Using a shallow aquifer as heat sink - Introducing the CSIRO Groundwater Cooling project

Abstract

The CSIRO Groundwater Cooling (GWC) project is developing the technologies and knowledge needed to demonstrate the viability of a geothermal solution for cooling Australia\\\'s largest supercomputer, the Pawsey Centre, Perth. The system works by pumping cool water (21°C) from an aquifer located approximately 35 to 120 m depth, through an above-ground heat exchanger to cool the supercomputer. The now heated water (30°C) is then reinjected back into the same aquifer, slightly downstream, resulting in no net consumption of water. The two warm water injection boreholes are separated from the two cold extraction wells by approximately 340 m. Separating the injection and production bores are an additional two boreholes where cold water is injected back into the aquifer. This serves to contain the thermal plume migrating from the warm injection wells away from the extraction zone. The requirements and optimal usage of this screening functionality forms part of the research questions the GWC project will be investigating in the coming years. Nine monitoring wells located in the close proximity to the site have been equipped with sondes to collect temperature, pH and other water quality data. These data will be in part be used to calibrate numerical simulations to help quantify uncertainty, calibrated with various measurements, including real time data as well as regular manual sample analyses. The repository for these data will be maintained at the Pawsey Centre and will be made available to the research community by new web portals. This is the first time groundwater cooling is being used on this scale in metropolitan Australia. The system is efficient, environmentally friendly, works year-round, and will save significant quantities of water compared with conventional cooling towers. The technology concept, if deployed more widely, has the potential to replace cooling towers in commercial and residential buildings all over Perth. This would be a significant milestone in establishing Perth as one of the world’s first geothermally cooled cities.