Drive for nukes ignores vast geothermal resource

Wednesday, December 6, 2006

The federal government's Uranium Mining, Processing and Nuclear Energy Review, released on November 21, had only one real purpose — to provide John Howard with "evidence" for championing the nuclear power cycle.
What other conclusion can we come to, when the review made its assessments while ignoring Australia's most spectacular renewable energy resource — the "hot dry rock" geothermal energy of the Cooper Basin and other regions.

"Nuclear power is the least-cost low-emission technology", the review baldly asserted. There was no sign that the review panel had seriously researched the alternatives. Under its terms of reference, it was not even required to do so. But armed with its assumption that no lower-cost renewable alternative to nuclear energy was even in prospect, the panel went on to urge that 25 nuclear power plants be built in Australia by 2050, in close proximity to major cities.

Actually, if review chief Ziggy Switkowski and his team had wanted to inform themselves on the real potential of Australia's prime renewable energy source, all they needed to do was to read the Australian. In an upbeat article on September 9, the newspaper detailed how the potentially recoverable geothermal energy in the Cooper Basin, in South Australia's far north-east, equates to Australia's current electricity consumption for 450 years.

A little more web-browsing would have convinced the panel members that exploiting the "hot dry rock" geothermal resource in the Cooper Basin was no pie-in-the-sky technofantasy. The basic "hot dry rock" concept was demonstrated to work in 2004 at the Soultz-sous-Forêt geothermal prospect in northern France. Testing at this site in the period since has yielded encouraging results. Now that the concept has been shown to be feasible, the argument that the technology involved is unproven holds little weight. With few exceptions, the techniques used are borrowed from the oil industry, where they are familiar practice.

In Australia, investors are impressed enough with the potential of geothermal energy to have committed some $500 million to fund exploration and development work by no fewer than 14 companies. Drilling at several sites, including in the Cooper Basin, has revealed natural conditions markedly more favourable than those in France.

Once producing, Australia's geothermal resources will release no greenhouse gases or other pollutants. Unlike wind or solar, they will provide continuous, dependable base-load power. Moreover, and giving the complete lie to Switkowski, the electricity they produce will be cheap — probably about half the all-up cost of power from nuclear plants. Modeling by energy companies suggests that the cost will be about 4 cents per kilowatt hour, similar to natural gas and only marginally more than coal.

When the stock exchange is abuzz with talk of the promise of geothermal energy, it's hard to believe that news of this potential has really passed government advisers by. The reason why Switkowski's panel pronounced as it did is that Australia's hot rock riches don't fit into Howard's political agenda.

Wedge master Howard has scented an opportunity to split the Labor Party still further on the nuclear issue, while painting the Coalition an improbable shade of green. That's aside from the fact that Australia's corporate rich's hunger for the full nuclear cycle, from uranium mining, through uranium enrichment and nuclear power plants, to reprocessing and storing the world's reactor wastes.

Developing geothermal energy might promise to give Australia one of the world's cleanest, greenest power generation industries. But at the end of the yellowcake road lies something far more enticing for the business chiefs — decade upon decade of nuclear industry megaprofits. Beside the money to be made at the most lucrative points of the nuclear cycle, geothermal power is strictly food for energy industry minnows.

Energy extraction

What's the nature of the geothermal resource that the Australian enthused over in its September coverage, then shut up about in the whole pages it devoted to the nuclear option in mid-November?

Across large stretches of Australia, granites containing radiogenic elements such as uranium, thorium and potassium occur at depths from three to six kilometres, and are overlain by thick deposits of sedimentary rocks that have low thermal conductivity. The slow decay of the radioactive elements in the granites produces heat, which is kept from escaping by the insulating rocks higher up. In the Cooper Basin, an area of 1000 square kilometres has an average temperature of 270*C at a depth of five kilometres.

Like most rocks, the granites contain natural fissures which can be expanded using an oil industry technique known as fracturing. A bore is sunk into the granites and water at very high pressure is pumped in. Numerous mini-earthquakes are set off and when the pressure is released the result is a permanent, many-fold increase in the permeability of the fracture systems.

Other bores can then be sunk as far as a kilometre away, and the process repeated. If the geologists have calculated correctly, the fracture zones interconnect. Water pumped down one bore will emerge from others as superheated steam, which can be used to generate electricity; the steam can then be condensed and recycled. Although the heat has its origins in radioactive decay, the granites are virtually insoluble and, essentially, no radioactive material reaches the surface.

Over a period of perhaps 20 years, the temperature of the rocks in the underground "heat exchanger" falls to the point where extraction of further heat becomes uneconomic. But if the process is halted for several decades, the temperatures build up again.

As already indicated, the technologies used in "hot dry rock" energy extraction of deep drilling, rock fracturing, and managing hot fluids are already well developed. The fact that so much use is made of established technologies suggests that the timelines for bringing sizable geothermal plants on stream should be reasonably short shorter, in all likelihood, than for nuclear power. As with all deep drilling, there are risk factors that mean particular holes can be expensive "duds".

Lower risk

Nevertheless, the presence of granites at the required temperatures can be predicted with a high degree of certainty, and this means that the business risks involved in developing geothermal energy should be relatively low — much less, for example, than in the case of drilling for new oilfields — provided that the power generated can be got to consumers. Australia's largest geothermal prospects are 500 kilometres or more from the nearest electrical grid connection.

These distances are not extreme by world standards, and with modern transmission technology, the losses of current en route to consumers would be surprisingly small. In any case, Australia's geothermal prospects are not all in the remote inland. The project that is probably closest to commercial operation, at Paralana in the North Flinders region of South Australia, is only 130 kilometres from the grid. Other prospects are near the border between South Australia and Victoria, and in the Hunter Valley region of New South Wales.

Also, the building of transmission lines to remote generating plants would allow the development of resources along the way. In South Australia, a number of promising mineral deposits lie along the so-called Moomba-Adelaide corridor.

Nevertheless, the cost of building and upgrading the infrastructure needed to make geothermal energy a prime supplier of Australia's future energy needs would be massive — as much as $800 million for a grid connection to the Cooper Basin. Development on this scale requires huge financial resources, along with an ability to plan over decades. It is thus a legitimate function of governments, rather than of private investors.

The federal government, in particular, needs to commit itself to making an exhaustive, open investigation of geothermal energy as the bedrock of eastern Australia's future electricity supplies. If the prospects pan out — as the evidence suggests they will — the private developers should be taken over, and the necessary funds should be put into the coordinated development of publicly-owned energy systems based on renewable power sources.

Howard's plans are, of course, diametrically different.
The more the federal government locks Australia into the nuclear option, the more potential investors in geothermal energy will conclude that the really big money will not be coming their direction. Plans will be put on hold, then scrapped. Politicians will continue to mouth off about greenhouse gas reduction, but will argue that the commitment to nuclear energy is too entrenched to allow a shift to alternatives. Unless, that is, masses of people revolt against an absurdity, and go on to organise and campaign to compel a change of course.

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