Geothermal energy to power Kalgoorlie's Goldfields Oasis Recreation Centre

A remarkable innovation will see geothermal energy harnessed on a commercial scale to heat the main swimming pool at the Goldfields Oasis Recreation Centre in Kalgoorlie.

The geothermal water heating system is almost complete and will soon be heating the Oasis' Olympic swimming pool.

Kalgoorlie-Boulder City Council (CKB) Director of Social Services Tony Chisholm says geothermal heating is the final part of a clean energy project that also uses solar thermal heating and photovoltaics.

Chisholm explains "CKB council recognised the need to utilise clean energy to meet the rising expense of heating the centre and the pool, especially since there was funding available for this sort of project.

"We anticipate a four year payback on the geothermal project.

"The water temperature we are getting from underground is warmer than we expected.

"Originally we had only anticipated heating the water to 18 degrees Centigrade, but we're seeing temperatures of 23 degrees."

Project consultant Greg Benvenuti expects this temperature to fall, adding "the temperature of undisturbed ground in Kalgoorlie is 23 degrees, although over time the temperature will fall (and) we will be able to equilibrate the ground at around 15 degrees."

The geothermal heating system comprises two sections; a shallow network of coiled thin tubing buried horizontally in a trench 1.5m deep and a deep series of vertical tubes.

Chisholm adds "the CKB originally looked at using a 30 metre deep geothermal system but decided against it as it required the use of refrigerants. The council was concerned about the risk of leakage."

The chosen deep system, however, doesn't require refrigerants and is made up of 50 x 127 mm wide boreholes drilled to a depth of 100 metres underground. An elongated 'U' made of high quality plastic pipes was then fed into each of the holes. Then a conductive grout pumped around the pipes.

The connected pipes feed water from the deep system to the shallow system. Both the sections have been filled with water and sealed.

The warmed water is circulated and pumped to the pool building. Using heat exchangers, (now being installed) heat is transferred to the heat pumps, commonly used in normal heating-cooling systems. They upgrade the heat and warm the swimming-pool water.

Chisholm concludes "once all three systems are running there will be sufficient energy to be used for air-cooling the rest of the complex too. The system has been designed with this in mind."

The Community energy Efficiency Program and Low Emissions Energy Fund provided partial funding, with CKB making up the balance.

The system is the first closed-loop system of its kind to heat a swimming pool in Western Australia. Others are open-loop systems (drawing up existing groundwater, usually from an aquifer, taking the heat and then returning water into the ground).

By contrast, the Kalgoorlie system is closed-loopit only circulates the water in the pipes not affecting local groundwater.

The Goldfields Oasis was also recently recognised with a Gold Award at the Australian Health & Fitness Industry Quality Awards. 

Image: Rooftop mounted solar panels at the Goldfields Oasis.

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