Ethanol for drinking, Ethanol for fuel.

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When Ethanol is talked about as a fuel, it's the same exact molecule in alcoholic beverages, right?

If that's the case, what is it about Ethanol that makes it preferable as a fuel to other alcohols? Is it just that we already have the capacity to ferment ethanol from sugars easily, or is ethanol somehow preferable to other alcohols?

Thanks,
Jacob
 

Answers and Replies

  • #2
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According to me, there are two reasons : firstly, important, ethanol can be made from fermentation of sugar and other biomass materials. Secondly, ethanol's properties are about the same to gasoline, i mean viscority, density, vapour pressure, etc..
 
  • #3
Astronuc
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When Ethanol is talked about as a fuel, it's the same exact molecule in alcoholic beverages, right?
Yes, it is the same ethyl alchohol ( CH3CH2OH) that one finds in alcoholic beverages like beer, wine, and liquors, all the way up to Everclear.

If that's the case, what is it about Ethanol that makes it preferable as a fuel to other alcohols? Is it just that we already have the capacity to ferment ethanol from sugars easily, or is ethanol somehow preferable to other alcohols?
As haiha mentioned, one factor is the raw material used to produce ethanol - sugar (from corn primarily) and biomass, which must be digested or converted to sugars and then sugars fermented.

Another key factor is that ethanol is the least toxic alcohol. All others, e.g. methanol (wood alcohol), propyl/isopropyl alcohol (rubbing alcohol) and others are exceedingly toxic to humans and other lifeforms.

http://en.wikipedia.org/wiki/Ethanol

http://www.ethanolrfa.org/resource/made/ [Broken]

http://www.ethanol.org/production.html [Broken]

http://www.eia.doe.gov/oiaf/analysispaper/biomass.html [Broken]

Methanol is produced by hydrolyzing CO, although is can be obtained from distructive distillation of wood. http://en.wikipedia.org/wiki/Methanol

http://www.iags.org/methanolsources.htm

http://www.chemlink.com.au/methanol.htm

http://www.iforest.com/docs/FactSheetMethanol_Final.pdf

http://www.methanex.com/
 
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  • #4
chemisttree
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Ethanol has more energy per gallon than methanol

ethanol 75,500 BTU/gal
methanol 64,500 BTU/gal (14.5% less energy than ethanol)

Why is ethanol the most popular alternative alcohol fuel? You cannot discount the influence that special interest groups have on this question. Most methanol is made by controlled oxidation of methane. Much more expensive isopropanol is made by the oxidation of propene. They are petroleum products fed into a chemical industry.

Ethanol can be made from plant products and fermented biologically. The farming interests have significant influence on the availability/price of fuel from this source as this industry receives huge government subsidies.
 
  • #5
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Most methanol is made by controlled oxidation of methane. ...
Are you sure about that? what you mean by controlled oxidation? I thought methanol is made from mixture H2 / CO.
 
  • #6
mgb_phys
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When Ethanol is talked about as a fuel, it's the same exact molecule in alcoholic beverages, right?
As an alcoholic beverage it's also a pretty good fuel!

Cycling at 20mph uses around 1000calories/hour.
A shot of vodka is 64 calories.
So 15 shots/hour would get you 20miles on a bike (Most countries don't have DUI laws for bicycles).

If your SUV does 20mpg, it would need 1 gallon (128 shots) of Ethanol85 to do 20miles.
 
  • #7
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In addition to what has been said, ethanol is preferable as fuel for internal combustion engines, with respect to other longer chain alcohols, because it has a lower boiling point and an higher O.N. (at least with respect to linear chain primary alcohols) and has a cleaner combustion (less HC and particulates).
The best (concerning engine performance) however is methanol: higher O.N, lower boiling point, higher vaporization enthalpy (this means low temperature of the fuel/air mix and so higher density of the mix and less engine heat problems), higher energy per unit volume of the air/fuel mix.
 
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  • #8
chemisttree
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Are you sure about that? what you mean by controlled oxidation? I thought methanol is made from mixture H2 / CO.
You are referring to the syngas route. Both syngas (CH4 + H20 <---> CO + 3H2) and partially oxidized methane (CH4 + O2 <----> CO2 + H2) are used in that process to feed the water gas shift reaction.
 

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