User:Randerson110/High Altitude Wind Power

High Altitude Wind Power refers to systems and devices for wind power generation at heights that exceed those achieved by traditional tower mounted wind turbines, which today is approximately 100m. Typically such a system involves a tether rather than a tower for mooring the system to the ground. The concept is more general than an Airborne wind turbine as the method for power extraction may involve tethered free flying wings, airfoils, or kites, in addition to more traditional turbines in which the airfoils are fixed around a rotating hub.

The primary motivation for pursuing high altitude wind power is that the wind has higher speed and blows more consistently at higher altitudes. The power that can be extracted from the wind is proportional to the cube of the windspeed, such that a doubling of windspeed can produce 8 times the power for the same swept area. Recent analyses of global windspeed data spanning over 20 years suggest that higher altitude winds are also more constant, thereby mitigating the intermittency problem which reduces the economic and practical attractiveness of traditional windmills. This same research also suggests that, while more constant than ground level winds, high altitude winds are nevertheless not entirely constant, either, and so should likely not be considered a form of baseload or dispatchable power.

High Altitude Wind Resource Characterization
Archer and Caldeira's work here.

Power Extraction Device Concepts
There are many concepts for devices to extract power from high altitude wind. These can be categorized by some defining characteristics of the designs. First, the generators may either be located on the ground, or may be "on board" the device at altitude.

Textile/Solid Lift/Drag

Companies Developing High Altitude Wind Power Devices
Makani Sky WindPower Magenn Joby Energy WindLift SkyMill KiteGen

Practical Considerations and Common Concerns
Discussions of these concepts and devices inevitably raise a number of common questions and concerns regarding their practicality. Here we attempt to present the best technically sound arguments both for and against the practicality of deploying such devices.


 * What about collisions with airplanes?

Air traffic safety is certainly an important consideration in the design and implementation of high altitude wind power devices. It is instructive to consider other situations which require the coordination of safe air travel and avoidance of high altitude objects.


 * What if a tether breaks?


 * What about adverse weather conditions like storms and lightning?


 * What about all the birds that will be killed?