Thread: E85 fuel FAQ
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Old 07-08-2005, 10:54 PM   #4
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Join Date: Jan 2002
Location: 13.239@102.85 @ 5800 ft on 13T
2002 Impreza WRX


The energy balance question

Some sources say that fuel ethanol requires more energy than it returns is this true?

No not really based on recent studies using very detailed analysis of actual energy inputs currently used, in modern farming and state of the art ethanol plants the numbers come out as below. Note that gasoline actually delivers less energy than was expended getting it into your tank.
It has a negative energy balance. Which is exactly the claim the anti-ethanol lobby is blaming fuel ethanol with as a good reason not to use it.

Fuel ethanol returns:
+31% (Wang - 2002)
+34% (Shapouri - 2002)
+21% (Graboski - 2002)
Fuel ethanol with state of the art production techniques can return +68% (Wang - 2002)

Gasoline energy balance (GREET V1.6)

Conventional gasoline -19%
Reformulated Gasoline -20%
MTBE -33%


A USDA study released in 2004 found that ethanol may net as much as 67% more energy than it takes to produce. Argonne is one of the US Department of Energy's largest research centers.

Report on the new study :

The cellulose based ethanol production will actually return nearly 100% energy because it will use its own waste product stream for process energy.

Using the cellulose based process also eliminates the argument that more land will be required to grow corn than is available. Fact is many crops can be used to brew ethanol.

A list of common production sources of the above include.

sugar cane
Sugar beets

It can also be commercially prepared from cellulose treated by enzymes. Sources include:

waste paper
scrap rags
grasses (switch grass)
crop waste


We're not talking about the total substitution of ethanol for gasoline, but a concerted effort to displace as much as possible. The U. S. is already the worlds second highest consumer of fuel ethanol behind Brazil. Every barrel of fuel ethanol burned replaces 3/4 of a barrel of petroleum on a energy content basis. At current oil prices nearing $70 per barrel that is a significant amount of money payed out to U.S. suppliers for a commodity instead of to foreign suppliers. Given that money rolls over 5-6 times in an economy before it get sequestered in a long term capital investment, that means $350 dollars of net benefit to our economy for each barrel of fuel ethanol consumed vs a negative $50 of loss of revenue to the overseas supplier.

Yes I know that much of that money gets passed through the hands of U.S. companies but the end point is still the overseas oil producer.

Even more important, the energy inputs for fuel ethanol production are in large measure low quality heat requirements that can be met with domestic sources of energy which we have in great abundance, like Coal or waste heat from other processes.

How does fuel ethanol rank on Green house gas production ?

Using E85 you have a very favorable green house gas production picture. The CO2 produced when burning the ethanol portion of the fuel is totally recovered by the next seasons crop. This is the definition of a renewable fuel.

In short your "Net" green house gas production is only 15% of what it would be on straight gasoline. That is the equivalent of getting 6.7 times your normal gas mileage.

[edit 02/11/07 - 06/03/07]
how to make a simple conversion to a FFV with your Subaru see posts
#806, 809, 819, 821 ( page 33), post 828,(page 34), post 869 (page 35) post 918 (pg 37)

post 944 (page 37 cold start problems due to summer/winter blend switch over.

post 946 (page 38 -- emissions test on E85)

discussion regarding walbro fuel pumps and E85

IMPORTANT update on FFV auto tune
post 950 ( page 38 very lean on open loop running Autotune if you turn down fuel pressure )

The Jan 2008 HotRod Magazine has an article on E85 that is quite positive on its use as a performance fuel.
(although nothing new in the article that has not known for several years by E85 experimenters)

They have the results of a back to back dyno test of 100 octane race gasoline vs E85 on a 402 CID LS2 , 10.2:1 compression ratio, crate engine, done by Wheel to Wheel Powertrain in Madison Heights Michigan.
Gasoline (100 octane race gas) 540 hp @ 6000 rpm, 509 ft-lb torque @ 5200
E85 ------------------------ 546 hp @ 6000 rpm, 524 ft-lb torque @ 5200

With a turbocharger kit installed fueled on E85 :
13 psi boost -- 850 hp @ 5900 rpm, 833 ft-lb torque @ 5000 rpm
no comparison to gasoline you can't run that kind of boost on it with this engine.


"There's no sense even trying it with this boost and compression," Urban says."You just can't do this with pump gas" With its knock-stifling 105 road octane, E85 is a pump fuel that performs like race fuel. "I love this stuff," Urban says. "Its high-octane fuel for everyone, 105 you can buy on the road"
[edit] 04/21/08
fuel line sizing -- see post #1296 page 52

Seasonal fuel blends -- see post #1367 page 55

Injector sizing --- see post #1409 page 57

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Last edited by hotrod; 07-02-2008 at 04:34 AM.
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