Tuesday marked a busy day for National Grid PLC (LSE:NG.)’s system operating wing (ESO), as balancing the UK’s energy market became a straining task, burdened by cold weather and strikes in France.
As arctic winds gripped the UK, the ESO looked to shore up energy supply, exploring the use of a demand flexibility service, the balancing market and, of course, spare coal power stations.
Two of the UK’s five back-up coal stations, operated by EDF energy, were used for between six and seven hours each, complementing gas-power which provided over 50% of the UK’s power on Tuesday, as per ESO figures.
Some £4.64mln was spent on the balancing market during the day too, up 154% and 440% on Monday and Sunday respectively, as the ESO grappled to keep the lights on by paying generators to up production in real time.
The ESO paid Coryton power station in Essex charged as much as £1,950/MWh on Tuesday evening, up from an average of between £200 and £400, while bids were also accepted for power at £999/MWh and £750/MWh from other gas plants.
Although coal accounted for just 1.8% of the UK’s power mix, this was up from 0.2% and 0.3% on Saturday and Sunday.
Yesterday #gas generated 54.0% of British electricity followed by wind 14.2%, nuclear 11.3%, imports 9.1%, biomass 5.4%, solar 2.9%, coal 1.8%, hydro 1.3%, other 0.0% *excl. non-renewable distributed generation pic.twitter.com/Ge2XvHoid5
— National Grid ESO (@NationalGridESO) March 8, 2023
A supply scare had been prompted by colder weather, but also strikes by thousands of French power workers over planned pension reforms, leading the UK to up exports across the channel, under an agreement with its operator RTE.
How it happened
The ESO ordered the first of its five back-up coal power units to warm, at EDF’s West Burton A power station, just after 14:30 on Monday afternoon, anticipating tighter margins the next day.
Almost eight hours later, it issued an ‘electricity margin notice,’ prompting generators to alert it of any spare capacity they would have between 16:30 and 20:30 on Tuesday.
In the following hours, the operator ordered three further coal stations online, two at Drax Group (LSE:DRX)’s power station in North Yorkshire and another at West Burton A.
A demand flexibility service, offering households money off bills to slash usage, was then proposed at 10:00am on Tuesday for a day later, as tension built over the expected supply squeeze, later being cancelled at 14:30.
By this point, West Burton’s coal units were being synced to the grid, ready to produce a combined 520MW of power, with both being online by 14:50, likely prompting the ESO to cancel its margin notice just 25 minutes later.
The two coal units then helped to power Britain for over six hours until 20:45, at which point both were de-synced and switched off, the ESO told Proactive.
Drax’s stations were not used, it added, also being cooled on Tuesday afternoon.
The use of the back-up coal plants marks the first time the UK has had to call on its spare utilities this winter, kept open under the instruction of the government, anticipating supply shortfalls this winter.
Regulator Ofgem announced in February it was mulling changes for the balancing market, meanwhile, aiming to stem "excessive" benefits gained by generators selling power to the ESO at short notice, as reflected by Tuesday's shenanigans.