I come to this question after a few thoughts on capacitors.
A capacitor essentially transfers (and stores) energy using an electric field through an insulator. The plates of a capacitor are not connected, in the sense that the electricity is not passed through using a true conductive path.
Consider a simple, two-plate capacitor. This capacitor has a charge, a capacitance, and a distance separating the plates. If we increase the charge, the capacitance increases. If we decrease the distance, capacitance increases. Therefor, if we increase the distance, we will lower the capacitance, but if we comparatively increase the charge, the capacitance will remain the same. The insulator would simply be the air.
So if we have two highly-charged plates, separated by a distance, shouldn't it be possible, in theory, to have a single-wire connection rather than a whole circuit?
Best Answer
Your capacitor misconceptions aside, it is possible to deliver power by effectively one wire. Driving an antenna is an example of one wire power delivery. Power is delivered to the antenna via the transmitter and the antenna radiates the energy as an electromagnetic wave.