The $11 billion Metro Tunnel rail link project, which will run under central Melbourne, is one of Australia’s biggest infrastructure projects, but there has been some unusual ground testing going on at the sites of two of the new underground stations.

University of Melbourne researchers have been pumping water underground through plastic pipes tagged with sensors to test the ground’s potential to retain and transfer heat – its so-called ‘thermal conductivity’. Such geothermal energy has the potential to significantly cut the power cost of keeping the stations cool in summer and heated in winter.

So far the results have been positive and a pilot study is about to startIf adopted, it could be the high-profile contract needed to kick start a greenhouse gas-friendly Australian geothermal industry. The technology is already widely used in North America and Northern Europe, including in underground train stations in Switzerland and the UK, but is barely heard of here.

Geothermal energy is based on the simple idea that we can use the constant temperature found as little as five metres underground to help regulate temperatures inside buildings.

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