User:Jesrad/AtmosphericElectricity

A potential but controversial and at most very experimental power source for seasteads could be atmospheric electricity. The principle is very simple: electrical potential rises at 100 to 300 V per meter of altitude from the ground, so tethering a balloon with conducting wire would bring this wire to a potential of up to millions of Volts, and connecting this wire to one end of a transducer and the other end to the sea or ground would make it possible to obtain useable electrical current directly, with no moving parts and no fuel. It can be thought of as a continuous, controlled St Elmo's Fire.

Where does this electricity come from ? There are two explanations: one is that the solar wind rips electrons from the top of the atmosphere (ionosphere), inducing a potential difference between the top and the bottom of it. Another is that this potential difference is created by the "pumping" effect of stormclouds everywhere over the planet, until locally discharged through lightning. This permanent charging through electrostatic "pumping" is considered an important part of the atmospheric electrical circuit. The top of the atmosphere, being at very low pressure, is conductive and equalizes the high electrical potential across the whole planet, so any device that taps into this potential energy reserve would work everywhere within the same conditions, and this reserve would be shared between different such devices regardless of their respective positions.

Why isn't it already in wide use ?

• The tethers are a hazard to aircraft, complicating the already heavily regulated domain of air transportation.
• The current density (in Amperes) obtained from such a device depends on its resistivity and its electrical potential (which itself depends upon its altitude). The potential goes down as electricity is drawn from the device, reducing the current density down to the point where an equilibrium is reached: at that point there are as many electrons flowing through the tether as there are air molecules being ionized by the balloon element. There are numerous techniques for improving the ionization capability of a static conductor, which mainly involve increasing its surface electrical field: the use of very thin wires, which have a high surface/volume ratio, is one of those techniques.
• The tether has to be thick in order to conduct any useful current density: this makes it heavy, which means the balloon has to be bigger (=more expensive) and necessitates more maintenance with increased scale.
• The balloon is just as suceptible of being damaged by bad weather as any dirigible and blimp, so winds and storms limit the useability of this method of power generation (as with solar and wind power).
• Oleg Jefimenko estimates that a single fine point can draw a millionth of an ampere: designing a balloon ionizer / collector for higher current density can be challenging.
• Altitudes over 200 meters charge the wire at potentials above 20000 V, which require adding electrical insulation material around the wire and anything it connects to, in order to avoid energy losses from unwanted ionization at the bottom end of the device.

An alleged benefit of this kind of power generator is that it discharges stormclouds and reduces the risk of lightning strikes.