Did you ever wondered how do they power an entire city with electricity ?

No need to wonder: Power grids.
A modern miracle. 

No...I already know how it is done.

Yes.  I read about it.  I highly recommend it.

Recycled Duracell batteries -there are billions of them. 

I read that there is enough atomic power in a common grain of sand to power a city for months. However, it would be too difficult to extract from common sand, so we use uranium based sand that can more readily give up the energy in the form of heat. It's sort of like an atomic bomb that is controlled in slow motion. BBBBBBBBBBBBOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOMMMMMMMMMMMMM!!!!

No, I have never "wondered" how, or at least if I did I was very young, and I learnt very quickly.

It's done "simply" by generating very large quantities of electricity!

The national grids Don Barzini mentions are the means to distribute the electricity.