Crystals as an energy source

[glilly]

but for AC to be usable, the compress/release cycle would have to be very regular. so you can’t line a room with piezoelectric quartz and pay some schmucks to jump up and down. no viable energy there.

As said before, AC doesn’t have to be particularly regular if your user is going to be a light bulb.

It would have to be very regular (and synchronized to the cycles on the grid) if you were going to augment your friendly local power consortium.