SKM Geothermal Report

In Collaboration with:

The Geothermal Resources of Victoria

THE SUSTAINABLE ENERGY AUTHORITY OF VICTORIA

Final 25 February 2005

In Collaboration with:

The Geothermal Resources of Victoria

THE SUSTAINABLE ENERGY AUTHORITY OF VICTORIA

Final 25 February 2005

Sinclair Knight Merz ABN 37 001 024 095 590 Orrong Road, Armadale 3143 PO Box 2500 Malvern VIC 3144 Australia Tel: +61 3 9248 3100 Fax: +61 3 9248 3364 Web: www.skmconsulting.com COPYRIGHT: The concepts and information contained in this document are the property of Sinclair Knight Merz Pty Ltd. Use or copying of this document in whole or in part without the written permission of Sinclair Knight Merz constitutes an infringement of copyright.

Geothermal Resources of Victoria

Contents

1. Executive Summary 1

2. Introduction 3

3. Objectives 5

4. Measured Temperatures 6 4.1 Temperature Gradients 6

5. Calculation of Geothermal Temperatures 12 5.1 Heatflow data in Victoria 12 5.2 Heatflow estimates and data quality 13 5.3 Geothermal models 14 5.4 State-wide estimates of geothermal temperatures 15

6. Potential Volumetric Yield of Geothermal Wells 17

7. Mapping Geothermal Temperatures 19 7.1 Temperatures at Greater Depths – Hot Dry Rock Potential 42

8. Data Gaps 46 8.1 Recommendation for Further Work 47 8.2 Indicative Drilling Costs 47

9. Electricity Generation Technologies 48 9.1 Steam Rankine Cycle 48 9.2 Organic Rankine Cycle 48 9.2.1 Introduction 48 9.2.2 Process Description 49 9.2.3 Plant Costs 51 9.2.4 Energy Conversion Efficiency 51 9.3 Kalina Cycle® 52 9.3.1 Introduction 52 9.3.2 Process Description 53 9.3.3 Plant Costs 55 9.3.4 Energy Conversion Efficiency 55

10. Geothermal Direct-Use 57 10.1 General Review of Direct Geothermal Uses 57 10.2 Geothermal Heat Pumps 58 10.3 Space Heating and District Heating 59

SINCLAIR KNIGHT MERZ

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10.4 Bathing and Swimming 59 10.5 Greenhouse Heating 60 10.6 Aquaculture Pond Heating 60 10.7 Industrial Uses 60 10.8 Cooling and Air Conditioning 61 10.9 Agricultural Drying 61 10.10 Direct Use Economics 61

11. Existing Geothermal Applications 64 11.1 Electricity Generation 64 11.2 District heating in Portland 66 11.3 Geothermal heat pumps the New AGSO Building 76

12. Environmental Effects of Geothermal Use 83 12.1 Resource Depletion 83 12.2 Venting of Gases. 84 12.3 Noise 84 12.4 Disposal of Wastewater 85 12.5 Land Subsidence 85 12.6 Environmental benefits 87

13. Conclusions 89

14. References 91

Appendix A Compilation of all Measured Temperature Data 94


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Figures Figure 1 Geothermal Gradients – All Bores 7

Figure 2 Average Geothermal Temperature Gradients in Victoria 9

Figure 3 Average Geothermal Temperature Gradients in the Otway Basin 10

Figure 4 Average Geothermal Temperature Gradients in the Gippsland Basin 11

Figure 5 Deep Sedimentary Basins and Locations of Measured Geothermal Temperatures 20

Figure 6 Temperatures at 500m Depth 21

Figure 7 Temperatures at 500 m depth for the Otway Basin 24

Figure 8 Geothermal Temperatures at 500m depth for the Gippsland Basin 26

Figure 9 Geothermal Temperatures (Degrees C) at 1000m Depth 29

Figure 10 Geothermal Temperatures at 1000m depth in the Otway Basin 33

Figure 11 Geothermal Temperatures at 1000m Depth in the Gippsland Basin 35

Figure 12 Geothermal Temperatures (Degrees C) at 1500m Depth 37

Figure 13 Geothermal Temperatures at 1500m depth in the Otway Basin 39

Figure 14 Geothermal Temperatures at 1500m Depth in the Gippsland Basin 41

Figure 15 Hot Dry Rock Development (supplied by Geodynamics Limited) 44

Figure 16 Simplified Schematic of ORC Power Plant 50

Figure 17 Indicative Thermal to Electric Conversion Efficiency for ORC Plants 52

Figure 18 Simplified Schematic of a Representative Kalina Cycle® 54

Figure 19 Claimed Efficiency Advantage of Kalina Cycle® over ORC 56

Figure 20 Geothermal Energy Cost as a Function of Plant Capacity 63

Figure 21 Location of geothermal plants in Australia (from Burns et al 2000) 64

Figure 22 Layout of the Portland Geothermal District Heating System (courtesy of Glenelg Shire Council) 68

Figure 23 Construction Details of the Henty Park Geothermal Production Bore 73

Figure 24 Henty Park Production Bore Wellhead 74


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Figure 25 Henty Park Cooling Towers 75

Figure 26 Water Level Observations in the Portland Geothermal Aquifer 76

Figure 27 Schematic Layout of the AGSO Building and its Surrounds 77

Figure 28 The Borefield Has been Restored to Lawn and Garden (Photo Courtesy John Coffey, Davis Langdon) 78

Figure 29 Water Circulation Pumps (Photo courtesy Stephen Read, Geoscience Australia) 79

Figure 30 Banks of Small Diameter Pipes Transfer Water and Heat Between the Bore Field and the Heat Pump Units (Photo courtesy Stephen Read, Geoscience Australia) 80

Figure 31 Geothermal Heat Pump Installation (Photo courtesy Stephen Read, Geoscience Australia) 81

Figure 32 Geothermal Heat Pumps Housed in Cabinets Inside the Buildings (Photo Courtesy John Coffey, Davis Langdon) 82

Figure 33 Carbon Emissions from Energy Production by Fuel (DiPippo, 1988) 87


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Tables Table 1 Heatflow data for Western Victoria 14

Table 2 Calculated Temperatures. 16

Table 3 Measured Temperatures Shown in Figure 6 in Areas Other Than the Gippsland and Otway Basins. 22

Table 4 Calculated Temperatures Shown in Figure 6 22

Table 5 Specific Capacity Data Shown in Figure 6, Figure 7 and Figure 8 23

Table 6 Measured Temperatures in the Otway Basin Shown in Figure 6 and Figure 7 25

Table 7 Measured Temperatures in the Gippsland Basin Shown in Figure 6 and Figure 8 27

Table 8 Measured Temperatures Shown in Figure 9 in Areas Other Than the Gippsland and Otway Basins. 30


Table 10 Specific Capacity Data Shown in Figure 9, Figure 10 and Figure 11 31

Table 11 Measured Temperatures Shown in the Otway Basin Shown in Figure 9 and Figure 10.34

Table 12 Measured Temperatures in the Gippsland Basin Shown in Figure 9 and Figure 11. 36


Table 14 Measured Temperatures in the Otway Basin Shown in Figure 12 and Figure 13. 40

Table 15 Measured Temperatures in the Gippsland Basin Shown in Figure 12 and Figure 14. 42

Table 16 Temperatures Calculated at 3000 and 5000m Depth 45

Table 17 Indicative Drilling Costs in Victoria (Data Provided by Sides Engineering) 47

Table 18 Categories of Direct Use of Geothermal Energy, World-Wide 57

Table 19 Details of Heating Facilities Included in the Portland Geothermal District Heating Scheme (information courtesy Glenelg Shire Council) 69

Table 20 Geothermal Exploration and Construction Noise Levels 85


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Document history and status Revision Date issued Reviewed by Approved by Date approved Revision type

Draft 29 June 2004 B Barnett

Rev A 12-Jul-04 T Dobbie S de Kretser Sections 9 & 10 updated for reissue.

Rev A 12 July 2004 I Swane B Barnett 13 July 2004 Final

Rev B 25 Feb. 2005 B Barnett B Barnett 25 Feb 2005 Final

Distribution of copies Revision Copy no Quantity Issued to

Draft 1 1 M Wheatley, SEAV in PDF Form

Rev A 1 1 M Wheatley, & G Henry SEAV in PDF Form

Rev B 1 1 G Henry SEAV in PDF Form

Printed: 31 March 2006

Last saved: 30 March 2006 01:22 PM

File name: I:\WCMS\Projects\WC02886\Deliverables\Report_version_5.doc

Author: Brian Barnett

Project manager: Brian Barnett

Name of organisation: Sustainable Energy Authority of Victoria

Name of project: Mapping the Geothermal Resources of Victoria

Name of document: Geothermal Resources of Victoria

Document version: Revision B (Final)

Project number: WC02886



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1. Executive Summary This report presents information on the geothermal resources of Victoria as obtained from a search of state groundwater and petroleum bores databases. In general, temperature data are collected and recorded incidentally in bores that have been drilled for purposes other than exploring or defining geothermal resources. Accordingly, the quality of much of the available temperature data is questionable and care has been taken to reject any inconsistent or obviously erroneous data. Of particular concern is the systematic understatement of temperatures in the databases. This arises from the fact that most measurements in deep bores are made while the well’s temperature is recovering in the period immediately following the circulation of cool drilling fluids. During the course of this study attempts have been made, wherever possible, to correct recorded temperatures to allow for this discrepancy. However a lack of sufficiently detailed temperature information has prevented an accurate extrapolation of temperatures in many cases. Accordingly, the results presented in this report are generally considered to be conservative estimates of the prevailing geothermal temperatures within the state (i.e. temperatures presented are equal to or lower than real formation temperature).

Average geothermal gradients in the sedimentary basins (i.e. the Gippsland, Otway and Murray Basins) were found to be between 3 and 4ºC per 100 m depth which is marginally above the worldwide average background level of 3ºC/100 m. An obvious “hot spot” in the geothermal gradients appears to be present in the Latrobe Valley in the Gippsland Basin where geothermal gradients are as high as 7.3ºC/100 m. The high gradients are associated with relatively high measured temperatures (up to 70ºC) in bores that are less than 800 m in depth. The reason for this anomaly is not well understood but is believed to be associated with the thick coal measures present at this location. The elevated geothermal gradients are only observed in bores that are less than 800 m deep. At greater depths the temperatures appear to revert to the average geothermal gradient of the Gippsland Basin.

Where measured data are not available, the geothermal temperatures have been augmented by temperatures that have been calculated on the basis of heat flow and rock property estimates and assumptions. The resultant combined data sets are presented as maps of geothermal temperature at 500, 1000 and 1500 m depth.

