This is the ninth 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 on working days. 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 2008/09. 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” were 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 2008/09 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 2008/09:
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 winter 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 60 GW applied to the demand data. The 60 GW offset is indicative of how much dispatchable power was needed in 2008/09 to meet peak demand. The figure also shows the mean temperature of the Central England Temperature (HadCET) series:
The figure above shows that there were alternating spells of mild and cold weather, with a long cold spell during, and for a week after the Christmas/New Year holiday period. The consumption data shown above has been demodulated, the following figure shows the important 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 60 GB of dispatchable supply, with and without the contribution of wind power:
The figure above shows that total wind power at 2016/17 levels would provide an extra 1.0 GW of reserve capacity, a low figure relative to the total wind power capacity of around 15 GW.
The lowest-reserve days
The following figure shows the half-hourly weather conditions measured at Cambridge for the entire cold spell in December/January:
The following Met Office weather summary confirms that some days of this period had light winds across England:
26th to 31st December: A return to very cold, but mostly dry conditions. Easterly winds developed, ushering in some very cold low-level air from the continent. Initially, cloud amounts were variable and most places saw some decent sunny spells, but there were sharp frosts night and morning. With time, cloud amounts tended to increase, and as winds fell light, freezing fog became more of a problem and night frosts became locally severe. With fog and low cloud persisting all day towards the end of the year, many places on the 30th and 31st had daytime maxima below freezing including -2.6 °C at Shap, and -3.6 °C at Keswick. Night minima included -9.6 °C at Shap and -7.2 °C at Woodford (Greater Manchester).
The following synoptic chart for 31st December 2008 confirms the widespread light winds:
Conclusions will be drawn elsewhere on this blog, taking account of all winters.