Update: At 12:35pm National Grid ESO cancelled the CM notice.
At 11:34am National Grid ESO has issued a Capacity Market (CM) notice for this afternoon, with the margin set to fall below the set threshold.
The notice is to commence at 4pm today (Thursday 3 December) as the margin has fallen below 500MW, the buffer the operator uses to secure supply.
It noted that the Transmission Demand and Operating Margin was at 46,017MW, while the aggregate capacity of Balancing Mechanism (BM) units expected to be just 46,303MW.
On twitter, National Grid ESO added that “while we have enough #electricity generation to meet demand, a capacity market notice has been issued for this evening".
“It doesn't mean that there’s a risk to supply; it only means that the buffer of 500MW above our forecasted demand & operating margin has been eaten into.”
This follows low winds and falling temperatures causing power prices to spike dramatically just last week on the evening of 26 November, reaching over £300/MWh. This event also caused National Grid ESO to warn of tight margins.
The ESO also put out an Electricity Margin Notice on 4 November as it predicted a shortfall of 477MW, and in September issued a Capacity Market notice warning after the margin had dropped below its 500MW threshold.