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Author Topic: Ethanol  (Read 8743 times)

Offline JDG8R

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Ethanol
« on: 28/04/2006 00:43:30 »
How much energy required to produce 1 gal gasoline?

How much energy required to produce 1 gal ethanol?

How much energy does 1 gal of gas contain?

How much energy does 1 gal of ethanol contain?

Assume the crude has been delivered to the refinery, and that the grain has been shipped to the distillery.


 

Offline Hadrian

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Re: Ethanol
« Reply #1 on: 28/04/2006 11:26:12 »

Here is some info from 2003 on this subject

Energy Required to Produce Ethanol
T. W. Patzek
April 9, 2003
Bottom line:
1. In a car engine, the water produced by fuel combustion is not condensed; therefore, one needs
to use the low heating values for both gasoline (125000 Btu/gal) and ethanol (76000 Btu/gal).
2. The energy content of 1 gallon of ethanol is then equal to 0.6 gallons of gasoline. Conversely
burning one gallon of gasoline is equivalent to burning 1.6 gallons of ethanol.
3. According to the most reliable estimates by Pimentel, 40% more energy is used to produce
ethanol from corn than is gained from burning it. According to the most skewed, optimistic
estimate from USDA, about 30% more energy is gained from burning corn ethanol than is
used to produce it.
4. In other words, to produce one gallon of ethanol (0.6 gallons of gasoline), one needs to burn
0.88 gallons of gasoline equivalent according to Pimentel, and only 0.5 gallons of gasoline
equivalent according to USDA.
5. About 300 million gallons of gasoline are burned in the U.S. every day by cars and light
trucks. If this gasoline were to be replaced with ethanol, one would need to produce each
day 525 million gallons of ethanol. In order to produce this volume of ethanol between 468
(Pimentel) and 266 (USDA) million gallons of gasoline equivalent would have to be burned
every day.
6. It is difficult to imagine burning an equivalent of practically all currently used gasoline to
produce ethanol.
7. The shear stupidity of this proposition is mind-boggling. The fact that some people in
government, industry and academia talk about “clean ethanol” from corn, should give every
citizen a pause.
   



What you do speaks so loudly that I cannot hear what you say.
 

Offline JDG8R

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Re: Ethanol
« Reply #2 on: 01/05/2006 02:27:30 »
Hadrian thanks for the info.  Some is helpful. But does the "cut and paste" answer you provided "Assume the crude has been delivered to the refinery, and that the grain has been shipped to the distillery"?

I want to use this assumption to see if it is even necessary to consider pre-delivery production costs of either crude or ethanol source material to make a preliminary comparison of the potential of each.

Also, your source seems to be basing it on corn ethanol, what if its sugar cane or grass- based?  I should have been more specific.

"7. The shear stupidity of this proposition is mind-boggling. The fact that some people in
government, industry and academia talk about “clean ethanol” from corn, should give every
citizen a pause."

Since this is "Naked Science", editorial comments aren't needed.  The sheer stupidity of a source who can't spell does not lend credence to his views.
« Last Edit: 01/05/2006 04:04:57 by JDG8R »
 

Offline Hadrian

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Re: Ethanol
« Reply #3 on: 01/05/2006 10:27:20 »

What answers to this do you have?




:D


What you do speaks so loudly that I cannot hear what you say.
 

Offline Cut Chemist

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Re: Ethanol
« Reply #4 on: 09/05/2006 02:48:30 »
Corn ethanol is a renewable resource
Gasoline is not.

Also, the term "clean fuel" refers to the products produced when it burns, and octane rarely combusts completely in an engine.  Which forms carbon chains that dissipate into the atmosphere.  However ethanol does combust completely, even in an engine.  (It forms 2CO2 and 6H2O)

I'm assuming you probably used the heat of formation of gasoline to derive the amount of energy that gasoline provides.        

The fact that gasoline does not burn completely skews the numbers you have given, because all of the energy from the gasoline is not being used in a cars engine anyway.  There are unburned carbon chains that exit as exhaust and also get deposited on the heads and in the oil as engine buildup.  

Ethanol does not produce long unburned carbon chains.  Hense it burns "cleaner."  More of the energy is converted into mechanical energy.  (It also produces less carbon monoxide)  

Also you can't grow gasoline.  From an economic standpoint, there are thousands of companies already in operation that produce ethanol for various uses.  It wouldn't be hard for them to upgrade to supply more for the automobile industry.  You have to dig gasoline up from under the ground, and it takes thousands of years to replenish.
 

another_someone

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Re: Ethanol
« Reply #5 on: 09/05/2006 03:17:00 »
quote:
Originally posted by Cut Chemist
The fact that gasoline does not burn completely skews the numbers you have given, because all of the energy from the gasoline is not being used in a cars engine anyway.  There are unburned carbon chains that exit as exhaust and also get deposited on the heads and in the oil as engine buildup.  