The maps of geothermal temperature presented in this report indicate that temperatures between 30 and 60ºC, are present over much of the state at depths of 500 to 1500 m. The feasibility of extracting geothermal waters at these temperatures is strongly influenced by the geology and hydrogeology of the deep sedimentary basins. Experience at drilling deep groundwater bores has demonstrated that substantial volumes of water can be obtained from the aquifers within the thick unconsolidated Tertiary age sediments found in the Gippsland, Otway and Murray basins. Bores that penetrate into the underlying basement rocks rely on encountering fractures and faults in the




rock mass to obtain production. Accordingly, the chances of a bore delivering useable quantities of geothermal water from depth depends on whether the unconsolidated sediments extend to sufficient depth for the required temperature. The assessment of geothermal resources in this environment should therefore be accompanied by maps of the surface of the deep bedrock to help define deep drilling targets for production bores. Geothermal temperature maps of the Gippsland Basin presented in this report (refer to Figure 8, Figure 11 and Figure 14 for temperatures at 500, 1000 and 1500 m respectively) include basement elevation data to help define the region at each depth where the unconsolidated sediments can be expected. Similar basement mapping for the Otway and Murray basin should be carried out in future to help define production bore target depths and locations in these basins.

Geothermal water easily accessible in Victoria can be used for a number of direct uses. The temperature of water easily accessible within 1000 m of the surface over much of the state is ideal for numerous applications, such as space heating, including the heating of greenhouses, bathing (both in spas and heated swimming pools), aquaculture pond heating and agricultural drying.

The geothermal waters of the Otway Basin are currently being used to great advantage in a district heating scheme in Portland. The system, jointly operated by Glenelg Shire Council and Portland Coast water provides water and space heating to municipal and administrative buildings, swimming pools, hotel and hospital. The scheme has been operational since the early 1980’s and has provided substantial savings in fuel costs while at the same time reducing greenhouse gas emissions. It is a clear demonstration of an appropriate use of the resources that are present throughout the entire basin.

The temperature of geothermal water within 2000 m of the surface in Victoria is not sufficiently high for generating electricity in a conventional steam turbine. Organic Rankine Cycle and Kalina Cycle® electricity generation technologies could possibly be applied in Victoria. However the expected plant efficiencies at temperatures less than 100ºC are so low that such developments are unlikely to be economic. Similarly, geothermal temperatures in that depth region easily accessible by drilling are generally too low to be able to support a successful Hot Dry Rock development under current economic conditions and with currently proven technologies. Local, thermal anomalies identified in the Gippsland and Otway Basins could however represent exploration targets for potential Hot Dry Rock developments.




2. Introduction Sinclair Knight Merz in collaboration with Professor James Cull of Monash University (trading as Monash Geoscope) was commissioned by the Sustainable Energy Authority of Victoria to develop an updated assessment of the geothermal resources of Victoria. The commission is aimed at updating work carried out in the 1980’s by the Department of Industry Technology and Resources and the Victorian Solar Energy Council. This study culminated in the publication in 1987 of a report entitled “Geothermal Resources of Victoria” by R. L. King, A. J. Ford, D. R. Stanley, P. R. Kenley and M. K. Cecil (King et al, 1987).

Principal sources of data used in the study include various data bases of petroleum, groundwater and mining bores that are maintained and operated by Sinclair Knight Merz and by the Department of Primary Industries, Minerals and Petroleum.

Few bores have been drilled in Victoria for the express purpose of exploring or developing geothermal resources. Most of the deep bores that have been drilled were aimed at minerals and petroleum exploration and production and at defining, monitoring and producing groundwater. Accordingly, the available geothermal temperature data are sparse and have been recorded for purposes other than for defining geothermal reserves. The resultant body of data is considered to be of relatively poor quality as little attention has been paid to recording stable temperatures that accurately reflect the true formation temperature at the measurement depth. In the current study every attempt has been made to obtain the most reliable and accurate temperatures from the available body of information. Where necessary, conservative estimates of formation temperature and geothermal gradient have been adopted.

The majority of geothermal temperature data have been obtained from wells drilled in the Otway and Gippsland sedimentary basins. The relatively high concentration of bores and temperature measurements in these areas reflects the location of oil, gas and minerals exploration and the existence of thick, permeable sediments from which substantial quantities of groundwater can be obtained. Deep bores and geothermal temperature measurements are scarce in the Murray Basin reflecting the lack of petroleum and deep mineral exploration carried out in the region. Similarly, no deep geothermal temperatures have been found in the Central Highland area where thick sedimentary sequences and the potential for deep groundwater production are absent. The absence of deep measured temperatures in the central and northern parts of the state does not necessarily reflect poor geothermal potential.

In order to in-fill geothermal temperatures and gradients in those areas that have few recorded deep temperatures, geothermal temperatures have been calculated based on measured and assumed values of thermal conductivity and heat flow. Estimates have been made at the centre of each of the 1:250 000 series map sheets that cover the state. The calculated data have then been used to




augment the measured data to prepare maps of geothermal temperature and geothermal gradients that cover the entire state. Calculations of geothermal temperatures presented in Section 5 (and in Table 16) of this report were provided and reported by Professor Jim Cull of Monash University, School of Geosciences who was engaged under a separate commission by the Sustainable Energy Authority of Victoria.




3. Objectives The principal objectives of the study are:

To collect all geothermal temperature data that has become available since the publication of King et al (1987).

To incorporate all new geothermal data in maps that illustrate the geothermal resources of Victoria.

To assess the geology and hydraulic characteristics of the geothermally prospective areas to help define targets for and potential yields of geothermal bores.

To assess geothermal heat flow throughout the state to help map the potential geothermal resources across the entire state, including those areas where temperatures have not been defined by measurements in deep bores.

To review currently proven technologies for the generation of electricity from low grade geothermal resources that may be applicable for Victoria’s geothermal reserves.

To review and highlight possible uses for low grade geothermal resources in Victoria.




4. Measured Temperatures Bottom-hole temperatures are routinely measured during oil and gas exploration. Many of these results are contained in Well Completion Reports submitted to The Department of Primary Industry Minerals and Petroleum under the terms of the Petroleum (Submerged Land) Act 1967 (Nicholas et al, 1980). Data quality varies according to the logging procedures adopted by each company and the instruments available but some data are suitable for estimates of heat flow (Cull & Denham 1979; Middleton 1979) or for defining true formation temperature. A common problem with the available data is that the majority of temperature measurements are collected on petroleum wells soon after circulation of cool drilling fluids ceases. The resultant temperatures rarely reflect the real formation temperature and are invariably lower than stable formation temperature. Occasionally the Well Completion Reports include sufficient transient temperature data to enable an extrapolative estimate of true formation temperature.

In addition to deep petroleum wells, a number of deep groundwater bores have been drilled in Victoria for water supply and deep basin monitoring purposes. Temperature data from such bores are occasionally measured and recorded in bore databases maintained by the Department of Sustainability and Environment and by the Department of Primary Industries.

Interrogation of the various databases of deep bores drilled in the state has resulted in the collection of a substantial body of geothermal temperature data. A complete inventory of geothermal temperature measurements obtained during the course of the current study is presented in Appendix A. A total of 269 measured data was extracted from the DPI databases and from SKM records. Most bores with measured temperature data are located within the Otway and Gippsland sedimentary basins.

4.1 Temperature Gradients The measured temperature data have been plotted against measurement depth in Figure 1. Here it can be seen that the bores located in the Gippsland Basin display elevated temperatures and a slightly elevated gradient compared to those located in the Otway Basin. Average gradients are not dissimilar to the global average background gradients of 3 to 3.5ºC per 100 m of depth (ie. average geothermal gradients in volcanically inactive regions).

Anomalous gradients can be seen in those bores in the Gippsland Basin that are located in the Latrobe Valley. This subset of the Gippsland Basin bores displays a much higher geothermal gradient, in the order of 7.3ºC per 100 m of depth. It is interesting to note that the anomaly is only apparent in shallow bores in the Latrobe Valley (i.e. bores that are less than about 800 m depth). Measured temperatures in deeper bores in the area fall on the average Gippsland Basin geothermal gradient. Anomalous temperatures in this region have been identified previously and various theories have been put forward to explain these observations. In general it is agreed that the




Data from four deep bores drilled in the Murray Basin are included in Figure 1. Unfortunately this does not represent a sufficient body of data from which an average geothermal gradient can be determined for the basin. However it is clear from Figure 1 that the few temperatures measured in Murray Basin bores are not substantially different from the average gradients observed in the Otway and Gippsland basins. An interesting conclusion drawn from the temperature data plotted in Figure 1 is that, apart from local anomalies within each basin, the average geothermal gradients are relatively uniform within the three basins. This observation is supported by the geothermal temperature gradient map for Victoria as presented in Figure 2.

Figure 1 Geothermal Gradients – All Bores

anomalous gradients in the region are associated with the extensive coal deposits found in the Latrobe Valley. Whether the shallow geothermal anomaly is related to the low thermal conductivity of the coal beds, thermo-chemical reactions occurring naturally in the coal beds or artificial elevation of shallow gradients through the upward migration of deep high temperature waters in response to coal mine dewatering operations is yet to be confirmed.

y = 29.477x - 336.663.4 C/100m

y = 26.183x - 494.993.8C/100m

y = 13.715x - 202.187.3C/100m

0 60 80 100 120 140 160

-500

0

500

1000

1500

2000

2500

3000

3500

4000

0 20 4

Temperature (Degrees C)

Dep

th (m

)

Otways BasinGippsland BasinLa Trobe Valley (Subset of Gippsland)Murray BasinOtways Average GradientGippsland Average GradientLa Trobe Valley


Figure 2 Average Geothermal Temperature Gradients in Victoria




Figure 3 Average Geothermal Temperature Gradients in the Otway Basin






Figure 4 Average Geothermal Temperature Gradients in the Gippsland Basin


5. Calculation of Geothermal Temperatures

5.1 Heatflow data in Victoria Heatflow (Q; mW/m2) can be calculated most simply from the expression

λβ Q =

where λ(W/mK) is the thermal conductivity at any depth and β (C/km) is the corresponding geothermal gradient over the same interval.

Normally β is determined from discrete measurements over 5-10 m intervals but values of λ are available only for small isolated core samples 2-3 cm in length. Consequently there is a sampling error in any isolated calculation and the results may contain a significant bias. Estimates of high precision are normally restricted to uniform sections characterised by constant linear gradients. More elaborate reductions are possible, but the necessary samples for each significant unit are not available in this instance.

South-east Australia is generally considered to be a region of high surface heatflow relative to the global average (close to 62 mW/m2). In Victoria values in the range 80-120 mW/m2 are consistent with observations in Tasmania and South Australia confirming systematic trends from the passive Precambrian to the more active Phanerozoic subcrops. However great care is required in constructing more elaborate models of crustal evolution based on these thermal constraints. In particular there are serious limitations on the quality of the data and the number of observations available.

