Before we harness it can we just figure out the mechanics first? 

 that is necessary first step, really, it's just the question of what you can do to create a massive positive electrostatic charge on a material so when a conductor is connected to a negative charged object the current jumps through the conductor and you get your discharge 

 yeah, damp ground is important, as is carbon levels, as both increase conductivity

but i think the hard part is how to make something that has the required positive potential at the upper end of your conductor

it obviously can't just be another capacitor, because that's what is at the other end, you see what i mean?

needs to be some kind of device that induces a massive positive charge somehow, or some material that you can induce this state repeatedly or cheaply

i mean, think like, why does wool carpet and many kinds of polyurethane rubber when rubbed, pull electrons out of the rubber and then discharge when you touch earth?

whatever this rubbing process entails, how can i get that passively, how can i make an electrostatic adsorbing surface dump all its electrons so it can suck them up from somewhere

the key would be how you can bootstrap that process, because i'm pretty sure you could make it run overunity so long as you aren't pulling more up than is down there