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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 Name
Current Owner
Commissioning Date
Total Installed Capacity (MWe)
Cumulative Capacity (MWe)
Wairakei Contact Energy 1958-63 193 193
Kawerau Norske Skog Tasman 1966 10 203
Wairakei Contact Energy 1982 -36 167
Kawerau Binary (TG1) Nova Energy 1989 2.4 169
Ohaaki Contact Energy 1989 114* 283
Kawerau Binary (TG2) Bay of Plenty Electricity 1993 3.5 287
Ohaaki Rerating Contact Energy 1996 -10 277
Wairakei BP Contact Energy 1996 5 282
Poihipi Road Contact Energy 1996 55 337
Rotokawa Mighty River Power 1997 29 366
Ngawha Top Energy 1998 10 376
Mokai 1 Tuaropaki Power Company 1999 55 431
Ohaaki Derating Contact Energy 2001 -38 393
Rotokawa Extension Mighty River Power 2003 6 399
Kawerau BP Decom Norske Skog Tasman 2004 -10 389
Kawerau BP2 Norske Skog Tasman 2004 8 397
Wairakei Binary Contact Energy 2005 14.4 411
Mokai 2 Tuaropaki Power Company 2005 39 450
Ohaaki Derating Contact Energy 2005 -16 434
Mokai 3 Tuaropaki Power Company 2007 17 451
Ohaaki Rerating Contact Energy 2007 10 461
Kawerau Mighty River Power & partners 2008 100 561
KA24 Eastland Group 2008 8.3 569
Ngawha 2 Top Energy 2008 15 584
Nga Awa Purua
Mighty River Power & Tauhara North No. 2 Trust 2010 140 724
Te Huka Contact Energy 2010 23 747
TOPP1 Norske Skog Tasman 2013 25 772
Ngatamariki Mighty River Power 2013 82 854
* 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.

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The following table indicates upcoming developments.

Capacity (MW)
Te Mihi I
Consents in place through Board of Inquiry for a 240 MW development, contracts signed, under construction, production drilling progressing. This will replace 45 MW of existing Wairakei plant but this initial stage will result in a 114 MW net gain.
Te Ahi O Maui (KA22)
Eastland Group and Kawerau A8D Ahuwhenua Trust & Innovations Development Group
Project up to 50 MW announced but still requires consents and contracts.
Tauhara II
Consents in place through Board of Inquiry. Production drilling to follow.
Tikitere Trust (and partners)
currently in consenting and investigation stage.
Rotoma No 1 Inc
Consents under appeal.
Contact & Taheke 8C and the Adjoining Blocks Inc
3 Exploration wells drilled.
Te ia o Tutea
MRP, Okere Inc and Ruahine Kuharua Inc
Agreement for explanation and cooperative development
By 2025
Balance of unspecified projects including late stages of existing developments

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