22 May 2008

NEW LARGE GEOTHERMAL STORAGE PROJECT IN ZURICH/SWITZERLAND FOR HEATING AND COOLING

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During the renovation of a major Grand Hotel in Zurich a complete new domestic
heating and cooling system was 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 ~10’000 m length. Supported by additional heat recovery, the
subsurface storage will supply 1 GWh 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.