Magenn's MARS prototype

Wired takes a look at several companies working on high altitude wind turbines: ranging from floating, kite-like devices tethered to long power cables to quaint-looking power-generating flying machines.

The devices are very diverse. Magenn‘s helium-filled devices resemble floating kites; Sky Windpower has a ‘controlled helicopter’ with four rotary blades keeping it suspended. Kite Gen’s devices describe a figure eight in the air.

There’s no doubt the wind is stronger at high altitudes, and the devices would take up less ground space, perhaps avoiding one key objection to wind turbines. The attractions are many:

Wind’s power — energy which can be used to do work like spinning magnets to generate electricity — varies with the cube of its speed. So, a small increase in wind speed can lead to a big increase in the amount of mechanical energy you can harvest. High-altitude wind blows fast, is spread nicely across the globe, and is easier to predict than terrestrial wind.

Companies also claim the devices would pose less of a threat to avian life, and emit lower noise pollution than regular wind turbines.

But they’re not without drawbacks.