The application, filed for in June 2011, notes that most contemporary wind turbines convert kinetic energy from wind into mechanical energy, or in some cases electricity. Basic windmill technology is well known: wind energy is asserted on a mill's sails or blades and is converted into rotational energy through a drive shaft, which then powers machinery or, more recently, electric generators. It is apparent that the process is dependent on a steady supply of wind which, as Apple's filing notes, is highly variable.
In some embodiments, heat is generated from the friction created between blades connected to the rotor shaft and the low-heat-capacity fluid, such as mercury, ethanol or an inert gas, in which they are immersed. Thermal energy is stored in an insulated vessel. A thermally insulating component like a radiator or conductive rod can be used to selectively transfer heat from the low-heat-capacity fluid to the working based on electrical demand. Finally, the working fluid boils and creates steam which rotates a turbine connected to an electric generator.
Whether Apple plans to deploy such a wind turbine system is unclear, but Cupertino is investing heavily in alternative energy sources like solar and natural gas "energy servers," as seen at the company's Maiden, N.C. data center.