New Large Geothermal Storage Project in Zurich, Switzerland for Heating and Cooling

Abstract

During the renovation of a major Grand Hotel in Zurich a complete new domestic heating and cooling system will be installed. A gas-driven absorption heat pump will supply the required heating and cooling energy. A massive reduction of electricity costs in summer is intended. A geothermal energy storage of ~250'000 m3 will be exploited by borehole heat exchangers with totally ~10'000m length. Supported by additional heat recovery, the subsurface storage will supply 1GWh in winter. From spring to autumn, the hotel will be cooled (1 GWh) by the same storage system. Additional waste heat will be used for hot water generation. The paper describes the effects of different utilization concepts to the thermal subsurface fields. In particular, the requirements of a hotel specializing in wellness spa applications involve sophisticated dimensioning of this low-enthalpy plant. The 3D model accounts for individual thermal interaction of the borehole heat exchangers in surface and for different topographic and climatic conditions at this mountainous site.