Underground Seasonal Heat Storage for a Solar Heating System in Neckarsulm, Germany

Abstract

In Neckarsulm in the south-west of Germany a new building area with approximately 1300 flats and terraced houses will be realized within the next 5 years. A solar assisted district heating system with underground seasonal heat storage is used for heat supply. A solar contribution of about 50 % to the total heat demand (space heating and domestic hot water) is planned. With this system a duct beat store with temperatures up to 80?C without heat pump is realized for the first time in Germany. Until now a system with 2.700 m2 collector area and a duct store with a volume of 20.000 m3 is built. The store consists of 168 Polybuthene-Double-U-pipes inserted in 30 m deep boreholes in a square pattern of 2 m. The stratigraphy at the location is sedimentary rock, different kinds of claystone in the upper layers and limestone underneath. First charging experiments were carried out sucessfully for validating a simplified computer model of the duct store. Further measurements will he used for the development of a calculation model which takes into account the combined heat and moisture transport in the Hound.