Reducing losses in district heating storage at scale in Høje Taastrup

OUR IMPACT

A contract has been awarded to design and deliver a large-scale lid solution for a 70,000 m³ pit thermal energy storage (PTES) system in Høje Taastrup, Denmark. The storage is part of an integrated district heating system serving a large urban area.

The lid covers approximately 11,000 m² and plays a central role in the overall system performance. Its primary function is to minimise heat loss and ensure stable operation over the lifetime of the storage.

The design addresses one of the key challenges in PTES systems: managing moisture, air and external conditions. The solution includes controlled handling of vapor, rainfall and ventilation, ensuring that insulation performance is maintained over time.

At system level, the storage acts as a thermal battery with a capacity of around 3,300 MWh. Heat is stored when production costs are low and released when demand increases, supporting flexible and efficient operation of the district heating network.

The project demonstrates how engineering of critical components—such as the lid—directly affects the viability of large-scale thermal storage. By reducing heat loss and operational risk, the solution contributes to making PTES a more reliable infrastructure asset.

The design builds on prior full-scale testing and operational experience, where improved lid construction has already shown reduced maintenance needs and better overall system performance.

WHY IT MATTERS

Thermal storage performance depends on details. Well-engineered lid solutions reduce heat loss, lower operational risk and improve the long-term viability of large-scale storage systems.

This article was originally published under Aalborg CSP and has been editorially adapted for Aalborg HCS.