Start-up price for geo exchange is not cheap, due to the cost of using a drill rig and is also dependant on how many bores need to be made to achieve thermal regulation. Image: Geoexchange ENVIRONMENTAL concerns and rising energy costs are driving innovation at the Durack Institute of Technology in Geraldton.
Geoexchange is a system of environmental control for buildings being investigated as a replacement for existing standard air conditioning units.
The coastal location of the Durack Institute is highly corrosive due to salt spray exposure and this atmosphere shortens the serviceable life of traditional air conditioning units within an average of ten years.
Start-up price for geo exchange is not cheap, due to the cost of using a drill rig and is also dependant on how many bores need to be made to achieve thermal regulation.
The Institute’s manager for physical resources, Craig Jerrard led a team in drilling a test bore on campus to examine the properties of the ground and see what the exchange would be like.
Mr Jerrard says during the process they encountered some problems with large voids filled with sea water which had to be pumped out, making placement of the heat exchange pipe more difficult.
“The upside of the seawater issue is that once the pipe is in place, the surrounding water makes an ideal heat sink,” he says.
In this experiment a hole was drilled sixty metres into the ground and a looped heat exchange pipe was placed and attached to an above-ground heat pump unit.
This piping could be filled with a refrigerant but to minimise the environmental risk in case of leakage, they used water which is also what would be used if the program goes full scale.
After placement of the low voltage pump, a 48 hour series of testing began where they sent heated water through the pipe and measured temperature differentials between where the water was introduced, where it returned and how long it took for the water to cool to a useful temperature.
The simplicity of geo-exchange means placement of units is very low impact.
Mr Jerrard says, “You wouldn’t see anything [there], it’s just a witches hat over a piece of pipe but that just proves how limited the actual footprint is, it could be placed in car parks, ovals or even in bushland”.
Preliminary results looked positive and these were passed on to a consultant who will evaluate how many holes would need to be drilled and judge the financial and environmental viability of taking the project further.
