GNS Science Report

© Institute of Geological and Nuclear Sciences Limited, 2015 www.gns.cri.nz

ISSN 1177-2425 (Print) ISSN 2350-3424 (Online) ISBN 978-1-927278-40-6 (Print) ISBN 978-0-478-19926-0 (Online)

J.P. Hall c/o GNS Science, Wairakei Research Centre, Private Bag 2000, Taupo 3352,

New Zealand M.D. Climo GNS Science, Wairakei Research Centre, Private Bag 2000, Taupo 3352,

New Zealand

BIBLIOGRAPHIC REFERENCE

Hall, J.P.; Climo, M.D. 2015. Geothermal Direct Use in New Zealand: Industrial Heat Park Opportunities, GNS Science Report 2014/17. 36 p.

http://www.gns.cri.nz/

GNS Science Report 2014/17 i

CONTENTS

ABSTRACT .......................................................................................................................... III

KEYWORDS ......................................................................................................................... III

1.0 INTRODUCTION ........................................................................................................ 1

2.0 GEOTHERMAL RESOURCES IN NEW ZEALAND .................................................... 2

3.0 POTENTIAL INDUSTRIAL USES FOR GEOTHERMAL HEAT ................................. 5

3.1 Forestry ......................................................................................................................... 5 3.1.1 Heat Treatment – Timber Drying ....................................................................... 6 3.1.2 Engineered Wood Products .............................................................................. 6

3.2 Biofuels .......................................................................................................................... 7 3.3 Agriculture ..................................................................................................................... 7

3.3.1 Production ......................................................................................................... 8 3.3.1.1 Greenhouses...................................................................................... 8 3.3.1.2 Aquaculture ........................................................................................ 8

3.3.2 Processing ......................................................................................................... 9 3.3.2.1 Dairy Products ................................................................................... 9 3.3.2.2 Horticulture Crops ............................................................................10 3.3.2.3 Honey and Bee Products .................................................................12 3.3.2.4 Meat, Leather and Wool Processing ................................................13 3.3.2.5 Fish Drying .......................................................................................13 3.3.2.6 Fishmeal and Fish Oil Processing ...................................................14

3.4 Other Processes .......................................................................................................... 14 3.4.1 Manufacturing .................................................................................................. 14 3.4.2 Chilling and Refrigeration ................................................................................ 15 3.4.3 Wastewater Treatment .................................................................................... 15

3.5 Minerals and Mining .................................................................................................... 16 3.5.1 Mineral Extraction from Geothermal Brines .................................................... 16 3.5.2 Heap Leaching ................................................................................................ 16

4.0 INDUSTRIAL HEAT PARKS .................................................................................... 17

4.1 Existing Geothermal Energy Infrastructures ............................................................... 17 4.1.1 Klamath Falls, USA ......................................................................................... 17 4.1.2 Elko, USA ........................................................................................................ 19 4.1.3 Reykjavik, Iceland ........................................................................................... 19 4.1.4 Kawerau, New Zealand ................................................................................... 19 4.1.5 Mokai, New Zealand ........................................................................................ 20 4.1.6 Rotorua, New Zealand .................................................................................... 20

4.2 New Zealand Heat Park Examples (non-geothermal) ................................................. 21 4.2.1 Dunedin Energy Centre ................................................................................... 21 4.2.2 Washdyke Energy Cluster ............................................................................... 21

4.3 Heat Park Planning...................................................................................................... 21 4.3.1 Climate Influence ............................................................................................. 21 4.3.2 Economics ....................................................................................................... 23 4.3.3 Project Goals ................................................................................................... 24

GNS Science Report 2014/17 ii

5.0 CONCLUSIONS ....................................................................................................... 25

6.0 ACKNOWLEDGMENTS ........................................................................................... 25

7.0 REFERENCES ......................................................................................................... 26

FIGURES

Figure 2.1 Known geothermal fields, classification and TVZ boundary within the central volcanic region (CVR) of New Zealand’s North Island. ............................................................................... 3

Figure 2.2 Geothermal direct use in New Zealand (2012) by category, presented by (A) relative number of installed operations; (B) by relative energy use. .......................................................... 4

Figure 2.3 Screenshot (from http://data.gns.cri.nz/geothermal/wms.html) of the Geothermal Use Database map of New Zealand (left) and an image of applications in parts of the Waikato and Bay of Plenty regions (right). ................................................................................................. 4

Figure 3.2 Softening/melting points of various polymers (Wolcott and Englund, 1999)) ................................ 6 Figure 3.3 Possible thermally enhanced heap leaching system (Trexler et al., 1991). ................................ 16 Figure 4.1 Klamath Falls DHS location map, 2005 (Brown, 2007) .............................................................. 18 Figure 4.2 NTGA distribution network (NTGA, 2012). ................................................................................. 20 Figure 4.3 Average annual maximum temperatures (World Weather Online, 2014). .................................. 22 Figure 4.4 Average annual minimum temperatures (World Weather Online, 2014). ................................... 22 Figure 4.5 Load factor vs. cost of energy (Rafferty, 2003). .......................................................................... 23

TABLES

Table 3.1 New Zealand’s top exported agricultural products by quantity (tonnes), for both processed and unprocessed (Food and Agriculture Organisation of the United Nations (FAO), 2011). ............................................................................................................................... 7

Table 3.2 Growing temperatures for typical greenhouse crops (Lund et al., 1998) ...................................... 8 Table 3.3 Dairy cattle statistics (Statistics New Zealand, 2012a). ................................................................ 9 Table 3.4 Harvested hectares of fruits and vegetables in North Island regions (modified from

Statistics New Zealand, 2012a) .................................................................................................. 11 Table 3.5 Harvested hectares of grain in North Island regions (modified from Statistics New

Zealand, 2012a) ......................................................................................................................... 11 Table 3.6 Other applications in food processing (modified from Rafferty, 2003). ....................................... 12 Table 3.7 Total livestock numbers (Statistics New Zealand, 2012a). ......................................................... 13 Table 3.8 Other industrial processes (modified from Rafferty, 2003) ......................................................... 14

APPENDICES

APPENDIX 1: GEOTHERMAL FIELDS IN NEW ZEALAND ................................................ 30

APPENDIX TABLES

Table A 1.1 Summary of geothermal areas in New Zealand. ........................................................................ 31

GNS Science Report 2014/17 iii

ABSTRACT

Applications for direct use of geothermal heat energy for other than electricity generation include small domestic use, moderate commercial enterprise and large, industrial scale processes. Existing examples in New Zealand include timber and milk processing, geothermal tourism, balneology, and commercial and domestic heating.

Direct geothermal energy use offers a proven energy alternative to fossil fuels for heat energy in regions endowed with geothermal resources.

