So what you are saying is that there would be a limited number of these devices that could be used , otherwise
... reduce or even eliminate the effectiveness of the radio broadcast itself
Yes. Buildings and hills already do this quite significantly anyway. They're effectively RF scavengers that dissipate their captured energy as heat.
Sure we could put the antennas on the surfaces of these things so the effect is no worse that it was anyway. But the space available for that it limited and it's so widely distributed that wiring them all up would be quite costly. To be more effective you'd probably have to build walls of them - blocking some of the radio signal from reaching receivers beyond the wall.
the above would be more along the lines of no cost or free energy because it uses the heat produced by our sun.
but it can use any heat source , maybe we could even wear them to power our devices because we emit heat.
Solar power isn't free energy.
We can already get electricity from the sun. This is just and improvement on that. It's still not free energy. Not no cost either. Somebody has to produce the nantennas just like somebody has to produce solar panels today.
We can also generate electricity from the wind. We don't have to pay for the wind, it's just free! But that's not what free energy means either.
