Aalborg CSP received an order from Dronninglund Fjernvarme to deliver a new lid solution for the district heating plant’s Pit Thermal Energy Storage (PTES) system. The new durable and operationally stable lid design enables dewatering and vapor diffusion contributing to higher efficiency and reliability.


Client:       Dronninglund Fjernvarme
Location:    Dronninglund, Denmark
Status:    Operational
Technology:     PTES lid
Area - PTES lid:     8,260 m2
Expected lifetime:     25 years

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

Accumulation of water in the insulation layers had caused irreparable damage to Dronninglund Fjernvarme's original Pit Thermal Energy Storage (PTES) lid. The district heating heating plant therefore searched for a new long-term solution that would ensure operational stability. The new durable and operationally stable lid solution from Aalborg CSP, which is certified by Lloyd's Register, handles air, water and moisture accumulation in an efficient way.

A diffusion-open construction allows for vapor to diffuse through the upper liner above the insulation. The lid is furthermore divided into nine sections for improved rainfall handling. Each section is designed with a slight fall towards the center where a pump directs the water away from the surface of the lid. These unique design features minimize heat loss as well as increase the efficiency and reliability of the complete energy system. 

Re-using material reduces environmental footprint

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. 


Andreas Zourellis
VP Sales - International
District heating / industrial solar technologies
Phone: +45 50 30 00 25 
E-mail: azo@aalborgcsp.com