[127361]

Well the ground is creating that exact opposing electric field anyway. If trees were planted to the same height as the wire, then the loss to the electric company is the same.

He's just in effect increasing the height of the ground slightly and tapping the potential difference. You might as well park a car underneath it, attach a wire between the body and ground, and get same or better results, because the surface area is larger (capacitively coupled).

[ThrowawayTestr]

It's not, you're increasing the total resistance felt by the line. There is no free energy.

[tankenmate]

My point wasn't "there's no free energy", of course the energy has to come from somewhere. But transmission lines have parasitic loss anyway. My point is that rather than that energy being lost to the environment generally it can be directed to a specific circuit and used. Obviously though this is a much much lower amount of energy than can be "actively" harvested.

[ThrowawayTestr]

Any amount of harvesting increases losses.