This report provides an introduction to the geothermal resources in New Zealand, and a comprehensive documentation of processes using geothermal heat both in New Zealand and internationally. These include forestry and wood processing, biofuels, agricultural production and processing, manufacturing, refrigeration, wastewater treatment and mineral processing.

One approach to encouraging direct geothermal energy use is by reducing barriers to uptake by establishing geothermal, industrial/commercial scale heat parks. These parks share thermal energy distribution systems amongst multiple users, providing higher efficiencies and cost savings compared to individual heating systems.

KEYWORDS

Geothermal direct use, geothermal energy; commercial processing; industrial processing; energy demand; New Zealand, heat park, thermal infrastructure.

GNS Science Report 2014/17 1

1.0 INTRODUCTION

New Zealand in 2014 used geothermal resources to generate about 16% of the nation’s annual electricity production. Geothermal energy is also used in direct heating applications and is part of the tourism sector.

In New Zealand, there is interest in promoting greater direct use of geothermal energy.

Some of the challenges in achieving this goal are:

1. provision of planning and support for direct use development in practical ways;

2. identifying specific direct use applications for development; and

3. identifying businesses that might avail themselves to the opportunities proffered by being located in a geothermal heat park and utilising the thermal resources available.

The concept of industrial geothermal heat parks is explored, including suggested applications/industries. Examples are given of heat parks in New Zealand and internationally.

Direct geothermal use has the potential to catalyse new start-up commercial and industrial applications, and to encourage existing industries to rely less on fossil fuels and electricity for process energy.


2.0 GEOTHERMAL RESOURCES IN NEW ZEALAND

New Zealand is well endowed with geothermal resources. New Zealand’s high temperature, convective geothermal fields are located in the Taupo Volcanic Zone (TVZ) and at Ngawha in Northland (Figure 2.1). These fields have been classified by the regional authorities (Regional Councils) into development categories such as: permitted for high capacity developments, limited capacity developments, or protected against any development. A summary of some publically available technical data and field classifications for geothermal areas is listed in Table A 1.1 (Appendix 1).

Geothermal power generation is an established industry in New Zealand, supplying about 16% of the nation’s electricity demand during 2014 (Ministry of Business, Innovation and Employment, 2014). Power plants commissioned in the last few years include Mighty River Power’s (MRP) Ngatamariki station in 2013, Norske Skog Tasman’s TOPP1 (2013), and Contact Energy’s Te Mihi station (2014).

Direct use of geothermal heat is a significant part of New Zealand’s geothermal energy portfolio (Carey et al., 2015). The most widespread direct use is in bathing and hot pools (Figure 2.2). However, the largest energy use is industrial processing (Figure 2.2), with Kawerau hosting the world’s largest direct-use applications processing timber and paper (White, 2009). Recent, applications include the Miraka milk processing plant at Mokai (2011).

Figure 2.3 shows a screen shot from GNS Science’s publically-accessible online database and web map of geothermal use in New Zealand (http://data.gns.cri.nz/geothermal/). This tool is to raise awareness of geothermal energy use, as well as collating data for national reporting and spatial analysis. Use type has been categorised into electricity generation, aquaculture, agriculture, industrial processes, bathing, geothermal tourism, space heating/cooling, and geothermal (ground source) heat pumps. The dataset can assist developers to identify potential locations for new applications, and where resource temperatures might be available. Future developments to this tool could include adding hot spring locations, temperature depth profiles and thermal field boundaries.

There is potential to increase the direct use of geothermal energy in New Zealand by substituting non-geothermal based fuels that are used in currently established thermal processes near geothermal resources. Electricity demand is predicted to experience minimal growth in the wake of the recent power plant additions (White, 2013). Regional Councils, District Councils and businesses are looking for new opportunities to promote local economic growth (e.g., Industrial Symbiosis Kawerau, 2014; Grow Rotorua, 2014). Direct-use geothermal projects present as opportunities to stimulate economic growth using renewable energy solutions.


Figure 2.1 Known geothermal fields, classification and TVZ boundary within the central volcanic region (CVR)

of New Zealand’s North Island. Ngawha geothermal system shown in inset.


Figure 2.2 Geothermal direct use in New Zealand (2012) by category, presented by (A) relative number of installed operations; (B) by relative energy use. Figures exclude domestic use, geothermal heat pumps and non-commercial bathing.

Figure 2.3 Screenshot (from http://data.gns.cri.nz/geothermal/wms.html) of the Geothermal Use Database

map of New Zealand (left) and an image of applications in parts of the Waikato and Bay of Plenty regions (right). Categories include electricity generation (red), aquaculture (dark blue), agriculture (yellow), industrial processes (orange), bathing (light blue), geothermal tourism (green), and space heating/cooling (purple).

(B

(A

http://data.gns.cri.nz/geothermal/wms.html


3.0 POTENTIAL INDUSTRIAL USES FOR GEOTHERMAL HEAT

Many processes that use heat can use geothermal energy directly, instead of, or to supplement to other fuels.

New Zealand's economy, people and environment depend on the success of land-based industries. The temperature of the geothermal fluid available has to match the temperature required for the process (Figure 3.1). Some applications will be more appropriate than others for development.

Figure 3.1 Lindal diagram showing potential use for geothermal energy, as a function of the temperature

required for the process (redrawn from Geothermal Education Office, US).

A number of commercial and industrial scale applications are explored in more detail in the following section.

3.1 FORESTRY

Forestry is an important export earner for New Zealand, worth around $5b per annum (Ministry for Primary Industries (MPI), 2014b); forestry is New Zealand’s third largest export earner after dairy and meat (MPI, 2014b). The total volume of wood harvested is around 25 million cubic metres, or which around 70% is exported. In 2012, the product share of exports was logs (35%), sawn timber (19%), manufactured wood products (16%), paper and paper products (15%) and wood pulp (12%) (Statistics New Zealand, 2012b).

Wood and paper processing have a significant demand for thermal energy. The largest thermal energy demand is for intermediate heat (100°C-300°C). This makes forestry operations ideal to co-locate with geothermal resources.


3.1.1 Heat Treatment – Timber Drying

Several timber products require thermal process heat. Natural air-drying of timber is slow, and expensive. For New Zealand grown Radiata Pine, natural drying often results in uneven and unpredictable product quality. Controlled drying improves the overall quality of the timber and reduces warping. Geothermally-heated timber-drying kilns are in use in Kawerau, Ohaaki and Tauhara. The kilns are a large oven in which the enclosed heated air is circulated to draw moisture from the timber, exhausting it to the atmosphere. Pre-treatment of timber requires temperatures between 80°C-150°C (Thain et al., 2006; Bell et al., 2014).

