|
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 434 MWe is currently installed,
of which 370 MWe is useable because of physical
or regulatory constraints. Existing development
thus represents only about 10 % of the total high
temperature resource.
Assessment of New Zealand’s
High Temperature Geothermal Resources
(based on a stored heat calculation)
Source: Lawless 2002
| 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
|
Table Notes:
- Excludes Lake Rotorua
- Excludes Lake Rotoiti
- Includes Waikite
- Mean temperature through acessible reservoir
thickness and area, not maximum, and for
developed fields, before exploitation
- Three values are 10, 50 and 90th percentiles
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
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
| 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
|
30
|
40
|
155
|
| Ketetahi |
100
|
0
|
0
|
0
|
0
|
| Mangakino |
47
|
47
|
0
|
0
|
47
|
| Mokai |
140
|
140
|
94
|
5
|
32
|
| Ngatamariki |
120
|
120
|
0
|
0
|
120
|
| Ngawha |
75
|
38
|
10
|
8
|
25
|
| Ohaaki |
130
|
130
|
50
|
17
|
52
|
| Orakei Korako |
110
|
0
|
0
|
0
|
0
|
| Reporoa |
42
|
0
|
0
|
0
|
0
|
| Rotokawa |
300
|
300
|
35
|
8
|
256
|
| Rotoma |
35
|
10
|
0
|
0
|
10
|
| Rotorua |
35
|
18
|
6
|
45
|
2
|
| Tauhara |
320
|
160
|
2
|
1
|
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 |
|
|
|
|
1248
|
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 all 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
See Other Geothermal Energy
Content
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