Marstal Fjernvarme was in need of a new lid for their Pit Thermal Energy Storage (PTES) system, as the original lid was damaged due to moisture accumulation resulting in a significant heat loss. Since installation, Aalborg CSP's unique lid design has contributed to an increase in the plant's solar energy share from 45% to 55%.


Client:       Marstal Fjernvarme
Location:    Marstal, Denmark
Status:    Operational
Technology:     PTES lid
Area - PTES lid:     10,000m2
Expected lifetime:     25 years

The new diffusion-open and sectionized lid design prevents accumulation of air, water and moisture inside the insulation and enables safe and efficient dewatering. Besides an increase in the solar energy share from 45% to 55 %, Marstal Fjernvarme has gained a full-automatic plant which requires a minimum of maintenance and supervision.

The turnkey project in Marstal included design and installation of the complete lid solution including design of diffuser, liner work, installation of control system, electrical connections as well as installation of a rainwater pump system. The project was carried out by Arcon-Sunmark, but Aalborg CSP has since then acquired all know-how and intellectual properties related to the PTES technology.