From Jan Meulendijk
Hadrian Jeffs repeats what one reads over and over again: that wind turbines are shut down at wind speeds over 25 metres per second (3 December, p 25).
I have always wondered why this is necessary. From my sailing days I clearly remember the variable-pitch propeller. This goes into “vane position” for sailing, just like the rotor blades of wind turbines when turned off. Progressively adjusting the pitch of the blades as the wind speed increases above a certain level would effectively reduce their rotational speed – presumably to within acceptable limits, even with very much higher wind speeds – while maintaining power output.
I would expect there to be more noise from such blades set this way, but given the noise generated by the wind itself at those speeds, that would probably not be audible anyway. So what’s the catch?
Haverfordwest, Pembrokeshire, UK
