50/60Hz harvesting ?

Has there been any progress in harvesting some energy from power mains radiation lately ?
Not RF, not thermal, not piezo, but the plain fields in the vicinity of megawatt power transmission lines.

What to expect from long barbed wire fences under/near transmission lines, rectified ? Several milliwatts ?

Maaany years ago I attempted toying a 60Hz tuned receiver (just coil and capacitor) under buzzing power lines but had no proper equipment to evaluate. Later, in conversations about the subject, seemed the tuning was not a necessary approach, just a plain long wire would suffice. Opinions ?

I am very undecided about this subject.

Against:
Where I am there are three wires overhead. The average voltage is zero. At a distance you should get a zero field. Up close one phase will dominate.
The three wires (4) change order regularly. If you had a way to get power from the right side wire, every 500 feet the wires change place and the next wire to be on the right side will be of a different phase. The phases add up to "zero".

for:
I used to live in a very rural place. (central/Northern Alberta Canada) Here the farmers often have one mile of fence under a power line. In Alberta I know of 10 miles of fence under very high voltage lines form a coal burning plant. In these rural places some people do not have electricity. I know one man why climes to power his house form the fence. He explained; he must keep a constant load on the fence to keep the voltage constant. I could see he had lights on all day and there was no low voltage power lines with in miles.

myth :
I really don't know it you can get power form the power line at a voltage high enough to be useful. My "aginst" comments make me think no. But I have seen it. Maybe I was fooled again.