How turmoil in France exposed Britain’s delicate electricity supply
As households across Britain got on with their weekends, the mood in National Grid’s control room in Warwick was starting to darken last Saturday.
Just days before, forecasts for the week ahead had suggested healthy electricity supplies, well above requirements, to meet the country’s needs at the start of the week.
Yet as Monday drew closer, and weather and electricity trading patterns started to become clearer, doubts started to creep in. Workers at the electricity system operator [ESO] were no longer so sure that there would be enough electricity to meet demand and reserve requirements.
The outlook darkened for a number of reasons: temperatures were on the way to -2C in some parts of the country, with the wind looking not particularly strong.
Crucially, however, it was the situation across the Channel that forced the Grid’s hand.
Similar weather patterns abroad, combined with strains on France’s electricity system as a result of outages and strikes, meant electricity imports from abroad could not be guaranteed.
ESO decided to activate its emergency winter plans.
“[Britain] saw a clear reliance on interconnector capacity in order to meet our demand and reserve requirements,” a senior National Grid representative told industry this week.
“We weren't certain we could achieve this. We were also uncertain about generation availability in the cold weather.”
Over the weekend, night shift workers continued to assess the picture, and decided to act. At around 3am on Sunday morning, they asked Drax and EDF to get spare coal units ready.
The move marked the first step in a turbulent week for the electricity system, with National Grid ESO repeatedly turning to new contingency measures to shore up supplies.
For the first time, British households were twice paid to cut their usage during peak times, with an estimated 700,000 taking steps such as turning off the washing machine or delaying dinner.
In the end, the power supplies proved to be more resilient than feared, with buffer supplies healthy at all times.
But the turbulent week is a sign of the delicacy of the current electricity system, and the challenges of switching to a cleaner one.
“I think it's a sign of what the energy system is going to become in the future,” says Phil Hewitt, director at market experts EnAppSys.
“We have really cheap generation that is around a lot of the time, but then it isn’t at certain times, which means we then encourage everybody to switch stuff off or we have emergency generation that comes on at very high prices.
“Maybe in about five years' time we will have the weather forecast and the power forecast.”
The coal plants that have been warmed up three times this week were initially scheduled to shut down in September 2022 as part of the push away from coal to cut carbon emissions.
However, ministers asked them to stay open amid concerns about gas shortages due to Russia’s war on Ukraine and outages on France’s nuclear fleet.
The “demand flexibility scheme” in which households are paid to cut their usage at peak times was also introduced to the same concerns.
Gas shortages have not been the problem this winter, however. Gas-fired power plants supplied about 46pc of Britain’s electricity over the past week, albeit at a steep price.
Instead, weather patterns and activities across the Channel have turned out to be the biggest influence.
Britain is increasingly reliant on electricity imports from France and others under a long-term strategy intended to help balance out supply as the Grid shifts to greater reliance on more intermittent sources, namely wind and solar. Power cables now connect Britain to France, the Netherlands, Belgium, Norway and Ireland.
However, the trade cuts both ways and France can call on Britain for extra electricity too. Pressure starts to build when both countries are seeing higher demand.
It was around 1.30pm on Sunday lunchtime, that National Grid realised they would need to call on households to cut demand the following day after the outlook for imports for Monday became clearer.
France’s electricity demand is particularly high when the weather is cold as a result of the country’s widespread use of electric heaters. As in Britain, temperatures there dropped at the start of the week.
The situation was made worse by problems within France’s nuclear fleet, which left it with lower than usual output. Maintenance and corrosion problems left 14 of its 56 reactors offline on Monday and Tuesday.
“Our system operating plans for the evening peak showed a shortfall of generation when compared with operating margin requirements,” the senior National Grid worker told industry. “We went to the evening - that was the area that we felt was most at risk.”
In the end, Britain imported heavily from France and elsewhere during both periods when households were asked to cut usage, with generation on both sides healthier than expected.
“During the DFS event [on Monday] we were importing about 4.6GW -4.7GW which is not maximum but nothing unusual,” says Shivam Malhotra, consultant at market experts LCP Delta.
National Grid was not able to trade across the interconnectors to secure top-up imports from France beyond those secured by other traders, however, given constraints in France.
Strains in France were again felt in Britain on Thursday, however, when the ESO asked coal-fired power plants to warm for a third time. That came after a request from France’s grid operator, RTE, sparked by concerns that strikes in France would affect output there.
Workers across the country are protesting President Emmanuel Macron's plans to reform the country's pension system, which would see the retirement age pushed up by two years to 64.
EDF said its French nuclear output was down by 1,000 megawatts as of 3.45pm French time on Thursday amid the strikes, although the UK coal plants were ultimately not needed.
Help for France’s grid came a day after National Grid had to ask France and other operators for emergency assistance on Wednesday to help it cope with a network fault.
Britain’s own network is not without its issues. Generation has been cut by the closure of two major British nuclear plants this year.
Meanwhile, not enough cables have been built to move abundant electricity produced by new wind farms to where it is needed. National Grid was this week paying wind farms to stop generating even as it paid households to curb their supplies.
“These are increasingly concerning times for the security of our electricity supplies,” says Tom Greatrex, chief executive of the Nuclear Industry Association.
RTE stressed it had not asked for coal plants specifically to be used if it needed extra supplies, and noted the units had already been warmed that week for Britain's supplies, meaning National Grid effectively only had to keep them warm.
It added: "RTE's role is not to choose one method of electricity production over another; its role is to make sure enough electricity production is available to meet the needs of French consumers,"