Bill Gunshannon wrote:


Try tracing the power from the battery in the car all the way back
to it's origination. Take all the "efficiencies" into consideration.
Now tell me how wasteful the gasoline engine really is.

It's not bad. Depending on where you are, you can figure the overall
loss between the plant and your doorstep to be between 10% and 15%.
(Mind you if you live in some place like Hawaii where the grid is rather
small, it can be better than that).

Efficiency of the power plant itself isn't so good, it's on the order
of a 35% loss on the average. Can be better in some places, worse in others
but that's about typical for coal or gas fired systems. (Now, if you live
in someplace like Hawaii it's worse than that because you have to take into
account the waste in getting the coal out to you which is pretty substantial
in such places.)

Efficiency of the motors is very close to 100%. I don't know what the
efficiency of the battery is and that could be a big issue although that's
a thing that is still improving.

Figure typical gasoline engines have maybe 10% to 30% efficiency. Again that
is a ballpark number... you can guarantee that an Olds 442 in stop and go
traffic isn't going to get anything like that, and you might do better than
that on the highway with a small modern engine.

But I'm thinking if you did the math more precisely it would tend to be a
tossup.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."