Capacity Market Notice triggers National Grid warning system

31st October 2016 | Commercial Energy

The End of British Summer Time (BST), or more specifically, the Capacity Market Notice (CMN) has triggered the National Grid warning system: the capacity market notice has been used for the first time as clocks change and unexpected outages put extra pressure on the UK power network: traditionally the week in which the UK moves back to Greenwich Means Time (GMT) is one of the tightest for electricity supplies.

The CMN is used to warn power companies to keep a closer eye on the energy market because the gap between supply and demand was narrowing. Ofgem, the energy regulator, also permitted the activation of another measure, the Supplemental Balancing Reserve, 24 hours earlier than planned.

The SBR involves the grid paying dormant power plants to become operational again during winter, in case they are required to boost the UK’s power supply: its activation is understood to have been prompted by unexpected outages when plants began firing up for winter.

Industry analysts said the actions did not signal the likelihood of winter blackouts, but warned that they were a symptom of an energy crunch which will probably increase household bills.

The Eggborough coal plant in North Yorkshire was among generators charging up to £1,500 per megawatt hour for electricity at short notice, compared with average prices of about £50/MWh a day in advance.

CMNs are issued automatically, four hours ahead of when the grid’s excess capacity is forecast to fall below 500MW. This threshold is over and above the standard capacity margin safety net the grid maintains in order to ward off power cuts. But the notice indicates concern that the gap between supply and demand is falling below the level the grid would like.

The week when the UK moves back to GMT is traditionally one of the tightest for electricity supply, because the darker evenings mean people use more power. The changing of the clocks also coincides with a period in which plants that have been offline during the low-demand summer months are yet to fire up again in readiness for winter.

More information available on the website below