Proof of Concept and Dimensioning
A district heating system supplies hot water from a central heat source (e.g. combined heat and power plant) to multiple buildings via a network of pipes. In order to increase the proportion of renewable energy sources used for heating buildings, solar thermal collectors can be used to capture solar radiation and transfer it to a heat transfer fluid. The difficulty with solar energy for heating is that the heat supply, mainly occurring in the summer months, does not line up with the heat demand of the winter months. One potential solution to overcome this challenge is storing the heat won during the summer months in deep boreholes.
Deep borehole energy storage technology is not yet ready for the commercial market. However, multiple examples exist worldwide to investigate the potential and increase the efficiency of these storage systems. Sizing and calculating a seasonal energy storage system has multiple levels of complexity: e.g. time and location dependent weather data and building heat consumption, subterranean heat dissipation from the energy storage, as well as the effects of heat pumps and control systems. In order to move this technology forward to being ready for market, the system as a whole and its potential for improvement needs to be investigated and understood.