[ExI] Electric cars without batteries

[Keith Henson]

2010/10/24 John Clark <jonkc at bellsouth.net>:
> On Oct 23, 2010, at 3:09 PM, Keith Henson wrote:
>
>> The obvious way is to direct couple the turbine to an AC generator.
>> No gears.
>
> You're still going to need gears, expensive and complicated ones too. A gas
> turbine, especially a small gas turbine like you'd have in a car, would have
> a very very high RPM but have little torque, too little torque to operate an
> electric generator, you'd have to gear it down, way way down.

Sigh.  The power output from a turbine is the product of the RPM and
the torque.  Reduction gears reduce the speed and increase the torque
while introducing loses.  But you can use any RPM for an AC generator.
 It just changes the frequency.

> Just incidentally, that's the way diesel electric locomotives work.
>
> As the name implies in that case the electrical generator is powered by a
> diesel engine, a device that produces a huge amount of torque but has a slow
> RPM, the very opposite of a gas turbine.

At the time I worked in the EMD plant, locomotive engines ran at 900
RPM.  It would be no problem to replace one with a equal power 9000
RPM turbine.  The point is that after you have electric power you can
drive electric motors over a wide speed range.

Keith