Blaze affecting vital subsea cable hits backup energy supply cushion, adding to industry troubles
Last modified on Thu 7 Oct 2021 04.01 EDT
The risk of winter blackouts has increased after a fire affecting a key subsea cable further eroded Great Britain’s backup electricity supply cushion, already diminished by the shutdown of gas plants and nuclear reactors.
The National Grid’s electricity system operator, ESO, said the “de-rated margin” – the amount of excess capacity that could be called upon if needed – was expected to be 6.6% or 3.9 gigawatts (GW).
That would be higher than the margins seen in 2015-16 and the following year. But the ESO said a worst-case scenario, such as multiple power plant outages, low wind speeds, and a bitterly cold winter, could cause the margin plunge to just 4.2%, or 2.5GW.
That would be well below the 5.1% it forecast in 2015, before a notoriously difficult winter when National Grid was forced to ask businesses to reduce their electricity usage to keep the lights on.
With margins likely to be tighter than the Grid would like, it expects to issue a similar number of electricity market notices to last year, when it sent six of the official pleas to energy suppliers to increase the amount of electricity they make available.
The ESO took the unusual step this year of issuing an early version of its Winter Outlook, its annual assessment of Great Britain’s electricity safety net.
It said at the time that the margin could fall to 5.3%, owing to the retirements of the Dungeness B and Hunterston B nuclear power stations and shutdowns at the Baglan Bay, Severn Power and Sutton Bridge gas power stations.
But its worst-case scenario has worsened since September, when a large fire affected the IFA high-voltage power cables importing electricity from France. Half of the 2GW cable is expected to be unavailable until March.
Despite the downgrade, National Grid said there was no risk of blackouts as a result of the tighter margin.
Fintan Slye, the executive directive of ESO, said: “The Winter Outlook confirms that we expect to have sufficient capacity and the tools needed to meet demand this winter. Margins are well within the reliability standard and therefore we are confident that there will be enough capacity available to keep Britain’s lights on.”
However, speaking at an event hosted by the Financial Times on Wednesday, the National Grid chief executive, John Pettigrew, said the gap between supply and demand could be smaller than in recent years.
Tighter margins can lead to higher bills as the Grid faces the excess cost of paying energy suppliers more for extra supplies to top up the backup margin.
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