[Ernie Rogers]

From Concrete:

No good answer

I think this thread is proof that there is no good way to compare oil burners & EVs
it is obvious our world views preclude agreement (opinion based math?)
whatever standard you pick will make people mad.

Leave MPG for oil burners and move the EVs to their own standard

Jamesqf said:

I think there is a fairly reasonable way to compare: start from the other end and do it experimentally. Find someone (or better, several someones) who've done EV conversion on say a Geo Metro. Find the same model that's unconverted, have them both drive a measured course keeping same speed &c, and for best results swap drivers in the middle.

Divide gallons used by KWh used, and there's your conversion factor. You can use that to work backwards through the supply chain to get total efficiency.

In my post, I suggested using pump-to-shaft efficiencies of 70% for an EV and 30% for a gasser, with all other parts equal, and then we can calculate the conversion factor.

From DCB:

I don't *think* I need a program to show me how to multiply by 3/7ths, but thanks anyway Ernie.

(And, of course, he's right—I could have thought of that!)

At that point, Jamesqf and Concrete started to wander outside the box.

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.

If we had included the losses from well to pump /mine to plug, the overall efficiencies would be--

Adding in:
Average utility: about 40% (Wang gives 38.1% for U.S. average, to plug)
Average refinery: about 80% (From Wang, from 79% to 82%, to pump)

Gives:
EV...........0.40 x 0.70 = 0.28
Gasser.....0.80 x 0.30 = 0.24

So, overall from well-to-wheels, an EV is 28% efficient and a gasser is 24%. (Based on all the assumptions. Somebody will surely disagree.)

Then, the conversion factor is--

34 kWh/gal x (.24 /.28) = 29 kWh per gallon of gasoline

What do you think, would people agree to this conversion? It means that if the EV and the gasser have equal mpgs, then the two cars use exactly the same amount of energy, counting all steps from the mine or well to the wheels.

Ernie Rogers