DONALD Payne clambered under the Mt Eliza home and pointed to an unspectacular collection of pipes, a pump and metal boxes.
"If we installed a geothermal heat pump like this in every house in Australia, we could meet the 2020 emissions targets with these alone," he said.
Dr Payne is a pioneer of Australia's geothermal energy industry. He works at the University of Melbourne's School of Physics and is a director of Direct Energy, one of the nation's first geothermal energy installation companies.
His firm installs geothermal heat pumps (GHPs) for homes, with 60 systems operating or being installed throughout Australia.
He installed the nation's first at his family's holiday house on the Bellarine Peninsula.
"GHPs use up to 75 per cent less energy than conventional heating and cooling systems by using the earth rather than ambient air as a heat source."
Remarkably, the Mt Eliza house, which is on the cliff edge overlooking Ranelagh Beach, has a 17.5-kilowatt system for the house and a 10.5-kW set-up for the spa pool with energy coming from eight 30-metre deep holes of 70mm diameter. Twenty-four holes 15 metres deep would do the same job.
Refrigerant gas travels down through a sealed system of copper pipes and returns to the surface heated to about 55 degrees C.
Similar systems use water but have to travel much deeper - 100 metres or more - and the bore holes are twice the diameter.
Dr Payne says: "No matter where you live, the underground temperature remains relatively constant all year, even though outdoor temperatures may vary widely. Geothermal systems utilise this stable resource as a renewable energy source for the home.
"One compact unit can provide heating, cooling and water heating. You can have radiant hydronic floor or panel heating, chilled water cooling, forced air central heating and cooling, heating for swimming pools and spas, and domestic or commercial hot water."
Dr Payne says domestic GHPs would become more popular if governments introduced rebates for geothermal technology.
The owner of the Mt Eliza house, who does not want to be named, said other energy-saving features in his home included high-efficiency appliances, tinted low-energy double-glazed windows (with a low ultra-
violet value of 1.64) from Innovative Aluminium of Windsor (www.innovative aluminium.com.au), and insulated foam that is sprayed onto walls and ceilings.
And the cost of GHPs?
Normal heat pumps (above ground, using the sun) and GHPs cost about the same but drilling is the extra expense. Dr Payne says drilling costs $10,000-$20,000, depending on terrain and other factors.
"The Mt Eliza house has high-velocity air ducts and this adds to the cost beyond what is typical."
Direct Energy has its own installers and also uses trained plumbers, refrigeration mechanics and drillers.
"Putting GHPs in every house is not going to happen overnight, but geothermal has a great contribution to make."
Details: www.directenergy.com.au
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HOW IT WORKS
HEATING: Liquid refrigerant enters copper pipes in the ground and evaporates, which absorbs large quantities of heat from the surrounding earth. The refrigerant then flows through the pipes, absorbs heat from the earth and stores it in vapour form for later release.
COOLING: Refrigerant is compressed into hot vapour after absorbing heat from the building. The hot vapour enters pipes in the ground and is condensed into liquid by the cool surrounding earth. The refrigerant leaves the pipes as warm liquid.
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