Use a nuclear fission powerplant with broken safety
An old nuclear power plant minus all the safety features that keep it from melting down. You can probably fire it up and keep it running for a few minutes before it inevitably explodes. As long as enough of the electric net is available or temporarily repaired, you could transfer the energy outside of the meltdown radius to boot up the artefact. After that, the entire area surrounding the plant will turn into a no-go zone and the powerplant will be rendered useless.
A nuclear powerplant with the safety features destroyed does not require any outside influence to destroy, it will quickly overheat and have a catastrophic meltdown. A nuclear fission reaction will naturally spiral out of control and destroy the entire powerplant unless security features are in check. This is what makes them so dangerous and why many people are opposed to them.
How nuclear fission works
A short and basic explanation of the workings of a reactor: at the core, a nuclear fission plant contains a large amount of radioactive material. Radioactive material undergoes a powerful reaction that creates lots of energy when you bombard it with small particles. However, the reaction that generates the energy also creates more of the particles that sustain the reaction, at a better than 1:1 ratio. This means that, uncontrolled, the reaction will go faster and faster, producing more and more energy, until the plant will be unable to control all of the energy being produced and has what is called a "meltdown", at which point the powerplant is destroyed and the radioactive material is spread far and wide. This radioactive material is harmful to life and sent out in such large quantities that the site of the meltdown will be rendered uninhabitable for decades. (There was a meltdown at Chernobyl around the time I was born; I'm nearing my 30s and the area is still uninhabitable)
What a nuclear fission powerplant does is try to sustain the reaction over a long period of time by absorbing the generated particles that would make the reaction spiral out of control back into harmless material. This is done through what are called "control rods", which absorb the same particles that the radioactive material does, but not doing anything with them.
As long as the control rods work; the energy produced by the nuclear fission plant is fairly constant and maintainable. If the control rods fail, horrible, horrible things will happen. If you fire up a nuclear fission plant with broken control rods, no external influence is neccesary; the powerplant will destroy itself. This is why many people are opposed to nuclear fission; if anything goes wrong, rather than the reaction failing, it will destroy itself catasthrophically.
This is why I suggested a nuclear plant rather than a coal or solar plant; nuclear plants will always fail spectacularly, and most of the design of the facility is not dedicated to producing energy but to keep it from exploding.
For more information on how nuclear fission works, read up here:
It explains the difference between nuclear powerplants and nuclear bombs, and you'll see that the only difference is that the power plant is trying to control the natural thing that would happen if you allowed radioactive material to react to particles; while an atomic bomb doesn't.
Bonus feature: you'll either need some (temporary) fast transportation to get the people who boot the powerplant the hell out as soon as it starts pumping, or you'll need to draw straws for who gets to stare a meltdown in the face.