| Authors |
Thomas POULET, Peter SCHAUBS, Praveen Kumar RACHADONDA, Grant DOUGLAS, Daniel LESTER, Guy METCALFE, Heather SHELDON, Rebecca TUNG, Lynn REID, Klaus REGENAUER-LIEB, Mike TREFRY |
| Abstract |
Perth, in Western Australia, is a fast growing city with 1.9 million inhabitants and over 3% annual growth rate in population. At the same time, the natural water resources have declined by a factor of three over the last 30 years. Traditional cooling technologies used in the dry climate employ cooling towers, which use significant amount of fresh water via evaporation and rejection of waste water. Another important aspect is that cooling towers do not operate effectively at a critical wet bulb temperature of 22°C, which is reached more frequently in recent years due to tropical incursions. Therefore, cooling towers can be ineffective in Perth for hours on at least 30 days during summer. The CSIRO Groundwater Cooling (GWC) project has been designed to address these critical problems to cool the Pawsey Centre, Australia’s latest supercomputer, with ambient temperature water. The requirement of 21°C water makes this an ideal application for groundwater cooling. The system design has therefore been developed 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. Two warm water injection boreholes are separated from two cold extraction wells by approximately 340 m. An additional two boreholes are placed in between and potentially serve as a screen by reinjecting cold water to prevent thermal breakthrough. 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 are in part 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 is maintained by CSIRO and partly available to the research community through web portals. Numerical simulations are performed using various codes, including MOOSE, from Idaho National Laboratory, to model the performance of the GWC system, considering fully coupled multiphysics processes. These include thermo-hydro-chemo-mechanical feedbacks such as reservoir damage evolution and bio-geochemical feedbacks. The resulting simulator is being benchmarked against natural data and novel data assimilation tools will be developed for incorporation of the incoming stream of measurement through the cyber-infrastructure. The overarching aim is to be able to upscale the current installation for 2.3 MW cooling to a broadly applicable technology. This is the first time groundwater cooling is being used on this scale in metropolitan Australia. The system was designed to be efficient, environmentally friendly, working year-round, and to save significant quantities of water compared to 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. |