Earlier this month, Contact Energy chief executive Steve Barrett said there was the potential to double the contribution geothermal power made to the country’s electricity needs over the next 10 years.

All New Zealand’s geothermal power comes from geothermal fields located in the central North Island, in and around the Volcanic Plateau.

Barrett said the current 450MW of geothermal capacity, of which Contact supplied 66%, could be doubled to provide about 14% of New Zealand’s total electricity generation capacity.

Already Contact had a drilling program in several of its geothermal fields, including Te Mihi and Ohaaki, to add another 39MW of generation capacity to its central North Island stations, Barrett said.

Also this month, government-owned Mighty River Power (MRP) announced plans to develop its central North Island's geothermal fields, with consultations underway for a new MRP station at Kawerau.

That field is believed to have capacity of up to 300MW. But the station, which the government has just awarded 1.2 million internationally recognised emissions trading units, will have an initial capacity of up to 80MW.

MRP is also involved in exploratory drilling near Mangakino to determine whether a station there would be viable. Initial results are expected towards the end of the year.

MRP has existing geothermal stations at Mokai and Rotokawa. The Mokai plant capacity recently expanded to almost 100MW, while MRP is hoping to at least double Rotokawa’s capacity to 66MW in the next few months.

Rotorua geologist Ashley Cody recently said he believed up to a third of New Zealand's electricity could ultimately come from geothermal power. Geothermal drilling costs about the same as drilling an onshore Taranaki oil or gas well – about NZ$3-5 million.

The other major NZ electricity players – hydro king Meridian Energy, TrustPower and Genesis Energy – are focusing on wind power projects for future generation, not geothermal, and further significant hydro opportunities are limited.