An application of seasonal borehole thermal energy system in Finland

Abstract

Borehole thermal energy system is an important component of the future low temperature heating networks. Applications of such systems are available around the world presenting various configurations. However, the mobility of the system from solar assisted to industrial heat has not yet evaluated. A 3D model of borehole thermal energy system created similar to Drake landing solar community project configuration. This model is validated with experimental measurements. The accuracy of the model estimated at 95%. Experimental measurements further utilized to create an artificial neural network model to predict modes of operation (charging/discharging). The accuracy of the model calculated at 97%. This study presents a possible application of storing excess heat from combined heat and power plants in Sodankylä, Finland. The municipality of Sodankylä is planning construction of new combined heat and power plants. These plants systematically shutdown during summer season leaving 1.53 ​MW of excess heat. The heat surplus can be stored in a heat storage. Simulations reveal that the model has storage capacity between 250 ​kW and 285 ​kW. In addition, there is a potential of five borehole thermal energy storage to store the entire excess heat. The novelty of the study is to test the mobility of borehole thermal energy system from solar assisted storage to industrial excess heat storage. The model used in a standardized manner considering the conventional combined heat and power plants supply temperature for working configuration of heat storage.

Keywords

• borehole Thermal energy storage
• 4G district heating system
• 3D model of ground heat storage
• Artificial neural network model
• Low temperature heating network