CoolIP index                                                          Most recent edit: Tuesday November 20, 2012

* See legal note below.


The Ground as an AWES Hub

Many of our best AWES ideas emerged early, but take years to understand in the simplest most direct way. The "GroundHub" POV below is a typical case. Once we do see clearly, the leap in progress is exciting.


Many AWES schemes involve kites going around a carousel, circular track, or cableway. These can be seen as true turbines, in the sense that the ground surface itself becomes a megascale hub structure. This sort AWES "groundhub" has the golden advantage of megascalability, with no added mass aloft. Large hubs also favor direct generation of electricity by high-speed motion, by impinging the generator load at the rim*.

The problem is, this is a vertical axis hub, and we know that an ideal windpower axis is oriented along the wind direction like a HAWT. We have at several solutions at hand. The most common and trickiest idea is to fly kites along the circle in complex orbits, with phases for power and recovery of upwind distance. KiteLab developed Whipple-Tree approach with lines and pulleys to allow the tilting of the entire circle of kites to better face the wind, as a sort of autogyro. Its been shown that circling kites can be cross-linked by lines to integrate them, for reduced mishaps and control requirement. A kite arch spanned over a kite-turbine, or even an array of them, can allow kite turbine operation square to the wind.

A major variant is a generating ground-hub much like a classic rotary engine, but driven by radiating pumped lines from adjoining kite fields. All kinds of kite-pumping schemes (rotary or oscillating) can feed-in power in-phase. This maximizes the ground structure portion and minimizes need for steel and concrete structure. Land and airspace efficiency can also be maximized. Kite farms like this may be an optimal gigascale AWES configuration for true utility-scale generation.

CoolIP**            ~Dave Santos               Nov. 20, 2012                        AirborneWindEnergy/message/7975

* To answer a recent Forum question- Impinging a load on a wheel rim is mechanically practical and efficient (gear principle). Powered land vehicles operate nicely by this principle. Ground hub ideas scale the wheel to unprecedented sizes, with impinged generators easily brought to bear.

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