I have as an example, a Lexus electric axle. It's 68 HP rating is 50 kW. Assume [arguable] parity for generation.
254,5 mē is 18 meters diameter. Or 19.8 yards. Or 59 feet.
I think the best way would be to weld the spider gears and put it on top of a gravity vortex water mill, where it's up above the water. That would require a sizable creek and impoundment dam.