Aalborg CSP received the order to design and deliver a 11,000 m2 insulating lid for a 70,000 m3 integrated Pit Thermal Energy Storage system in Høje Taastrup near Copenhagen, Denmark. The patented lid design prevents accumulation of air, water and moisture inside the insulation in an efficient way increasing the efficiency and reliability of the storage and ensuring long-term durability of the storage.
Tailor-made lid solution for large-scale, low temperature energy storage
Aalborg CSP received the order from the two Danish utility companies, Høje Taastrup Fjernvarme and VEKS, to design and deliver a 11,000 m2 insulating lid for the parties 70,000 m3 Integrated PTES system currently under establishment in Høje Taastrup near Copenhagen, Denmark. The purpose of the PTES lid is to minimize the heat loss inside the PTES. The lid solution from Aalborg CSP is based on the development of a durable technology, which ensures stable operation over the lifetime of the project.
The integrated PTES project in Høje Taastrup is an example of flexible and efficient sector coupling of electricity and district heating.
The PTES in Høje Taastrup is a thermal storage functioning as a thermal battery with a capacity of 3,300 MWh. The thermal battery is charged by heat from the transmission grid and discharged to the district heating network when the demand for heating increases. The heat is stored, when the price on heating is low and is utilized later on, when the price for heating increases.
With the unique solution from Aalborg CSP, Høje Taastrup and VEKS will benefit from a PTES solution with a lid that prevents accumulation of air, water and moisture inside the insulation in an efficient way. The PTES lid helps increase the efficiency and reliability of the storage and ensures long-term durability of the storage.
Lid design reduces heat loss and boost the efficiency of the PTES
The lid solution, which will be installed in Høje Taastrup is based on a new and patented design developed with primary focus on making a bankable investment and removing risks in the design, operation and maintenance conditions, which a PTES will be exposed to throughout the lifetime of the system.
The purpose of the new design is to address and solve the problems and challenges as well as minimizing the risks, which are typically experienced during the installation and operation of a PTES. This design improves the quality and reliability of PTES systems, contributes to lower heating bills for the consumers and adds flexibility to the energy system.
The lid solution from Aalborg CSP differs from traditional PTES lids in a number of ways, which controls internal vapor, external rainfall, automatic ventilation and lid insulation.
The unique design features of the new lid include, among other things, a diffusion-open top cover construction. This allows for vapor to diffuse through the upper liner above the insulation rather than accumulating inside the construction. The diffusion open cover therefore improves the insulation ability of the PTES and reduces the heat loss inside the storage.
Moreover, the lid is divided into sections for improved rainfall handling, which makes it possible to drain the surface of the lid safely and efficiently with a minimum of ongoing maintenance. Each section has an inward fall towards the storage center, which leads rainwater away from the surface of the lid. The inward fall on each section furthermore allows for air pockets, that would otherwise develop underneath the lid construction, to be led away.
The 11,000 m2 lid in Høje Taastrup is divided into 10 sections and thus includes 10 pumping wells, which will lead rainwater away from the surface of the storage.
These unique design features minimize the heat loss inside the PTES and is contributing to increased efficiency and reliability of the complete energy system.
A full-scale version of the new lid design has been tested at Marstal Fjernvarme. In Marstal, the new lid replaced the original one, which was of a previous design and damaged due to moisture accumulation inside the lid construction. This replacement has resulted in a full-automatic operation with a minimum of maintenance and supervision.