Geothermal firm to tap Perth city centre hot rocks

Australian geothermal specialist Green Rock Energy has this week announced it is to tap extensive geothermal resources under the city of Perth in order to power air-conditioning facilities at the University of Western Australia (UWA).

Geothermal resources are often used to provide heating in Europe and elsewhere, as well as electricity, but Green Rock's project is thought to be the first in the world to provide energy for air-conditioning, the use of which places the heaviest demand on electricity resources during peak demand periods over the Australian summer.

The project will replace UWA's electricity powered compression chillers, which provide cold water for air conditioning, with absorption chillers powered using geothermal heat.

Green Rock chief executive Adrian Larking said the project will replace about 5MW, or one third, of the grid-supplied energy used to power the University's air conditioning plants.

Unlike other major metropolitan centres in Australia, the city of Perth sits atop a 15km deep sedimentary basin with numerous heated aquifers that can be used for geothermal energy.

Two geothermal wells will be drilled on the campus to a depth of three kilometres to source the hot water, which has an estimated temperature of 100C. The hot water will then be pumped through a heat exchanger before being returned to the aquifer.

The temperature of the Perth aquifer is considered sufficient to provide heating and cooling facilities, but not enough to generate base-load electricity.

If the UWA project is successful, Green Rock also hopes to strike an agreement to provide geothermal-powered heating and cooling for a new housing estate called Alkimos to be built north of Perth. It said the project had the potential to replace 50MW of conventional electricity consumption.

The company is also investigating the provision of heating and cooling facilities for other industrial and commercial buildings in the city, including office buildings, data centres, and cold storage facilities.

Larking hopes to begin drilling later this year or early in 2010, with the view to bringing the project into production by 2011. If so, it will likely be the first commercial-scale geothermal project in Australia.