In Høje Taastrup, Denmark, the green transition necessitated a reduction in heating costs. The potential for harnessing renewable heat sources and improving the efficiency of district heating water was identified through heat storage and reuse. This project is part of Denmark’s extensive efforts in thermal energy storage (TES), with a particular focus on Tank TES (TTES) and Pit Thermal Energy Storage (PTES) technologies. 

The PTES in Høje Taastrup is a 16-meter deep, 70,000 m³ thermal storage unit functioning as a thermal battery with a capacity of 3,300 MWh. This thermal battery is charged by heat from the transmission grid and discharged into the district heating network when heating demand increases. Heat is stored when the price is low and utilized later when prices rise, enabling pricing to range from as low as EUR 4 per kWh to less than EUR 1 per kWh. The PTES solution from Aalborg CSP efficiently prevents air, water, and moisture accumulation inside the insulation, enhancing storage efficiency, reliability, and long-term durability. 

This reservoir is a prime example of efficient and flexible sector coupling between the electricity and heating sectors. It showcases a solution that not only benefits the climate but is also cost-effective for consumers.