Windfarms and Birds

To: "birding-aus" <>
Subject: Windfarms and Birds
From: "Robert Inglis" <>
Date: Wed, 12 Apr 2006 12:47:14 +1000
Ref: Paul Taylor's posting Wed, 12 Apr 2006 08:25:54 +1000.

Note: I am not criticising Paul Taylor; I am simply commenting on a statement 
in the content of the
Paul is quoting from another source and I am suspicious of sources such as 

"The small turbines are dangerous to various raptors that hunt
  California Ground Squirrels in the area. The larger units turn slower
  and, being elevated higher, are less hazardous to the local wildlife."

I don't understand the reasoning.
If the squirrels can climb the towers then it wouldn't matter how high they 
I would have thought that tall towers would be more hazardous to birds, 
including raptors.
Larger turbines would have longer blades. Longer blades would probably spin at 
lower revolutions
than shorter blades.
However, the tip speed of longer blades would still be extremely high even at 
low revs.
I believe that the tip speed may be in excess of the speed of sound.
(Hence the noise problem.)
At such speeds the significant part of the blade would probably be 'invisible', 
at least to human
Perhaps they are also 'invisible' to the eyes of birds?
I would also think that the height of the tower has more to do with the length 
of the blades than
anything else and, no matter how high the tower, the tips of the blades would 
always be at about the
same minimum height from the ground.


Ref: "windfarms" posted by Terry Bishop, Tue, 11 Apr 2006 18:43:21 +1000.

Terry said:
"Located on Carcoar Dam, south of Orange NSW, Blayney Wind Farm is one of the 
largest in New South
Wales. The wind farm consists of 15 turbines. Each of these is 45 meters high 
with a rotor diameter
exceeding 45 meters. The capacity of each turbine is 660kW and the total 
generation of the farm is

Such a windfarm is, in my opinion, insignificant and is not a reasonable 
example to quote when
examining the issues involved.
Before wind generation of power could be considered viable in this country that 
farm would have to
be magnified several thousand times.
Imagine that!

Of course, the provision of windfarms will probably follow the same principle 
as that used in 'land
development': small windfarms will be installed at a regular rate spaced a significant distance apart;
these farms would then be expanded gradually until they join up in several very 
big farms covering
very large tracts of land. By the time the effect is really noticeable it is 
too late.

Bob Inglis
Sandstone Point
SE Qld


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