From: pvr@wang.com ()
Subject: Re: Flywheel batteries as EV power source
Organization: Wang Labs, Lowell MA, USA
Date: Tue, 15 Dec 1992 14:49:38 GMT

jeh@cmkrnl.com writes:

>In article <Bz6nuM.LCo@acsu.buffalo.edu>, v064mb9k@ubvmsd.cc.buffalo.edu 
>(NEIL GANDLER) writes:
>>  I just have finished reading the latest Popular Science issue. Jan 93.
>> On p. 27 they discuss flywheel power as a possible energy source for 
>> future Ev's. Claimed advantges are a cruising rnage of over 600 miles
>> on an overnight charge on GM's Impact. With a battery weight of only
>> 600 pounds and a life of 25,000 miles and with no chemical waste when
>> disposed this new power source could revolutionise the
>> EV industry. Why is this technology not being looked into more. What
>> are the dissadvantages. What is this technology exactly. How is
>> mechanical energy stored in such great amounts. 

   For a much more informative but unfortunatly brief description
read the IEEE Spectrum article on battery technology that
appeared a month or two ago.   It discuses various battery designs
in terms efficiency, power density, hazzards, etc.   The article
has a sidebar that discusses flywheel energy storage.   The energy
density was about double the best of even the exotic batteries.
They held their energy for weeks.   They were safe both chemically
and mechanically.   Some of the people doing research were mentioned
so you could get more information.
   
>To be usable for an electric vehicle, you need a massy, large-diameter
>flywheel that spins at phenomenal speeds.

   This is not true, the article says that the highest energy density
is gotten from small light flywheels spinning at high speed.


>  It is made with high-tech materials (carbon
>fibers, that sort of thing) so that it won't tear itself apart.

    The carbon fiber is good for the high speeds used but it also
safe in the event of a rotor failure.   It disintegrates when it hits
the wall of the vacuum chamber.   A steel rotor would penetrate
any resonable chamber and be a hazzard to anyone near by.

>It must be
>spun in a vacuum chamber or else a lot of the stored energy goes to heating the
>air.  It must be Floated on near-frictionless bearings, such as magnetic
>bearings, and coupling to the outside is via a magnetic clutch (ie the flywheel
>shaft does not extend outside the enclosure).  

>All of this is easy to dream up but a bit hard to actually build, especially in
>production quantities. 

   The article points out that machinery that is sealed in a chamber
has been reliably built for many years and that it lasts for 40 years or
more.   Home refrigerators being the best example.

>The flywheel must be arranged with a vertical axis so that gyroscopic effects
>don't make it impossible to turn the car.  Still, you need to worry about these
>effects whenever the car enters a sharply-banked road or freeway ramp.  

>Popular Science publishes an awful lot of "gee-whiz" stuff, with the 
>implication that these things are just around the corner.  It often isn't so,
>and I don't think it's so with the flywheel-powered EV. 

   That is true, so read the Spectrum article for better information.
--
>>>>>>>>>>>> Peter Reilley ..... pvr@wiis.wang.com ..... KA1LAT <<<<<<<<<<<<<
                     Well, that about says it.
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