Quote:
Originally Posted by Arctic Fox
I had this thought today;
Suppose I have a car that gets 15 miles per gallon of gasoline.
I trade that in for one that gets 30 miles per gallon of gasoline.
But then I switch from using gasoline, to using E85 ethanol.
I lose 10-15% mileage, yet I'm still getting higher mileage per gallon of fuel that I was with the old car.
The question: Is this still considered progress?
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I'm going to put this into some numbers that are useful for comparison.
15MPG on Petrol = 2254 Wh/mile
30MPG on Petrol = 1127 Wh/mile
E85(assuming 85% Ethanol/15% Petrol) has 82,294 BTU/Gallon while Petrol has 116,090 BTU/Gallon. So E85 has 71% of the energy content of regular Petrol. Source:
AFDC Energy
Convert BTU to watts.
E85= 24,102 Wh
Petrol = 34,000 Wh
If you lose 15% range(I've heard this is typical on non-FFVs and older FFVs alike) than that is 25.5MPG. So your energy consumption per mile would be 945 Wh/Mile. That is a reduction of 57.7% of your original consumption.
I believe it's progress simply because that is a huge reduction in overall Fossil fuel consumption and it significantly reduces energy consumption. The only problem is how much does it cost you per mile? Prices are still too high here, but lately Ethanol prices have gone down while Gasoline is going up.
Tjts, that chart is only useful for purely scientific purposes. A more practical comparison is how much Corn Ethanol costs per unit of energy compared to regular Petrol. Corn Ethanol was cheaper in the near past, before the Biofuel mandate, and more recently the market price of Ethanol has dropped but it's not sustainable.
redpoint5, Ethanol is infact a more efficient fuel than Gasoline, it is simply not as energy dense. Strangely, Octane for blends from E50-E85 is about the same, 95 1/2 octane AKI, still better than pump gas at 93 but not what you'd expect. Plenty of the hotrodders, tuners, and engine builders swear by it. I've heard E85 is just shy of C16 leaded fuel but either way it is vastly underutilized in a FFV.
BTW, according to federal law it is ILLEGAL for manufacturer's to test MPG on anything but test grade Gasoline. The EPA MPG numbers are based solely on energy content, not on real world driving with E70-E85.
EPA FAQ