The complications associated with determinations of heat flow have been reviewed by Cull (1982). Early data obtained in Tasmania and Victoria have been obtained both in tunnels and boreholes under a variety of conditions. Many of the basic conditions now assumed for reliable estimates of heat flow have not been previously available and significant approximations and corrections have been required to generate the available database. It is possible for some locations that the total error will exceed 25%. In these circumstances interpretations of crustal evolution should be based only on general trends.

In more recent years some excellent results have been obtained at Lancefield in central Victoria (Cull 1983). Values of 77.2 mW/m2 for this site are significantly lower than those obtained at Stawell and Castlemaine (~120 mW/m2) using more primitive equipment. The lower values are more consistent with global trends and may be considered more realistic in view of the subdued geothermal activity in the region. Elsewhere some reasonable estimates have been obtained for Mt Gambier in spite of complications associated with groundwater movements (Cull 1979). Values of






92 mW/m2 for this location suggest a trend consistent with the progressive migration of recent volcanism from central to southern Victoria.

Values of heat flow in central and southern Victoria are at least 25-50% above the global average. They indicate an area of active crustal evolution possibly involving mechanisms of crustal extension and melt emplacement (Gray and Cull 1992). Spatial wavelengths in the geothermal data may require anomalous heat production at mid-crustal levels. Detachment models or melt emplacement are sufficient for this purpose and are consistent with the available heat flow data.

5.2 Heatflow estimates and data quality The most recent estimates of surface heatflow for Western Victoria have been obtained at Horsham (89.6 mW/m2) and Warracknabeel (97.6 mW/m2). The results are significantly less than previous values obtained at Stawell and Castlemaine and support data obtained at Lancefield. Consequently, crustal models based on hot-spot migration and rapid cooling of high level melt emplacements may require revision (Purss & Cull, 2001). However, more general models based on mid-crustal detachments or underplating mechanisms do not require the preservation of a specific spatial anomaly and consequently remain unaffected. Previous inconsistencies between surface heatflow and surface heat production are eliminated if reasonable estimates of thermal conductivity are adopted for processing the previous Stawell and Castlemaine data.

Core samples have been obtained from the interpreted Palaeozoic basement in western Victoria and consist of veined mudstones and shales along with some altered basalt. These correspond to constant linear segments of geothermal gradient in each hole and heatflow values have been calculated directly according to equation (1) using the average of three core samples for each location. The results from each hole are in broad agreement. The geothermal gradient for the basement in each location is close to 23ºC/km and the average thermal conductivity for each location is close to 4.0 W/m/K. The results are internally consistent and suggest a uniformity in thermal history over distances of 50 km. The results for Horsham (VIMP3) and Warracknabeel (VIMP14) are given along with other locations in Table 1.

Data for Portland and Otway are based on bottom-hole temperatures obtained in oil wells along with best estimates for thermal conductivity using lithological logs. Consequently they are provided only as a guide to the regional trends and may require corrections exceeding 20%. Extensive site descriptions are available for Lancefield and Mt Gambier (Cull 1983, and Cull 1979) while more basic descriptions for Stawell and Castlemaine are provided by Sass (1964). In general, geothermal gradients are normally well determined but estimates of thermal conductivity are much more erratic. Few core samples are available, sample preparation is complex and local anomalies are common. Consequently extreme values for Castlemaine and Stawell may be related to sampling errors ranging up to 20%. Conductivity data adjusted on this basis provide much greater internal




consistency with only minor discrepancies compared to observations in a uniform felsic granite near Lancefield.

Previous distinctions between heatflow in the I- and S-type granites (Sawka & Chappell 1986) are eliminated and there are no indications of extreme (negative) values of reduced heat flow (the mantle component) in western Victoria. Greater linearity is obtained in correlations relating heatflow and heat production with a mantle component close to 30 mW/m2 along with a characteristic depth of approximately 20 km.

Table 1 Heatflow data for Western Victoria

Location Latitude Longitude d(m) λ β Q

Horsham 36.862 142 195 3.93 22.8 89.6 Warracknabeel 36.483 142.347 131 4.1 23.8 97.6 Lancefield 37.136 144.774 160 2.53 30.5 77.2 Stawell 37.05 142.78 300 4.33 27.1 117 (93.8)* Castlemaine 37.05 144.22 165 4.88 24.2 121 (94.4) Mt Gambier 37.75 140.89 243 3.21 28.6 91.8 Portland 38.33 141.67 1300 3.25 30.7 (99.9) Otway 38.2 141.2 1000 3 34.9 (103) Port Campbell 38.6 143 4000 2.5 31 (77.5) Murrayville 35.33 141.183 400 3 31 (93)

* ( ) estimate using approximate conductivities +/- 20%

5.3 Geothermal models New heatflow data obtained at Horsham and Warracknabeel require major revisions to the thermal models proposed for western Victoria by Sass and Lachenbruch (1979). In particular the new data provide no support for the spatial wavelengths associated with previous data obtained at Stawell and Castlemaine (Table 1). The revised data suggest a more regional trend for thermal evolution with heatflow values generally exceeding 90 mW/m2. There are no inconsistencies with the longer time constants associated with mid-crustal underplating or detachment models, but there is also no evidence for a systematic progression of high level melt emplacements followed by rapid cooling.

Plate migration over a mantle hot-spot has been suggested to explain the apparent southwards younging of central volcanoes in western Victoria. However the nature of the mantle mechanism remains subject to debate (Johnson 1989). Surface manifestations suggest several separate point source plumes operating simultaneously along the eastern coast of Australia. These may be part of a single convection cell within the mantle producing a linear heat source with penetration of the brittle crust assisted by stress field migration (tearing). Johnson (1989) indicates some difficulties with the stress model proposed by Pilger (1982) in relation to current indications of compression.




However some extension or deformation at the base of the crust may be essential to accommodate progressive variations in the radius of curvature caused by plate migration.

The revised heatflow data remain high by global standards and clearly distinguish the active orogenic belts in the east (>90 mW/m2) from the stable Precambrian cratons in the west (<40 mW/m2). Part of this excess may be attributed to elevated radiogenic distributions (U, K, Th) persisting to mid-crustal depths of 15-20 km (Sawka & Chappell 1986). However the required concentrations (>3 µW/m3 ) are normally associated only with granitic bodies highly differentiated towards the surface and consequently some advective contribution would normally be anticipated. Mid-crustal melt emplacements, underplating (Ewart 1989), or diapir mechanisms (Lister & Etheridge 1989) are sufficient to provide continual heating at the required rate while avoiding rapid lateral gradations in surface heatflow.

Models based on underplating and advection were first suggested by Sass and Lachenbruch (1979) to explain the spatial wavelengths observed in the available heatflow data. In essence it is assumed that there should be some correlation between heatflow and the apparent migration of central volcanoes. Mid-crustal melt emplacements were required to accommodate high values for heatflow observed only at Stawell and Castlemaine (119, 121 mW/m2) but with cooling rates sufficient to avoid regional heating. However more recent observations at Lancefield, Horsham, and Warracknabeel provide contrary evidence and fail to indicate any diagnostic spatial trends in that area consistent with lateral equilibration.

Other models of structural evolution based on stress relaxation for eastern Australia have been suggested by Zhang et al (1996). The results are consistent with regional compression and deformation by gravity loading with spreading normal to an apparent linear trend in regional seismicity (Spassov et al 1997). However the critical rheological parameters are highly sensitive to variations in temperature and additional heatflow data are required to constrain the range of possible solutions prior to second-order interpretations. Any new heatflow data may also be expected to affect simple relaxation models proposed by Cull et al (1991) to explain the nature of xenolith geotherms and underplating volumes in southeast Australia.

5.4 State-wide estimates of geothermal temperatures Apart from variations in heat production, sub-surface temperatures are controlled by variations in thermal conductivity (equation 1). Consequently the nature of the surface layer must be considered in any calculation of the geothermal gradient. Crustal rocks vary in thermal conductivity over a relatively small range depending primarily on porosity and density. Values near 3.0 W/m/K are typical for most granites and near-surface basement rocks however a typical basin sequence requires more elaborate analysis. In particular, thermal conductivities may be less than 0.5 W/m/K




in major coal beds extending throughout the Gippsland, Otway, and Murray Basin sequences (e.g. Gloe et al 1988).

Table 2 represent temperatures calculated at depths of 500, 1000, 3000, and 5000m using representative geological sections for each 1:250,000 map area. The results reflect the approximations in any extrapolation of data in Table 1 and the indicative estimates of thermal conductivity as a function of depth to basement in each region. These results provide a general indication of temperature at target depths. However some additional possibilities cannot be excluded. In particular there is some potential for vertical water flow in major crustal faults giving rise to anomalous temperatures within localised areas. These may provide a short-circuit for water at greater depths allowing heat to be extracted with less expensive drilling. However there is no evidence for the large flow rates required for industrial applications and even in favourable regions some decrease in productivity could be anticipated during dewatering, loss of pressure, and closure of vertical fissures.

Table 2 Calculated Temperatures.

Map Sheet Temperatures (C) Calculated at Depths of VIC Grid Coordinates

500m 1000m 3000m 5000m Easting Northing MILDURA 35 51 104 158 2201457 2772502 OUYEN 32 47 99 150 2205246 2661574 HORSHAM 35 52 112 172 2209033 2550678 HAMILTON 36 53 115 176 2212820 2439779 PORTLAND 39 59 122 185 2216609 2328846 BALRANALD 33 49 105 161 2339278 2776122 SWAN HILL 35 51 109 167 2341318 2665148 ST ARNAUD 31 45 100 155 2343357 2554206 BALLARAT 29 42 90 138 2345397 2443262 COLAC 37 55 113 172 2347437 2332282 DENILIQUIN 32 47 99 150 2477429 2666578 BENDIGO 29 43 93 143 2477721 2555617 MELBOURNE 28 41 88 135 2478012 2444655 QUEENSCLIFFE 32 47 99 150 2478304 2333657 JERILDERIE 33 49 104 159 2613547 2665863 WANGARATTA 29 43 93 143 2612090 2554912 WARBURTON 29 43 93 143 2610633 2443958 WARRAGUL 36 53 110 167 2609175 2332969 WAGGA 29 43 93 143 2749635 2663003 TALLANGATTA 31 45 100 155 2746431 2552089 BAIRNSDALE 33 49 106 162 2743226 2441172 SALE 37 55 114 173 2740020 2330220 MALLACOOTA 31 45 100 155 2875758 2436298




6. Potential Volumetric Yield of Geothermal Wells

In considering the geothermal potential of Victoria it is not only necessary to map subsurface temperatures, it is also important to consider the ability of deep geothermal wells to deliver hot water in quantities required for any potential application or use of the geothermal energy. The volume of water that can be extracted from a well is in turn dependent on aquifer hydraulic characteristics, well design, and the sustainable yield of the aquifer (e.g. whether the available volume of groundwater is limited by environmental factors). The aim of this part of the study is to identify the most likely volumes of warm water that can be expected from a well on the basis of measured data from existing wells. The scope of this assessment does not extend to an evaluation of the total groundwater resource and, as a result, this assessment does not include an evaluation of sustainable yield of any region or aquifer. In several parts of the State the Rural Water Authorities (who are responsible for the licensing and management of groundwater) have established Water Supply Protection Areas (WSPA) where the sustainable yield has been evaluated and restrictions to groundwater pumping have been imposed. The location of these WSPA’s and the restrictions that apply can be obtained from the relevant Rural Water Authority.