Ethanol does not produce long unburned carbon chains.  Hense it burns "cleaner."  More of the energy is converted into mechanical energy.  (It also produces less carbon monoxide)  



Carbon monoxide and unburnt fuel should not be an issue if you run the engine lean (the more likely unwanted combustion products, in a lean burn engine, I would have thought to oxides of nitrogen).

quote:

Also you can't grow gasoline.  From an economic standpoint, there are thousands of companies already in operation that produce ethanol for various uses.  It wouldn't be hard for them to upgrade to supply more for the automobile industry.



The problem, as I see it, is not that of upgrading the conversion process, but of upgrading the supply of corn to satisfy a substantial proportion of the demand for hydrocarbon fuels.

quote:

You have to dig gasoline up from under the ground, and it takes thousands of years to replenish.



This is true, but at present, it is there, and would be foolish not to use it (with the proviso that nothing lasts forever).

Extensive growing of cord for ethanol cannot be done indefinitely either, since the corn will use up minerals from the soil which will need to be replenished.



George
 

Offline Cut Chemist

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Re: Ethanol
« Reply #6 on: 09/05/2006 04:29:59 »
What about the slowwwwww process of switching to hybrid cars
I am much more for research to integrate these products to the common market.

If cars could consume less fuel that would be more of a step in the right direction.

And once the gasoline was used up corn ethanol might be a more feasable option, because less fuel would be required neways.
 

Offline Cut Chemist

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Re: Ethanol
« Reply #7 on: 09/05/2006 04:33:23 »
besides you being from the UK,
I would expect support from any option to try and overturn the US's greed and conquest for oil;) j/k
 

Offline Cut Chemist

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Re: Ethanol
« Reply #8 on: 09/05/2006 04:53:47 »
plus if you break down
you have half of the makings for a party in your gas tank [8D] !!!
 

another_someone

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Re: Ethanol
« Reply #9 on: 09/05/2006 11:24:22 »
quote:
Originally posted by Cut Chemist
What about the slowwwwww process of switching to hybrid cars



I agree that this is now a proven technology, and it is disappointing to see such a slow implementation of the technology.

1) I suspect the reasons might be either tied up with patents (unfortunately, modern intellectual property monopolies can slow down the wider use of technologies).

2) The general slowness in introducing new models.  The cost of tooling up for a radically new mass market model can be enormous, and this can only happen on a very slow timescale (requiring the building of new production lines).

quote:

If cars could consume less fuel that would be more of a step in the right direction.



This is an ongoing process that has been happening over time, and continues to happen; but it is an evolutionary rather than a revolutionary process.

quote:

And once the gasoline was used up corn ethanol might be a more feasable option, because less fuel would be required neways.



The fact is, for all the doom mongers, it will still be many decades (very possibly even more than a century) before all crude oil reserves are used up; although there is no doubt that the cheapest supplies will be used up before then, and it will become more expensive to extract some of the more remote supplies.

As for alternatives to petrol (gasoline), in Europe, LPG and CNG are the most mature, but at present they are both are similarly extracted from deep drilling, and will have the same long term problems as petrol.  CNG, I also believe, is only a limited energy content, but on the other hand, since this is just another name for methane, it can be biologically produced, as well as having extensive reserves in methyl hydrates.

Another biological fuel that is very easy to switch to is vegetable derived oils.  These can easily be fed into unmodified diesel engines.  The biggest obstacle to this (apart from an adequate supply of product for the market) is one of taxation.  We have already had one incidence of a motorist who fed his diesel car with cooking oil being prosecuted for tax evasion for not paying the appropriate excise duty for motor fuel.  Another problem, although I have no doubt that the matter could be overcome, is the rather distinctive smell that is produced when burning cooking oil in a motor car engine.

quote:

besides you being from the UK,
I would expect support from any option to try and overturn the US's greed and conquest for oil



And being from the US, I would have thought you should be giving unconditional support to your esteemed leader :D
There is much that I despise about GWB's policies (but, given our own esteemed leader is doing much the same on many matters, it is scarcely an issue that can be regarded as dividing the two nations), but it is a matter of looking at the facts of each case, and not the person; and in the case of Kyoto, it is the one area in which I (and some others over here who may also object to other aspects of his policy) actually agree with.



George
 

Offline bigggmike1

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Re: Ethanol
« Reply #10 on: 18/05/2006 00:29:37 »
I've grown in love with this forum.  Real, educated people willing to talk about real issues.  I think it's great that we're using science (the truth about the world) to discuss these issues.

I read up on all the previous posts on the ethanol subject.  I'm glad this is being talked about because I've been doing some of my own research on it during the past few weeks.

Frankly put, corn-derived ethanol has a negative net energy output, meaning it takes more energy to produce it than is available in it as a resource.  I think alternatives energy resources need to be researched more and be made more efficient.  The gallons of carbon-based fuel used in harvesters and in shipping trucks exceed the number of gallons of ethanol we get.
Sure, ethanol does burn cleaner, but when we are consuming and exhausting carbon-based fuels in order to harvest corn and produce ethanol we are polluting the environment just as much.

