From: James Rogers (jamesr@best.com)
Date: Fri Apr 25 1997 - 18:57:21 MDT
At 08:39 PM 4/24/97 -0400, Michael Lorrey wrote:
>Until fuel cells become compact enough to be really usefull, which I
>think will happen in 5-10 years at most, the optimum power system for a
>car is a small 15kW gas turbine generator running electric drive motors
>and maintaining an electric charge in a battery system 1/10th the size
>of that currently used in electric cars, which is only needed for on
>demand power needs (acceleration). The turbine runs at constant max
>efficiency, like a large power plant, is compact, with a high power
>density.
The problem with gas turbines, even if you buffer the energy like you
describe above, is that they are inefficient in city driving environments.
A car driving on surface streets or rush hour traffic spends most of its
time at idle or near idle. If your commute is anything like mine, your
small battery buffer would become full quite quickly, forcing you to idle
the turbine. Since idling turbines are horribly inefficient, I suspect the
actual savings from this configuration would minimal. If we applied
turbine technology to highway driving, then you would see significant gains
in efficiency, but in this instance you don't really need the electrical
conversion anyway.
I've driven a turbine powered car before, and they are very nice. Lots of
power and very smooth acceleration. Supposedly some company is working on
a prototype turbine that can idle nearly as efficiently as a vanilla
internal combustion engine. Turbines actually make a lot of sense if you
are looking for a lot of power in a compact package. The turbine car that
I drove put out in excess of 600 horsepower, but was as fuel efficient as
most sports cars in the 400 horsepower range.
-James Rogers
jamesr@best.com
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