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I actually live right in center of the corn belt and every gas station has gas w/o ethanol. I believe the problem is likely your state decision makers and who has influence over them.
Well, no kidding. Did you figure I thought the ethanol just leapt by itself out of the corn fields and into the gasoline supply?
While your formula is correct, on the energy content of ethanol fuels, it fails to take into account the fact that an engine properly designed to run on ethanol blends (higher compression, increased timing) can negate much of the difference.
... While engine timing can be advanced on an E85 car running E85, the compression ratio which is where the real benefit comes in, remains unchanged. An E85 car could safely run 11.5+:1 compression, however a pure gas engine would suffer from knock at those compression levels, forcing the manufacturers and engine builders to make the engines with more traditional 9.5-10:1 compression to run on regular gas.
An experimental "engine" has been built at Oak Ridge National Laboratory to run on a broad range of fuels from gasoline to E85 at a compression ratio of 12.87, when operated in a de-rated manner for gasoline in order to maintain compatibility.
A report on the experimental engine concludes:
Quote:
"... high CR can increase the efficiency of ethanol
fuel blends, and as a result, the fuel economy penalty
associated with the lower energy content of E85 can be reduced by about twenty percent."
To get a rough estimate of the effect of compression ratio on engine efficiency, consider the simplified equation for the thermal efficiency of a four stroke internal combustion engine which appears as Equation 1 on Page 6 of the above paper:
η = 1 - 1/(CR^(γ-1))
where η denotes the thermal efficiency, CR is the compression ratio, and γ denotes the usual ratio of the air/fuel mixture specific heats at constant pressure and at constant volume. The value of γ varies during the combustion cycle, but a value commonly used in engineering textbooks on thermodynamics is 1.27. Using the above equation and assuming a CR of 10 for a pure gasoline engine and a CR of 13 for a pure ethanol engine, the thermal efficiency rises from 46% to 50% in going from a CR of 10 to a CR of 13 (the actual fuel-energy-to-wheels efficiency is much lower, ≈15% due to mechanical friction in the engine, pumping losses, etc.). Hence thermal efficiency is increased by a factor of 50/46 or ≈ 8%; while the energy density of pure ethanol is only about 66% of pure gasoline.
So no, a higher compression ratio does not recapture what is lost by the lower energy density of ethanol.
I would prefer gas with no ethanol in it at all, if I could get it. I'm not sure what I can get that does not have the "hooch" already in it, maybe avgas.
There are a couple of sites that will show you where no-ETOH gas can be had.
An experimental "engine" has been built at Oak Ridge National Laboratory to run on a broad range of fuels from gasoline to E85 at a compression ratio of 12.87, when operated in a de-rated manner for gasoline in order to maintain compatibility.
A report on the experimental engine concludes:
To get a rough estimate of the effect of compression ratio on engine efficiency, consider the simplified equation for the thermal efficiency of a four stroke internal combustion engine which appears as Equation 1 on Page 6 of the above paper:
η = 1 - 1/(CR^(γ-1))
where η denotes the thermal efficiency, CR is the compression ratio, and γ denotes the usual ratio of the air/fuel mixture specific heats at constant pressure and at constant volume. The value of γ varies during the combustion cycle, but a value commonly used in engineering textbooks on thermodynamics is 1.27. Using the above equation and assuming a CR of 10 for a pure gasoline engine and a CR of 13 for a pure ethanol engine, the thermal efficiency rises from 46% to 50% in going from a CR of 10 to a CR of 13 (the actual fuel-energy-to-wheels efficiency is much lower, ≈15% due to mechanical friction in the engine, pumping losses, etc.). Hence thermal efficiency is increased by a factor of 50/46 or ≈ 8%; while the energy density of pure ethanol is only about 66% of pure gasoline.
So no, a higher compression ratio does not recapture what is lost by the lower energy density of ethanol.
All very interesting, but it isn't taking into account the current trends within the auto industry to recapture the lost MPG. GM, Ford, Delphi and several others are currently working on engines and associated componenets that would allow a CR of 16:1 on high ethanol blends. Add in turbocharging, more aggressive timing, direct injection and variable cam/valve phasing and they are getting within 5%-10% of what can be done with a straight gas engine.
That isn't even beginning to touch on the fact that ethanol engines produce more power per liter than a gas engine, owing to the ability to run higher CR and more aggressive timing. That would allow you to build a smaller E85 engine that still produced identical power to a larger gas engine. Current trends show 1.4 I4's optimized for E85 that are capable of producing power comparable to current 2.4 I4's (in the 200hp range) and return better MPG.
There is also another offshoot working on optimizing V6 engines that could be valid replacements for diesels. GM has taken a standard 3.2 V6, optimized it for E85 and added turbocharging and built a motor that produces identical power to the current 6.6 Duramax diesel, while returning 40% better MPG and greatly reduced emissions.
Again, my only argument is that ethanol itself is not a bad fuel. The way our country is going about using it, is what's wrong.
But the nergy content of ethnol will always be a fasctor in the end.You can alos do mnay thng to gasoline with other additves to further increase power and efficncy has we hav sen in the past.But for the average perosn now the fact isw that takig tha same vehciles as consumer reports did means between 20% and 27% overall less milage per tank.Its real world that people are interested in really.
