabolized into harmful byproducts an hopefully is excreted without being metabolized. But don't try this at home. Winos are experts and have years of training:)
 
Chemist checking in. Alcohols are not necessarily more corrosive to rubbers etc, it is just that cars were designed to withstand petrol, not alcohols. All the gaskets etc can be reformulated to withstand alcohols and in modern cars often are.

Some metals such as magnesium and possibly aluminium alloys are corroded faster by alcohols than water. This is probably because water initially gives a tight oxide protective layer after the initial attack. Alcohols do not and the corrosive attack (essentially metal + alcohol = soluble metal alkoxide) continues. To stop this, a little water is added to the alcohols which restores the oxide layer
 
Just one more on invisible alcohol flames: Model aeroplane engines run on methanol, too. Way back when we played with line-controlled model planes, I remember one of my friends starting his plane, run to the control handle and fly, as we used to. Then coming round towards me, I noticed the paper cladding on the wings flaking off, and very soon it went down. Only then could we spot the flames.

When priming the engine, he had been sloppy and splashed fuel out over the whole thing, and as the engine caught, it set the whole thing on fire :eye-poppi .

Hans
 
You must log in or register to reply here.

Back
Top Bottom