Vertical axis wind turbine

1. A vertical axis wind turbine comprising:

an upstanding support structure;

a generator disposed on the support structure;

a central shaft in rotatable communication with the generator and disposed along a central axis of the vertical-axis wind turbine;

a plurality of struts extending from the central shaft; and

a plurality of blades, each blade disposed at an end of a corresponding strut and oriented substantially vertically, each blade including an internal blade extension element and an internal pocket, wherein the blade extension element is operable to translate within the pocket relative to a trailing edge of the blade to lengthen or shorten a chord-length of the blade.

2. The vertical axis wind turbine of claim 1 , further comprising a central hub disposed between the central shaft and the plurality of struts and a bearing or other bearing component for supporting the central shaft.

3. The vertical axis wind turbine of claim 1 , wherein the support structure comprises a vertically-oriented support column and a plurality of stay cables or rods connected at an upper end of the support column.

4. The vertical axis wind turbine of claim 1 , said turbine comprising a plurality of said generators wherein each of the plurality of generators has a different rating.

5. The vertical axis wind turbine of claim 1 , said turbine comprising a plurality of said generators wherein each of the plurality of generators has the same rating.

6. The vertical axis wind turbine of claim 1 , further comprising a gear box disposed between the central shaft and the generator and in rotatable communication with the central shaft and generator for changing the rotational speed of the generators relative to the central shaft.

7. The vertical axis wind turbine of claim 1 , wherein each blade further includes an internal blade extension mechanism operable to extend and retract the blade extension element, the blade extension mechanism further including a linear actuator.

8. The vertical axis wind turbine of claim 1 , wherein the blade is a symmetric airfoil, with substantially the NACA0018 or NACA0025 shape.

9. The vertical axis wind turbine of claim 1 , further comprising an electronic control system operable to cause the blade extension mechanism to translate the blade extension element by a communicated distance.

10. The vertical axis wind turbine of claim 1 , further comprising a power management subsystem for capturing, filtering, and transmitting electrical power from the generator to a load.

11. The vertical axis wind turbine of claim 10 , wherein the power management subsystem induces a forward current in the generator when the measured wind speed is above a minimum speed required for the blades to rotate, but below the wind speed required to overcome a static friction exerted on the central shaft and the blades, the power management subsystem further induces a backward current in the generator if a tip speed ratio is above a predefined value, if the speed of the blades is above a nominal speed, or to maintain a predetermined optimal torque curve, the power management subsystem including a control circuit for making the generator act as a brake to slow or stop the shaft, the struts, and the blades.

12. The vertical axis wind turbine of claim 11 , wherein the power management subsystem includes a regenerative drive circuit for converting DC voltage into AC voltage and for recapturing electrical power when the control circuit is acting as a brake.