Deep Heat

Eight kinds of beer and freshly shucked oysters make the Innamincka Hotel an oasis for travelers on Australia's remote Strzelecki Track. But keeping food and drink cold in the Outback isn't cheap. Every three weeks a diesel tanker must make a 1,600-km round trip from Port Augusta, South Australia, to keep the generators running.

Not, perhaps, for much longer. By Christmas, the dozen or so residents of Innamincka, about 1,100 km north of Adelaide, have been promised a miracle: free electricity for decades to come. If all goes to plan, the beer will soon be cooled by zero-emissions renewable energy trapped deep beneath the surrounding desert.

"It's an absolutely brilliant thing," says Leon Cartledge, manager of the hotel, which in busy times gulps about $20,000 worth of diesel a month. "For one thing, you'll be able to come out to the bush and not hear generators humming. And it will be clean power."

Affordable, carbon-free energy available around the clock is the Holy Grail in a world that aspires to cut greenhouse-gas output even as it uses ever more electricity. Solar power can't provide it; nor can wind. And while nuclear power could do so, many Australians oppose it.

One answer may come from tapping the heat stored in rock strata at least 5 km below the surface in many parts of the world, including Europe, India, China, the U.S. and Australasia. A report by the Massachusetts Institute of Technology last year argued that by mid-century, this type of geothermal energy could supply 10% of America's power.

Innamincka has some of the hottest rocks anywhere, and Geodynamics has spent $150 million drilling deep into them. The biggest and most advanced of some 40 companies seeking to capture Australia's underground heat, it aims to be the first to prove that deep-earth geothermal power is commercially viable. Geothermal is already a bit player in the power business: underground water heated by volcanoes is already used for heating and electricity generation in countries like Iceland and New Zealand. But supplies of natural hot water are limited. The new push is to mimic nature by creating artificial water-heating systems using hot subterranean granites. The resource is potentially endless: while each patch of rock will cool as its energy is drawn off, it will heat up again if left alone.

In theory, says Geodynamics chief executive Gerry Grove-White, there's enough heat in the rocks of the Cooper Basin, on which Innamincka sits, to replace all the coal-fired power stations in Australia for more than 250 years. He says one cubic kilometer of hot granite has about the same stored energy as 40 million barrels of oil. With several thousand cubic kilometers of these granites, Australia has enough heat to last millennia.

"We're being watched worldwide," says Grove-White, a British power-industry veteran whose experience covers four continents and every system, from wind and hydro to nuclear and coal. "The climate debate has focused an awful lot of interest on the commercial development of these resources."

The Innamincka granites are buried under 3 km of sedimentary rock, which acts like a blanket on a bed. Heat is generated by the radioactive decay of elements in the granite, but it can't escape. Five km below the surface, the rocks' temperature is 250°C.

The original plan was to pump water deep underground under high pressure, in order to crack the granites and create a path for the water to flow. Superheated by contact with the rock, the water would be pumped to the surface from a second well 1 km away, to create steam to drive a power turbine, then be pumped into the earth again.

The big surprise, says Grove-White, was that there was no need to add water: it was already there, trapped underground at high pressure for the past 3 million years. Getting the hot water to the surface hasn't been easy, and one well had to be abandoned. But Geodynamics now says the flow from 4 km deep is sufficiently strong and hot to run a 1-MW power station by the end of the year — enough to power the drilling-camp site and Innamincka.

High power costs and their benefits
With partner origin energy, a big Australian oil and gas company, Geodynamics now plans to build enough wells to run a 50-MW commercial power plant by 2011. That feat will need much deeper wells and better water flows. If it works, Geodynamics will build more wells to produce 500 MW — about the output of a modern gas-turbine power plant — by 2015.

There are some obvious challenges. Power from coal-fired plants is cheaper. And the closest connection point to the national electricity grid is 500 km away. But Grove-White says geothermal power will become economic once coal and gas plants have to pay for their carbon emissions, which he expects to happen in an Australian carbon-trading scheme due to start in 2010. While the transmission lines will be expensive, their cost — $500 million or more — is included in the business model.

The real trick will be extracting enough hot water to make the 50-MW plant work. If the engineering challenges of great depth and heat can be overcome, the company will follow a cookie-cutter approach and build nine more sets of wells to produce 500 MW.

Eagerly watching progress are Australia's other geothermal companies. The most advanced, Petratherm, plans to drill its own well near South Australia's Flinders Ranges later this year and produce commercial amounts of power before Geodynamics does. Petratherm, with projects in Spain and interests in China, already has an agreement to supply 7.5 MW of power to the Beverley uranium mine, 11 km from its drilling site. The company won't go as deep as Geodynamics. Instead, it will try to push its water through 200°C sedimentary rock, just above the hot granites.

"The big issue for the industry," says Petratherm's managing director, Terry Kallis, "is to prove flow." In other words, can water be pumped out fast and hot enough to drive that turbine on the surface — and keep doing so for decades? "I'm confident Australia will be the first" to achieve this, Kallis says, because "we have the hottest rocks in the world of this type."

In Innamincka, Leon Cartledge has his fingers crossed for the pioneering project to succeed. He thinks a hot-rocks power plant could draw curious tourists to sample his beer and oysters. Throw in free electricity, and "a business like this might even stand to make a profit."

But it's a tough place for trailblazers, as other local tourist attractions attest. Nearby are the graves of explorers Robert O'Hara Burke and William John Wills, who died of sickness and starvation in 1861 on their way back to Melbourne after crossing the continent from south to north. Geodynamics insists its prospects remain very much alive. Grove-White is so confident he's even come up with an advertising slogan for the pub: Have a cold beer from the hottest rocks. "It's got a nice ring to it," he says.