The National Grid issued a surprise supply warning for Tuesday evening saying that UK capacity was close to being reached, as temperatures dropped and people returned home.
A notice of “tight electricity margin” was sent out warning of a potential shortage from 7pm, saying that the buffer of spare capacity will narrow.
The warning was issued for the evening time when demand tends to increase, as people return home from work and outside temperatures drop, and revealed that the grid is struggling to match demand with supply.
The National Grid soon dropped the warning as contingency plans kicked in, but industry experts warned it was a sign of “much tighter days ahead”.
“The notices are intended to be a signal that the risk of a System Stress Event in the GB electricity network is higher than under normal circumstances,” the National Grid said.
Warnings are issued when “there may be less generation available” than operators expect will be needed “to meet national electricity demand”.
Phil Hewitt, director at Enappsys, said: “This is the first tight day of the winter but it is not super tight. It is a small appetiser of tightness, there will be much tighter days ahead.”
A cold spell has hit the UK this week with colder-than-normal temperatures, forecaster Maxar Technologies LLC said in a report.
Minimum temperatures will be as low as 3ºC in London and 1ºC in Newcastle on Tuesday, which will drive up gas and power demand before temperatures rise again next week.
As winter bites, temperatures will drop further and there is also a drop in the amount of wind power generated.
The nation is going into the coldest months of the year with its tightest supply buffer for seven years, and National Grid Plc has modelled the risk of power cuts in the event of a gas shortage that would restrict supplies to power stations.
That has prompted it to pay hundreds of millions of pounds in utilities to extend operations at highly polluting coal plants that were due to shut permanently this year.
Wind power output was as low as 3,958 megawatts around noon on Tuesday, compared with more than 10,000 megawatts a day earlier.