An elevator/skip that is driven by the Earth's electric field.

[al onestone]

I consider the possibility of an elevator that is driven by the Earth's electric field. The jist of my idea is as follows;

The Earth's electric field is roughly 150 Volts/meter directed radially downward towards the Earth. This fades away as you get further from the surface of the Earth. The Earth's surface is negatively charged and the ionosphere is positively charged.

In order to use the Earth's electric field, E, to levitate/elevate an object, the object must be charged up with a net static electrical charge. The net charge, q, must be negative so that the Lorentz force, F, gives the object upward motion in accordance with the relation,

F = qE

For a Silicon object of dimensions 1m x 0.1m x 0.01m (weight 2.3kg) we require a net electric charge of 0.15 Coulombs (electrons). This is a lot of charge.

Practical limitations;

The Earth's electric field will dissipate near a grounded tower (like a building) so the whole elevator device needs to be insulated from ground.

The high charge requirement causes an electrical discharge at a specific "breakdown threshold" that is relatively low for air, so the whole object must be insulated (possibly emersed in oil).

Should the object be conducting or semiconducting or insulating (like the belt in a Van der Graaf)?

Theory;

To electrostatically charge a conducting object with a DC voltage supply follows the capacitance model, C=Q/V and C=(dielectric constant)*(surface area of plates)/(distance of separation of plates), or the self capacitance model, C=4pi*(dielectric constant)*(radius of surface)
So in order to minimise the demand for a large voltage in the charging circuit we need to maximise the surface area. Does it make sense to have a conducting sheet with a large surface area that is layered so that it all fits into one small volume, or does the charge only collect on the highest and lowest sheet in the stack?

[Kelly_Bramble]

Does it make sense to have a conducting sheet with a large surface area that is layered so that it all fits into one small volume, or does the charge only collect on the highest and lowest sheet in the stack?

No, it does not make sense...

[Timelord]

conducting sheet with a large surface area that is layered so that it all fits into one small volume

He is describing a capacitor. The charge collects all over the surface.