3.1.2 Engineered Wood Products

Secondary processing, e.g., the creation of higher value manufactured wood products from timber, is a significant opportunity to grow business and retain a greater share of manufacturing revenues in New Zealand. Currently about 35% of timber is exported as logs, to be processed in other countries.

Engineered wood products include fibreboard (particleboard, medium density, hardboard), laminated timber, plywood, structural insulated panel, and wood-plastic composites. These products can be constructed of several thin wood layers or mulched wood chips and fibre that are combined into solid pieces using an adhesive. Depending on the type of adhesive used, the wood materials and adhesive need to be pressed together and dried over a temperature range of 115°C-155°C (Selbo, 1975).

Infusing plastic with wood fibre creates a wood-plastic composite. This material is currently used as a replacement for preservative-treated wood. This material maintains the characteristics of wood based construction materials, with the polymer helping to prevent water absorption (Wolcott and Englund, 1999). The plastic material is usually shipped in pellet form, and then heated to a temperature that allows it to bond with individual wood fibres. The thermal decomposition of wood occurs above 225°C, therefore the plastic must have a lower melting point to be infused. Figure 3.2 shows the melting point of different types of plastics used for creating the composite (Wolcott and Englund, 1999). Geothermal direct heat on an industrial scale should be considered for use in these processes.

Figure 3.2 Softening/melting points of various polymers (Wolcott and Englund, 1999))


3.2 BIOFUELS

Technologies exist and are being developed for converting biomass into biofuels (i.e., liquid and gaseous transport fuels). Biofuels are one way of reducing reliance on fossil fuels.

Biofuel production from purpose-grown forests is not currently economically competitive (Hall and Jack, 2008), but potential exists for improved economics using second-generation feedstocks, such as woody biomass.

Woody biomass is typically burned to create process heat for timber processing. Co-location of forestry and geothermal resources means that geothermal energy can be used to supply process heat, while biomass residues can be put to higher value uses, such as biofuels.

One such project is being investigated at Kawerau, where the aim is to produce crude oil from sawdust, which can then be refined into diesel or petrol.

3.3 AGRICULTURE

Agriculture is one of New Zealand’s primary industries, supplying horticultural and pastoral produce for both domestic and international markets. Agriculture, along with the food and forestry sectors, generates 70% of New Zealand's merchandise export earnings and around 12% of Gross Domestic Product (MPI, 2014a). New Zealand is the world's largest dairy and sheep meat exporter. New Zealand's horticultural industry is based largely on the export of kiwifruit, pip fruit (apples and pears), wine, and fresh and processed vegetables.

The ranking of New Zealand’s processed and unprocessed export products by volume are detailed in Table 3.1. Thermal energy is used in both production and processing systems. A number of raw materials could be considered for further processing with geothermal energy to create a higher valued export.

Table 3.1 New Zealand’s top exported agricultural products by quantity (tonnes), for both processed and unprocessed (Food and Agriculture Organisation of the United Nations (FAO), 2011).

Ranking Processed Unprocessed 1 Milk – whole dried Kiwi fruit 2 Milk – skimmed dried Apples 3 Cheese, whole – cow Butter – cow’s milk 4 Wine Meat – sheep 5 Food preparations Meat – cattle boneless (beef and veal) 6 Wool – degreased Onions, shallots – green 7 Milk products of natural constituents Meal meat 8 Tallow Pumpkins, squash and gourds 9 Potatoes – frozen Milk, whole fresh – cow

10 Vegetables – frozen Fat – cattle 11 Food preparations – flour malt extract Offal edible – cattle 12 Wool – greasy Potatoes 13 Beverages – non alcoholic Meat – cattle 14 Cream – fresh Waters, ice etc. 15 Offal edible – sheep Vegetables fresh 16 Sugar – refined Meat – game 17 Fruit – prepared Avocados 18 Infant food Pears 19 Vegetables – preserved Meat – chicken 20 Skins – sheep with wool Chillies and peppers – green


3.3.1 Production

3.3.1.1 Greenhouses

Greenhouses can be used to grow crops year round. Low grade heat (25-90°C) is typically required, which makes this opportunity accessible to regions with low temperature geothermal resources (<150°C). New Zealand already has geothermally-heated greenhouses established in Rotorua, Taupo, Mokai, and Tauranga.

Geothermal fluids can be used to heat, irrigate or sterilise soil in open field agriculture or to create a microclimate in a greenhouse for cultivation of fruit, vegetables or flowers, out of season or in an unnatural climate. The four basic methods of providing and distributing heat into a greenhouse are bare pipe, finned pipe, fan coil air heater for space heating and buried pipe for soil heating. Temperatures of geothermal water should be between 60°C-80°C, with the quantity of hot water depending on the optimum growing temperature for the selected crop (Table 3.2), size of the greenhouse, and the area’s climate conditions.

There are also several glasshouses internationally using fossil fuels, which benefit from the by-products of combustion, by redirecting carbon dioxide (CO2) into the greenhouse, which increases growth rates. Research has been conducted to separate CO2 from geothermal fluids in New Zealand for the same purposes. There is as yet no commercial operation using CO2 from geothermal sources, due to the cost in removing the hydrogen sulphide, which is toxic to some plant species (Foster, 1995) from the gas stream.

Table 3.2 Growing temperatures for typical greenhouse crops (Lund et al., 1998)

Produce Day Time Temperature (°C)

Night Time Temperature (°C)

Peppers 20-30 16-20

Tomatoes 21-25 17-20

Cucumber 25-28 21

Lettuce 25 20

Poinsettias 21-27 19-22

Carnations 25 10

Geraniums 21-27 18

3.3.1.2 Aquaculture

Aquaculture is the raising of plants or animals in water; coastal waters, rivers, lakes and in constructed tanks on land. Aquaculture is set to play a larger part in New Zealand’s economy; the goal is to grow aquaculture from a $200m industry to a $1b industry by 2025 (MPI, 2013).

The aim of geothermal aquaculture is to heat water to the optimum temperature for aquatic animal and plant growth. Species raised include carp, catfish, bass, tilapia, mullet, eels, salmon, sturgeon, shrimp, lobster, crayfish, crabs, oysters, clams, scallops, mussels and abalone. In addition, there is a rising interest in aquaculture crops such as water hyacinth, duckweed, algae species, kelp and spirulina.


This low temperature application, typically sustaining 13°C-30°C growing conditions, can increase the growth rate of species 50-100% (Lund, 2014a). Malaysian Freshwater Prawns (macrobrachium rosenbergii) are farmed at 24°C at Wairakei (near Taupo) to produce about 16 tonnes of prawns per year. Water for the ponds comes from the Waikato River (10°C) and is recirculated around the ponds, being heated in a plate heat exchanger (55°C) that uses geothermal water from the Wairakei Geothermal Power Plant.

