Variability in North Sea wind energy and the potential for prolonged winter wind drought

The United Kingdom is committed to substantially increasing offshore wind capacity in its drive to decarbonise electricity production and achieve net zero. If low wind episodes-or 'wind drought' events-occur during high energy demand periods, energy security may be threatened without alternative supply. The challenge of managing the variability of wind power will increase into the future as its share in the energy mix increases. This study focuses attention on the North Sea as a centre of current and planned offshore wind resource, and on the winter season, given the occurrence of weather patterns that risk security of supply. We use a large climate model ensemble, providing a dataset an order of magnitude larger than the reanalysis-based observations, to better sample wind drought events. This leads to a more robust estimate of their frequency and persistence and their dynamical teleconnections compared with the observational record. We define week-long wind drought events, based on a 20th percentile threshold in 10 m wind speed, during which wind power is estimated to be around half that in a typical week of winter. Wind drought events of up to two consecutive weeks have been observed, but the model indicates a 1-in-40 chance of three or more continuous weeks of wind drought each winter, with the single most prolonged simulated event lasting 5 weeks. There is a doubling of the likelihood of these prolonged wind drought events during El Nino, indicating that monitoring and predicting the state of the tropical Pacific may be useful in assessing the risk of wind drought events in an upcoming winter.