Wind generation in the UK during the summer of 2018

By Daniel Drew

The record breaking summer of 2018 has featured in a number of recent blog posts (link1 and link 2), but one area not discussed is the impact of the prevailing hot, sunny and calm conditions on the electricity system in the UK- particularly the level of wind power generation. I was able to experience this first hand as in the spring of 2018 I started a 1-year placement in the energy forecasting team at National Grid (as part of the UKRI Industrial Innovation Fellowships ).

Figure 1: The daily mean wind power output for Great Britain during the summer of 2018. Based on data from

The proportion of the UK’s electricity provided by wind power has been growing rapidly over the last 10 years from only 1.5% in 2008 to 17% in 2017 (more than double the amount provided by coal). Wind generation is typically lower in the summer months, in 2017 wind provided 12.9% of the UK’s electricity needs from June to August. Several media reports have speculated this figure will be a lot lower for 2018, however we have to wait for the official energy figures to be published by the Department for Business, Energy and Industrial Strategy to confirm this.

Initial data provided by GridwatchUK, suggests that between June and August this year the level of wind generation was generally low. Expressed in terms of capacity factor (energy production as a proportion of the theoretical maximum), the level of wind generation in the UK was approximately 19.0%. Additionally, there were several periods where generation was persistently low for a number of days. For example, from the 11th – 14th July the capacity factor of wind generation was below 10% for 74 consecutive hours.

Given the relatively short period of time the wind farms have been operating, it is difficult to place events like this into context using measured power output data. Fortunately, work carried out by University of Reading and National Grid  developed a method for creating a synthetic long term hourly time series of wind generation (1980-present) based on the current distribution of wind capacity. Using the data produced in this study, shows that while the summer 2018 wind generation is lower than 38-year summer mean of 21.0%, it is far from the lowest value in the dataset (16.6% based on the meteorological conditions experienced in 1983). Additionally, the period of persistently low generation experienced in July (74 hours below 10%) occurs on average twice per year across the 38-year period. In summary, based on the figures currently available, the level of wind generation during the summer of 2018 was lower than average but within the limits of a 38-year climatology.

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