To undertake this assessment specific capacity data (defined as the rate of water yielded per unit drawdown in m3/day/m) were assembled, together with other data that could be used to calculate a specific capacity (e.g. transmissivity) that had been measured and recorded for existing wells. Note that the yield estimates made by drillers when completing a bore were not considered for this assessment because of the uncertainty associated with flow measurements and the fact that few records include both drawdown and pumping rate records.

The search for data included the GMS database used by the Rural Water Authorities to record data from licensed bores, the GDB (which pre-dates the GMS), and the ELIXIR database which records reports produced by Government Departments including the Geological Survey of Victoria. The search resulted in 103 wells being identified with specific capacity or related data. However, only 22 wells were identified with data from depths greater than 500 m (i.e. at target depths for a geothermal well). During our search for data it became clear that more information on other deep bores (>500 m) drilled by the State Government is likely to exist. However, this information is stored in a form that is not easily accessed through databases. These sources include the Geological Survey Unpublished Reports and the “Daily Boring Records” dating back to the late 19th Century. Examination of these records has the potential to provide specific capacity data on 50 to 100 deep wells. The ELIXIR database search also identified a number of miscellaneous reports that may also contain additional data.




The available yield data from deep bores have been broadly categorised according to depth and are presented in Figure 6 and Table 5 and in Figure 9 and Table 10 for 500 m and 1000 m depths, respectively.

The bore yield information obtained as part of this study has been almost exclusively obtained from bores completed in the deep unconsolidated sediments found within the Otway and Gippsland basins. This result simply reflects the fact that almost all deep groundwater pumping bores drilled in the state have been targeted to obtain production from the unconsolidated Tertiary age sediments that overly the much older consolidated basement rocks in the sedimentary basins.

The distinction between the thick unconsolidated sediments and the underlying basement rocks is significant in terms of hydrogeology and well productivity. The unconsolidated sediments found in these basins contain large volumes of water stored in the pores between the sediment particles. The pores that provide the storage volume for water also enable water to move through the formation. The aquifers associated with these sedimentary sequences are therefore considered to exhibit “porous media” type water storage and transmission characteristics and bores completed in such aquifers typically yield significant quantities of water under pumping. On the other hand the underlying consolidated rocks are “fractured rock” type aquifers that have limited water storage and transmission characteristics associated with interstitial porosity and with relatively sparse fracture networks within the rock mass. While good production can be expected when a bore intersects conductive fractures in the basement, bores that do not encounter such fractures are poorly yielding. Because of the relatively sparse nature of the fracturing and jointing in the basement rocks, the chances of obtaining significant volumes of water from the basement are much less than when the bore is completed in the unconsolidated sediments. Experience with drilling bores and tunnelling (e.g. in underground mines) into the basement rocks in Victoria suggests that relatively poor yields can generally be expected and that the drilling of productive bores requires careful targeting of the bore to intersect mapped faults or fractures in the rock mass.

Additional information on the productivity of deep bores may be obtained from an extensive search and review of unpublished Geological Survey reports. Alternatively the testing of existing deep bores could be used to provide additional information at a number of sites throughout the state. Given that a substantial number of specific capacity estimates have been found for bores in the Otway Basin, it would be advisable to concentrate any future effort on the Gippsland and Murray Basins. Similarly there are no existing estimates of productivity of deep bores extracting water from fractures in basement rocks. The acquisition of such data would provide a useful guide for prospective developers of geothermal energy.




7. Mapping Geothermal Temperatures Figure 5 shows the broad distinction between regions of outcropping sediments and basement rocks. The location and extents of the three principal sedimentary basins are obvious. Also shown on Figure 5 are the locations at which bore temperature measurements are available.

Measured temperatures between the depths of about 300 m and 700 m were assembled and combined with the estimated temperatures at 500 m depth as described in Section 5 above. The resulting data set was contoured using the Surfer 8 software package (Golden Software). Data from depths outside the prescribed depth range have been incorporated in the analysis where they add important information to the data set (i.e. in areas where data are sparse or where temperatures from shallower or deeper levels help define a minimum temperature at 500 m depth). Isothermal contour maps at a nominal depth of 500 m are presented in Figure 6 to Figure 8. Figure 6 shows the geothermal isotherms for the entire state while Figure 7 and Figure 8 show isotherms for the Otway and Gippsland sedimentary basins respectively. A similar analysis was carried out for reference levels of 1000 m and 1500 m depth and results are presented in Figure 9 to Figure 14.

In viewing the temperature contour maps presented herein it is important to understand the reliability and accuracy of the data from which the maps have been developed. In particular it is important to appreciate that deep measured temperatures often underestimate the true formation temperature. Systematic underestimation of temperature arises from the fact that measurements are often made during a period of heating following well drilling. Anomalous temperatures may also arise from measurements of temperature that are affected by internal circulation of water within the well at the time of measurement. Such phenomena are often observed in deep geothermal bores drilled into regions where there are substantial natural vertical pressure gradients in the geothermal reservoir exposed to the well. In particular cool water may enter a bore and descend to lower, hotter aquifers where an over-pressured, shallow aquifer is intersected by the bore. Internal flows and associated temperature distortions can also arise from an up-flow of hotter waters into a shallow, under-pressured aquifer. Identifying and understanding anomalous geothermal temperature measurements is a complex and involved process and requires careful analysis of continuous temperature-depth logs. In the absence of such detailed temperature measurements it is not possible to fully understand and rationalise all available temperature data. Even though attempts have been made to remove obvious anomalies from the maps, localised highs and lows in the geothermal temperature maps should be viewed with caution.

Temperature contour maps of the Gippsland Basin presented in Figure 8, Figure 11 and Figure 14 are shown with an overlay defining the lateral extent of the unconsolidated sediments at the relevant reference level (ie. 500, 100 and 1500 m respectively). The intention is to provide an indication of the region in which economic production rates can be anticipated. Wells screened in the sediments can be expected to deliver large quantities of water while bores screened in the




Figure 5 Deep Sedimentary Basins and Locations of Measured Geothermal Temperatures

Maps of geothermal temperatures across the entire state (Figure 6 to Figure 14) have been derived from a compilation of measured and calculated data. It should be noted that the reliability of these maps is low in areas where there are few measured data. In particular the extrapolation of elevated temperatures into areas in which there are few or no measured data is speculative.

basement rocks will be productive only if substantial secondary permeability (faults, fractures formation contacts etc) can be located.

Otways Basin

MurrayBasin

Gippsland Basin

Temperature Measurement

Outcropping Sediment

Outcropping Basement Rocks

Latrobe Valley




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C OPYRIGH T: The con ce pts and info rma tio n contained in this d ocument are the copyr igh t o f the Su sta in able Energy Autho rity Victor ia. Use or copying o f the d ocu ment in whole or in p art without t he w ritten p erm issio n of th e Sustainable En ergy Au thor ity Victoria con stitute s a n infringe ment o f copyright. Maps included in th is do cu ment w ere prepared for the Su st ain able Energy Autho rity Victor ia by Sincla ir Knight M erz Pty. Lt d. Sincla ir Knight M erz Pt y. Ltd. do es not w arrant th at this docum ent is definitive n or f ree of er ror and does not a ccep t liabilit y f or a ny loss caused o r ar ising from reliance up on information p rovided here in.

Source: i:w cm s/pro jects/WC 02886 /Te ch nical/Plots/all_state _500m _T. sr f

Sustainable Energy Authority Victoria

Temperatures at 500m Depth0 20 40 60 80 km

Melbourne

Ballarat

Sale

Traralgon

Horsham

Hamilton

Mildura

Swan Hill

Echuca WodongaWangaratta

Note: Much of the information on this map is interpolated from sparsely distributed data. Information presented in those regions where there are few measurements should be used with caution.

Calculated Temperature

Measured Temperature

Major Road

Figure 6 Temperatures at 500m Depth




Table 3 Measured Temperatures Shown in Figure 6 in Areas Other Than the Gippsland and Otway Basins.

Bore Temperature (C)

Depth (m)

VIC Grid Easting

VIC Grid Northing

GUNAMALARY 2 45 718 2153894 2678301 MILDURA WEST 1 44 429 2170154 2766721 MILDURA WEST 2 50 598 2158898 2766345

Table 4 Calculated Temperatures Shown in Figure 6

Map Sheet Temperature (C)

Depth (m)

VIC Grid Easting

VIC Grid Northing

MILDURA 35 500 2201457 2772502 OUYEN 32 500 2205245 2661574 HORSHAM 35 500 2209033 2550677 HAMILTON 36 500 2212820 2439779 PORTLAND 39 500 2216609 2328845 BALRANALD 33 500 2339277 2776121 SWAN HILL 35 500 2341317 2665148 ST ARNAUD 31 500 2343357 2554205 BALLARAT 29 500 2345397 2443261 COLAC 37 500 2347437 2332282 DENILIQUIN 32 500 2477429 2666577 BENDIGO 29 500 2477720 2555617 MELBOURNE 28 500 2478012 2444654 QUEENSCLIFFE 32 500 2478303 2333656 JERILDERIE 33 500 2613546 2665862 WANGARATTA 29 500 2612089 2554911 WARBURTON 29 500 2610632 2443958 WARRAGUL 36 500 2609175 2332969 WAGGA 29 500 2749635 2663003 TALLANGATTA 31 500 2746430 2552088 BAIRNSDALE 33 500 2743225 2441172 SALE 37 500 2740019 2330220 MALLACOOTA 31 500 2875758 2436297




Table 5 Specific Capacity Data Shown in Figure 6, Figure 7 and Figure 8

Bore Specific Capacity (m3/daym) Depth VIC Grid Easting VIC Grid Northing

Ardno 2 385 301 2145263 2406119 Drik Drik 1 38 309 2174180 2383788 Malanganee 4 245 330 2147140 2397187 Mumbannar 6 125 358 2159943 2393913 Coonimur 1 98 393 2338214 2725401 Heywood 14 200 471 2203095 2368330 Cobboboonee 2 23 471 2183233 2365766 Heywood 11 58 473 2203501 2368922 115867 (GMS No.) 434 496 2425641 2345062 Glenaulin 2 56 537 2188289 2382572 Homerton 4 57 594 2212162 2367144 Belfast 13 997 600 2256315 2342958 Yangery 1 32 640 2270090 2352249 62106 (BCL No.) 420 649 2256314 2342908 Mumbannar 1 48 716 2166139 2402637




385

38

245 125

23 58

434

56

57

100032

48

200

420

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85

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C OPYRIGH T: The con ce pts and info rma tio n contained in this d ocument are the copyr igh t o f the Su sta in able Energy Autho rity Victor ia. Use o r copying o f the d ocument in whole or in p art without t he w ritten p erm issio n of th e Sustainable En ergy Au thor ity Victoria con stitute s a n infringe ment o f copyright. Maps included in th is do cu ment w ere prepared for the Su st ain able Energy Autho rity Victo ria by Sincla ir Knight M erz Pty. Lt d. Sincla ir Knight M erz Pt y. Ltd. do es not w arrant th at this docum ent is definitive nor f ree of er ror and does not a ccep t liabilit y f or a ny loss caused o r ar ising from reliance up on information p rovided h ere in.

