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.

Champagne hot pool in RotoruaNew 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
Field
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
Orakei-Korako  
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
Tikitere-Taheke2  
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. Recent consent hearings suggest a conservative approach may be required for the few fields near urban areas (Kawerau, Ngawha, Rotorua, Tauhara and Tokaanu), so in the calculations below the capacities have been halved. 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 1100 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

Field
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
225
130
9
58
Ketetahi
100
0
0
0
0
Mangakino
47
47
0
0
47
Mokai
140
140
111
7
4
Ngatamariki
120
120
0
0
120
Ngawha
75
38
25
5
9
Ohaaki
130
130
60
17
37
Orakei Korako
110
0
0
0
0
Reporoa
42
0
0
0
0
Rotokawa
300
300
35
11
252
Rotoma
35
35
0
0
35
Rotorua
35
18
6
45
2
Tauhara
320
160
2
3
158
Te Kopia
96
0
0
0
0
Tikitere-Taheke
240
240
0
0
240
Tokaanu
200
100
0
45
99
Waimangu
280
0
0
0
0
Waiotapu
340
0
0
0
0
Wairakei
510
510
230
30
47
Total
1115

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 Ngati Tuwharetoa (Bay of Plenty) interests.

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