Ok… science fiction idea:

Electrons have “spin”: intrinsic angular momentum. This intrinsic angular momentum, however weird it may be, can still be expressed like regular Newtonian angular momentum.
Angular momentum must be conserved.
If you take a bunch of electrons, all with the same spin, and squish them down into a black hole, you’d have a black hole that is spinning. And it would probably be spinning STUPID fast. Like, relativistically fast.

It would also be HILARIOUSLY negatively charged.

In fact, it might even be a naked singularity. Or, more accurately, a naked ringularity.

Because like charges repel, you can now put this thing inside a negatively charged sphere and it will stay in the middle.

You’d have to make sure this sphere is as negatively charged as the naked singularity to make sure it doesn’t try to equalize the charge by touching. That’ll be a neat trick.

But now you have a black hole in a sphere.

You’d have to make this sphere be in another sphere, and make the gap nothing but hard vacuum to keep the inner sphere from discharging.

Now you have a black hole in a sphere that you can hold without being electrocuted by more electrons than what you can find in the entire eastern seaboard passing through your heart.

Unfortunately, it is also undergoing Hawking radiation. Vigorously. Because small black holes radiate more, and that relation is exponential.

So now you have a black hole in a ball that is emitting gamma rays or at least x rays like a motherfucker.

Let’s say you have a way to stabilize the spontaneous wormholes in the quantum foam, and do so in a way that anything coming out of this ball is wormhole’d back in.

So now you have a black hole in a ball that is NOT emitting gamma like Chyrnobyl on crack.

A very quickly spinning black hole.

That inner negatively charged casing is being bombarded with Gamma rays from both sides.

Now, gamma rays are kinda slippery lil bastards and they have a tendency to just shoot right on by… but occasionally, they’ll hit.

Gamma is ionizing, meaning it will knock electrons loose.

Fortunately, these electrons have precisely NOWHERE to go. Hard vacuum on one side and Holy Fucking Shit levels of negative charge on the other.

Assuming this inner casing is metallic, the electron would just start pinging around the metallic matrix - metals are already pretty loosey-goosey about them…

So it’s not like that’s particularly weird. If anything, this metal just has more electrons bouncing around inside it than usual.

Fortunately, a spinning negatively charged black hole has no magnetic field - the charge itself is not moving. No movement, no flux. No flux, no induced magnetic field. No magnetic field, no induced current in the metal, no loss of angular momentum.

Here’s where it gets interesting…

This metal is probably REALLY hot. It’s got electrons, excited by getting blasted seventeen ways to Sunday by gamma radiation, bouncing around it like kittens on crack. It’s not “current” so to speak - it’s all random. But electrons are still moving in it, and that makes heat.

Heat… emits. And not just infrared, but that alone would be enough.

Because spinning black holes have something called an Ergosphere.

And this is the part where people start calling HAX.

If you were to fly a spaceship into the ergosphere of a big spinning black hole, and dump your spend fuel tank in a way that it crosses the actual event horizon, the black hole will boost your velocity by giving you some of its angular momentum. This is called the Penrose Process.

A similar thing can be done with light… only light can’t go faster. So that extra kinetic energy from the sacrificed light ends up just shortening the ergosphere-transiting light’s wavelength.

This is called Superradiant Scattering.

So now you have a bunch of radiation being randomly emitted into a spinning black hole. SOME of it is bound to end up trapped in the photosphere… SOMS is bound to go in all the way as the “sacrifice”… and SOME of it is bound to end up in the ergosphere. Which will get a hearty kick.

This penrose process/Superradiant scattering WILL reduce the singularity’s angular momentum. Slowly, but still.

However, if my fermi estimates (that’s a technical term for “bullshit napkin math”) are even close to correct, the angular momentum loss isn’t enough to account for the output.

I think this theoretical device might actually be harvesting energy from background quantum fluctuations (which is where Hawking radiation comes from) and boosting it up into something more energetic, making it consistent, and thus a useable power source.

Obviously this depends on two very fictiony bits of science fiction: hard vacuum and stabilized quantum foam wormholes.

But yeah… if you configure that stabilized quantum foam to not be a perfect inward reflector, the fraction of light coming out will be plenty for some photovoltaic panels.

So now you have a ball that harvests usable energy from… *checks notes* Virtual particles that technically shouldn’t exist?

Oh, wait, no, having an output without an input means the singularity will still evaporate.

Hawking radiation -> shoving an electron around -> blackbody radiation -> Superradiant scattering -> output

So an input is required to keep the thing from evaporating and blowing the fuck up. It will slow down the evaporation process, but yeah… this thing needs fuel. And the fuel can’t have any charge, or else it’ll either not want to go in (if negative) or will reduce the negative charge of the thing

So that will have to either be neutrons, neutrinos, or light, off the top of my head.

Neutrinos would be ideal because they would be able to pass straight through all the other stuff and get hoovered up by the singularity.

But their mass is so small that background neutrinos aren’t enough…

Wait.

Wait, they might be enough! Because the evaporation process is slowed down!