One might want to try a lesser height and do so in good weather. Why isn't everyone on to this!!!??
Good question, the e-field gradient is real and as you say free for the taking, however there is a catch. It is a result of "static" electricity (think Van Der Graaf Generator).
Electrical generators in use for power generation today use moving magnetic fields crossing wire coils to induce an electric current in the coils of the generator and because of the low impedance of the circuit, relatively large currents can flow.
Static electricity is the result of air currents which result in "sorting" charged particles into regions of largely negative particles and regions depleted of negative particles leaving them with a net positive charge. These regions are separated by air which is an insulator and represents a high impedance allowing high voltages to develop. In a thunder storm voltages can build to millions of volts but even on a clear sunny day voltages can build to hundreds of volts per meter above the surface. Ten thousand volts is unable to flash over (as lightning) because of the impedance of the air itself.
In sum, our power grid has a low impedance allowing large currents to flow. Static electricity exists in a high impedance environment and develops high voltages. If you tried to connect the static electricity to lets say and electric motor, the low impedance motor would draw almost no current from the high impedance environment (Ohm's law). Without current flow the motor generates no magnetic fields to speak off and it does not turn. The same can be said for electric lights and other low impedance devices that depend on current flow to do their jobs.
Not to worry, all is not lost. Motors that we use today depend on the interaction of magnetic fields (the result of current flowing) which cause torque and subsequently rotate the output and do useful work. It is possible to build a motor that utilize the interaction of electrostatic fields (where + repels + and attracts -, instead of N repels N and attracts S). Now the deal breaker...
Because we are dealing with a high impedance environment, even though we have very high voltage available we get very little current flowing through our electrostatic motor. So what? Well it happens the power output from a motor is represented by the product of voltage and current (watts). Static electricity is not going to work to provide useful power output.
There are niche applications where static electricity may find a home, the electret microphone comes to mind. I have also witnessed logic cards in a servo controller working (half assed) with the logic power disconnected. Trouble shooting the card found that it was trying to run on a static charge.
I hope that makes it clear...
Regards,
GtG
Well that just ruins “The Next Big Thing”.