> Zero emissions, silent, no illumination, etc.
Mostly silent. High voltage transmission lines may have a low-frequency hum. You have to stand directly under them to hear it though.
Which you would, if they were crossing over your house. Probably not worse than many other mundane things though.
There's a high-voltage line that crosses over a park (with soccer fields etc...) near me, and you can hear it crackling whenever you're there. I'm sure it's a noisy radio environment.
Over time as some dirty coats the insulators, and on high humidity days some kind of crackling is clearly audible in a fairly wide radio close to the towers.
Also, transmission towers are usually the best lightning rods for miles in a given location, and it is fucking unsettling to live close to them during storms. Not to mention they are an eye sore.
I was looking at buying a house with big transmission lines crossing over the property. It was a misty not-quite-raining day when I went to look at it, and you could hear the lines crackling and humming the whole time you were outside. I figured I’d have to give up ham radio if I moved there, ha.