I would have started by an orbiting station (or even an orbiting ring-shaped station), staying at a safe distance from the horizon, from which the masses would be droped.

Is it still too unrealistic?

For the radiation energy, it sure makes sense! Moreover isn't it any hard radiations emitted when the hadrons' quarks are torn from each other on reaching the events horizon?

If your station is in orbit, then so is the mass you want to drop into the black hole. Orbital mechanics works quite differently to what you are used to from the surface of a planet.

But the black hole is very small as far as I know, maybe we could build an orbital ring around it, attach alternators to the orbital ring and then feed "ropes" to the alternator one one end and on the other end let them fall into the black hole.

By "ropes" I mean charged particles and by alternators I mean just very powerful electromagnets that can extract the energy of the charged particles falling into the black hole.

My point was that things attached to the outer core of an orbital ring are not in 0 G, but they feel the actual gravity at the particular height the orbital ring is orbiting -- on Earth if you would be sitting on an orbital ring situated at a height of say 300km, you would feel as though you were sitting on a 300km mountain; maybe on a primordial black hole you could build an orbital ring just a few km from the black hole and have spokes going down very close to the black hole (maybe active structures to overcome our current material strength limitations) and let charged particles fall into the black hole and extract their energy as they fall into the black hole.

Or maybe the black hole is small enough that a very crude electromagnets field could just encompass all of the black hole and it could very easily extract all that sweet energy of a charged particle falling into the black hole with an electromagnet an amateur could build in his garage.