system
Given the following post, respond as if you're commenting on Reddit:
human
is all electrical energy really mechanical energy, due to it being the movement of electrons?

Because, if the electrons aren't being destroyed/converted into anything, and are actually just moving around, then the energies they can be converted to (ie. light) must be something else?  all i can figure is, it's the movement... am i wrong?
gpt
Yes, it's the movement.  Nope, it's not KE, Kinetic Energy of electrons.   Their masses are way too small, and an electric current is far too slow a motion.

We can easily store significant energy in the rim of a spinning flywheel, since the flywheel is massive and moving fast.

But say we have an electric current in a thick ring of metal (or better, superconductor.)   A closed loop of conductor with a circulating electric current does resemble a flywheel.   But the mobile electrons of the metal are tens of thousands of times less massive than the metal atoms.   And, if we store kilojoules of electrical energy in the ring, those electrons move extremely slowly:  milimeters per minute.  As a "flywheel" the electron population in the conductive ring is way too slow, and way too light.

What the hell is going on?

Your conductive ring of course is an electromagnet.  The energy is actually stored in the surrounding magnetic field, and not stored inside the individual moving particles.  (And if we embed the ring in iron powder, we can store far more energy while keeping both the drift-speed of electrons and the value of electric current the same.)

Here's a weird concept: with the above ring, if we know the electron drift speed, then we can rotate the ring backwards just fast enough that those electrons remain still wrt Earth, while the positive metal ions are now flowing in a circle.   The kilojoules of stored magnetic energy isn't changed significantly, but now the flow is composed of massive positive-charged particles, while the light negative electrons have stopped flowing. The stored energy remains about the same, yet those flowing atoms (ions) are extremely massive!   For inductive energy storage, the important thing is the charge of the moving particles, and not their mass.

E&M is weird.