Source :i: wcms/proje cts/WC 0288 6/Technica l/Plots/Otways_500 m_T.srf


Otway Basin Temperatures at 500m Depth

0 20 40 60 80 km

Port FairyWarrnambool

ColacSorrento

Geelong

Melbourne

Ballarat




Specific Capacity (Values in m^3/day/m)

Major Road

Figure 7 Temperatures at 500 m depth for the Otway Basin

Geother

SINCLAIR KNIGHT

C:

mal Resources of Victoria

MERZ

\Documents and Settings\PMunivrana\Local Settings\Temporary Internet Files\OLKF\SKM Geothermal Report - final.doc PAGE 25

Table 6 Measured Temperatures in the Otway Basin Shown in Figure 6 and Figure 7

Bore Temperature (C) Depth (m) VIC Grid

Easting VIC Grid Northing

COLAC 00010 37 384 2377161 2350263 SOUTH CARAMUT 1 36 430 2278463 2385808 PALPARA 00004 28 445 2146077 2384336 COLONGULAC 00012 38 450 2331798 2360750 TANDAROOK 00002 34 454 2337687 2349397 TULLICH 1 34 464 2160008 2435033 WAARRE 15003 32 501 2337534 2315602 PAARATTE 00002 31 548 2325744 2318505 HOMERTON 00004 33 575.6 2212163 2367149 PAARATTE 08011 25 576 2323284 2327138 MURROON 00024 39 590 2392815 2341708 GLENAULIN 00002 33 592.5 2188288 2382574 MURROON 00023 39 598 2393123 2341912 NARRAWONG 00016 31 613 2209830 2364258 CODRINGTON 00001 35 629 2232312 2355325 PENINSULAR HOTSPRINGS

45 637 2481050 2347379




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COPYRIGH T: The co ncepts and inf orm ation containe d in this documen t are the cop yr ig ht of the S ustain able Energy Autho rity Victo ria. U se or cop ying of the documen t in who le or in part without the w ritten perm ission of t he Sustainab le Energ y Author it y Victor ia co nstitu tes an infring ement of copyrigh t. Map s included in this d ocument were prepared fo r th e Sustain able Energy Auth ority Victo ria by Sinclair Knight M erz Pty. L td. Sinclair Knight M erz Pty. Ltd. d oes not w arrant that th is docum ent is definitive nor free of er ro r an d does no t accep t liab ility for a ny lo ss caused or a rising fro m re liance u pon informat ion pro vided herein .

Source :i: wcms/proje ct s/W C028 86/Technica l/Plots/Gip pslan d_500 m_T.sr f


Gippsland Basin Temperatures at 500m Depth

0 20 40 60 80 km




Area of Bedrock at 500m Depth

Major Road

Figure 8 Geothermal Temperatures at 500m depth for the Gippsland Basin




Table 7 Measured Temperatures in the Gippsland Basin Shown in Figure 6 and Figure 8



ALBERTON EAST 00003 38 370.9 2646475 2319603

WORANGA 00015 35 470 2646431 2327644

MARYVALE 00942 65 500 2626659 2367896

TONG BONG 00182 34 515.1 2642902 2357230

STRATFORD 00017 36 525 2684077 2391619

YARRAM YARRAM 08002

31 234.8 2644384 2325048

WILLUNG 00179 30 249 2658349 2349334

BOODYARN 00006 21 305 2654657 2334358

WILLUNG 00182 23 305 2648430 2352959

WORANGA 00016 29 310 2649379 2327369

BOODYARN 00004 18 333 2659077 2338350

WULLA WULLOCK 00004 23 365.8 2680695 2356042

ROSEDALE 00307 51 702 2651491 2369192

WINNINDOO 45 33.8 250 2653124 2384366

HOLEY PLAINS 174 22 277 2667299 2368324

MARYVALE 2291 48 285 2620184 2362010

ALBERTON EAST 10003 35 287 2646433 2317788

YINNAR 122 40.5 300 2617727 2351084

DENISON 54 36 329 2653375 2384418

STRADBROKE 51 21.9 335 2663451 2353016

LOY YANG 1185 45.4 339 2636478 2362053

TRARALGON 377 36 350 2632827 2358167

WILLUNG 196 29.5 369 2654622 2358696

TRARALGON 256 45.9 383 2631781 2357668

HAZELWOOD 1320 51 434 2621603 2355954

TONG BONG 182 26 461 2642904 2357223

TONG BONG 176 41.5 517 2645686 2359864

MARYVALE 8001 70 524 2626226 2368530

BOOLA BOOLA 1 63.8 558 2627244 2372303

TRARALGON 286 62.5 582 2635010 2366947

BAIRNSDALE 6 58.9 584 2736530 2396046

ROSEDALE 307 52 585 2651491 2369190

HAZELWOOD 1333 56 594 2625515 2358500

WINNINDOO 46 65 679 2651687 2375861

LOY YANG 2390 62 715 2644285 2368210




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C OPYRIGH T: The con ce pts and info rma tio n contained in this d ocument are the copyr igh t o f the Su sta in able Energy Autho rity Victor ia. Use or copying o f the d ocument in whole o r in p art without t he w ritten p erm issio n of th e Sustainable En ergy Au thor ity Victoria con stitute s a n infringe ment o f copyright. Maps included in t his do cu ment w ere prepared for the Su st ain able Energy Autho rity Victor ia by Sincla ir Knight M erz Pty. Lt d. Sincla ir Knight M erz Pt y. Ltd. do es not w arrant t hat this docum ent is definitive nor f ree of er ror and does not a ccep t liabilit y f or a ny loss caused o r ar ising from reliance up on information p rovided here in.

Source: i:w cm s/pro jects/WC 02886 /Te ch nical/Plots/all_state _1000 m_T.srf



Melbourne

Ballarat

Sale

Traralgon

Horsham

Hamilton

Mildura

Swan Hill





Major Road

Figure 9 Geothermal Temperatures (Degrees C) at 1000m Depth




Table 8 Measured Temperatures Shown in Figure 9 in Areas Other Than the Gippsland and Otway Basins.


Depth (m)

VIC Grid Easting

VIC Grid Northing

GUNAMALARY 2 60 718 2153894 2678301



Depth (m)

VIC Grid Easting

VIC Grid Northing





Table 10 Specific Capacity Data Shown in Figure 9, Figure 10 and Figure 11

Bore Specific Capacity (m3/day m) Depth VIC Grid Easting VIC Grid Northing

Heywood 10 53 737 2203621 2368790 Tarragal 3 134 931 2190178 2343442 Mouzi 1 50 946 2189425 2357232 Portland 2 50 951 2203436 2346739 Trewalla 5 78 971 2191989 2346661 Portland 13 1134 1133 2203243 2340632 Portland 8 206 1175 2203377 2341089 Portland 11 375 1184 2203627 2341039 Portland 3 161 1200 2201989 2345426




53

50

5078

15

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5055

6065

70

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85

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C OPYRIGH T: The con ce pts and info rma tio n contained in this d ocument are the copyr igh t o f the Su sta in able Energy Autho rity Victor ia. Use o r copying o f the d ocument in whole or in p art without t he w ritten p erm issio n of th e Sustainable En ergy Au thor ity Victoria con stitute s a n infringe ment o f copyright. Maps included in th is do cu ment w ere prepared for the Su st ain able Energy Autho rity Victo ria by Sincla ir Knight M erz Pty. Lt d. Sincla ir Knight M erz Pt y. Ltd. do es not w arrant th at this docum ent is definitive nor f ree of error and does not a ccep t liabilit y f or a ny loss caused o r ar ising from reliance up on information p rovided h ere in.

Source :i: wcms/proje cts/WC 0288 6/Technica l/Plots/Otways_100 0m_T.srf


Otway Basin Temperatures at 1000m Depth0 20 40 60 80 km

Port Fairy

WarrnamboolColac

Sorrento

Geelong

Melbourne

Ballarat

1341150206375161




Specific Capacity (Values in m^3/day/m)

Major Road

Figure 10 Geothermal Temperatures at 1000m depth in the Otway Basin




Table 11 Measured Temperatures Shown in the Otway Basin Shown in Figure 9 and Figure 10.



PAARATTE 08004 50 895 2324905 2320620 NARRAWATURK 00006 50 907 2313395 2327533 BESSIEBELLE 08003 41 921 2227745 2366529 TIMBOON 00005 36 921.4 2323933 2333294 WANGOOM 00002 44 922.93 2281958 2344558 TARRAGAL 00003 35 934 2190177 2343444 SHAW 1 39 960 2241792 2358435 MOUZIE 00001 43 960.5 2189425 2357235 CURDIE VALE 1 58 964 2306933 2325219 LINDON 2 40 970 2194367 2375935 NIRRANDA 00008 62 982 2302983 2329846 TREWALLA 00005 39 983.3 2191988 2346666 NARRAWATURK 08029 45 998 2318963 2325379 HOTSPUR 1 58 1000 2198930 2393095 ARDONACHIE 00002 39 1021.7 2224473 2384502 ARDONACHIE 00002 39 1022 2224473 2384502 PORTLAND 00002 50 1030 2203434 2346749 WARRONG 00005 48 1034 2264110 2358320 PAARATTE 08001 53 1067 2323547 2327144 DARTMOOR 00025 38 1100.88 2171586 2392032 PENINSULAR HOTSPRINGS

50 1000 2481050 2347379




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Sale

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COPYRIGH T: The co ncepts and inf orm ation containe d in this documen t are the cop yr ig ht of the S ustain able Energy Autho rity Victo ria. U se or cop ying of the documen t in who le or in part without the w ritten perm ission of t he Sustainab le Energ y Author it y Victor ia co nstitu tes an infring ement of copyrigh t. Map s included in this d ocument were prepared fo r th e Sustain able Energy Auth ority Victo ria by Sinclair Knight M erz Pty. L td. Sinclair Knight M erz Pty. Ltd. d oes not w arrant that th is docum ent is definitive nor free of erro r an d does no t accep t liab ility for a ny lo ss caused or a ris ing fro m re liance u pon informat ion pro vided herein .

