New uses sought for thermal resource

ON STREAM: Te Mihi power station. PHOTO/SUPPLIED 150814POWER

Future will see more direct applications

The official launch of Contact's Te Mihi power station in Wairakei this week could be the last big new power station to open in New Zealand for the rest of the decade. A combination of full capacity and flattening demand, together with the trend towards energy conservation, could see increasing exploration of alternative uses for the energy available from the region's massive geothermal resource.

Experts commissioned by Rotorua District Council's economic development agency Grow Rotorua Ltd were in Rotorua this week working on potential commercial geothermal projects, said Grow Rotorua chief executive Francis Pauwels.

New Zealand expert James White and Australia's Charles Davidson were commissioned earlier this year as part of an ongoing focus to develop geothermal resources to create jobs and business opportunities. The idea was to identify a range of successful business models from global research.

Mr Pauwels said Grow Rotorua had put back the delivery date of its project in order to allow the experts to work on projects in Rotorua and gain local experience of the resource and its commercial potential.

"It all comes back to what is the available supply and the nature of the supply and what is the sustainable use of it," he said. "It comes back to fuel supply - that always has to be the place to start." Each project had to be treated on a case-by-case basis to assess the quality of the chemical composition, the flow rate and whether the supply was sustainable, he said.

Brian Carey, president of the New Zealand Geothermal Association, said the use of geothermal energy in direct applications was likely to increase.

The latest 166 megawatt Te Mihi geothermal power station was the final stage in the Wairakei investment programme. But Mr Carey said that although Contact had geothermal resource consents to develop 250 megawatts of additional power at Tauhara, he thought it unlikely this would happen until at least the end of the decade.

"Power demand is not increasing and has actually decreased over the past three years as people take up new energy-efficient technologies," said Mr Carey, who is a geothermal resource management specialist for GNS Science, based at the Wairakei Research Centre.

"The expectation in the industry is that the next large generation plant will probably be around the end of this decade and maybe a little bit later." And while that would probably be geothermal there was "no rush" to get the next plant up and running.

Instead there were other options for geothermal such as direct heating.

"There are opportunities for New Zealand to take this up more than we are at the moment," he said.

Mr Carey cited the moves by Grow Rotorua, and said the Taupo District Council was also exploring ways of fostering direct applications. The Kawerau Symbiosis project was also looking at ways of encouraging direct heat using the timber resource to produce liquid fuels.

Other established direct geothermal applications in Rotorua included gerbera growers, Harald and Connie Esendam of PlentyFlora using geothermal energy for its glasshouses, and Arataki Honey's use of geothermal energy for honey processing and heating.

"These operations are never going to be as big as a big power station, they are going to be much more small to mid-industrial size," said Mr Carey. "But this is where we are going to see movement on geothermal use in the next few years."