Nuclear and gas generator outages expected this winter could once again push availability over Britain’s power backbone to expensive short-term peaks, National Grid-ESO foresees.
Issuing its Winter Outlook Early View, the operator anticipates a base case de-rated margin of 4.3 GW, equivalent to 7.3% of peak demand forecast for any putative average cold spell (ACS) at 59.5GW.
Upper and lower scenarios will fall roughly 2GW above or below that de-rated base, the operator calculates. All three scenarios fall within the government-set Reliability Standard of 3 hours LOLE ( loss of load expectation).
Honouring the recently deceased Donald Rumsfeld’s known knowns, the Grid cites long-term anticipated winter outages at CCGT spinners Sutton Bridge, Severn Power and Baglan Bay, as well as at nukes Dungeness B and Hunterston B.
Positives in the same category are more interconnector capacity than in 2020-21. The IFA2 to France which debuted last winter, and the new NSL to Norway will both be available, the second after October.
Known unknowns possibly triggering worst cases – and thus highest day ahead prices – include unexpected cold snaps during ‘shoulder months’ entering or exiting the season.
In the tightest case, a margin of 3.1 GW or 5.3% of anticipated peak could arise from two large generators being offline throughout the winter, or a combination of one big outage and higher demand. Such constraints would be unprecedented since the Capacity Mechanism began delivering capacity in 2017-18.
The NG-ESO anticipates Britain’s emergence from lockdown means no repeat of the 3% to 4% fall-off in demand seen last winter.
Prices leapt last winter to record highs, including January to March’s prolonged, wind-less cold spell. Day ahead trades hit almost £1,500 per MWh. On 8 January the Balancing Market set a record of £4,00 per MWh.