As someone pointed out earlier, corn is a renewable resource, but soil fertility takes more time to renew.  One of the US's major problems in agriculture right now is soil fertility depletion.

My last, more humanitary point is that people in 3rd world countries are starving while we are using a viable food source for negative net energy production.  There are some serious moral downfalls here people.  Perhaps these corn resources would be better used to put an end to world hunger instead of producing a fuel with a negative net energy output.

Farmers are loving the push for ethanol because it's driving up the demand for their harvest and thus the price.  

I wish our politicians (especially our "brilliant" president) would look into this issue as much as we do.  Of coures an "energy alternative" sounds great to common America, but seriously, when you sum up the economic and opportunity costs of producing ethanol, it ain't that great.
 

Offline VAlibrarian

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Re: Ethanol
« Reply #11 on: 22/05/2006 01:45:58 »
Hey Bigmike-
I share your enthusiasm for this symposium of science. The sound bite nature of science in the world of politics is indeed unfortunate, and since many Americans seem to learn most of their science from Presidential speeches, this is counterproductive in terms of our education.

Where ethanol is concerned, our President himself admits that corn is not the ideal source for ethanol as it takes alot of gasoline to run the process that gets the corn made into ethanol. Yes indeed it does take as much gasoline as it saves, which makes it basically a waste of effort. He mentioned in one speech that switchgrass or some other source of cellulose would be more efficient. That's correct, and I appreciate the effort made by that speechwriter, but George probably does not understand much of this and is just looking for a way to say something optimistic. Do not worry about the oil crisis, everything will be fine in a few years when we all use ethanol. The problem is that the crisis is today.  

Brazil has been working on the techniques of ethanol production for years and has a few things to teach us. There is also one experimental plant in Canada that is using wheat straw as raw material for ethanol, with a special enzyme to break down the cellulose. I heard about that on national public radio.

I believe that renewable energy has a great deal of promise to reduce our addiction to oil, if we actually work on it in a realistic way instead of throwing money at it in a way that will delight corn farmers. But I think it silly that the American government and many American voters have such an aversion to the very concept of collective conservation. High prices in the U.K. have resulted in a degree of conservation that saves billions of dollars of your money annually, while we cling to low taxes and pass those billions over to oil producing nations of whom we are not fond.

chris wiegard
 

Offline Atomic-S

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Re: Ethanol
« Reply #12 on: 28/05/2006 03:11:56 »
quote:
My last, more humanitary point is that people in 3rd world countries are starving while we are using a viable food source for negative net energy production. There are some serious moral downfalls here people. Perhaps these corn resources would be better used to put an end to world hunger instead of producing a fuel with a negative net energy output.
Why, then, are not these corn resources  being used even now to alleviate hunger in the 3rd world , seeing that the corn in question is not currently being used for substantial fuel-ethanol production? It would seem that the consumption of corn by fuelmaking processes is not the actual reason for 3rd World hunger.
 

another_someone

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Re: Ethanol
« Reply #13 on: 28/05/2006 14:26:05 »
quote:
Originally posted by bigggmike1
My last, more humanitary point is that people in 3rd world countries are starving while we are using a viable food source for negative net energy production.  There are some serious moral downfalls here people.  Perhaps these corn resources would be better used to put an end to world hunger instead of producing a fuel with a negative net energy output.



I agree with Atomic-S's response, dumping large amounts of grain produced by the West onto third world market does nothing other than undermine their ability to grow their own food.  Short term emergency aid in response to a natural disaster is one thing, but parachuting in a regular supply of grain will just create permanent dependence upon that aid.

The solution to third world hunger is to create self-sufficiency in those countries, not to create dependency.



George
 

Offline gerbil

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Re: Ethanol
« Reply #14 on: 12/06/2006 05:33:22 »
Further to Chris Weigard's post regarding the regressive nature of the current US administration's energy policies, I most heartily agree.  I guess it's asking too much to get an ex(?) oil man like Mr Bush to get his head around something so radical getting your energy from somewhere other than a hole in Saudi Arabia.  Speaking of which, has anyone read this?:

newbielink:http://www.biofuelreview.com/content/view/93/2/ [nonactive]
 

Offline JDG8R

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Re: Ethanol
« Reply #15 on: 13/06/2006 23:41:48 »
How much energy required to produce 1 gal gasoline?

How much energy required to produce 1 gal ethanol?

How much energy does 1 gal of gas contain?

How much energy does 1 gal of ethanol contain?

Assume the crude has been delivered to the refinery, and that the grain has been shipped to the distillery.
 

The Naked Scientists Forum

Re: Ethanol
« Reply #15 on: 13/06/2006 23:41:48 »

 

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