A wind entrepreneur wrote to me last week pointing to the increased variability of wind speeds over the UK. Until recently, he wrote, average monthly wind speeds only very infrequently departed more than 30% from the norm from the month. In the last year, however, he said that we’ve had two months of very high speeds (more than 30% greater than the monthly average) and one very low speed period (30% less than the average for the month). This matters; greater variability of output from wind turbines means more need for backup resources.
Does the data match the entrepreneur’s instinct that variability is increasing? A quick look at average wind speeds since the beginning of 2001 argues it does. The average month now varies about 13% from the norm, up from 9.5% in 2001. This isn’t a large amount, and the data doesn’t suggest a very clear trend, but if variability is increasing it will add to future problems balancing UK electricity supply. And higher winter wind speeds will cause more destruction, as they did over many parts of the UK in February of this year.