A HOT spring tucked away in Sembawang might just hold the key to Singapore's untapped geothermal power potential, and at least one geologist is going full steam ahead on the idea.

The spring at Gambas Avenue produces water at 70 deg C and lures visitors keen to test its rumoured curative powers, but it could have a bit more than that to offer.

Dr Grahame Oliver believes the energy that heats the unassuming spring could be tapped - based on his geologic predictions and evidence from Singapore quarries - to power 50,000 homes here.

He told scientists at the annual meeting of the Asia Oceania Geosciences Society yesterday that the concept needed further study, but added: 'I see this as a new look at Singapore's geology, with a new geothermal model that explains existing hot spots.'

Geothermal energy stems from the earth's heat and is usually tapped at the boundaries of tectonic plates, such as those in Indonesia, where there are natural heat sources near the surface.

Dr Oliver, a visiting don at the National University of Singapore teaching mainly petroleum geosciences, said that while Singapore is not at a plate boundary, sources of geothermal energy can be located by following hot springs.

The Gambas Avenue spring suggests it sits atop a bed of hot rock - in this case, granite. Much of north and central Singapore sits on granite, which generates infinitesimal amounts of its own heat, Dr Oliver said.

This heat accumulates over millions of years and, when combined with the earth's other natural heat, great warmth can be found nearer the surface in granite than in other types of rock.

Dr Oliver's search for the water's source and direction has taken him to quarries in Bukit Timah and Little Guilin in Bukit Gombak.

He found joints and faults in the rock that channelled rainwater to the north-east and south-west and onto the spring at Sembawang.

Read the full story in Saturday's edition of The Straits Times.

caiwj@sph.com.sg