Polaric Energy

This would obviously require extensive construction work, none the less here it is. It is a means of exploiting the Earths own electromagnetic feild for electricity (I don't know if anyone's already suggested this).

We would first build magnetic-material arreys at the northern and southern poles of the planet, which would have to extend high into the atmosphere (perhaps multiple towers), which would be linked together across the planets curvature by a skeleton of conductive metals through which electric current would spread.

What I know of equilibrium in nature (self-confessed as "not an awful lot") tells me that in order to maintain its EMfeild at the poles, the earth would first need to fill up the proposed skeleton with all the current it could take. Any drain on the system once maximum capacity had been established might be quickly, if not instantly replenished.

Large conductor blocks set beneath cities would also need to be filled up, and from there the cities in question would gain their power supply.

I am of an opinion that the "charge up" time would cause environmental upset.

I'm not sure, really, wither there is all that much land to build such an arrey on at either pole, but the Japanese do practice artificial means of land extension and perhaps this could be used in this case.