Reducing heat loss in district heating storage systems in Dronninglund

OUR IMPACT

A contract has been awarded to upgrade an existing pit thermal energy storage (PTES) system in Dronninglund, Denmark. The project addresses a critical issue: failure of the original lid construction due to moisture accumulation in the insulation layers, which led to irreversible damage.

The solution focuses on replacing the lid with a redesigned, certified system while reusing as much of the existing insulation as possible. This approach reduces both cost and environmental impact, while restoring the storage’s functionality.

At the core of the upgrade is an engineered lid solution designed to control moisture, prevent heat loss and ensure long-term structural stability. Certified by Lloyd’s Register, the design supports reliable operation over a projected lifetime of around 25 years.

The project was awarded following a public tender with a strong emphasis on cost efficiency and technical reliability. The selected solution combines both: a robust design that addresses known failure mechanisms and an approach that minimises material replacement.

The storage system is part of a broader district heating setup serving around 1,400 consumers. With a capacity of approximately 5,500 MWh, the PTES acts as a central buffer—balancing heat production and demand across the network.

WHY IT MATTERS

Many early thermal storage systems face performance issues over time.
 This project shows how targeted upgrades—especially lid design—can restore efficiency and extend asset lifetime without full replacement.

This article was originally published under Aalborg CSP and has been editorially adapted for aalborg hc systems.