Why is it not possible to make a device operate by forcibly putting electrons into the system, closing the loop, and having electron repulsion do the job of making charge flow?
Making electrons flow is what creates electricity. So if we are able to put electrons into a system, close the loop so the electrons have no where to go, then the electrons would be constantly bouncing around together. This would cause charge to flow around and create electricity.
What am I not taking into account here?
Best Answer
You're getting lot's of things wrong here.
That term is a relic from the past when people didn't know much about current, voltage and other macroscopic electrical quantities. Let alone electromagnetic theory. That term can be used correctly only in non-technical/scientific contexts or only in the vaguest of sense. In other words: you don't measure "electricity", you measure a bunch of well-defined physical quantities related to electrical phenomena.
From a technical point of view, what you call "electricity" in the sense of "some kind of energy that allows us to do stuff" is called "electrical energy" or "electrical power".
Currents can generate power only if they flow through a system that is able to draw energy from them. The electrons have to lose energy to provide power to the "outside world". In other words, they must travel across some sort of potential barrier. In technical terms, if the electrons moving from point A to point B are to generate power, there must be a voltage across those two points (point A must be at a lower voltage than point B, in particular).
In this scenario electrons, even if moving, wouldn't be able to generate power, because any point of a perfect conductor is at the same potential. So there is no voltage drop, hence no power.
Of course I have neglected lots of additional problems that arise when you consider the true nature of electrons, which are not tiny weeny balls of matter, but quantum particles to which classical reasoning cannot be applied coherently.
BTW, it has already been hinted to by others in this thread that you can have a continuous flow of current in a ring-shaped superconductor body. The electrical resistance is virtually 0 and the electrons don't lose energy while moving (ideally). There have been experiments in which such a "circular current" has been maintained for days (IIRC) without further external energy provision.
Remember: energy in nature cannot be created. It can only be transformed from a form into another. This is called the Energy Conservation Law and it's a basic principle of the Universe that no validated scientific experiment has ever been able to disprove.
Any time anyone has "witnessed" phenomena that violated that conservation principle, it has been established by scientific analysis that the phenomena were observed without taking correct measurement into account or that some other experimental mistake has been made (assuming there wasn't bad faith and the phenomena were not part of a scam).
Truly scientifically proving that the Energy Conservation Law is not universally valid would be a discovery worth a couple of Nobel prizes!