The message
from David Hansen contains these words:

"Low wind speed conditions affecting 90% or more of the UK would
occur in around one hour every five years during winter;
The chance of wind turbines shutting down due to high wind speed
conditions is very rare - high winds affecting 40% or more of the UK
would occur in around one hour every 10 years."

Never trust politicians statistics. It doesn't take anywhere near that
extreme of wind conditions to cripple the power output from wind farms.
And stationary highs with very light winds over most of the country (as
at present) are a feature of the UK weather.

On the myth of wild fluctuations in wind output it has this to say:

"The most likely change in power output from a diversified wind
power system from one hour to the next is less than plus or minus
2.5% of the total installed wind power capacity. Larger changes from
one hour to the next do occur - a change in hourly output equal to
around plus or minus 20% of the installed wind power capacity is
likely to happen about once per year.

Rate of change in output is a red herring. What matters is the amount of
conventional capacity that has to be kept on standby and/or used to
produce the difference between wind farm capacity and actual output.

Has anybody got a figure for the actual average output of the current
wind farms as compared with their theoretical maximum?

--
Roger Chapman