Denmark’s Grid Hits Its Ceiling

A grey, windless day over the North Sea is no longer just a weather problem. In Denmark it has a name: dunkelflaute, the stretch when wind and solar production fall together across a wide area. For a country that has closed much of its domestic backup generation, those still days now mean pulling electricity through undersea cables from Sweden, Norway and Germany (Politiken). In 2025 Denmark imported more electricity from its neighbours than in any previous year (Portfolio.hu).

For Malta, the Danish case is worth watching because the mechanism is familiar. A small system can look stable until the cables, substations and emergency options are tested together. Denmark is testing a wider European assumption: that interconnectors can replace the power stations countries are retiring.

Denmark's grid is running out of room

Weather is only the first pressure point. Energinet, Denmark's grid operator, says data centres, hydrogen plants and battery projects have applied for grid connections totalling about 60 GW. That is roughly eight times Denmark's current peak demand (Energinet). Much of it is speculative, as companies file early and many projects will never be built. But even a fraction of those requests would strain a grid already unable to keep pace. Energinet has stopped accepting new transmission-level connection applications.

District heating shows the squeeze from the demand side. Around one in four Danish district-heating companies say their grid connections have been delayed or that they received less capacity than requested. The industry group Dansk Fjernvarme expects electricity's share in district heating to rise from about 10% today to 45% by 2035 (Via Ritzau). The equation is becoming harder: more electric demand, fewer domestic plants, and a grid with little spare room.

Who sells power, who pays for it

Europe's electricity market sends power from cheaper zones to more expensive ones through cross-border cables until those cables are full (European Commission). That works when the shortage is local. It becomes far less comfortable when the same weather pattern hits several countries at once.

France shows the value of keeping generation that can be switched on. In the first half of 2026, France exported a net 51 TWh, earning producers about €3 billion and generating roughly €1.3 billion in cable-usage revenue for RTE, the French grid operator (Le Figaro). France sold at an average of about €61.9/MWh. Importing countries paid almost double, around €111.6/MWh (Les Énergies Renouvelables). Nuclear power gives France dispatchable supply, and dispatchable supply becomes profitable when neighbours are short.

That does not mean French consumers are spared. Household tariffs will rise 2.5% on 1 August for about 19.37 million households (Challenges). Networks and backup capacity cost money even when wholesale prices fall. In the same six months, French wholesale markets recorded 407 hours of negative prices, when surplus electricity had nowhere profitable to go. The power may be cheap for those hours; the infrastructure is not.

Sweden shows a different distribution of gains and losses. Its grid is split into pricing zones, so southern regions closest to Denmark face higher wholesale prices when Danish demand pulls electricity across the border (GP). Swedish generators gain from selling into a tight Danish market. Swedish households in the same zones pay more. The Danish island of Bornholm has only 35 MW of guaranteed import capacity from Sweden, well below the cable's technical limit, because stress on southern Swedish grids limits what can be promised (Bornholm.nu).

Germany is paying for its own insurance. The Bundesnetzagentur, Germany's energy regulator, holds 7,407 MW of grid reserve for winter 2026/27: plants kept outside the normal market and switched on only in emergencies (Bundesnetzagentur). Berlin passed a capacity-market law in May 2026 that will pay power plants and batteries to exist and remain available, even if they rarely run. That is backup Denmark chose not to keep.

Finland points to the physical risk. When one of its two undersea links to Estonia went offline for repairs, prices rose and supply tightened immediately (Grivolt). A cable can be congested, under maintenance, or out of service precisely when it is most needed.

ENTSO-E, the body coordinating Europe's grid operators, runs continent-wide assessments of whether countries will have enough power during stress periods, because cross-border support is conditional rather than automatic (ENTSO-E, ACER). Denmark exposes the bargain underneath Europe's greener electricity system. Interconnectors lower costs in normal times. They do not guarantee power when wind drops across a whole region. Countries that kept plants they can switch on will set the price. Countries that trusted the cables may discover the bill in the hardest hours.