A report out by the John Muir Trust is now officially saying, what a lot of us have seen to be patently obvious for some time. What took them so long.
PRINCIPAL FINDINGS in respect of analysis of electricity generation from all the U.K. windfarms which are metered by National Grid, November 2008 to December 2010. The following five statements are common assertions made by both the wind industry and Government representatives and agencies. This Report examines those assertions.
- “Wind turbines will generate on average 30% of their rated capacity over a year.”
- “The wind is always blowing somewhere.”
- “Periods of widespread low wind are infrequent.”
- “The probability of very low wind output coinciding with peak electricity demand is slight.”
- “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:
- 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.
- 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).
- 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.
- 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.
- 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.
The rest can be found HERE.