Australian "hot rocks" offer 26,000 yrs of power

SYDNEY Wed Aug 20, 2008 4:36pm EDT

An undated graphic illustration shows a geothermal technology Australian companies are developing to generate electricity from the heat of ancient rocks buried deep below the red sands of the Australian outback. REUTERS/Handout

An undated graphic illustration shows a geothermal technology Australian companies are developing to generate electricity from the heat of ancient rocks buried deep below the red sands of the Australian outback.

Credit: Reuters/Handout

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SYDNEY (Reuters) - Barely one percent of Australia's untapped geothermal energy could produce 26,000 years worth of clean electricity, scientists said, as the government announced a A$50 million (US$43 million) project to help develop the technology.

Australia is the world's biggest coal exporter with coal used to generate about 77 percent of its electricity. Its reliance on coal for generating electricity makes it the world's biggest per-person polluter, with five times more emissions per head than China.

"Geothermal energy which is sometimes known as hot rocks has got a huge potential for Australia, both as a solution to climate change and in terms of national energy security," said Resource Minister Martin Ferguson.

To produce power from geothermal energy, water is pumped below ground where it is heated and the heat energy used to generate power.

Geoscience Australia has mapped the nation's geothermal energy, using temperature recordings from decades of drilling by energy and exploration firms, sometimes to a depth of five kms (three miles).

A total of 5,722 petroleum and mineral boreholes across Australia were used to generate the map.

"One percent of reserves would produce 26,000 years of energy supplies," Geoscience's Anthony Budd told Reuters on Wednesday.

Budd said "hot rocks" needed to be 150 degrees Celsius to produce electricity, which was achievable at a depth of one to five kms, noting temperature rose deeper into the earth's crust.

An Australian Geothermal Energy Association report this week forecast it could potentially produce 2,200 megawatts of baseload power by 2020, adding that represented up to 40 percent of Australia's 2020 renewable energy target.

The association estimated A$12 billion would need to be invested to develop the 2,200 megawatts of power, but added the cost of generating electricity would fall to acceptable levels by the time commercial projects were up and running.

It estimated it would cost A$120 per megawatt hour from a small pilot plant producing 10 to 50 megawatts of power, and A$80 per megawatt hour for a large scale plant of 300 megawatts or greater.

"The upper cost boundary will decline over time because the level of uncertainty is expected to narrow as the industry grows. This cost is expected to be lowest cost of any form of renewable or low emissions energy," it said.

The government's geothermal drilling project will see different technologies used at various locations around Australia to try and determine the best technology for converting "hot rock" energy into electricity.

Ferguson said the first commercially viable geothermal power plants could be in place within four to five years.

"Geothermal energy provides clean base-load power and is potentially a very important contributor to Australia's energy mix in a carbon-constrained world," he said.

Prime Minister Kevin Rudd won power last November in part by promising to sign the Kyoto Protocol, which sets binding limits on emissions from developed countries, and to cut emissions by 60 percent of 2000 levels by 2050.

($1=A$1.15)

(Editing by Sanjeev Miglani)

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