3.3.2 Processing

The following are some of the benefits of food processing and preservation (Barrett, 2002):

1. Increased frequency of harvest.

2. Consumption in regions distant from the growing region.

3. Prolonged shelf life and arrested deterioration during storage.

4. Improved nutritional quality and digestibility of some foods.

5. Enhanced microbiological and chemical safety of food.

6. Long-term storage in case of drought or famine.

7. Increased variety of desirability of foods (added value).

8. Improved quality control and a more consistent product.

9. Extraction of key nutrients for health or medical uses (oils, protein concentrates).

10. Enhanced convenience and reduced preparation time prior to consumption.

Food processing can include dehydration, canning and sterilisation. Processing using geothermal energy can enable New Zealand’s agricultural businesses and farmers to export larger volumes of specialised goods to more distant and larger markets.

3.3.2.1 Dairy Products

The dairy industry is one of the fastest growing industries in New Zealand. Table 3.3 shows the current number of dairy cattle and the percentage increase since 2007 by region.

Table 3.3 Dairy cattle statistics (Statistics New Zealand, 2012a).

Region Total Dairy Cattle – June 2012 (000)

2007 2012 % Change Northland 367 398 8

Auckland 87 89 2

Waikato 1,669 1,832 9

Bay of Plenty 299 312 4

Gisborne 5 8 43

Hawkes Bay 61 55 -10

Taranaki 480 492 2

Manawatu-Wanganui 300 357 19

Wellington 73 80 10


Dairy processes that require a thermal energy input are listed below (Fellows and Hampton, 1992; Southward, 2002):

• Pasteurization: 63-72°C.

• Ultra High Temperature (UHT) treatment: 121°C.

• Cultured/fermented dairy products: 70°C preheat, 43-45°C incubation.

• Cheese making: 40°C.

• Casein protein concentrate: 20-95°C, drying 60-95°C.

Geothermal heating is currently used at Miraka, a milk processing plant owned by the Tuaropaki Trust. Geothermal heat is used to create powdered milk and UHT treated milk for export. Geothermal energy could play an increasingly active role in dairy product manufacturing, where geothermal resources co-locate with dairy production and processing.

3.3.2.2 Horticulture Crops

Domestic retail sales of fresh and processed vegetables are estimated at $1 billion each year while export earnings range between $500 and $600 million. Frozen peas, sweet corn, mixed vegetables, potatoes, carrot juice, tomato paste and purees are the main processed vegetable products (HortNZ, 2015).

There is opportunity for geothermal to play in the processing and storage of raw materials. Using the heat, products can be cleaned, preserved, or cooked before being shipped to commercial markets. Table 3.4 and Table 3.5 show the various types of crops grown on a large scale in the North Island that can be transported to a processing site in a geothermal region. For example, drying using geothermal heat could contribute to creating higher valued agriculture based products. Internationally, geothermally dried crops include garlic, onion, chilli, rice, wheat, fruit, alfalfa, seaweed, and coconut.

Many of the fruit and vegetable crops can be dehydrated between 50-100°C. Dehydrating crops requires a warm dry environment where the moisture content is controlled (Sumotarto, 2007). Geothermal examples include onions dehydrated in Nevada, USA. Onions are transported from the neighbouring state of California to take advantage of the geothermal resource. The drying process operates at 50-99°C (Lund, 2003). Also, grain drying occurs in Kamojang, Indonesia. A 160°C geothermal resource supplies a 1000 W dehydrator that produces end-use drying temperatures between 40-45°C.

Geothermal heat has been used to create high protein feedstock for sheep and chicken livestock at the Taupo Lucerne Company, near Ohaaki.

Other food processing methods include canning, milling, and cooking. Many industrial processes require steam for their primary process, and sometimes hot water for secondary parts of the process. Table 3.6 shows a few examples not previously mentioned of industrial food processes that take place in the United States and their end-use steam/hot water temperatures.


Table 3.4 Harvested hectares of fruits and vegetables in North Island regions (modified from Statistics New Zealand, 2012a) [where C = confidential; - = zero].

Total Hectares Harvested as of June 30 2012

Region Apples Avocados Kiwifruit Wine Grapes

Blackcurrants Onions Potatoes Buttercup Squash

Peas (Fresh and Processed Peas)

Sweet Corn

Northland 20 1,550 570 80 - C 20 C C 80

Auckland 100 150 360 300 - 1,620 1,440 C 30 40

Waikato 140 180 730 30 - 1,840 2,070 C C 40

Bay of Plenty 10 2,080 9,910 C C C C C - 20

Gisborne 110 60 330 1,690 - C C 2,410 280 2,490

Hawke's Bay 5,120 30 220 4,940 C 660 590 3,250 2,130 1,050

Taranaki C 60 - C - C 20 C - C

Manawatu-Wanganui 30 20 C 10 - 390 1,260 240 40 20

Wellington C 20 C 900 C C 20 C C C

Table 3.5 Harvested hectares of grain in North Island regions (modified from Statistics New Zealand, 2012a) [where C = confidential; - = zero].

Total Hectares Harvested as of June 30 2012

Region Wheat Barley Maize Grain

Northland C - 400

Auckland - C 1,600

Waikato 200 400 4,200

Bay of Plenty - - 3,200

Gisborne - C 2,600

Hawke's Bay 300 1,600 3,500

Taranaki C 100 200

Manawatu-Wanganui 1,200 4,900 2,800

Wellington 800 2,100 400

Total North Island 2,600 9,200 18,900


Table 3.6 Other applications in food processing (modified from Rafferty, 2003).

Process Highest Input Temperature °C

Lowest Input Temperature °C

Wet corn milling 121 93

Canned fruit 121 60

Meat packing 121 82

Canned drinks 121 -

Malt beverages 121 -

Cakes/pies 121 -

Bread/cake 121 60

Canned vegetables 121 -

Cane sugar refining 149 60

Beet sugar refining 137 -

3.3.2.3 Honey and Bee Products

Bee keeping yields a multitude of different products. Some of these materials require heat for processing between 30°C-100°C, which could be supplied by geothermal energy.

Honey is consumed in baked goods, confectionery, cereal, snack bars, spreads, fruit and nut mixtures, ice cream, milk products, alcoholic and non-alcoholic beverages. It is also found in medicinal products, cosmetics, and tobacco products. Heat can be used (<30°C) in assisting to extract honey from the combs. Honey can be collected with centrifugal force, pressing out from the combs, or by removing the wax caps on each comb and allowing the honey to ooze out of the comb. Increasing the temperature of the honey makes the honey less viscous allowing it to flow more freely. Purification and pasteurisation can be done with filtering and heating (<80°C). Reducing the moisture content increases storage life, and can be achieved by heating the honey to between 30°C and 35°C (Piana and Krell, 1996). Honey also runs the risk of fermentation due to the presence of certain yeasts. This can be prevented by keeping the honey in cold storage or by briefly raising the temperature of the honey to between 60°C and 65°C.

