Dronninglund Fjernvarme required an upgrade of their existing PTES system containing a less reliable lid solution. As water accumulation within the insulation layers proved to be unrepairable, the district heating plant searched the market for the ideal solution to solve the challenges. After a public tender with a special focus on re-using as much of the previous insulation as possible in order to reduce the environmental footprint as well as the cost for the heat consumers in Dronninglund, Aalborg CSP was awarded the contract.

Low-cost, high-quality lid for scalable low-temperature energy storage

For the project, Aalborg CSP is applying their Lloyd’s certified PTES lid and energy storage solution, which meets all necessary requirements in terms of design and functionality as well as sustainability.

The lid solution to be installed in Dronninglund enables dewatering and vapor diffusion ensuring lower heat loss in the PTES and contributing to higher efficiency and reliability of the complete energy system. A diffusion-open construction allows for vapor to diffuse through the upper liner above the insulation rather than accumulating inside the construction. The lid is furthermore divided into sections, which addresses and solves issues with water ponding in case of rainfall, air accumulation, and thermal expansion.  Each section is designed with an inward fall towards a pumping well at the center, which ensures the removal of water.

Re-using material reduces environmental footprint

Given the background for the new PTES solution in Dronninglund, a large amount of old insulation was suitable for reuse and as such it was possible for Aalborg CSP to recycle these materials in the best way and provide the district heating plant with a cost-effective and sustainable solution. Hence, a key element within the offered solution became cost optimization and re-integration of the old insulation material.

Aalborg CSP’s unique lid solution was also used at another Danish district heating plant (Marstal Fjernvarme), where it replaced an original, damaged lid. The replacement resulted in a full-automatic operation with a minimum of maintenance and supervision. Likewise, the heat loss inside the PTES was reduced, thereby increasing the efficiency.