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

By Michael Perry

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.