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Navy_Navy_Navy Admin
Joined: 07 May 2004 Posts: 5777
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GM1954 Seaman Recruit
Joined: 02 Aug 2004 Posts: 17 Location: Naperville, Illinois
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Posted: Mon Sep 27, 2004 4:48 pm Post subject: |
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You are probably right on with the energy equivalent. The number you hear quoted alot is 30% less energy per gallon. However, Miles per gallon is identical to that of gasoline. And miles per dollar is the same or better.
Here's why. 85% ethanol has an octane rating of 105. This means you can run at a much higher compression than with gasoline and extract more power, even though the fuel has less energy per gram than gasoline. In the engines designed to use ethanol and/or gasoline, the knock sensor will advance the engine timing when ethanol or any combination of ethanol/gasoline is used. The net effect is similar to building an engine with a higher compression ratio.
Gasoline in the same engine will ignite near top dead center of the piston stroke, partially burn on the down stroke, and finish off combustion in the catalytic converter. As I implied above, ethanol burns almost entirely in the engine, thus more power and great fuel economy. There is a reason why Indy cars and dragsters use alcohol as a fuel. You can run really high compressions without sending the heads into the grandstands.
That's more than you wanted to know. It's just that I get a great deal of satisfaction from filling up the tank. I think of a guy, half a world away, sitting on a camel or in Rolls-Royce counting fewer tanker trucks leaving the oil field. |
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JCJR Lt.Jg.
Joined: 24 Aug 2004 Posts: 114
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Posted: Mon Sep 27, 2004 9:41 pm Post subject: |
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GM1954 wrote: | You are probably right on with the energy equivalent. The number you hear quoted alot is 30% less energy per gallon. However, Miles per gallon is identical to that of gasoline. And miles per dollar is the same or better.
Here's why. 85% ethanol has an octane rating of 105. This means you can run at a much higher compression than with gasoline and extract more power, even though the fuel has less energy per gram than gasoline. In the engines designed to use ethanol and/or gasoline, the knock sensor will advance the engine timing when ethanol or any combination of ethanol/gasoline is used. The net effect is similar to building an engine with a higher compression ratio.
Gasoline in the same engine will ignite near top dead center of the piston stroke, partially burn on the down stroke, and finish off combustion in the catalytic converter. As I implied above, ethanol burns almost entirely in the engine, thus more power and great fuel economy. There is a reason why Indy cars and dragsters use alcohol as a fuel. You can run really high compressions without sending the heads into the grandstands.
That's more than you wanted to know. It's just that I get a great deal of satisfaction from filling up the tank. I think of a guy, half a world away, sitting on a camel or in Rolls-Royce counting fewer tanker trucks leaving the oil field. |
I appreciate all the details. Thanks.
Doing a bit of web-browsing, looks like there are co-generation opportunities on corn ethanol.
Looks like they can extract corn oil as a co-product along with ethanol production.
Some folks have already started burning corn oil and other vegetable oils in their diesel vehicles (especially in Europe, where vegatable oil is cheaper than petroleum diesel fuel).
At worst case, if farmers could only got enough vegetable diesel fuel from the corn->ethanol process, sufficient to run their machinery, it might make the situation more "energy-profitable"? |
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