Source :i: wcms/proje ct s/W C028 86/Technica l/Plots/Gip pslan d_100 0m_T.srf



0 20 40 60 80 km





Major Road

Figure 11 Geothermal Temperatures at 1000m Depth in the Gippsland Basin




Table 12 Measured Temperatures in the Gippsland Basin Shown in Figure 9 and Figure 11.



DENISON 00057 55 872 2662748 2379794 WULLA WULLOCK 00004 40 895 2680695 2356042 WURRUK WURRUK 00013

47 900 2677007 2374319

HAZELWOOD 01395 58 1000 2620154 2356845 SALE 00013 64 1049.76 2694520 2374007 BENGWORDEN SOUTH 00006

50 1057.5 2713050 2379806

LOY YANG 01675 65 790 2643005 2367954 TRARALGON 00286 65 840 2635010 2366954 DENISON 00053 53 854 2666400 2375536 ROSEDALE 301 50.5 817 2661060 2370219 HOLEY PLAINS 185 38.2 904 2671406 2368735




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C OPYRIGH T: The con ce pts and info rma tio n contained in this d ocument are the copyr igh t o f the Su sta in able Energy Autho rity Victor ia. Use or copying o f the d ocument in whole o r in p art without t he w ritten p erm issio n of th e Sustainable En ergy Au thor ity Victoria con stitute s a n infringe ment o f copyright. Maps included in t his do cu ment w ere prepared for the Su st ain able Energy Autho rity Victor ia by Sincla ir Knight M erz Pty. Lt d. Sincla ir Knight M erz Pt y. Ltd. do es not w arrant t hat this docum ent is definitive nor f ree of error and does not a ccep t liabilit y f or a ny loss caused o r ar ising from reliance up on information p rovided here in.

Source: i:w cm s/pro jects/WC 02886 /Te ch nical/Plots/all_state _1500 m_T.srf



Melbourne

Ballarat

Sale

Traralgon

Horsham

Hamilton

Mildura

Swan Hill





Major Road

Figure 12 Geothermal Temperatures (Degrees C) at 1500m Depth






Depth (m)

VIC Grid Easting

VIC Grid Northing





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C OPYRIGH T: The con ce pts and info rma tio n contained in this d ocument are the copyr igh t o f the Su sta in able Energy Autho rity Victor ia. Use o r copying o f the d ocument in whole or in p art without t he w ritten p erm issio n of th e Sustainable En ergy Au thor ity Victoria con stitute s a n infringe ment o f copyright. Maps included in th is do cu ment w ere prepared for the Su st ain able Energy Autho rity Victo ria by Sincla ir Knight M erz Pty. Lt d. Sincla ir Knight M erz Pt y. Ltd. do es not w arrant th at this docum ent is definitive nor f ree of error and does not a ccep t liabilit y f or a ny loss caused o r ar ising from reliance up on information p rovided h ere in.

Source :i: wcms/proje cts/WC 0288 6/Technica l/Plots/Otways_150 0m_T.srf


Otway Basin Temperatures at 1500m Depth0 20 40 60 80 km

Port Fairy

WarrnamboolColac

Sorrento

Geelong

Melbourne

Ballarat




Major Road

Figure 13 Geothermal Temperatures at 1500m depth in the Otway Basin




Table 14 Measured Temperatures in the Otway Basin Shown in Figure 12 and Figure 13.



PORTLAND 00003 59 1421 2202066 2345500 HENKE 1 62 1430 2165676 2381834 BESSIEBELLE 08002 48 1459 2231589 2361345 KRAMBRUK 00013 60 1475 2382814 2301830 IONA 1 57 1490 2328680 2323587 SQUATTER 1 55 1500 2160167 2396275 ARDNO 00002 52 1500 2145262 2406120 PAARATTE 08008 55 1509 2327208 2325877 CASTERTON 2 65.6 1524 2166834 2421312 DRAJURK 08005 65 1526 2166832 2421312 WARRACBARUNAH 2 75 1527 2395925 2369337 PAARATTE 08007 62 1531 2321755 2325918 GARVOC 1 67 1533 2314372 2351375 YAMBUK 00002 55 1535 2242873 2347162 KENTBRUCK 00003 57 1575 2174432 2368894 NORTH PAARATTE 2 60 1580 2323310 2326029 NARRAWONG 00016 63 1625 2209830 2364258




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Bairnsdale

Orbost

COPYRIGH T: The co ncepts and inf orm ation containe d in this documen t are the cop yr ig ht of the S ustain able Energy Autho rity Victo ria. U se or cop ying of the documen t in who le or in part without the w ritten perm ission of t he Sustainab le Energ y Author it y Victor ia co nstitu tes an infring ement of copyrigh t. Map s included in this d ocument were prepared fo r th e Sustain able Energy Auth ority Victo ria by Sinclair Knight M erz Pty. L td. Sinclair Knight M erz Pty. Ltd. d oes not w arrant that th is docum ent is definitive nor free of er ro r an d does no t accep t liab ility for a ny lo ss caused or a rising fro m re liance u pon informat ion pro vided herein .

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Figure 14 Geothermal Temperatures at 1500m Depth in the Gippsland Basin




Table 15 Measured Temperatures in the Gippsland Basin Shown in Figure 12 and Figure 14.


Depth (m)

VIC Grid Easting

VIC Grid Northing

SPOON BAY 1 63 1400 2716452 2377287 ST MARGARET ISLAND 1 67 1422 2659914 2316823 NORTH SEASPRAY 2 68 1624 2693081 2353432 SALT LAKE 1 72 1642 2682319 2337462 CARR'S CREEK 1 50 1670 2698268 2354420 COLLIERS HILL 1 61 1710 2700878 2364685 LOY YANG 1A 80 1736 2636580 2359879 WOODSIDE SOUTH 1 58 1772 2666413 2323803

It is believed that most of the available existing measurements of geothermal temperatures in Victoria have been obtained from searches of the various databases carried out during this project. Additional information from areas in which there are few measurements would require the drilling of deep exploration bores specifically aimed at providing this information. The indicative costs of drilling such bores are shown in Table 17. The relative paucity of data in the Murray Basin and in areas of bedrock outcrop in the central highlands suggests that these areas should form the principal targets for any further data acquisition.

7.1 Temperatures at Greater Depths – Hot Dry Rock Potential Hot Dry Rock technology is currently being evaluated and developed in the Cooper Basin in South Australia. In this project the anomalously high geothermal temperatures in deep granites are being targeted for energy extraction and electricity generation. The project involves the drilling of deep bores to more than 4 000 m where temperatures are expected to be in excess of 250ºC. Australia’s deepest well (Habanero #1 is 4 420 m deep) has recently been completed by Geodynamics Ltd as part of this project1. The energy extraction technology involves the artificial fracturing of deep, relatively impermeable rocks to establish a flow path in the formation between injection and production bores (refer to Figure 15 for a schematic showing Hot Dry Rock technology). Cool water pumped down an injection well, flows through the fractured reservoir where the water extracts heat from the rocks and is then pumped out of the production well. The hot water thus produced may be used to generate electricity using standard Organic Rankine Cycle or Kalina Cycle® technology (refer to Section 9.2). The basic resource requirements for an economically successful Hot Dry Rock development are:

1 www.geodynamics.com.au/IRM/company




Elevated temperatures. Resource temperatures (i.e. temperatures measured in the ground at the depth of the productive reservoir) in excess of 200°C are generally considered to be required for economic development. The Hot Dry Rock process results in the production of water at temperatures somewhat lower than the prevailing resource temperature. Accordingly the minimum resource temperature required to sustain an economical development is correspondingly higher than for standard geothermal developments in which water is produced at temperatures close to the prevailing resource temperature.

A geological stress regime amenable to the development of a set of fractures (preferably horizontally oriented) linking the injection and production bores.

The development of a successful Hot Dry Rock project in Victoria would involve the location and subsequent exploitation of geothermal resources at temperatures that greatly exceed those measured in existing bores. However the existence of high geothermal temperatures in Victoria at great depth cannot be discounted.

Estimates of deep formation temperatures based on thermal properties of deep rocks and on heat flow estimates are presented in Table 16. Predicted deep temperatures presented in Table 16 suggest that bores greater than 5000m depth will be required to encounter temperatures of 200°C. Drilling bores to such depths is at or beyond the limits of readily available drilling rigs in Victoria. Furthermore, the expense of constructing bores to these depths would guarantee an uneconomic outcome for any Hot Dry Rock development.

It should however be noted that the estimates of deep geothermal temperatures included in Table 16 are based on regional estimates of heat flow and thermal conductivity and the chance of there existing limited areas of locally elevated geothermal gradients should not be entirely discounted. In fact anomalously high geothermal gradients measured in bores in the Latrobe Valley (refer to Figure 4) suggest that temperatures exceeding 260°C may be encountered at 2000m depth at this location.

It may be concluded that local thermal anomalies identified in the Gippsland and Otway Basins may represent prospective sites for Hot Dry Rock developments. Otherwise, estimated deep temperatures throughout much of the state are generally insufficient to support economical development of Hot Dry Rock electricity generation with currently proven technologies and under current economic conditions.


Figure 15 Hot Dry Rock Development (supplied by Geodynamics Limited)






Table 16 Temperatures Calculated at 3000 and 5000m Depth

Map Temperature at 3000m Depth (C) Temperature at 5000m Depth (C)

MILDURA 104 158OUYEN 99 150HORSHAM 112 172HAMILTON 115 176PORTLAND 122 185BALRANALD 105 161SWAN HILL 109 167ST ARNAUD 100 155BALLARAT 90 138COLAC 113 172DENILIQUIN 99 150BENDIGO 93 143MELBOURNE 88 135QUEENSCLIFFE 99 150JERILDERIE 104 159WANGARATTA 93 143WARBURTON 93 143WARRAGUL 110 167WAGGA 93 143TALLANGATTA 100 155BAIRNSDALE 106 162SALE 114 173MALLACOOTA 100 155Note: Temperatures presented in this table have been calculated from measured and assumed rock properties and heat flows. Measured temperatures at shallower levels suggest that localised temperature anomalies may be present in which substantially higher temperatures may be expected (eg. in the Latrobe Valley, Gippsland Basin).




8. Data Gaps The distribution of bores for which measured temperatures are available is presented in Figure 5. Here it can be seen that temperature measurements are effectively restricted to the Otway and Gippsland Basins. Few measured temperatures are available within the Murray Basin and no measured temperatures have been found in bores drilled in the Central Highlands. The reason for the uneven distribution of measured temperatures is related to the following factors:

Onshore petroleum exploration has been essentially restricted to the Gippsland and Otway basins.

