Back to top
Back to all articlesBack to all articles

National Grid Issues Warning Over Tight Electricity Supply


The National Grid Electricity System Operator (ESO) has cautioned that the balance between power supply and demand will be close this evening and has called for more generating capacity to be made available.

The latest squeeze on the country’s electricity supply’s is due to the availability of fewer-than-anticipated generators at peak time and projected forecast low output from renewable resources.

Tom Edwards, analyst at the energy consultancy Cornwall Insight, also attributed the shortages to lower-than-expected imports through interconnectors, the subsea cables through which the UK trades electricity with Belgium, France, Ireland and the Netherlands.

The ESO said that the electricity supply is not at risk and that blackouts aren’t likely. However, it is calling on the market to mobilise more capacity to increase its buffer.

National Grid ESO tweeted yesterday evening: “While we have enough generation to meet demand, we have issued an electricity margin notice (EMN) for tomorrow [Wednesday] evening. This is a routine signal that we send to the market to indicate that we would like a larger cushion of spare capacity.”

This is the second time in the last two months that the ESO has taken the unusual step of warning the market that power supplies are tight.

In mid-October, National Grid issued a similar caution, after a lull in wind impacted renewables’ contribution at the same time several gas, coal and biomass plants became partly or wholly unavailable due to unexpected outages. 

Supplies were even tighter in September, triggering an automatic warming to the market that the cushion between supply and demand had fallen below the standard 500MW threshold. It was the first time that buffer had been breached since November 2015, when a string of coal-fired power stations experienced breakdowns.

In both September and October, the power supply made it through the pinch point unscathed. But supplies will continue to be tighter throughout the winter than in previous years, largely due to planned outages at the Dungeness and Hunterston B nuclear power stations.

This winter National Grid anticipates having a 4.8GW cushion of extra electricity, or 8.3% of total supply. This is smaller than the 7.8GW cushion it had during the winter of 2019-20 but still well within the reliability standards prescribed by the government.

The effects of a second lockdown, predicted to dampen electricity demand, although likely not by the 20% seen in the spring, will spare the country winter blackouts. Without the predicted drop in demand, supply margins would have shrunk to 5.9% of supply, narrowly above the 5.1% recorded in the winter of 2015-16, when National Grid was forced to ask businesses to limit their electricity consumption.

Lauren Smith
Lauren Smith

Lauren Smith has worked as a journalist and copywriter for most of the last decade, covering technology, energy, and consumer rights, in the US and UK.

Read all articlesRead all articles