>>509930566The amount of energy per unit distance in the sky is so small that the tower to extract a meaningful quantity makes it prohibatively expensive.
You'd have to piggyback off of an existing structure like a radio tower and the free energy there would only power a tiny bit, and barely even pay for the equipment to extract that power.
A windmill with 5 foot blades up there turning a crank produces more power, which is why the people who want power use that before trying to extract a few watts and volts from the fact that chaifing on the atmosphere produces a current.