Development Potential

Geothermal energy has the potential to make a significant contribution to New Zealand’s energy requirements, either through electricity generation or, with even higher levels of efficiency, as a direct source of heat. However, because geothermal steam cannot be transported for more than a few tens of kilometres, the opportunities for direct use are limited and large-scale electricity generation is the most attractive option.

New Zealand has substantial geothermal resources that are accessible and untapped. The most comprehensive recent assessment of New Zealand’s high temperature geothermal resources is that by Lawless (2002), the total resource is estimated as equivalent to a median value of 3600 MWe of electrical generation, using only existing technology. A total of 584 MWe is currently installed. Existing development thus represents only about 15 % of the total high temperature resource.

Assessment of New Zealand’s High Temperature Geothermal Resources

Based on a stored heat calculation: Source: Lawless 2002

Table Notes:

  1. Excludes Lake Rotorua
  2. Excludes Lake Rotoiti
  3. Includes Waikite
  4. Mean temperature through acessible reservoir thickness and area, not maximum, and for developed fields, before exploitation
  5. Three values are 10, 50 and 90th percentile
Fields Resource
Area (km2)
Depth to
Reservoir
(m)
Resource Thickness
(m)
Void Space
%
Mean Temperature4
°C
Generating
Capacity5
MWe
min mode max min mode max   min mode max min mode max 10th med 90th
Atiamuri 0 0 5 800 1500 1700 2200 8 10 12 190 220 240 1 6 18
Horohoro 0 0 5 500 1800 2000 2500 8 10 12 180 200 240 1 5 15
Kawerau 25 35 40 400 1500 2100 2500 6 8 10 260 270 280 350 450 570
Ketetahi 10 12 30 800 1500 1700 2200 4 8 12 230 240 260 70 100 150
Mangakino 0 8 10 800 1500 1700 2200 8 10 12 200 230 250 20 47 70
Mokai 5 6 16 700 1300 1800 2300 8 10 12 260 280 290 95 140 220
Ngatamariki 8 10 12 400 1800 2100 2500 5 8 10 250 260 270 90 120 160
Ngawha 10 18 25 400 1800 2100 2500 3 4 6 220 240 260 50 75 120
Ohaaki 6 10 12 400 1800 2100 2500 6 8 10 260 270 280 100 130 170
OrakeiKorako 8 10 12 400 1500 1800 2200 8 10 12 240 250 260 90 110 135
Reporoa 0 9 12 700 1000 1500 2000 8 10 12 220 230 240 20 42 65
Rotokawa 12 18 20 500 1800 2100 2500 6 10 12 260 280 290 230 300 400
Rotoma 4 5 6 500 1700 2000 2500 6 8 10 220 240 245 28 35 46
Rotorua1 2 4 8 500 1500 1800 2000 8 10 15 220 240 250 25 35 55
Tauhara 7 15 35 500 1700 2000 2500 10 12 15 240 260 270 200 320 500
Te Kopia 6 10 12 500 1700 2000 2500 6 10 12 230 240 250 75 96 120
TikitereTaheke2 15 35 40 500 1000 1800 2200 8 10 12 220 240 260 160 240 350
Tokaanu 10 20 30 800 1500 1700 2200 4 8 12 250 260 270 130 200 300
Waimangu 9 12 30 400 1800 2100 2500 8 10 15 250 260 270 180 280 420
Waiotapu3 15 20 30 500 1200 1800 2500 8 10 12 260 275 280 250 340 450
Wairakei 15 20 30 350 2000 2150 2650 10 15 20 250 255 265 380 510 670
Means and Totals: 9.5 250 2500 3600 5000

There are various limitations on field development. In some cases, Regional Councils place a high degree of protection on certain resources. As the calculations of field capacity assume a limited amount of stored heat, allowance has to be made by past extractive use of the resource. On this basis, the following table indicates over 1200 MW of additional capacity could eventually be developed over and above current developments, though not all of this will be economic. Over half of this potential capacity buildup would be brownfield stepouts from existing developments on proven fields.

Assessment of Restricted Geothermal Potential (Updated 2014)

Fields Generating
Capacity
(P50) (MW)
Capacity Minus Environmental Limitations (MW) Existing Generation or Use (MW) Equivalent Period of Past Use (years) Calculated Available Additional Capacity
(MW)
Atiamuri 6 0 0 0 0
Horohoro 5 5 0 0 5
Kawerau 450 450 165 13 213
Ketetahi 100 0 0 0 0
Mangakino 47 47 0 0 47
Mokai 140 140 115 11 Sustainable
(based on modelling
Ngatamariki 120 120 82 1 35
Ngawha 75 75 25 10 42
Ohaaki 130 130 60 25 20
Orakei Korako 110 0 0 0 0
Reporoa 42 0 0 0 0
Rotokawa 300 300 175 6 88
Rotoma 35 35 0 0 35
Rotorua 35 35 6 50 19
Tauhara 320 320 25 4 292
Te Kopia 96 0 0 0 0
Tikitere-Taheke 240 240 0 0 240
Tokaanu 200 200 0 50 199
Waimangu 280 0 0 0 0
Waiotapu 340 0 0 0 0
Wairakei 510 510 357 22 Sustainable
(based on modelling
Total 1235

A potentially important component of future development options has been the continued Government ownership of 102 unused geothermal wells in the Central North Island. These assets and their associated IP have been administered by Treasury. Government has signalled its intention to develop these assets by naming Mighty River Power as its developer. In an initial step Kawerau geothermal assets were transferred to Mighty River Power in July 2005, with a back-to-back deal for transfer to

Deep geothermal drilling and extraction technology has the potential to exploit additional sources of geothermal energy derived from the near-magmatic conditions in deep geothermal systems or systems without surface features. Developments based on these unexplored resources could result in new developments without undesirable effects such as subsidence.

Increased geothermal electricity generation in New Zealand can assist the short-term supply situation and also contribute significantly to long term generation growth. The barriers to ongoing development of geothermal energy in New Zealand are not technical, nor absolute cost, but regulatory and its cost relative to alternatives.

Publications

  • Lawless, J V 2002: New Zealand’s geothermal resource revisited. New Zealand Geothermal Association Annual Seminar, Taupo.
  • Lawless, J V 2004: New Zealand’s geothermal opportunities. New Zealand Geothermal Association Annual Seminar, Taupo.

Links

The Renewable Energy Industry Status Report – Wind, Hydro & Geothermal
EECA (2MB PDF)

Power Generation Options for New Zealand
Sinclair Knight Merz Limited
http://www.med.govt.nz/ers/electric/new-generation-options/skm/index.html

2000-2005 New Zealand Country Update
Michael Dunstall
Proceedings World Geothermal Congress 2005
http://geothermal.stanford.edu/pdf/WGC/2005/0111.pdf

1995-2000 Update report on the existing and planned use of geothermal energy for electricity generation and direct use in New Zealand
Ian Thain, Michael Dunstall
Proceedings World Geothermal Congress 2000
http://iga.igg.cnr.it/pdf/WGC/2000/R0093.PDF