Hostility to Wind Power

I'm OK with wind power. But here is a report commissioned by the Scottish John Muir Trust, a conservation society that apparently is hostile to wind farms, looking at some issues with wind power:

The following five statements are common assertions made by both the wind industry and Government representatives and agencies. This Report examines those assertions.

1. “Wind turbines will generate on average 30% of their rated capacity over a year.”


2. “The wind is always blowing somewhere.”


3. “Periods of widespread low wind are infrequent.”


4. “The probability of very low wind output coinciding with peak electricity demand is slight.”


5. “Pumped storage hydro can fill the generation gap during prolonged low wind periods.”

This analysis uses publicly available data for a 26 month period between November 2008 and December 2010 and the facts in respect of the above assertions are:

1. Average output from wind was 27.18% of metered capacity in 2009, 21.14% in 2010, and 24.08%
   between November 2008 and December 2010 inclusive.


2. There were 124 separate occasions from November 2008 till December 2010 when total generation from the windfarms metered by National Grid was less than 20MW. (Average capacity over the period was in excess of 1600MW).


3. The average frequency and duration of a low wind event of 20MW or less between November 2008 and December 2010 was once every 6.38 days for a period of 4.93 hours.


4. At each of the four highest peak demands of 2010 wind output was low being respectively 4.72%, 5.51%, 2.59% and 2.51% of capacity at peak demand.


5. The entire pumped storage hydro capacity in the UK can provide up to 2788MW for only 5 hours then it drops to 1060MW, and finally runs out of water after 22 hours.

...

During the study period, wind generation was:

• below 20% of capacity more than half the time.


• below 10% of capacity over one third of the time.


• below 2.5% capacity for the equivalent of one day in twelve.


• below 1.25% capacity for the equivalent of just under one day a month.

The discovery that for one third of the time wind output was less than 10% of capacity, and often significantly less than 10%, was an unexpected result of the analysis.

That is not very encouraging. I can report from personal experience that traveling on I-10 going through the San Gorgonia pass between Los Angeles and Palm Springs is quite a large number of wind farms and a disconcertingly large number of the windmills are "out of commission" at any given time. It has always puzzled me. I would think it is expensive to build these farms and to run them at a low utlization rate doesn't strike me as economically sensible.

Update 2011apr13: Here's a video of Tehachapi Pass which is north of the San Gorgonio pass I talk about above. But the video shows a similar condition: lots of idle windmills...



Here's a video of San Gorgonio pass: