Geothermal Energy & Electricity Generation

Geothermal energy produces about 13% of New Zealand’s electricity supply. Most of New Zealand’s installed geothermal generating capacity of about 750 MWe is situated in the Taupo Volcanic Zone, with another 25 MWe installed at Ngawha in Northland. The temperature and conditions of a particular geothermal reservoir determine which type of generation technology is used: dry steam, flash steam or binary cycle.

Cooling tower at Ohaaki geothermal power stationWhen the first generator was commissioned at Wairakei in 1958, it was only the second geothermal plant in the world to begin large-scale commercial operation and the first to exploit a wet (rather than dry steam) geothermal resource. The impetus for the development of Wairakei came in 1947 from severe electricity shortages following two dry years which restricted hydro generation, and a desire by the New Zealand Government for the electricity supply to be independent of imported fuel. New Zealand has recently faced similar situations

There are currently six fields used for geothermal electricity generation, which is dominated by Contact Energy Ltd (a listed company) and Mighty River Power (a State Owned Enterprise). A significant factor in recent geothermal projects has been the high level of commercial participation by Maori-owned enterprises.

Historical Changes in NZ Geothermal Electricity Generation Capacity

Plant NameCurrent OwnerCommissioning DateTotal Installed Capacity (MWe) Cumulative Capacity (MWe)
WairakeiContact Energy1958-63193193
KawerauNorske Skog Tasman196610203
WairakeiContact Energy1982-36167
Kawerau Binary (TG1)Nova Energy19892.4169
OhaakiContact Energy1989114*283
Kawerau Binary (TG2)Bay of Plenty Electricity19933.5287
Ohaaki ReratingContact Energy1996-10277
Wairakei BPContact Energy19965282
Poihipi RoadContact Energy199655337
RotokawaMighty River Power199729366
NgawhaTop Energy199810376
Mokai 1Tuaropaki Power Company199955431
Ohaaki DeratingContact Energy2001-38393
Rotokawa ExtensionMighty River Power20036399
Kawerau BP DecomNorske Skog Tasman2004-10389
Kawerau BP2Norske Skog Tasman20048397
Wairakei BinaryContact Energy200514.4411
Mokai 2Tuaropaki Power Company200539450
Ohaaki DeratingContact Energy2005-16434
Mokai 3Tuaropaki Power Company200717451
Ohaaki ReratingContact Energy200710461
KawerauMighty River Power & partners2008100561
KA24Eastland Group20088.3569
Ngawha 2Top Energy200815584
Nga Awa PuruaMighty River Power & Tauhara North No. 2 Trust2010140724
Te HukaContact Energy201023747
TOPP1Norske Skog Tasman201325772
NgatamarikiMighty River Power201382854
Te MihiContact Energy20141661020
Wairakei ReductionContact Energy2014-40980
TG1 RetirementNova Energy20142.4978
* Although Ohaaki still has 114 MWe of plant installed on site, one high pressure turbine is now decommissioned and other turbines operate on restricted duty. The station generates around 45 MWe due to field limitations.

The following table indicates upcoming developments.

StationCapacity (MW)OperationDeveloperComments
Ngawha 3502020Top EnergyDesign stage, probable well drilling 2018
Ngawha 450laterTop EnergyPlanning stage
Taheke??Contact & Taheke 8C and the Adjoining Blocks Inc3 Exploration wells drilled.
Te ia o Tutea (Taheke)??MRP, Okere Inc and Ruahine Kuharua IncAgreement for expansion and cooperative development
Tikitere<45>2020Tikitere Geothermal Power Limited and Ngati RangiteaorereBoth currently in consenting and investigation stage; unlikely to be complete in 2017.
Rotoma35>2020Rotoma No 1 IncConsents under appeal; unlikely to be complete in 2017.
Te Ahi O Maui (Kawerau)202018Eastland Group and Kawerau A8D Ahuwhenua Trust1 production, 2 reinjection wells drilled 2016.
Tauhara II240>2020ContactConsents in place through Board of Inquiry. Production drilling to follow; unlikely before 2018.
Misc400By 2025VariousBalance of unspecified projects including late stages of existing developments