Life Cycle Assessment and Cost Analysis of Medium Deep Borehole Thermal Energy Storage in District Heating Systems

Abstract

Seasonal thermal energy storage in medium deep borehole heat exchanger arrays is a very promising technology for increasing the share of sustainable heat sources in district heating grids, while minimizing the thermal impact on shallow aquifers. However, the integration of a medium deep borehole thermal energy storage system is highly dependent on its interaction with other heating components in the grid. Furthermore, the construction of medium deep borehole heat exchangers is accompanied by additional environmental burdens and large capital expenditures (CAPEX). Hence, their contribution for the mitigation of greenhouse gas emissions as well as the financial implications induced by medium deep borehole thermal energy storage systems are not quantified yet. In order to pursue these questions, an economic and environmental assessment tool has been developed, which is based on a life cycle approach (Welsch et al. 2018, Welsch 2019). It is able to consider different district heat generation options including solar thermal collectors, combined heat and power plants, conventional gas fired boilers and MD-BTES systems. Numerous district heat generation options are analysed under different economic and environmental boundary conditions and reveal the potentials of MD-BTES systems in future district heat production.