District heating plants are among Denmark’s largest flexible electricity consumers. With large hot water tanks, they can store surplus electricity as thermal energy for later use. Additionally, electric boilers help maintain grid balance by quickly adjusting power consumption in response to fluctuations in the electricity system.
During springtime, solar power often drives electricity prices down in the middle of the day. This benefits district heating customers, as electric boilers are activated to produce low-cost hot water. But when, for example, a cloud covers a solar park and creates an imbalance in the grid, district heating plants can also respond swiftly.
Through participation in the balancing services market, Energinet can activate these plants to pause their consumption and help restore balance – until the cloud passes and solar production resumes. The same applies when wind production exceeds expectations: if wind turbines generate more power than the grid can accommodate, electric boilers can absorb the surplus, preventing energy waste.
Denmark’s green transition and electrification are ongoing efforts, with a continued need for more solar and wind capacity. However, increased renewable energy also introduces greater variability in production, often with rapid shifts throughout the day. Flexible electricity consumption is therefore critical to managing these fluctuations.
Today, the district heating sector is one of the most important sources of flexible consumption – until future technologies like Power-to-X can also contribute.
“District heating has a built-in advantage when it comes to balancing the electricity system – our pipes and storage tanks act as thermal batteries. We can absorb excess electricity when solar and other renewables are producing at full capacity, and we can shut down heating elements when a cloud dims solar output. In this way, district heating supports the power system with both balancing and storage – functions the grid wasn’t originally designed to handle,” says Michael Søgaard Schrøder, Chief Consultant at Dansk Fjernvarme (Danish District Heating Association).
Energinet welcomes the flexibility of the district heating sector and considers it a key player in the green transition. Kia Marie Jerichau, Head of Flexibility and Balancing at Energinet, adds: “At Energinet, we welcome all participants – large and small – and district heating is certainly in the premier league of actors driving the green transition and electrification forward. In recent years, we’ve seen a surge of interest in balancing the grid. In 2024 alone, the number of new market participants in balancing services increased sevenfold compared to 2023. And we need all kinds of contributors – greenhouses, public swimming facilities, even aggregations of charging electric vehicles. Imagination is the only limit,” says Kia Marie Jerichau.
Energinet currently spends DKK 2–2.5 billion annually on system services to maintain power grid stability.
