Large-scale geothermal collector systems as a heat source for 5GDHC in the U.S. – A case study of three different cities and climate conditions

To explore the ecological potential of large-scale geothermal collector systems (LSC) as a renewable heating and cooling solution for residential units in the U.S. West Coast finite volume simulations (FVM) were carried out. This study investigates for the first time in the LSC performance outside of Europe, demonstrating their significant potential for district heating and cooling solutions. However, it also reveals challenges in warmer climates where cooling requirements exceed heating demands. LSC systems here struggle due to increased soil temperatures, limiting their use for cooling, necessitating additional air conditioning. The FVM simulations also demonstrated that there is no supplementary soil dryness effect by using LSC systems. LSC systems paired with ground-source heat pumps (GS-HP) could reduce CO₂ emissions by 72 % to 81 % compared to conventional Heating, Ventilation and Air Conditioning (HVAC) systems with economic benefits for residents. The efficiency comparison with air-source heat pumps (AS-HP) revealed a climate dependency of which solution is more efficient. This research outlines the ecological potential of LSC systems in diverse U.S. climates, marking a step forward in sector coupling and decarbonization strategies.