This is the eight in a series of posts that look at GB Wind Power, in particular at its ability to contribute to peak demand, which occurs in the early evening, reaching its highest values during winter cold spells. This post shows estimates for how much wind power would be produced if the 2016/17 wind generators encounter the weather conditions of the winter of 2007/08. Of particular interest is the wind power produced on the coldest evenings, quantified via the increase in minimum reserve capacity relative to a hypothetical no-wind system.
Data at 30-minute intervals for demand and “Estimated Embedded Wind” was downloaded from National Grid and used to estimate “Residual Consumption” and total wind power (both metered and embedded) at 2016/17 levels. “Residual Consumption” is the name given here to the sum of demand and embedded wind, and represents the consumption not met by other (non-wind) distributed generators. Metered wind power for 2016/17 is estimated by scaling up the embedded wind data to the typical levels seen for metered wind in late 2016. Embedded wind is scaled-up according to its total capacities in 2007/08 and 2016/17. See the NATIONAL GRID DATA page of this blog for a discussion of the accuracy of these estimation techniques.
The figure below shows the daily peak “Residual Consumption” (in red) and the estimated 2016/17 total wind power (metered plus embedded), for the winter weather of 2007/08:
The figure above shows the expected characteristics of GB wind power in winter 2016/17: it will be intermittent, it will be small compared with peak demand, and on some days it will almost vanish at the time of peak demand. To see the amount of wind power at the times of highest peak demand the data are plotted again in the figure below, with an arbitrary offset of 62 GW applied to the demand data. The 62 GW offset is indicative of how much dispatchable power was needed in 2007/08 to meet peak demand. The figure also shows the mean temperature of the Central England Temperature (HadCET) series:
The figure above shows mostly mild and windy weather, and that there were 2 cold (and relatively calm) spells, one in mid December that produced the highest demands, and a shorter one in February. The consumption data shown in the figure above has been demodulated, with the following figure showing the December cold spell in more detail:
To show more clearly the contribution of wind power to peak demand the following figure shows “Reserve Capacity”, for the arbitrary (though not unrealistic) choice of 63 GW of dispatchable supply, with and without the contribution of wind power:
The figure above shows that wind power at 2016/17 levels would provide an extra 0.9 GW of reserve capacity, a low figure relative to the total wind power capacity of around 15 GW. The figure above shows how wind power fails to achieve a substantial increase in reserve capacity: the high consumption day of 17th December benefits strongly, but the low wind day of 21st December does not.
The lowest reserve days
The following figure shows the half-hourly weather conditions measured at Cambridge for the entire cold spell in December:
The following synoptic charts for 20th and 21st December 2007 show that the cause of the cold air was a High pressure area near Scandinavia, bringing in cold continental air in a moderate Easterly wind:
Conclusions will be drawn elsewhere on this blog