Recently I came across this quote on the internet, about a person who apparently set up devices to extract electricity from the "air", on his own property:

> 
> I read an article a couple of years ago about this very thing, Someone
>  had lined the edge of their property with devices to capture bleed-off
>  from the transmission lines and was using it to power the house. They
>  were able to cut power bill to less than 10% of normal and the power
>  company sued them and won. It is illegal to "harvest" unused power
>  from transmission lines. I don't know if the same would apply to
>  radar/radio/etc... I would do some checking before I spent a lot of
>  money on equipment.
> 
> 
> 

I'm not interested in the legal side of things, but I'm wondering if one set up a device to extract energy in this way, will this method simply be scavenging energy that would otherwise be wasted, or is he somehow stealing the energy that would otherwise be used in the transmission lines?

Please explain the physics behind your response.