Bee’s wax can be extracted from other materials using a hot water bath between 59°C-85°C (Adjare, 1984). The wax is used in a large range of applications including paper, polish, varnish, paint, textiles, cosmetics, processed leather, ink, food, art supplies, pharmaceuticals, and candle products. It is also used to assist in food processing, dental procedures, castings and molds, electrical applications, and other industrial applications.

After pollen is collected from the hive, moisture content of the pollen must be reduced to below 10% through drying (up to 40°C-45°C) (Krell, 1996). Pollen is used in pharmaceutical, food (e.g., granola, cereal, and candy bars) and cosmetic products.

Royal jelly is used in dietary supplements, food products, and cosmetics. Most processing of royal jelly is by freeze-drying for preservation and storage (Piana, 1996).


Propolis has been claimed to possess several pharmaceutical properties and is an ingredient in some cosmetics and food preservatives. Extraction methods require an input of thermal energy between 35°C-60°C (Krell, 1996).

The Arataki Honey operation at Waiotapu, near Rotorua, uses geothermal energy to process their honey products.

3.3.2.4 Meat, Leather and Wool Processing

New Zealand’s pasture based-livestock industries include the dairy, deer, sheep, beef and wool sectors. The farming systems are based primarily on year-round grass fed livestock, housed outdoors. Table 3.7 shows the number of major livestock, excluding dairy cattle, which are located in areas with high temperature geothermal systems.

Table 3.7 Total livestock numbers (Statistics New Zealand, 2012a).

Region Total Livestock – June 2012 (000)

Sheep Beef Cattle Deer

Northland 441 381 5

Waikato 1,777 506 81

Bay of Plenty 323 93 42

Slaughtering and meat processing operations require energy for refrigeration, and processing (e.g., drying).

Wool scouring is a cleaning process where detergent and hot water are required to remove grease and dirt. There are several steps in the wool scouring process where hot water between 60°C-85°C is needed. Dyeing wool also requires thermal energy (McKinnon, 2002).

There are several steps to processing leather that involve the use of chemicals. At the end of the process, moisture needs to be removed from the leather. Geothermal temperatures between 30°C and 60°C can be used (Lund, 2014b).

3.3.2.5 Fish Drying

New Zealand’s seafood industry harvests about 600,000 tonnes from wild fisheries and aquaculture each year ($1.2b per annum), and is New Zealand’s fourth or fifth largest export earner (MPI, 2014a).

There are several opportunities for processing in the aquaculture industry. For example, Iceland uses geothermal heat to process 15,000 tonnes of cod that are shipped to Nigeria as a protein source. Two stages of drying require temperatures between 18°C-25°C, to reduce the water content to 15%, making it possible to store for long distance transport without spoiling. The consumption of geothermal heat used in this process in 2001 was about 550 TJ of energy from 2 million tonnes of geothermal fluid (Arason, 2003).


3.3.2.6 Fishmeal and Fish Oil Processing

Fishmeal, ground up fish or fish parts, is a nutrient dense product used as an animal feed or in fertilisers. As the dairy industry grows, the demand for fertiliser and animal feed increases and creates a larger domestic market. The core uses of fishmeal are feeding growing and high producing species, such as maturing fish and shrimp, and poultry and lactating dairy cattle (Miles and Chapman, 2012). In a study conducted by the University of Florida’s Department of Fisheries and Aquatic Sciences, high quality fishmeal has traded between US$385 and US$554 per tonne since the year 2000.

The process consists of heating/cooking; pre-straining, pressing or centrifugation; separation of the water, oil, and dry matter; oil polishing; evaporation, drying and storage. Of these stages, thermal energy is required for the initial heating/cooking, oil polishing, evaporation and drying. The required temperature ranges between 50°C-100°C (Fisheries and Aquaculture Department, 1986).

During fishmeal processing, fish oil is separated and can be used in pharmaceutical products and supplements.

3.4 OTHER PROCESSES

3.4.1 Manufacturing

There are a range of industrial processes that require heat input. Table 3.8 lists some manufactured products that utlilise process heat. Geothermal resources could be used at some stage in their processing.

Table 3.8 Other industrial processes (modified from Rafferty, 2003)

Production of Maximum End Use Temperature

(°C)

Production of Maximum End Use Temperature

(°C)

Acetate 121 Phosphoric acid 121

Manmade fabric finish 121 Potash 121

Dipped latex 110 Pharmaceutical preps 121

Molded latex 115 Alk/chlorine-soda ash 121

Acetelyene 121 Cement 60

Acrylics 82 Inorganic pigments 176

Alk/chlorine-mercury 121 Cumine phenol 260

Alk/chlorine-soda ash 121 Nylon 6 287

SBR rubber 121 EP rubber 215

Butyl rubber 121 PVC suspension 187

Polybutadiene 121 Sodium 135

Polyisoprene 121 Car bodies 121

Styrene 204


3.4.2 Chilling and Refrigeration

The dairy industry has a relatively high refrigeration demand, and if the aquaculture industry expands, there may be demand for seafood storage and freeze drying. Likewise there is a significant demand for refrigerated storage of horticultural crops (e.g., fruit, vegetables).

Conventional chilling and refrigeration units use electricity. An alternative is absorption chilling and refrigeration technologies, which use heat and are viable on an industrial scale.

• Absorption chilling refers to cooling cycles commonly using a lithium bromide solution to create temperatures for space cooling that are less than 0°C.

• Absorption refrigeration refers to a process that produces temperatures below 0°C for creating or storing ice, and storing perishable goods. Absorption refrigeration commonly uses an ammonia-water solution because the solution has a lower freezing point than pure water and lithium bromide solutions.

These technologies require temperatures between 80°C-120°C, which can be supplied by geothermal resources. Higher resource temperatures will yield higher process efficiency, and conversely, the lower the temperature, the larger the flow rate of geothermal fluids is required (Lund, 2014a).

Cooling for datacentres using geothermal energy is an opportunity that could offer reduced operating costs, a lower environmental footprint, and high reliability and availability. Using hot geothermal water (>150°C) in the datacentre’s cooling system will consume 50% less energy for cooling, remove reliance on electrical chiller systems, and should result in cost savings.

