Airborne Wind Energy systems

Ground-gen pumping

The most common device type is the intermittent generating solution, also known as ‘pumping’ or ‘yo-yo’

The airborne element is tethered to the ground at a fixed location. Kinetic energy of the air is converted to a force seeking to reel out the tether. The tether is allowed to extend by turning a drum connected to a generator, either directly or via hydraulics or similar. 
Operation consists of two phases: 
– The energy-producing (traction) phase, where the device extends the tether, and so generates electrical energy. 
– The recovery phase, where a smaller amount of electrical energy is used to pull the airborne element back to a lower height. 


The flight path of the device (and hence force on the tether) is controlled, taking advantage of crosswind motion to increase the energy produced in the traction phase and minimise the energy consumed in the recovery phase. 
Devices tend to follow either a helical or a translating figure of eight pattern. There may be more than one airborne element per ground-station (or foundation), with shared use of some components, enabling more continuous generation.


Onboard-generating devices are tethered to the ground at a fixed location. In normal operation, the tether is fixed length. The power conversion equipment is onboard the device, with one or more rotors driving generators. Power is then transmitted back down to the base station via the tether. The airborne element flies crosswind to augment the inflow. Motion may be circular or in a figure of eight: 

Ground-gen rotary

This device is fixed to the ground andconcept uses multiple aerofoils which are (usually) kept in the wind through a lifter kite, in modular rotors. The rotors connect together with tethers to rotate the structure. By keeping the tethers in tension, the rotation is transmitted to a ground station generator through torsion.  

Ground-gen pumping systems

Fly-gen systems

Ground-gen rotary systems

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