ENERGY: News Weekly
Hot rocks: is geothermal heat the way ahead for power generation?
, October 28, 2006
Despite the absence of active volcanoes, geysers or other forms of intense tectonic activity, scientists and engineers are confident geothermal heat will become a significant source for power generation in Australia.
A research paper presented in Turkey last year by scientists Prame Chopra and Fiona Holgate of the Australian National University highlighted these pioneering moves and pinpointed regions where such energy may eventually be tapped.
And a release from the Australian Earth Sciences Convention, held in Melbourne in July, identified some of Australia's sedimentary basins as prime sources of subterranean heat.
"One such basin is Queensland's Cooper Basin," a Convention spokesman said. "Where two wells have been drilled to more than 4350m into a granite where the rock temperature is 250C in an underground reservoir extending over an area of more than four square kilometres, believed to be the largest in the world.
"In September 2005 the first hot dry rock resource exploration was completed in South Australia.
"An evaluation confirmed the potential for a 1000MW electrical geothermal energy sources."
Similarly positive claims have been made in an assessment compiled by the Centre for International Economics (CIE) for Geodynamics Ltd of Brisbane, a pioneer in moves to tap below ground heat sources, also known as hot fractured rocks (HFR.)
The CIE report said that Australia already has 14 companies pursuing geothermal energy on 87 geothermal licences and work commitment of more than $500 million over the next five years.
Most of the activity centres on South Australia. "Geodymanics Ltd have established that there is a large scale HFR energy recourse located below the Cooper Basin, near Innamincka, on the SA side of the border with Queensland," the CIE report said.
"They have drilled the Habanero 1 and 2 wells into the hot granites and identified the resource as being the hottest outside of a volcanic region yet discovered - 287C at around five kilometres depth.
"What remains is to demonstrate the capacity of HFR to convert a natural resource into electrical energy on a competitive and commercial basis.
"Once that is achieved it could put Australia into a leading position in what could become a major global industry."
Geodynamics Ltd also has geothermal tenements in NSW and Queensland, including the NSW Hunter Valley. Other prospective areas include the Murray Basin; the Otway Basin (west of Melbourne); the Perth Basin; and McArthur Basin in the Northern Territory.
Unlike the hot wet geothermal energy tapped in New Zealand and Indonesia, in Australia water will need to be artificially infused into the systems.
Moreover, overseas projects have struggled to extract energy economically for a range of reasons including poor rock structure, low water flow rates and low rock temperatures.
Despite this Professor Sheik Rahman, head of a University of NSW research unit, believes Australia's hot rocks have the right temperatures and geological structure to be successfully exploited.
Dr Chopra has backed this claim. "We are the only country in the world we know of that has rocks at very high temperatures within easy drilling depths and where there is no volcanic activity," he says.
But there is a long way to go, warns Richard Dumbrell, a technical advisor with the School of Petroleum Engineering at the University of NSW.
"It's an enormous challenge and it shouldn't be misunderstood as being a fait accompli or simple in terms of developing it," Dumbrell said.
"But Australia can itself can take a major leading role."
The outlook, then, is guardedly optimistic. And if current expectations are met, CIE sets out a three-phase program to tap this subterranean energy source.
Phase one, CIE says, would see construction of a 40MW demonstration plan followed by the commercial development of the HFR sector with total generation capacity of 420MW by 2016.
The second phase would see industry expansions, including base-load generating capability providing an extra 1320MW by 2012.
Under phase three there another 2760MW of generating capacity would come on stream by 2030.
For such huge outputs transmission lines from the Cooper Basin region would be required thereby linking this new energy to Australia's national grid and thus the national electricity market.
Australia's so-called "dead heart" may yet become one of its greatest energy sources.