Re: electric car efficiency

[Steve Stegmann <stegmann@domain.elided>]

Tom,

To understand the efficiency difference between electric and gas cars
consider the following.

To get the overall efficiency you multiply together the efficiencies of
the various processes involved.

Gasoline:

Eff = drilling X refining X auto-engine
    =    .9    x   .9     x   .60  
    =  0.486

Battery:

Eff = coal-mine x generation x transmission x batt x elect-motor
    =    0.5         0.66     x   .96        x  .8  x   .98
    = 0.248

Fuel Cell:
Somewhere between the other two.

Remember that the mine energy needed is not needed as coal.  It all goes
in as diesel oil and electricity.  Most strip mine shovels are
electrically operated.  This makes the mine efficiency even worse than it
appears.

I guessed at the battery efficiency.  Can someone correct my batt
efficiency.

Draw your own conclusions.

steve.stegmann@domain.elided

Steve

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Steven A. Stegmann
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