Scientists hope to drill 500m-deep exploration wells into Dunedin Volcano

Marco Brenna (left) and Mike Palin, of the University of Otago geology department, with a map indicating Dunedin's ancient volcanic past. Photo / ODT

A team of Dunedin scientists is keen to drill two 500m-deep exploration wells into the 11 million-year-old Dunedin Volcano in a hunt for crucial geothermal energy.

Dr Mike Palin, of the University of Otago geology department, said significant amounts of carbon-based fuels were burned in New Zealand and elsewhere to generate heat for buildings and manufacturing.

He and several other geologist department colleagues were asking if residual heat from extinct volcanoes could be harnessed as a geothermal energy resource, "thereby reducing carbon-based fuel consumption and consequent greenhouse gas emissions".

The scientists hope to drill beneath the veneer of sedimentary rock to monitor any residual heat from the now solidified magma chamber that lies beneath, from the area's volcanic past.

If testing proves positive, heat could be captured by pumping water underground in a loop and bringing it back heated.

This was likely to require deeper drilling eventually.

Successful utilisation of this geothermal resource, if it was of sufficient size, would have long-term economic benefits both locally and nationally.

In Dunedin, the main users of heat were the Dunedin Hospital, Otago University and the central business district.

"Reduction in fuel costs will translate into direct economic benefit for them as well as indirect savings for central government through funding of health services and tertiary education," Dr Palin said.

Otago University and Dunedin Hospital already used some shared heating, and one possibility was that the new, redeveloped hospital could have some of its heating needs met from geothermal sources.

It is hoped to drill one exploratory well in central Dunedin, and another in the Port Chalmers-Portobello area, perhaps at the university's Portobello marine laboratory.

Dr Marco Brenna is the science leader of the proposal, and Dr Christian Ohneiser and Associate Prof Andrew Gorman are other group members.

The aim was to submit to the Ministry for Business, Innovation and Employment by tomorrow a concept proposal seeking support for the $1 million project through MBIE's Smart Ideas scheme.

MBIE would assess the proposal and indicate by March if it could be developed in more detail, Dr Palin said.

Measurements gained from the drill-related monitoring would also be used to generate a 4-D spatial-temporal geological model of the volcano, and to determine the extent of the geothermal resource.

Dr Palin outlined the geology group's vision for the drilling proposal in a talk he gave on their behalf at a recent Otago Energy Research Centre symposium.