Geothermal systems tap the earth’s natural heat

8 February 2012 – Geothermal systems are the latest technology to be embraced by wealthy residential clients who wish to be green leaders, according to architect Luigi Rosselli, with one of the firm’s Sydney clients recently installing a geothermal system that will see energy costs almost halved.

“Our clients are renovating a large house in Woollahra and while they wanted airconditioning, they were amenable to using geothermal technology, which uses a fraction of the power needed for a normal airconditioning system,” Rosselli says.

But the upfront capital and installation costs of geothermal are high so clients are usually motivated by their desire to be leaders in sustainable technology.

Luigi Rosselli

Luigi Rosselli Architects last year won the Milo Dunphy Sustainability Award from the Australian Institute of Architects NSW for one of its residential projects in Sydney’s eastern suburbs.

As we reported in an earlier story, the firm is proactive in getting clients to make sustainable choices, with Rosselli designing a clause in his contracts, for instance, that encourages clients to avoid airconditioning and in- floor heating or pay a penalty.

Half of the fee applied to these technologies by the firm is donated to carbon emission reduction advocacy groups.

Hugh Campbell, associate with Luigi Rosselli Architects, was closely involved with the Woollahra geothermal project. He says geothermal technology, which uses the heat stored in the ground to produce energy, can dramatically reduce a household’s energy bills. But because of the high upfront and installation costs, the systems are more popular in cold climate locations such as Europe and North America where payback times are faster.

“It is fairly unusual to put in one of the systems in Sydney. Geothermal is more widely used in Melbourne and Canberra but our clients were keen to make a difference.

“They have chosen to keep the original house rather than demolish it, something that we encourage because of the huge amounts of embodied energy in buildings. It’s not necessarily the cheapest option but it is the most sustainable,” says Mr Campbell.

The Woolahra geothermal drilling

Other technologies used in the project include ground water retention systems, photovoltaics, heat reclamation and grey water re-use.

“The other thing we are trying more at this end of the market is on-site gas generation, like the Blue Gen technology,” says Mr Campbell.

Melbourne-based geothermal company, Direct Energy, was chosen for the project. Winner of the Best green start up of 2011 in the Australian Start Up Smart Awards, (founded by entrepreneur Amanda Gome), Direct Energy is a privately owned Australian company and has a licence to use US-based direct exchange technology, as none of the systems are manufactured in Australia.

Direct Energy’s business development manager, Nicholas McGloin told The Fifth Estate that most geothermal systems installed in Australia have been water based, using plastic pipes. The one used in the Rosselli Architects project is a direct exchange system which uses copper loops and refrigerant instead of water.

“These are more suitable for smaller applications as they have higher efficiency,” says McGloin.

Australian clients
Direct Energy has installed 150 ground source heat pumps in Australia over the past three years, in a mix of high end residential and commercial projects. The company installs both water-based and direct exchange systems. Recent clients include Byron Bay Library, the Geoscience building in Canberra and the Ausgrid Learning Centre at Silverwater in Sydney, where 64 water loops were installed 100 metres under the ground and operate in conjunction with a tri-generation plant.

McGloin says the costs of installation for the direct exchange system are high but once in the ground the systems are virtually maintenance free and highly efficient.

“As a guide the smallest residential system can be installed for around $35,000 but as most of our projects have been more substantial architect designed homes, they have averaged around $55,000.”

At Woollahra the cost was around $250,000 but this was because of of the system’s complexity.

McGloin says:  “There were five systems of various sizes serving different zones and levels of the original house and the extension.

“It also had premium fittings and controls.”

On the Woollahra project the team also needed to bring in a 50 tonne crane to drill down 30 metres. Some caution was required because one of the tunnels for the Eastern Suburbs railway line runs below the block of land.

“Drilling is an issue in any CBD work, “ says McGloin. “There are underground streams, optical fibre cables, sewerage lines and railway tunnels to contend with.”

Worldwide geothermal use on the increase
According to figures from the International Geothermal Association (IGA), in 2010 10,900 megawatts of geothermal capacity was installed worldwide, generating enough electricity for around six million households. The potential is enormous says the IGA, estimating there is enough heat under the ground to meet the world’s energy needs for around 100,000 years.

The advantage of geothermal plants is that despite their high upfront and installation costs, they have very low operations costs, including zero fuel expense.

In the US the Environmental Protection Agency has identified geothermal heat pumps as a technology that significantly reduces greenhouse gas and other air emissions associated with heating, cooling and water heating residential buildings, while saving consumers money, compared to conventional technologies.

Research by Ruggero Bertani, executive director of the IGA and geothermal business development manager for Italian energy provider ENEL SpA, shows that Iceland is the world’s biggest user of geothermal energy per head of population, with 575 megawatts of installed capacity, one quarter of Iceland’s electricity usage. Iceland’s geothermal energy generation increased by 210 per cent between 2005 and 2010. This compares with a decline of 5 per cent in Australia over the same period.

Other countries investing heavily in geothermal power include Indonesia with 1197 MW of installed capacity in 2010, the Philippines (1904 MW) and Mexico (958 MW).

Bertani forecasts worldwide geothermal capacity to increase by 72 per cent between 2010 and 2015.

To see the research paper and table comparing geothermal use around the world click here. (

Government commitment lacking
Government rebate schemes for geothermal heat pumps exist in the US, Canada and UK but so far Australia has not extended incentives applied to the solar hot water industry to geothermal technologies.

The Australian Geothermal Energy Association, which entails both geothermal hot-rock & heat-pump technologies is actively lobbying for geothermal rebates.

Nicholas McGloin says Direct Energy has a very high inquiry rate but high installation costs can be prohibitive. He would like to see some government assistance made available to ground source heat pumps similar to that available for solar hot water systems.

“One of our directors, Professor Donald Payne from the University of Melbourne, recently organised a delegation of Canadian geothermal experts to visit Australia to talk to federal and state government representatives about the benefits and potential of geothermal technology,” says McGloin.

“In Canada, the US and Europe there is more incentive provided by government for ground-source heating.  Something like a REC [renewable energy certificate] would be good here.”