|Cost of electricity.
The cost of one kilowatt-hour of electricity:
Coal 5 cents. Natural gas 5.1 cents. Wind 5.3 cents. Nuclear 5.4 cents.
Solar, 23 cents.
Figures are in US dollars, and are probably bsed on either USA or European
figures, and thus would not, no doubt, reflect the true situation in Australia.
Source: National Geographic August 2005.
Wind tower size.
Generally in Australia, the tower is 70 metres high and the blades
25 to 50 metres long.
Source: AusWEA promotional document.
A tower 180 metres high with a 60 metre blade is being developed in
Source: National Goegraphic, Augut 2005.
The 'standard' seventy metre tower currently generate a rated 1.5 to
1.8 megawatts. With improvements in technology, thgis is being increased.
The efficiency however is around the 30% level which man that the actual
power generated is around 0.6 megawats. (The German development above is
expected to generate a rated 5 megawatts.)
Source: AusWEA promotional material.
The blades rotate at aboput 10 to 25 revolutions per minute. The wind-tip
speed can be up to 215 km/h. The prefered wind speed is from 14-90 km/h
- below 14 km/h the turbine generation is shut down as it is 'not worth
the wear and tear' on the generator, and after 90 km/h the turbine automatically
shuts down 'for self potection'.
Source: AusWEA documents. Note that zero revoloutions is not quoted
as the blades need to turn even without wind to minimise wear, and in so
doing draw electricity from the local grid. The shutting down of the turbine
is independant of the need for the blades (and hence the connecting gears)
to keep rotating at a slow speed even when there is little or no wind.
Wind energy targets.
AusWEA (Australian Wind Energy Association) has a target of 5,000 mgawatts
of wind energy to be installed in Australi by 2010. They note that this
is only 6% of the total electricty need. At slightly improved technbology,
this equates to some 2,500 wind turbines.