It generates light, not energy.
We are inundated with RF signals, which is what is powering this system. The magnetic fields are just amplifying the local electrical field.
When all modern human activity stops, that light will go out.
So the best use of this device is to give it to eco nazis and they can spend their lives sitting at home waiting for it to go dark.
Somebody mentioned that, if it was working as presented, it was probably acting like an antennae and picking up energy from other sources, like a nearby lamp