While there is little demand in New Zealand for below 0°C chilling, it is feasible with geothermal resources. For example, geothermal heat from a well discharging 75°C waters powers an ammonia-based refrigeration system that cools the Ice Museum at Chena Hot Springs in Alaska, during summer. Heat extracted from geothermal waters (via a heat exchanger) is adequate to run the compressor in the refrigeration unit that keeps the gigantic igloo frozen.

3.4.3 Wastewater Treatment

Geothermal energy might have a role in the treatment of residential, agricultural and industrial waste water. Wastewater is the biggest waste by volume in New Zealand. Approximately 1.5 billion litres of domestic wastewater is discharged into the environment daily (Ministry for the Environment, 2014). Industrial wastewater point-sources include dairy factories, pulp and paper mills, meat-works, manufacturing processes and more.

A geothermally-powered wastewater plant exists in San Bernardino, California which treats 80,000 m3/day. The process produces a sludge, which is then anaerobically digested in holding tanks. Here microorganisms feed on the organic compounds, where geothermal heat is used to control the temperature of the process. The geothermal brine of 58°C is run through a heat exchanger, and exits at 53°C (Lund, 2003).


3.5 MINERALS AND MINING

3.5.1 Mineral Extraction from Geothermal Brines

Geothermal fluids offer potential for the extraction of various metals and minerals. Geothermal fluids are heated as they travel through rock bodies. They become saturated with various minerals and metals that could be saleable products. Compared to other mining processes, there are no costs associated with dissolution of ore minerals into an aqueous phase because they are already in solution, albeit at a very low concentration.

Bourcier et al. (2005) suggest that silica, lithium, and zinc have the greatest potential to be economically extracted from geothermal brines. However, for low salinity New Zealand geothermal brines, zinc is not as relevant.

Proximity to geothermal resources also had the advantage of supplying a cost-effective heat supply for any mineral processes requiring heat input (e.g., dehydration, concentration, etc.).

3.5.2 Heap Leaching

In 2007, Bay of Plenty Regional Council published a report encouraging prospecting for gold, silver and other minerals (Healey, 2007). Though much of these minerals are believed to be epithermal, heap leaching can be used to extract minerals from non-epithermal deposits, if discovered.

Heap leaching involves a pile (or ‘heap’) of ground up ore. One method is to trickle a cyanide solution through the heap, dissolving and separating the gold from other materials. After the solution exits the heap it is stored in a pond from where the solution can be pumped through carbon-filled columns that recover the gold (Figure 3.3). A former operation in Nevada produced 21,000 kg of gold in 2001, using geothermal fluids (82°C) to increase the temperature of the process. Cyanide leaching is capable of recovering 95% of gold ore (Lund, 2003). Using geothermal heat to heat the cyanide improves recovery for gold and silver by 5 to 7% (Bloomquist, 2006).

Figure 3.3 Possible thermally enhanced heap leaching system (Trexler et al., 1991).


4.0 INDUSTRIAL HEAT PARKS

The development of industrial heat parks in geothermally-rich regions of New Zealand offer an opportunity to promote and increase geothermal energy use.

An industrial heat park is defined as a large-scale, thermal energy distribution infrastructure capable of delivering high quality steam/heat to multiple heat users. Heat parks have a similar goal to a district heating scheme (DHS), which are systems for distributing heat generated in a centralised location for residential and commercial space and water heating. In both systems, centralised heating plants/sources coupled with a distribution infrastructure can provide higher efficiencies, capital and operating cost savings, and better pollution control than localised heating systems. However, while an industrial heat park can provide space heating, its primary goal is to provide heat for industrial-scale manufacturing and processing.

One of the obstacles in a geothermal development using heat is the capital investment required for drilling wells and distribution equipment (e.g., heat exchangers, pumps, piping etc.). The goal of a heat park is to reduce the cost of capital and drilling requirements per heat user. In an industrial heat park, the developer handles regional consent processes, drilling, and infrastructure for distributing energy. Entrepreneurs/businesses purchase energy from the heat park developer, without having to be responsible for consenting, drilling, or infrastructural costs. This would make the uptake of geothermal energy easier. In addition, efficient design strategies reduce the cost of capital investment per installed capacity for multiple users.

The following examples are good references for devising new geothermal, multi-user systems in New Zealand.

4.1 EXISTING GEOTHERMAL ENERGY INFRASTRUCTURES

The geothermal infrastructures in the USA and Iceland are internationally recognised as some of the best examples of multi-user heating systems. These systems have commonly been referred to as DHSs, as a large portion of thermal energy is allocated to commercial and residential space heating.

In New Zealand, there are examples of distributed thermal heating systems. Kawerau and Mokai are geothermal industrial-scale heat parks. The energy clusters in Dunedin and Timaru are examples of shared heating infrastructure for industrial processes and space heating of commercial buildings. There is also a small residential geothermal group heating scheme in Rotorua servicing 19 residences.

4.1.1 Klamath Falls, USA

The Klamath Falls DHS was installed in 1981. Figure 4.1 is a simple representation of the piping network and end use locations. The system is primarily a space heating system, but also supplies heat to greenhouses, for snow melting and to a wastewater treatment plant.


Figure 4.1 Klamath Falls DHS location map, 2005 (Brown, 2007)

This is a successful system that demonstrates the effectiveness of a geothermal infrastructure. However, the system did experience difficulties in the first ten years of operation. The city had to overcome several hurdles over that period to make the system cost-effective. Around 600 homes use their own geothermal boreholes for heating instead of connecting to the DHS (Lund, 2014b). In the development phase, the community wanted evaluation of the new commercial DHS’s effects on the reservoir. This increased the capital cost of the project, as did some initial issues with construction materials. Also, since the system sold heat at a fixed cost of 50% the current cost of natural gas, the project was challenged when the price of gas dropped instead of increasing as originally projected.

The scheme was eventually accepted by the community, and has subsequently prospered. The aquifer testing showed that private wells would not be negatively affected by the new production wells. The distribution system was reconstructed with more reliable insulated steel and ductile iron components that only occasionally require replacement. Then in 1992, a marketing scheme began to attract more customers, avoiding the system being shut down. The system’s load varies with the weather, and in the 2005-2006 season reached about 4.4 MWt or nearly 75% of the available capacity. Though it took nearly 25 years to reach the original capacity of 5.9 MWt, the system is today benefiting the community economically, as was originally envisioned in the 1977 feasibility study (Brown, 2007).


4.1.2 Elko, USA

The Elko Heat Company DHS in Elko, Nevada (USA) was completed in 1982. It is one of two DHS in Elko. The primary application is space heating, with one user running a laundry and dry cleaning business (Bloomquist, 2004). The original purpose was to serve three users; a laundry, office building and casino/hotel. However, when the well was drilled it had a much higher capacity than expected (81°C, 63 L/s). As a result, an additional 16 customers have joined the system since it came online, including private residences, public buildings and private businesses.