Deep drilling for mineral exploration and deep mine dewatering operations are generally restricted to the Latrobe Valley of the Gippsland Basin.

Deep drilling for water supply bores has been limited to the deep sedimentary basins where large quantities of good quality water can be expected.

As a consequence, the confidence of the geothermal temperature maps presented in the above Section 7 is low in those regions where few or no temperature measurements are available. In general, the geothermal temperatures of the Murray Basin and Central Highlands regions are poorly defined.

Deep drilling in Victoria has demonstrated that reasonable water production can be expected from wells that are screened within the unconsolidated sediments. However, there is insufficient information to reliably map the lateral and vertical variability of water production (ie. yield) within the state except for the Otway Basin where a number of specific capacity estimates are available.

Production from the fractured bedrock is believed to be generally poor. In order to include the location of the sedimentary basins (ie. areas of potentially high yield) and bedrock (ie. areas where low yields are expected) in the geothermal maps it is necessary to map the base of the unconsolidated sediments in each of the major basins. This has been done in Gippsland and the maps of geothermal temperatures presented in this report include this information. Similar information should also be compiled for the Murray and Otway basins. Mapping bedrock structural contours should be possible by reviewing existing deep drilling and geophysical data.

The calculated temperature results (as opposed to the measured temperatures) in this report can be considerably improved by increasing the number of heatflow estimates in Victoria. Normally these require deep drilling followed by casing to ensure a return to thermal equilibration prior to observations of the geothermal gradient. Additional estimates may be obtained on an opportunity basis using holes drilled for stratigraphic logging or exploration programs. It is critical however to obtain core samples for measurements of thermal conductivity within the same holes used for observations of temperature.




8.1 Recommendation for Further Work A viable program to enhance the understanding of the geothermal resources of Victoria would include:

Review of existing groundwater observation bores to obtain existing core samples that could be used for laboratory estimation of thermal conductivity.

Review of stratigraphic drilling operations to secure future opportunities for heatflow data acquisition.

Search unpublished Geological Survey reports for additional “existing” data on specific capacity of deep bores.

Comprehensive mapping of bedrock surface in the Otway and Murray basins from existing information.

Systematic program of drilling to obtain geothermal temperature measurements and core at depths 200-300m in key locations in the Central Highlands and Murray Basin.

8.2 Indicative Drilling Costs The cost of deep drilling within the sedimentary basins of Victoria will depend on a number of site specific and project specific factors. The range of indicative costs for the drilling and construction of deep production bores is presented in Table 17

Table 17 Indicative Drilling Costs in Victoria (Data Provided by Sides Engineering)

Depth Indicative Cost $AU

500m $210 000 - $375 000 1000m $390 000 - $700 000 1500m $525 000 - $975 000

Costs in Table 17 have been estimated on the basis of drilling and constructing a production bore to a final screen/slotted casing diameter of 200mm. The higher estimate is based on using FRP casing and a stainless steel screen to increase bore longevity. The lower estimate assumes the bore is completed in mild steel casing with slotted mild steel production interval. The costs include mobilisation and demobilisation but do not include any contingency for drilling in consolidated rock, loss of circulation, stuck drill-string etc. The cost of drilling through bedrock, either beneath the sedimentary pile in the sedimentary basins or drilling in the central highlands region is expected to be higher than that indicated in Table 17.




9. Electricity Generation Technologies

9.1 Steam Rankine Cycle

Generation of electricity using geothermal resources has been practised for more than a century, since the first use at Larderello in Italy, in 1904. The advantage of using the geothermal resource in this manner is that the energy associated with the earth’s heat can be economically transported as electricity from the geothermal field to the market.

The steam Rankine cycle has been the conventional technology used for most worldwide geothermal power generation to date. The basic technology is analogous to the steam Rankine cycle used in thermal power plants except that the steam comes from the geothermal reservoir, rather than a boiler. Various technical enhancements to the condensing steam turbines have been implemented over the years to address the differences between geothermal and boiler-quality steam.

The most attractive geothermal fields for developers have been those with higher resource temperatures and production fluid enthalpies. In general as the resource temperature increases the proportion of steam available from the geothermal fluids at the surface also increases and so too its pressure. These conditions provide for more efficient operation of condensing steam turbines, and hence lower electricity production costs. For low enthalpy resources (i.e. lower resource temperatures), a low plant operating pressure is needed to maximise the amount of available steam, equipment is larger and hence more expensive, and a significant proportion of the available energy in the production fluid is rejected unused in the separated brine. Condensing steam plants are typically used for resource temperatures in excess of 175°C. If boiling water at 175°C is flashed down to a pressure of 2 bar (abs), the steam fraction is only 10.7 % by weight.

Australian hydrothermal resources generally do not provide the high fluid temperatures required for economical use of steam Rankine cycle generation.

There are several experienced and competent providers around the world for steam-turbine-based geothermal power plants and component equipment. Unit sizes are typically in the 20-80 MWe range, but are offered from less than 5 MWe up to 110 MWe.

9.2 Organic Rankine Cycle

9.2.1 Introduction

An organic Rankine cycle (ORC) power plant, which is also known as a “binary cycle” plant, makes use of a “working” or “motive” fluid with a lower boiling point than steam. The particular fluid is selected based on comparison of heat source temperature and motive fluid properties. Most




existing geothermal ORC plants use low boiling point hydrocarbons – normal pentane, iso-pentane or iso-butane. It is also possible to use refrigerants, other organic compounds or a mixture of hydrocarbons as the working fluid, although this is less common in practice.

ORC technology, which can achieve more effective use of the heat from a lower temperature geothermal fluid, has allowed economic exploitation of lower enthalpy resources, albeit typically at a higher cost per kilowatt (kW) than for a condensing steam plant on a higher enthalpy resource.

In most geothermal ORC plants using hot water as the heat source fluid, the supply temperature is in the 140-200°C range, although there are several installed plants using cooler fluids down to 100°C. A heat source temperature of around 90°C is generally considered to be the economic minimum for power generation using ORC technology.

The first geothermal ORC plant was built in Russia in the 1960’s, however extensive commercial application of the technology did not begin until the 1980’s. There are now dozens of geothermal ORC power plants in operation around the world, ranging in output from 200 kW to 125 MW. ORC technology is also used for power generation from waste heat, and for small-scale, gas-fired remote power generation. Individual unit sizes are typically in the range from 250 kW to 10 MW, although a single 65 MW turbine operated at the US DOE’s Heber binary demonstration plant for a period in the mid 1980’s. Ormat International dominates the ORC power plant market. Other current or previous technology providers include Turboden, Bibb & Associates (formerly The Ben Holt Company) and Barber Nichols Engineering.

9.2.2 Process Description

The working fluid operates in a contained, closed-loop cycle and is completely segregated from the heat source fluid. There are a number of possible variants of the cycle, in terms of heat exchange configuration, turbine configuration, etc, which may be selected as appropriate to the temperature and physical state(s) of heat source fluid. A simplified schematic diagram of a typical ORC power plant is presented in Figure 16.


Figure 16 Simplified Schematic of ORC Power Plant

Turbine

Feed Pump

Vapouriser

Heat sourcefluid

Cooled heatsource fluid

Preheater

Condenser

The working fluid absorbs heat from a heat source, in this case the hot geothermal fluid, via one or more shell-and-tube heat exchangers. This heat causes the working fluid to evaporate, producing the high-pressure vapour that is then expanded through a turbine-generator. The high-pressure motive fluid vapour passes through a liquid separator located on top or downstream of the vaporiser, prior to flowing into the turbine. The separator is required to remove entrained liquid droplets and to prevent impingement on the turbine blades.

The low pressure turbine exhaust vapour is then condensed, using either air-cooled heat exchangers (“fin-fan exchangers”), or a water-cooled, shell-and-tube condenser. Air cooling is appropriate in locations with limited water supplies, although the motive fluid outlet temperature is then limited by the prevailing ambient dry-bulb, rather than wet-bulb, temperature. This increase in “sink temperature” reduces the overall thermodynamic efficiency of the power cycle.

From the condenser, the liquid working fluid is pumped to high pressure and returned to the preheater to close the cycle. It is also possible to incorporate an additional heat exchanger into the cycle, normally known as a recuperator. In this exchanger, residual sensible heat in the low-pressure turbine exhaust stream is used for initial preheating of the cold liquid from the motive fluid pump, thus increasing the cycle efficiency. The decision to incorporate a recuperator into the cycle depends on the quantity of available heat in the turbine exhaust.

The heat source fluid can be liquid, vapour or two-phase. By virtue of the complete segregation of the working fluid from the heat source fluid, the ORC cycle also finds application at geothermal fields where the geothermal fluids would be difficult to handle in a conventional steam turbine (eg. corrosive fluid or high non-condensible gas content).






9.2.3 Plant Costs

Based on historical prices, the capital cost of an air-cooled ORC power plant fed by hot water would be between US$ 1250 and 1800 per kW (nett), for heat source temperatures in the 100-200°C range and for a 3 – 30 MWe multi-unit development.2 This cost would cover an EPC power plant, excluding the geothermal fluid supply and return reticulation systems. The historical prices vary quite widely in terms of $/kW (US$ 950 to over 2,000 /kW) and the plants in question have a wide range of operating conditions, making it difficult to draw firm correlations for the effects of project scale and resource temperature. However, the specific capital cost ($/kW) will certainly tend to increase as resource temperature decreases. The available temperature range between heat source and sink temperatures decreases and, as a result, the required surface area for heat exchangers and condenser must increase. The lower grade of heat supply also affects the operating conditions in the binary cycle, pushing equipment costs up. DiPippo (1999) provides estimated power plant costs for a 1 MWe binary plant that show an increase from US$ 1,550 /kW at 140°C resource temperature up to US$1,950 /kW at 100°C.

Data from several sources indicates that the operations and maintenance cost for an ORC plant can be expected to be in the range 0.007 – 0.011 A$/kWh depending, among other things, on the size of the plant.

9.2.4 Energy Conversion Efficiency

In order to assess the typical performance of an ORC binary plant, SKM turned to the various performance data held in our files from other existing and proposed projects. We have analysed the conversion efficiencies to electrical energy of the thermal energy absorbed from the geothermal fluid. In doing so, we have adjusted to allow for the effect of different geothermal fluid (heat source) temperatures and ambient (heat sink) temperatures on the efficiency. We have included typical allowances for the temperature approaches that would be achieved between fluids on each side of heat exchangers, though this would be optimised during design of any actual plant. Analysis is based on use of air-cooled condensers.

The results of our analysis are presented in Figure 17. Although these figures can only be considered as “representative”, they do illustrate the relative trends and are consistent with the data on which the analysis was based.

