Winter supply could be nearly constrained as last year, Grid warns


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.

The NG-ESO’s Winter Outlook prognostications are here.  The service provider welcomes participants’ views, emailed by the end of this week to


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