The total cost of the system in 1982 was $1.3m, with 60% of the cost covered by a US Department of Energy grant and the payback goal of 5 years was achieved. The system was built before reinjection was required, and is continuing surface disposal of the used geothermal fluid. When the capacity is expanded, reinjection wells will be required as will new production wells (Lattin, 2013). The operation and maintenance costs of the system are low. An expansion for an additional well is planned as long as the system continues to attract new customers (Lattin, 2013). The geochemistry of the fluid means corrosion is not a major issue. Only one user has detached through the system’s history after failing to retrofit their facilities. The system has remained economically feasible (Bloomquist, 2004).

4.1.3 Reykjavik, Iceland

Several DHS supply 90% of Iceland’s population with space and water heating. The DHS in Reykjavik is the largest in the world. When first installed it served only 3% of the population, but now serves 57% of Iceland’s total population, with an installed capacity of 750 MWth. The Reykjavik DHS replaced many coal fired heating systems that once heavily polluted the air. Several other towns also utilise DHS, including Hveragerdi, which uses geothermal heat for greenhouses and other industrial uses (Gunnlaugsson, 2004).

Iceland also uses geothermal heat for several industrial applications that are not all part of a district heating system. A collection of 20 companies dry 15,000 tonnes per year of fish products to ship to Nigeria. Thorverk, a seaweed manufacturer, uses geothermal heat to dry 2,000 and 4,000 tonnes of rockweed and kelp meal annually. Liquid carbon dioxide (2,000 tonnes/annum with 300 ppm of H2S) is produced from geothermal fluid for greenhouses, beverage carbonation, and other food industries. Other small scale industrial uses in Iceland include retreading car tires, wool washing, curing cement blocks, and bread baking (Industrial Users, 2010). Past examples, no longer operating, include a salt production plant and a diatomite plant.

4.1.4 Kawerau, New Zealand

Ngati Tuwharetoa Geothermal Assets (NTGA) is a New Zealand example of a geothermal heat park management group. They own several geothermal wells that supply heat to multiple businesses and processes, but do not own the industrial facilities or power plants they supply steam to. MRP manages and operates the wells for NTGA in an agreement that allows for the redirection of excess steam when needed to MRP’s power plants (Teat, 2012).

Kawerau is home to the largest direct-use applications in the world; the industrial timber drying and paper processing consumed 5.2 PJ of energy in 2012. The energy is provided to companies like Carter Holt Harvey, Norske Skog Tasman, and Svenska Cellulosa Aktiebolaget (SCA) from NTGA (Bloomer, 2011).

NTGA owns five production wells and three reinjection wells, supplying approximately 41 tonnes of steam per hour for industrial processes. In addition, an average of 287 tonnes is


supplied for electricity generation. The geothermal steam runs on a parallel circuit (Figure 4.2), not cascaded, supplying high quality steam for direct-use processes and electricity generation (Teat, 2012).

NTGA is looking at expanding the capacity of its infrastructure for future customers. The demonstrated economic benefit is attracting interest from further potential customers.

Figure 4.2 NTGA distribution network (NTGA, 2012).

4.1.5 Mokai, New Zealand

Tuaropaki Trust has established a large-scale, geothermal industrial heat park at Mokai, in the central North Island. The Tuaropaki geothermal power station was commissioned in 1999 and as of 2014 has a generating capacity of 113 MW. Additionally, the site has 11.7 ha of state-of-the-art climate controlled glasshouses, growing capsicums and tomatoes for export. The greenhouses are heated using steam from the Mokai Geothermal Field. In 2011, the Miraka dairy processing factory was commissioned. This plant produces dried milk powders using renewable electricity and steam from the Mokai Geothermal Field to run its processing operations. This is a world first for the whole milk powder processing industry. In 2014, the product range was extended to include UHT products.

4.1.6 Rotorua, New Zealand

Parklane is a residential housing development in Rotorua with a geothermal group heating scheme. One geothermal well provides heat to nineteen dwellings (Anderson, 1998).


4.2 NEW ZEALAND HEAT PARK EXAMPLES (NON-GEOTHERMAL)

New Zealand has several industrial heat parks that do not use geothermal energy. There is local experience in designing, building and successfully operating such systems. Two are discussed below.

4.2.1 Dunedin Energy Centre

The Dunedin Energy Centre pipeline network was commissioned in the 1960s as an inner city heat supply network. The 30 MWth capacity uses coal and wood residue (biomass) to service the space and water heating needs of the Dunedin Hospital and University of Otago and provides process heat for manufacturing and processing customers, including Cadbury Confectionary and Alsco (Energy for Industry (EFI), 2014).

4.2.2 Washdyke Energy Cluster

EFI established an industrial energy centre in Washdyke, Timaru in 2011. Stage 1 (20 MWth capacity) commissioned two boilers, one using south island lignite coal as an energy source, and the other biomass (EFI, 2014). These boilers supply steam for industrial manufacturing and process heat required by their customers; DB Breweries, NZ Light Leathers and Juice Products NZ. This shared heat energy infrastructure replaced aged heat plant on the customers individual sites. The customers were driven to change their heat use practises by challenging coal supply conditions and a requirement to reduce air pollution. There are plans for an additional 20 MWth capacity in future.

4.3 HEAT PARK PLANNING

The primary goal of a geothermal heat park is to supply sustainable energy for multiple users, and to minimise the capital needed for drilling. On a local level this means taking advantage of an energy resource unique to the region; reducing the need to use energy from other sources. A successful heat park sells enough thermal energy annually to meet operating and maintenance costs, ensuring that both suppliers and consumers experience a satisfactory return on their investment.

In an industrial geothermal heat park, large commercial and industrial processes are usually regarded as primary consumers. Some existing geothermal applications in New Zealand run economically using cascaded fluid, where the fluid has already been used at least once for a higher temperature process (e.g., power generation). Cascaded fluid can sometimes be too low in temperature, limiting the use options for customers.

4.3.1 Climate Influence

The goals and benefits of using a geothermal energy distribution infrastructure for industrial and commercial purposes are similar regardless of the country where it is established. The customer’s drive for space heating, however, is strongly correlated to the climate.

For example, the winter temperatures (Figure 4.3 and Figure 4.4) in Rotorua, Kawerau, and Taupo are not as cold as in Reykjavik (Iceland), Klamath Falls (US) or Elko (US); where DHS are established.


Figure 4.3 Average annual maximum temperatures (World Weather Online, 2014).

Figure 4.4 Average annual minimum temperatures (World Weather Online, 2014).


