On Mon, 10 Jan 2005 21:40:37 +0100, peter wrote:

Hello,
The system earth-ionosphere is not a battery but rather like a
condenser. The electrical field strength is in normal times
approximately 100 to 150 V/m.
Thats great, would you say. Alas, the dielectric is to performing, too
good an insulator, and all you can expect is a columnal current of about
20pA/m^2.

Hi peter,

The US has a project called HAARP which charges up the ionosphere to
study it for communication & defence applications. If they find ways
of overcoming the insulative properties of the ionosphere and
discharging it, perhaps it might be a mass source of power.

Sadly I don't know enough to comment on how that might be possible.