Business View Oceania | September 2020

55 BUSINESS VIEW OCEANIA SEPTEMBER 2020 GEOTHERMAL ENERGY of water along fractures creates the hot springs distributed on both the North and South Islands. The geothermal industry operates eight high- temperature geothermal fields in the North Island (Table 1). Internationally, New Zealand ranks fifth in terms of geothermal generation. Technologies Employed For power generation, geothermal operators employ condensing steam turbines and organic Rankin cycle (“binary”) gen-sets. For direct use applications, operators predominately use heat exchangers linked with kilns and dryers. Heat pump use has exploded over the past five years in residential construction, coupled with commercial “rebuild” applications following the Christchurch 2011 earthquake. Drilling comprises roughly a third of the cost of high-temperature development. The geothermal industry has specialist drilling contractors, well services, and field services operating in country. Conventional, top drive rigs drill most of the wells but explorers commonly employ mineral or geo- mechanical rigs for slim-hole investigation or monitor wells. Coil tubing units are employed for well work-overs and abandonments. Most drilling uses fresh water or aerated fluids; oil and gas type mud systems are rare. Growth New Zealand’s decarbonisation policy has stimulated innovation and development, particularly in the high-temperature sector. Rising carbon prices have swelled natural gas prices and threaten to economically strand existing baseload thermal plants. In addition, the country seeks to move aggressively into electrifying transportation. Geothermal operators are responding by investing in new capacity on existing fields. Top Energy is currently constructing a third MW binary plant (26 MWe) at Ngawha, Contact Energy is developing a second power station (100 MWe) at Tauhara, and Mercury Energy can potentially add another 20 -30 MWe binary unit at Ngatamariki. In addition, exploration for new development is likely to start at several locations. Geothermal energy competes directly with wind and solar PV technologies. There are no government subsidies or feed-in tariffs to support renewable investments; all energy sources compete on a level tax and price playing field. Greenhouse emissions are managed through an Table 1: High Temperature Geothermal Fields of the North Island FIELD OPERATOR CAPACITY MWE NET PLANTS 1ST COD YEAR Wairakei Contact Energy Ltd 352 4 1958 Rotokawa Mercury Energy Ltd 163 2 1997 Mokai Tauropaki Trust 104 2 1999 Tauhara Contact Energy Ltd. 26 1 2010 Ngatamariki Mercury Energy Ltd. 82 1 2013 Ohaaki Contact Energy Ltd. 42 1 1988 Kawerau A Ngati Tuwhateroa Geothermal Ventures 30 3 1966 Kawerau B Mercury Energy Ltd 100 1 2008 Kawerau C Eastland Generation Ltd 33 2 2008 Ngawha Top Energy Ltd. 25 2 1998 Totals 957 19