I said,
Quote:
Okay, there are some good ideas here. So, what if we follow Jamesqf's idea, combined with dcb's response? Let's have a gasser and an identical EV drive a distance so that the gasser uses one gallon of gas. The EV will use only 3/7 as much energy, or
(34 kWh for a gallon) x 3/7 = 14.57 kWh
So, Jamesqf, there's your conversion factor--
1 gallon of gasoline = 14.57 kWh
Nope, the electric boys wouldn't accept that.
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And, you replied--
Quote:
Originally Posted by trebuchet03
I can't put my finger on it - probably because I've only spent the time it took to read the post thinking about it...
That suggests that a higher efficiency EV in the experiment, what should be an independent variable, results in less energy in a gallon of fuel. This makes my intuition gland tingle.... It not sitting well with me (just yet) from a conservation of energy stand point.
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Excellent thinking, Tre,
Let's see if we can figure out what's wrong here. I think we have to understand Jamesqf's goal in setting this up. Maybe James is listening. He said to himself, "look, if two cars have identical efficiency in every respect except one is a gasser and the other is an EV, then why not say they have the same mpg or equivalent?" What we are doing is taking out of the comparison any natural advantage for either the gasser or the EV. Provided we can agree on what a "normal" gasser or EV power plant is capable of, this should work. I guessed the "normal" efficiencies for the gasser and the EV:
Gasser.......30% pump to shaft
EV............70% plug to shaft
And said in a loud voice that the vehicles are otherwise "the same."
From that, I got that such identical cars will have identical mpgs if we set the conversion to 1 gallon of gas = 15 kWh (for round numbers).
Okay, these were "normal" cars. If a gasser comes along that does better, getting say 40% from the engine, and a really low drag coefficient, and regen braking, then it will show a higher mpg. Likewise, if the EV is more efficient than the norm, say with a power transfer efficiency of 90%, and especially efficient body design, then it will score a higher mpg. (The conversion factor remains at 15, no matter how good the EV is.)
Phew, that was hard. You know, I am beginning to really like James' idea.
Ernie