Reposting of efficiency. ERROR in original

[Steve Stegmann <stegmann@domain.elided>]

Tom,

Sorry.  This has the gas engine efficiency changed to 0.28, and the
generation efficiency for a coal plant at 0.33.  This is based on a heat
rate for the power plant of around 9500 BTU/kwh.  I imagine this might be
better now but the difference is not too much.

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   .28  
    =  0.226

Battery:

Eff = coal-mine x generation x transmission x batt x elect-motor
    =    0.5         0.33     x   .96        x  .8  x   .98
    = 0.124

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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