4.3.2 Economics

The more continuously that a resource and system is used, the better the economic viability. The climatic influences mean that a district (space and water) heating scheme in Taupo, Rotorua or Kawerau would have a much lower system load factor overall than in a colder climate. Other factors such as population and district energy density would also be considerations.

The system load factor is the percentage of the year that the resource is being utilised. The cost of energy improves with increasing load factors (Figure 4.5; where 0.1 is 10% of the year, and 0.4 is 40% of the year).

Applications that are ameliorating the ambient temperature effects of a warmer climate will have a lower load factor than the same application in a colder climate. Typically space heating has a load factor between 0.15 and 0.20. Aquaculture can have a load factor between 0.5 and 0.8 (outdoor open ponds), and greenhouses between 0.18 and 0.50 (Rafferty, 2003; Lund, 2014a). In addition, aquaculture and greenhouse load factors are influenced by the type of crop or species being cultivated.

Industrial applications have higher load factors, between 0.4 and 0.7 (Lund, 2014a), making them an ideal target for new geothermal heat parks. For industrial-scale heat parks, space heating should be considered as a secondary use to providing heat for industrial processes. Demand for commercial space heating is also a valid market for thermal energy, and centralised heating schemes for commercial buildings might also be a consideration.

Figure 4.5 Load factor vs. cost of energy (Rafferty, 2003).


4.3.3 Project Goals

Having access to an industrial heat park will make the decision making process easier for business owners to adopt geothermal energy. Availability of heat parks whose geothermal wells and distribution pipelines are established and with available capacity will attract new business.

Ideally the system should be capable of supporting additional capacity without the need for more drilling. For example, NTGA offers such a service to their customers by managing the resource consents and drilling so their customers do not have to. It is debatable whether the system should be optimised for meeting maximum capacity on start-up for the quickest return on investment, or for easy installation of additional capacity (e.g., modular expansion).

Industrial geothermal heat park goals might include:

1. Staged installed capacity – 5, 10, 15, 20+ years.

2. Staged capacity increase through additional wells – 5, 10, 15, 20+ years.

3. Have all operating and maintenance costs and measures identified quickly, as systems may experience technical issues initially.

4. Maximise annual rate of return on the initial investment.

5. ‘Wish list’ of applications the system could support in the future.

6. Plan for land use availability for new energy uses.

7. Set aside energy exclusively for experimental/novel technology and pilot plants.

8. Identify industrial markets using other energy sources, who could attach to the heat park upon expiration of other energy commitment’s.

9. Encourage parties to commit to the reduction of greenhouse gas emissions.

10. Offer assistance and expertise in geothermal heat park and direct use application development.


5.0 CONCLUSIONS

Geothermal energy offers a proven energy alternative to fossil fuels in those regions endowed with geothermal resources. Geothermal direct heat use in New Zealand already includes timber and milk processing, geothermal tourism, balneology, and commercial and domestic heating.

There are considerably more opportunities for geothermal energy to provide a sustainable, cost effective energy solution. This includes increased utilisation in the forestry and agricultural sectors, as well as a range of industrial processing options.

The decision to use geothermal energy might appear daunting to a new entrant when facing the uncertainties of drilling and resource consent processes. Industrial heat parks are a recommended infrastructure to reduce uncertainty, and for providing heat for industrial-scale manufacturing and processing. There are existing examples of successful heat parks in internationally and in New Zealand. These thermal energy distribution systems share resources amongst multiple users, and have the benefit of higher efficiencies and capital and operating cost savings compared to localised heating systems. Businesses purchase energy from the heat park developer, without the having to manage consenting, drilling, or infrastructural costs. This approach can reduce barriers to uptake of geothermal energy.

6.0 ACKNOWLEDGMENTS

John Hall would like to acknowledge the support of various people during his time at GNS Science, New Zealand, who supported his direct use geothermal studies.

• GNS Science staff – Andy Blair, Anya Seward, Sophie Pearson, Samantha Alcaraz.

• John Lund – Oregon Institute of Technology.

• The many individuals who contributed time and information – Chloe Walker, Taupo District Council; Fritz Frohlke, Great Lake Taupo; Tania Hood, Energy Efficiency and Conservation Authority; Hamish Trolove, Energy Efficiency and Conservation Authority; Hien Dang, Energy Efficiency and Conservation Authority; Anna Morris, Ministry of Business, Innovation, and Employment; Nicole Kirkham, Ministry of Business, Innovation, and Employment.


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APPENDICES


APPENDIX 1: GEOTHERMAL FIELDS IN NEW ZEALAND

Table A 1.1 summarises the field classification for major geothermal systems (see Figure 2.1 for locations), as well as the approximate temperature and area of each resource. These data may change with the progression of subsurface research.

Other known geothermal areas do exist, but have not been included here as they are too small in scale for commercial or industrial scale developments, are offshore, or are outflows into lakes.


Table A 1.1 Summary of geothermal areas in New Zealand. Data has been sourced from: Climo et al., 2013; White, 2009; Cody, 2007; Milicich, 2010; Pearson, 2012; Bay of Plenty Regional Council, 2008; Waikato Regional Council, 2007; Lawless, 2004. *Development at Mangakino is currently not possible using existing technologies due to a lack of sufficient permeability.

Geothermal Area

Approximate Reservoir Temperature

(°C)

Approx. Surface Area of Resource

(km2) Regional Council Classification

Waikato Bay of Plenty

DEVELOPMENT

Ngawha 230 18 Activity monitored by the Northland Regional Council

Kawerau 270 40 Development systems group 4

Rotoma-Puhi Puhi 240 5 Development systems group 4

Ohaaki-Broadlands 270 10 Development

Ngatamariki 260 10 Development

Horohoro 200 5 Development

Rotokawa 280 18 Development

Mokai 280 6 Development

Wairakei-Tauhara 260 15 Development

Mangakino* 230 8 Development

LIMITED / CONDITIONAL

DEVELOPMENT

Taheke 240 2 Conditional development system group 3

Tikitere – Ruahine 240 10 Conditional development system

group 3

Rotoma – Tikorangi 240 5 Conditional development system

group 3

Lake Rotokawa – Mokoia 155 1 Conditional development system

group 3

Atiamuri 220 5 Limited development

Rotorua 240 4 Rotorua system group 2

Reporoa 230 10 Research

Tauranga – Mount Maunganui 65 200+ Conditional development group 5

Tokaanu Waihi-Hipaua 260 20 Limited development

NO DEVELOPMENT /

PROTECTED

Waikite 200 5 Protected

Waiotapu 275 20 Protected

Waimangu 260 15 Protected Protected systems group 1

Te Kopia 240 10 Protected

Orakei Korako 250 10 Protected

Tongariro 240 12 Protected

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