But the nergy content of ethnol will always be a fasctor in the end.You can alos do mnay thng to gasoline with other additves to further increase power and efficncy has we hav sen in the past.But for the average perosn now the fact isw that takig tha same vehciles as consumer reports did means between 20% and 27% overall less milage per tank.Its real world that people are interested in really.
I agree with you 100% and that was what I suppose I was trying to get at. There is no reason to villify the fuel, you can however villify our incredibly misguided energy policies that create the issue.
Many studies have pinned that an engine optimized to run on E40 or E50 can be made to be equally efficient to a gasoline engine. The problem is you can't optimize the engines without a national standard for fuel and being able to guarantee the availability.
Basically, the Fed needs to step up and determine whether or not ethanol based fuels are something we as a nation are going to pursue. If the answer is yes, than we need to work towards a national standard for fuels.
For instance, you could eliminate "mid-grade" at the pump and replace it with pre-mixed E40 or E50 alongside regular and premium with the goal of eventually completely phasing out regular gas. Another option is to simply blend the needed concentration at the pump. Using regular gas and E85, you could blend almost any concentration you wanted.
It all comes down to someone having the intelligence and foresight to set a realistic national energy policy. If ethanol isn't the answer, than it should be scrapped entirely. If it needs to be part of the energy solution, than create a standard so it can be used correctly.
That isn't even beginning to touch on the fact that ethanol engines produce more power per liter than a gas engine, owing to the ability to run higher CR and more aggressive timing.
Prove it with a link or some mathematical analysis. My previous post showed you are wrong.
Prove it with a link or some mathematical analysis. My previous post showed you are wrong.
It is a widely known fact, especially among the car tuners that E85 is essentially the equivalent of "race gas". The availability of E85 has had large impacts on the tuning scene.
Here is a thread about a very respected tuning shop in SoCal that gained 100+ hp and 75 ft.lbs. of torque on a mildly modified Evo versus what could be achieved with the best effort on 91 octane with the same mods:
Here's another tuner with a naturally aspirated Honda CRX that gained 5% power over the best 93 octane tune simply owing to the more aggressive timing allowed by running E85. The car in question competes nationally in SCCA races, where many folks are jumping on the E85 racing bandwagon.
The gains are only around 5% on a standard NA motor when you tune for E85. However, on a forced induction motor, the differences can be dramatic owing to the properties of the fuel to cool the charge and allow more aggressive timing and boost.
Here is an article from Ward's detailing a program where a standard GM 3.2L V6 was modified to use E85 with the EBDI concept and was able to create a motor that equalled the power of GM's 6.6L Duramax diesel.
The simple fact is that liter for liter (meaning engine size), you can make more power on E85 than you can with gas.
I was not talking about engine size. (Maybe you were, but you are all over the spectrum.) Let's keep it simple.
My points are:
A gallon of ethanol has about 2/3 the energy content of a gallon of gasoline.
Regardless of how much:
the compression is increased (16:1 if you want),
the spark is advanced,
the valve timing and valve overlap are adjusted,
one gallon of ethanol WILL NEVER GIVE as much mpg as one gallon of gasoline.
I thought your original argument was: "Yes, E85 gives 25% lower gas mileage when run in engines designed for gasoline or E10, but E85 gives almost equivalent mileage if run in engines designed to run on E85." If that is your belief, then I am saying you are wrong.
I was not talking about engine size. (Maybe you were, but you are all over the spectrum.) Let's keep it simple.
My points are:
A gallon of ethanol has about 2/3 the energy content of a gallon of gasoline.
Regardless of how much:
the compression is increased (16:1 if you want),
the spark is advanced,
the valve timing and valve overlap are adjusted,
one gallon of ethanol WILL NEVER GIVE as much mpg as one gallon of gasoline.
I thought your original argument was: "Yes, E85 gives 25% lower gas mileage when run in engines designed for gasoline or E10, but E85 gives almost equivalent mileage if run in engines designed to run on E85." If that is your belief, then I am saying you are wrong.
Ah, I was never arguing that E85 will give equal MPG to pure gas. What I said was that an engine optimized for E85 (or any ethanol blend) can cut the mileage penalty down to as little as 10% in current test engines, which can make ethanol the cheaper fuel to run.
However, that doesn't account for the fact that ethanol allows an engine to produce more power per liter than if it was run on pure gas. This would allow you to build smaller engines optimized for ethanol while not sacrificing power output. For instance, a 2.0L E85 optimized engine could produce the same power as a 2.4L gas engine. The smaller displacement, would allow you to recoup more of the MPG losses.
That fact can be dramatized further by using turbochargers in conjunction with even smaller engines allowing something as small as a turbo 1.4 oprimized for E85 to produce the same power as our 2.4L gas engine and achieve equal or possibly better fuel economy.
You are arguing a gallon of ethanol has less energy than a gallon of gas, period. You are right, but in the real world, ethanol has properties that allow us to make up for that lower energy content and neutralize enough of the difference to make it work economically. The problem is we don't have any standards to control it.
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Did you figure I thought the ethanol just leapt by itself out of the corn fields and into the gasoline supply?
