Techno-economic analysis of fifth-generation district heating and cooling combined with seasonal borehole thermal energy storage

Abstract

Fifth-generation district heating and cooling (5GDHC) is a promising solution to decarbonise future thermal energy systems. This paper investigates the potential of 5GDHC integrated with borehole thermal energy storage (BTES) in unlocking the synergies between heating and cooling via a bidirectional thermal network. A model for system design and operation simulation of 5GDHC is developed. In a case study, the proposed 5GDHC supplied by BTES facilitates the long-term balancing of heating and cooling demands despite the poor simultaneity between them. This enables 5GDHC to achieve overall advantages over modern heat pump driven systems, including lower levelized cost of energy, less greenhouse gas emission, higher exergy efficiency, and lower electricity peak load. One possible barrier of adopting 5GDHC is the high upfront cost, which mostly attributes to borehole drilling and booster heat pump installation. Demand scenarios with varying heating and cooling demand structures are analysed and show that the ratio of cooling to heating substantially affects the economic performance of 5GDHC coupled with BTES. When cooling to heating ratio is within the optimal range of 0.4–1.0, 5GDHC reaches lower levelized cost compared with modern heat pump driven systems and present-day gas-fired heating systems.