In the end, the solar eclipse did not cause the electricity grid to flicker. The early drop-off in solar generation was manageable, just as the National Energy System Operator (Neso), the state-owned body responsible for keeping the lights on, predicted. Gas-fired generators still had to be paid nose-bleed prices to fire up, and power via high-voltage interconnectors to continental Europe was also expensively sourced. But the system worked.
A summer of heatwaves, however, has highlighted European grids’ reliance on those interconnectors – including seven between the UK and the continent – in an age of extreme weather and greater use of intermittent renewables. On Thursday, another low-wind “heat dome” day, a fifth of power to the British grid was coming from the continent at 10am. Cables from France alone were meeting 11%, or 3.54 gigawatts, of demand, or more than twice as much as the output at that time from the UK’s entire fleet of windfarms.
The economic appeal of interconnectors is obvious: cross-border transfers should boost security. For Britain, as on Thursday, it can sometimes be cheaper to source from the continent, especially from France’s nuclear-dominated system, than use domestic gas-fired generation. And on sunny windy days when the UK’s renewables are producing a surplus, the flow can be in the other direction. Over the course of a full year, the UK currently imports roughly a tenth of its electricity.
The politics, on the other hand, have rarely looked messier. Neso cut off exports to the Netherlands at short notice during the now-famous evening of 23 June; an investigation continues into what, precisely, happened when the British grid was below its operational frequency limits, albeit not its statutory ones, for almost two hours. Meanwhile, the FT revealed last week (£) that Neso ordered wholesale market traders not to export power via four interconnectors in the day-ahead market during several hours in July to ensure Britain had enough electricity.
“The impact of Neso redispatching interconnectors close to real time can cause trouble, especially for smaller markets like Belgium and the Netherlands,” says Phil Hewitt, a director at the energy market specialist Montel. It is why the contractual setup was altered in May to limit late changes in direction on six links with Belgium, Denmark, France and the Netherlands to no more that 300 megawatts per cable. Peter Atherton, an independent energy analyst, says: “The UK is potentially seen as the weak link in the European system.”
One could regard the summer heatwave tensions as temporary. Demand for air conditioning has soared; heat affects the efficiency of gas-powered turbines; hotter rivers are not good for cooling French nuclear reactors. And the summer is when some generation capacity is taken offline for maintenance ahead of winter.
Yet deeper political tensions were apparent before the summer. Norway, with its massive hydro power, has banned more interconnectors after a consumer backlash over higher domestic electricity prices. A planned 1.4 gigawatt cable to Peterhead in Scotland, replicating the capacity of the existing North Sea Link cable with the UK, was scrapped by Oslo in 2023.
And a big possible threat on the horizon – barely discussed in the UK – could come if Marine Le Pen, ahead in the polls, wins next year’s presidential election. Her far-right National Rally party wants to pull France out of the European Union’s cross-border electricity system that is closely integrated with the UK’s. French energy companies are horrified; Le Pen argues local consumers would pay less.
“There would be price rises for UK consumers and questions for security of supply if the National Rally gets in in France and implements their policy,” Hewitt says. “Mainstream parties in Norway and Sweden are increasingly anti building more interconnectors – they’re saying ‘enough is enough’. If there is no more build-out and France says ‘we’re not going to send you any of our electricity’, the position looks more dicey.” Scaremongering? “It is an edge case, but political risk is there. Populism can cause trouble.”
Note that the Norwegian and French links are the critical ones. Cheap power typically flows into Britain via those cables all the time, whereas connections with Belgium, Denmark and the Netherlands are more two-way. “You do have to be careful that you are not overly reliant on interconnectors because it can make you vulnerable,” argues Hewitt. Put another way, Neso cannot control the politics at the other end of the cable.
In the medium to long term, the position should improve with the rollout of new renewables and nuclear generation capacity. Sometime in the 2030s, Britain should switch from being a net importer to a net exporter of electricity.
The shorter term, though, is another matter. Energy systems across Europe have become more complex, renewable generation is more decentralised, intraday price swings are more extreme. Balancing supply and demand has become harder.
Out of that mix, there is potential for energy nationalism to intensify. It is hard to dispute Atherton’s statement of political realities: “It is a fundamental fact of democratic life that no country will export power if it means potential blackouts in its own cities. It would be electoral suicide, whatever contracts you have in place.”
We’re not there yet. For the time being, pan-European cooperation still looks intact. But the politics of interconnectors have been a theme in many of this summer’s energy stories. Tensions are rising. Solar eclipses are easier.
