You can’t do geosync at the poles. But that doesn’t really matter; you don’t actually need the generator or the gearing.
When STS-46 and STS-75 dragged long wires through the earth’s magnetic field from orbit, the amount of energy collected was staggering; the tether’s drag on the spaceship was being very effectively converted to electricity (until the tether fried).
Anyway, there’s lots of ways to convert part of the earth’s motion to electricity - I already mentioned windmills and hydro turbines, of course. But it’s hard to find contraptions as aesthetically awesome as the gravity engine! Something about that Rube Goldberg/Heath Robinson pile of levers makes me wish it can work, although I highly doubt it does.
