In an interview on the ABC Science Show, Klaus Regenauer-Lieb is a professor of earth sciences at the University of Western Australia, said the hot water available in aquifers around Perth is sufficient to power the city entirely.
Professor Regenauer-Lieb pointed out that geothermal energy is already being used in Perth for at least five swimming pool project – the biggest being the Challenge Stadium, which has a drill hole about a kilometre deep. Hot water, at about 50°C is extracted to heat the pool through a heat exchange and the resulting cold water is pumped back into the ground in a closed loop.
The hot water comes from a sedimentary aquifer which is naturally permeable rock – unlike the hot dry rock in South Australia which has to be engineered to make it permeable.
According to Professor Regenauer-Lieb "If you punch a hole into Australia, into the middle of Australia, you will find that the water is coming up at about 100 degrees without pumping."
All major Australian cities, except Adelaide, have underlying hot sedimentary aquifers. In the case of Perth, Professor Regenauer-Lieb said thet "We have water available that is in permeable sedimentary layers that is in excess of 200 degrees hot, and we could use that water to power Perth entirely."