It’s clean, abundant, and will outlast humanity — so why aren’t more buildings tapping into the heat beneath our feet?
That question was on Curious Canberran Don Fletcher’s mind, after learning about the Geoscience Australia building in the ACT, which is heated and cooled using ambient temperatures in the earth’s crust.
“I had this vague memory that Geoscience had done this thing that seemed unusual 20 years ago of drilling all these holes to heat their building from ground heat exchange,” he said.
Concerned about Australia’s energy future, Don wanted to know why such systems weren’t used in other large buildings in the city.
“Here we’ve got another supply of heat that’s constant … it’s continuous, it’s free, it’s clean, there’s no surface infrastructure to speak of – it sounds wonderful!”
To learn more, Don and I met with geoscientist Anthony Budd and Geoscience Australia’s acting property operations manager Hanna Slattery, at their Canberra headquarters.
Curious Canberran Don Fletcher at the Geoscience Australia building speaks to acting property manager Hanna Slattery in the building’s plant room.
ABC News: Jordan Hayne
Beneath the earth, in the bowels of the heating system, Anthony brought up an important point: the heating at Geoscience Australia doesn’t draw on “true geothermal” energy.
“This sort of system, a geo-exchange system, isn’t really what I call a geothermal system,” he said.
“There’s a pretty big difference in concepts there.”
Hanna gave Don and I a guided tour of the system’s features, and a dummy’s guide to geo-exchange systems, which are also known as ground source heat pumps.
“This is probably the largest closed-loop geothermal system in the Southern Hemisphere, it certainly was at the time of construction,” she said.
350 sets of pipes service the building and circulate water beneath the ground, where the temperature is always constant.
In winter, that water is warmed to 17 degrees Celsius, then brought back up to ground level where heat pumps extract the heat and circulate it through the building.
In summer the process is reversed —heat is extracted from the air and the pipes are used to sink it into the ground.
“In summer we can cool the air temperature by rejecting heat into the ground, and in winter we can pull that heat back out,” Anthony said.
Ground source heat pump systems are much cheaper to run than gas or electric heating – and they’re environmentally friendly.
“They did do some costing at the time of construction, and they gave us projected savings, which they believed to be approximately $1 million over a 25-year life span,” Hanna said.
As the building was being constructed in the 1990s, the system was also seen as an experiment for Geoscience Australia to champion.
“It’s a purpose-built building, and I think the decision was that we could use a ground source heat pump to be a demonstrator for the technology,” Anthony said.
“Being a bunch of geoscientists and whatnot, the opportunity to drill 350 wells was too good to pass up.”
In my research I tracked down Zhenjun Ma from the University of Wollongong’s Sustainable Buildings Research Centre, who told me the upfront cost of installing the systems was prohibitive for many buildings.
At Geoscience Australia, Anthony explained that ground source heat pump systems were best suited to climates with hot summers and cold winters.
Zhenjun said much of Australia simply did not get cold enough to make the systems efficient.
“Ground source heat pumps really have a high performance under heating dominated climate conditions,” he said.
“In Australia … we are cooling dominated, which means we have a relatively low performance.”
But he said there was room to grow in places like Canberra and Melbourne.
Yass businessman Touie Smith is at the forefront of that growth, as one of the only people installing geo-exchange systems in the Canberra region.
I met him at property at Bowral in southern NSW, where he told me that in the past, the biggest thing holding this kind of heating back was the low cost of more established heating methods.
But as the cost of gas and electricity has risen, so too has the demand for his business.
“Classically in Australia we have had low energy costs, and we’ve seen a massive shift in the last 5-10 years,” he said.
Touie also agreed that skilled labour was hard to come by.
“Demand is exceeding what we’re able to produce at the moment,” he said.
“Our single biggest problem is finding skilled people that want to work in the industry.”
Before Don and I left Geoscience Australia, Anthony told us there was growth ahead for both geothermal energy and ground source heating in Australia.
“It is happening in Australia. There’s a new power plant which is due to be built at Winton in Queensland,” he said.
“There’s a housing development in Sydney, there are 800 houses being built by a single developer, and that developer took the decision to install a ground source heat pump in every dwelling.”
Afterwards, Don told me he was keen to see more investment in heating systems like the one used in Canberra.
“Canberra seems to be an ideal place … where this is going to work most easily.”
More about our questioner:
Don Fletcher has lived in Canberra for “something like 40 years”.
He worked with the ACT Government as an ecologist and has recently retired.
Don’s interested in Australia’s energy future, and wants to know more about alternative sources of power.
He asked Curious Canberra to investigate after stumbling across previous stories online.