Here's that patent on the USPTO site:
Why that's not the default behavior though...
His idea for ultra-efficient high-voltage, high-frequency AC power lines is a good example. It would probably work, but his proposed system required liquid insulation on the wires; it would be important to keep gases out of the medium, and the slightest break in a solid insulation like rubber or silicone (or gutta-percha) could basically turn the wire into the business end of a tesla coil.
So...I don't understand enough about the subject to say for sure, but we probably landed on 50-60Hz for a reason. I wonder why this one didn't wind up working out, but I'll bet it's described somewhere in the application which I've only skimmed.
Also, for anyone else trying to dive into it, 'condenser' = 'capacitor' in olde-speak.
It is similar with the choice of 3 phases for electrical power distribution, you can add more phases but it just adds to the cost with little benefit.
AC is used because it's very simple to step up to very high voltage for efficient long distance transmission and then back down to safer low voltages for use, while doing the same with DC requires significantly more complex electronics.
However, at very low frequencies you need to use very large transformers which cost a lot and look ugly, and at higher frequencies you lose efficiency due to skin effect .
50 Hz is a good compromise - transformers are of a practical size and skin depth is about 9 mm, which is larger than most conductors and therefore doesn't add much loss.
If you increase the frequency to just 10 kHz (which is still considered very low) the skin depth decreases to only 0.6 mm, and you would have significant loss on even moderate sized conductors.
Jeez, when it comes to electricity, it is just like peeling an onion with layers of ignorance...
My guess for the frequency, is that it is a harder conversion to perform with acceptable loss. Compatibility reasons doesn't allow for just bumping it up. Also let's not forget that AC frequency actually comes from the revolutions per second the power generator does, so there may be some other physical limiting factors here.
Last, some underground high power transmission lines are actually emerged into oil, to keep them cool.
I'm pretty sure that's the minimum to prevent perceptible light flicker.
Including "The attenuation of ELF waves is so low that they can travel completely around the Earth several times before decaying to negligible amplitude, and thus waves radiated from a source in opposite directions circumnavigating the Earth on a great circle path interfere with each other. At certain frequencies these oppositely directed waves are in phase and add (reinforce), causing standing waves. In other words, the closed spherical Earth-ionosphere cavity acts as a huge cavity resonator, enhancing ELF radiation at its resonant frequencies."
Does anyone have a technical explainer of Tesla in modern terminology?
Edit: sorry, I see you probably mean the content of the patent rather than the passage you quoted
Come to your own conclusions, but there's evidence that it was a hoax: https://en.wikipedia.org/wiki/Nikola_Tesla_electric_car_hoax
Hobbyists have been using the idea for years to run small radios.
Likewise that same ground current will screw up Telegraphs (etc) which try to use an earth-return path.
The problem for large scale energy harvesting is that the Earth is conductive, so any voltage differences are shorted out by the Earth itself and dissipated as heat.
To put it another way, the Earth is a lossy medium, so any signals are heavily attenuated by distance.