Europe is watching the skies for a gremlin that can roil its energy markets and stoke political tensions between neighboring countries. This weather phenomenon, known as the Dunkelflaute, has become a source of frustration to government ministers and a potential pitfall on their journey to cleaner energy.
A German term that translates to “dark doldrums,” Dunkelflaute refers to a spate of calm days when dense clouds descend over northern Europe. This weather pattern may occur two to 10 times a year, usually in the fall and winter, and lasts 24 hours or longer.
In the past, these spells of murky quiet would have made little difference to energy markets in Europe. But in recent years, as countries like Germany and Britain have spent billions to tackle climate change by shifting to cleaner sources of energy, the Dunkelflaute has gained notoriety.
A generation ago, Europe relied on steady, predictable flows of energy from nuclear and fossil fuel plants. Now, much of the region’s power comes from solar arrays and wind farms, whose output varies with the whims of the weather.
Advocates of wind and solar power stress that these technologies have lower costs because they do not burn gas or coal, but they can contribute to large price swings in the marketplace for power.
During the gloomy stillness of a Dunkelflaute, solar panels produce little power and wind turbines slow to a halt. Without these two mainstays of renewable energy, grid operators need to call on backup power plants like natural-gas-fired generators.
The cost of running these power plants is higher, which drives up prices when renewable sources are falling behind, said Steve Moody, trading director at Conrad Energy, a power trading company in Abingdon, England, that supplies electricity to the grid through batteries and other sources. “You will see high prices in periods of scarcity,” he said.
During a stretch of low wind in mid-December, for instance, British power prices briefly jumped to 485 pounds per megawatt-hour, well above an average of about £70 over the last year, according to Drax Electric Insights, a website that tracks power.
And Germany has suffered a particularly gloomy fall and winter this year, with electricity production down more than 5 percent compared with the same time the previous year. A Dunkelflaute in mid-December caused electricity prices to jump to 14 times their average.
Because a Dunkelflaute can blanket several countries at the same time, its effects can ripple through much of northern Europe, putting pressure on power systems. A Dunkelflaute in early November led to price surges in Denmark, the Netherlands and Belgium, as well as in Britain.
These weather systems often occur when the temperature is cold, testing the capacity of the power grid because affected countries may draw large volumes of gas. A Dunkelflaute, which can last several weeks, “can have potential impact on security of supply,” said an official of Britain’s National Energy System Operator during an industry webinar held this month to discuss their effects.
The growing use of renewable energy can also lead to times when wind and solar generation outpaces demand, leading to extremely low prices — a potential boon to consumers (but a problem for investors in power generation who may see lower profits than expected).
But attention has lately focused on the downsides, specifically that high power prices in countries like Germany and Denmark can spill over into markets like Norway’s and Sweden’s, straining relationships between neighboring countries.
To help ward off events like the Dunkelflaute, European neighbors have linked their power grids through a network of cables, often laid under the North and Baltic Seas. These conduits are intended to share power surpluses — like those that at times arise from Norway’s hydropower riches — and address deficits. The intent is to ensure sufficient supplies and smoother prices.
Earlier in this decade, for instance, a cable was constructed to bring Norwegian hydropower to Britain during quiet wind spells, while sending surplus wind energy the other direction.
A web of such cables now exists, and energy experts say more will be needed.
But even the strategy of sharing power comes with a drawback. When a power-hungry country like Germany sucks large volumes of electricity from its Scandinavian neighbors, this interconnected system can drive up the prices in the exporting countries, angering consumers.
“When there is no wind, we get high electricity prices with this failed electricity system,” Ebba Busch, Sweden’s economy minister, wrote in a post on social media.
Ms. Busch also blamed insufficient electricity and resulting high prices in Germany on Berlin’s decision to shut off its nuclear reactors last year, despite an energy crunch in the country caused by Russia cutting off natural gas supplies as part of its dispute with the West over the war in Ukraine.
Some power-exporting countries are threatening to turn to protectionism to buffer their citizens. Politicians in Norway have cast doubt on continuing to operate cables that bring Norwegian hydropower to Denmark, while Sweden has postponed building a second cable to Germany. In France, officials of the far-right National Rally party have also proposed curbing electricity exports from the country’s fleet of nuclear power stations.
The high recent prices have “created this kind of political backlash against cables,” said Amund Vik, a former Norwegian deputy energy minister and now a senior adviser to Eurasia Group, a political risk firm. Yet “the European energy system needs integration to be secure, as you do the energy transition” he added.
Analysts like Mr. Vik are skeptical that there will be a major retreat from the interdependent European power market that has been constructed over decades. But the friction may complicate the shift to cleaner energy. And with several more months of winter ahead, the next Dunkelflaute could be right around the corner.
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