August 22, 2008

Tiny Australian town of Innamincka finds cool solution to energy needs

Construction Corner

Korky Koroluk

You’ve never heard of Innamincka, a tiny (12 permanent residents) community in Australia. But those few people have built a tourist industry that draws as many as 50,000 visitors some years, all eager to experience the Australian outback.

Those visitors need to be kept cool, of course, so each year the tiny town spends $250,000 or more on diesel fuel to run its generators.

Soon, though, the locals will be keeping their cool with what they call “hot rocks,” an immense slab of granite buried far underground.

It’s an engineered version of geothermal heating from shallow beds of volcanic rock —the energy that provides most of Iceland’s heat.

When I first encountered heat pumps many years ago I was enthralled, because it had never occurred to me that the earth under my feet could be used to heat our house in the winter and cool it in the summer.

But I kept hearing about noise and vibration, about higher price and the resulting long payback time. Then, as the need to reduce our dependence on fossil fuels became apparent, we heard more and more about solar power, wind power, geofuels, everything it seemed, except earth energy.

Earth energy is now the catch-all term being used for energy extracted with heat pumps, and geothermal energy is the term applied to the energy the earth has stored as heat deep underground, beyond the reach of any heat-pump system.

Conventional geothermal systems are like those used in Iceland. But engineered geothermal systems (EGS) utilize the earth’s deep heat. Besides the systems in Iceland there are also conventional systems in California, drawing energy from hot springs.

In Innamincka, come January, the tiny town will be powered for free with electricity generated from heat mined from an immense slab of granite buried several kilometres below the surface.

After decades of development, this form of heat mining may have reached an important point. France has an experimental 1.5-megawatt power station that has just about finished its shake-out phase and is about to start continuous operation. Germany has a somewhat larger station already selling power — but heavily subsidized power. And the United States Department of Energy has said it will fund research EGS research.

The two European plants appear to have proven that the technology works — what scientists call proof of concept. But they have not yet shown that it is cost-effective, and that is where Innamincka enters the picture.

The slab of granite beneath the town is 1,000 square miles in area, and is covered with four kilometres of earth. The slab itself reaches a depth of 10 kilometres in places..

It is said to be the biggest, shallowest, and, at 290°C, the hottest non-volcanic rock formation in the world, and has the potential to produce five to 10 gigawatts of power. So the energy is there. A problem, though, is that it is 500 kilometres from the country’s power grid, so building the transmission line is adding to start-up costs.

Two wells, each four kilometres deep, have been drilled. Water has been forced down the injection well under high pressure to expand natural fractures in the granite, converting it into a porous heat exchanger. Turbines are being installed, and in just four or five months, the steam and hot water from the “hot rocks” four kilometres below will be powering those turbines in a one-megawatt demonstration plant.

The development has sparked interest all over Australia because the Innamincka project alone appears capable of supplying 20 per cent of the country’s electricity needs. Thirty-three companies are exploring geothermal potential in every one of the country’s states.

And Innamincka? The community will get free power for 10 years. Then the demonstration will be over and the meters will start spinning.

Korky Koroluk is an Ottawa freelance writer. Send comments to editor@dailycommercialnews.com

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