Hi Day
On (06 Nov 97) Day Brown wrote to all...
 DB> been wondering if several tons of rock or whatever, have been 
 DB> tried as mass on a flywheel for remote home power storage rather
 DB> than, or in addition to, batteries. 
I think I see the possible advantages, but I sure can see big disadvantages!
Maybe someone will correct my arithmetic, but the following is about right:
        The energy stored by a spinning flywheel increases as the cube of the
        speed. So for doubling the speed, you win eight times as much energy.
        The energy stored by a flywheel increases proportional to its weight.
        So for doubling the weight, you only get double the energy stored.
        The energy stored depends on the inertia of the rotor. As much mass 
s
        possible is concentrated at the perimeter. Mass near the shaft/
        bearings does not add usefully to energy storage.
        For practical energy storage the rotor needs to spin at extremely 
igh
        speeds- many thousands of rpm. This necessitates special attention to
        the dynamic balancing, the accuracy of machining, the uniformity in
        density for each of the rotating materials. I doubt whether rock or
        whatever, would have uniform density so vibration in service would be
        so severe as to preclude operation of a rock flywheel at high rpm.
Cheers...........ALEC
.........Fred Flinstone drove a dinosaur
... 
--- PPoint 1.92
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