2 The capital cost data are presented in US$ as this is the normal international currency referenced, and this basis removes the influence of the recent significant variations in US$ to A$ exchange rate.


Figure 17 Indicative Thermal to Electric Conversion Efficiency for ORC Plants

6.0

8.0

10.0

12.0

14.0

16.0

18.0

20.0

100 110 120 130 140 150 160 170 180 190 200

Heat Source Temperature (°C)

Ther

mal

to G

ross

Ele

ctric

Con

vers

ion

Effic

ienc

y (%

)

20°C ambient 25°C ambient 30°C ambient

It can be seen from Figure 17 that the conversion efficiency declines with heat source temperature. A cooler heat source temperature provides not only a lower quantity of available energy (difference between fluid energy at inlet and outlet conditions), but also reduced conversion efficiency because the quality of this energy is lower (a “lower grade” of energy).

Air-cooled ORC power plants have a relatively high parasitic power load, at around 10-12% of the gross power generation.

9.3 Kalina Cycle®

9.3.1 Introduction

The Kalina Cycle® is a variant of the closed Rankine binary cycle, but uses an ammonia-water mixture as the motive fluid. The basic process was developed by Dr. Alex Kalina and patented during the 1980’s. A 3.2 MWe demonstration plant operated for around 7,000 hours at the US DOE research facility at Canoga Park in the 1990’s. Two other Kalina plants have been constructed and are currently in operation:-

a 2 MWe plant operating on geothermal brine at Husavik, Iceland, which entered service in 2000.






a 4 MWe unit at Sumitomo Metals in Japan using low grade process waste heat, operating since 1999.

The current primary technology licensor is Recurrent Resources LLC, which has exclusive USA rights for the technology and non-exclusive rights elsewhere in the world. As of late 2003, the exclusive license for Kalina technology in Australia / New Zealand is held by Geodynamics Power Systems Pty Ltd.

Recurrent Resources is currently working on the development of “standard” designs for Kalina Cycle® plants of 5, 15 and 30 MWe nominal capacity. There are several prospective Kalina Cycle®

projects under consideration at the present time, but none is under construction.

9.3.2 Process Description

The Kalina Cycle® offers improved energy recovery efficiency over organic Rankine cycles through optimisation of the motive fluid vaporising and condensing characteristics to best match the available resource conditions. The inherent variable boiling point characteristic of a mixture allows the temperature profile through the motive fluid side of the evaporator to achieve a closer overall approach to that of the heat source fluid. This results in more effective heat transfer as the heat duty is not restricted by a single “pinch” point, as it is for a single component ORC fluid, boiling at a constant temperature. In addition, by varying the working fluid composition at several points in the cycle (by separating and later recombining streams), selected unit operations can take place under more advantageous thermodynamic conditions, further increasing cycle efficiency.

There are many variations on the basic Kalina Cycle®, for example to suit geothermal, direct fired or gas turbine combined cycle applications of various heat source temperature ranges. Some of these schemes are quite complex, but the general principle for geothermal (and other) applications is as shown in Figure 18 and described below.


Figure 18 Simplified Schematic of a Representative Kalina Cycle®

Turbine

Separator

Feed Pump

Condenser

Recuperator

Evaporator

Low concentrationammonia-water

Middle concentrationammonia-water

High concentrationammonia-water

Heat Source

Source:- Modified from Geodynamics Power Systems Pty Ltd

The Kalina Cycle® typically uses an ammonia-water solution of around 80 wt% ammonia, though individual streams in the cycle are richer or leaner to alter thermo-physical properties. At the condenser outlet the liquid is saturated at the condenser pressure. The feed pump then increases the stream pressure to above turbine inlet conditions. The high-pressure fluid is pre-heated to recover heat from the lean liquid existing separator before entering the evaporator. In the evaporator the ammonia water solution is partially vaporised by heat exchange with the geothermal fluid. The mixed phase fluid is separated into rich vapour (high ammonia concentration) and lean liquid (low ammonia concentration) components in the separator.

The working fluid vapour from the separator is expanded through the turbine to produce electricity. Conventional steam turbines, which are highly developed and readily available, are appropriate for this service. The liquid from the separator is cooled in the preheater, as noted earlier. The turbine exhaust vapour and lean liquid are cooled and condensed in the condenser, which can be water- or air-cooled. The recombined, cool liquid then passes to the feed pump to complete the cycle.

Increased cycle efficiency can be obtained using a low temperature recuperator (not shown in diagram) upstream of the condenser to transfer heat from the turbine exhaust vapour and lean separator liquid exchange heat to the cold working fluid from the feed pump. This additional heat recovery step was incorporated into the Kalina plant built in Iceland.






9.3.3 Plant Costs

For the Kalina Cycle®, Geodynamics has claimed that the capital cost per kW could be lower than that of a comparable ORC plant. This is largely on the basis of higher efficiency, which increases the power generated from a given amount of input heat. The only public domain data identified was a reference to Exergy’s bid price for the Husavik plant being equivalent to US$ 905 /kW (OCEES, 2003). At face value this is a very attractive price, but it must be recognised that this plant has a seawater cooling system with very low water temperature. An air-cooled system in Australia would be significantly more expensive due to the condenser cost, and the higher condensation temperature would reduce the “bottom line” – the power generated from an equivalent sized plant to Husavik. Furthermore, it is possible that the price offering for the Husavik plant may have been particularly keen in order to get the first geothermal Kalina plant constructed. There are a number of different versions of the general Kalina Cycle®, which have different process schemes and hence capital costs.

Since the nature of the constituent equipment items of the two cycles are quite similar, it is to be expected that operating and maintenance costs and issues would be broadly comparable.

9.3.4 Energy Conversion Efficiency

Geodynamics provided the chart shown in Figure 19, which shows the claimed efficiency advantage (or increased % generation) from using the Kalina Cycle® rather than ORC. This information is obviously very generic but is generally consistent with claims made elsewhere in published literature. Furthermore, the theoretical efficiency advantages of the Kalina Cycle®, as outlined in Section 9.3, are well documented (eg. Mlcak, 1996).


Figure 19 Claimed Efficiency Advantage of Kalina Cycle® over ORC

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10. Geothermal Direct-Use

10.1 General Review of Direct Geothermal Uses

There has been considerable interest in direct use of geothermal energy for many years. Many direct use applications are able to use lower temperature geothermal fluids (e.g. 50-100°C range) that are unsuitable for electricity generation and which are much more prevalent world-wide than moderate- or high-temperature systems.

In 1975, the Geo-Heat Center (GHC) was established at the Oregon Institute of Technology. The primary functions of the GHC were to disseminate information to potential users of geothermal resources, perform applied research on the use of low temperature resources, and to publish a quarterly newsletter on the progress and development of direct use geothermal energy in the United States and other countries. The GHC continues to provide geothermal services to the industry and operates a geothermal library of over 5000 volumes through the Geothermal Resources Council on-line library system. The quarterly GHC bulletins have, over the past 27 years, covered most of the established direct geothermal uses.

Every five years a review of world-wide direct use of geothermal energy has been undertaken, with the most recent being completed in 2000 (Lund and Freeston, 2000). This study categorises and quantifies the direct use of geothermal energy and provides trends between successive surveys. The results of the 2000 review are summarised in Table 18.

Table 18 Categories of Direct Use of Geothermal Energy, World-Wide

Capacity, MWt Utilisation, TJ/yr Capacity Factor (%) Category 2000 1995 2000 1995 2000 1995 Geothermal heat pumps 6,489 1,854 23,214 14,617 11 25 Space/district heating 4,954 2,579 59,696 38,230 38 47 Bathing & swimming 1,796 1,085 35,892 15,742 63 46 Greenhouse heating 1,371 1,085 19,035 15,742 44 46 Aquaculture pond heating 525 1,097 10,757 13,493 65 39 Industrial uses 494 544 10,536 10,120 68 59 Cooling & snow melting 108 115 968 1,124 29 25 Agricultural drying 69 67 954 1,124 44 53 Others 43 238 957 2,249 --- --- TOTAL 16,209 8,664 162,009 112,441

The data in Table 18 indicate that there are some categories that have seen increases in capacity and utilisation, others which have remained more or less static and even some that have declined:




Increases in both capacity and utilisation - geothermal heat pumps; space heating; bathing and swimming; and greenhouse heating.

Approximately stagnant – agricultural drying; industrial uses; cooling and snow melting

Declining capacity and utilisation – aquaculture; others

The “capacity factor” in Table 18 relates the energy “utilisation” to the nameplate “capacity”. In the utilisation figures, allowance is made for the fact that many direct use applications have a fluctuating (e.g. seasonal) heat load. This influences the economics as the annual average demand may be only a fraction of the design capacity of the equipment. Power generation and industrial uses have the advantage of being continuous processes with capacity factors often exceeding 90%.

Each of the main categories in Table 18 is discussed in more detail in the following sections. Sources of information include Lund and Freeston (2000), Lund (2000) and the Geo-Heat Centre.

10.2 Geothermal Heat Pumps

Geothermal heat pumps (GHPs), are devices used to provide heating and cooling (air conditioning) of buildings. The technology requires the transfer of heat between the building and the ground or groundwater. GHP’s do not rely on elevated or anomalous geothermal temperatures and hence do not have the same geographic restrictions that apply to geothermal electricity generation and direct use applications and, unlike hot dry rock technologies, GHPs are currently economically attractive. The use of GHPs is growing, particularly in areas with continental climates where there are large temperature variations between summer and winter. The popularity of GHP’s has seen a substantial growth in recent years, particularly in the USA and Europe. There are now more than half a million of these units installed in over 25 countries around the world, including an estimated 400 000 in the USA. In the year 2000, there were around 2,000 geothermal heat pumps operating in Australia. Typical unit sizes range from 5 to 20 kW for domestic use, and in excess of 150 kW for commercial or institutional installations. GHPs rely on the relatively constant temperature of the Earth and the groundwater present within 100 m of the surface. In areas with continental climates the Earth is warmer than the overlying atmosphere in winter and cooler in the summer. GHPs take advantage of this situation by transferring heat stored in the Earth into a building in winter, and transferring it back into the ground in summer. The Earth is therefore a heat source in winter and a heat sink in summer. GHPs are technically simple, comprising an earth connection subsystem (usually a series of pipes or loops buried in the ground), a heat pump, and a distribution subsystem which is typically a conventional ducted system that moves heated or cooled air throughout the building. There are number of alternative arrangements for exchanging heat with the Earth, “ground-coupled heat pumps” operate in a “closed-loop” configuration, whereby water is recirculated through pipes buried in the ground.




The transfer of heat is improved if the loop is immersed in water and hence efforts are often made to ensure that the closed loop is below or partially below the water table. The less common Groundwater Heat Pumps operate in an “open loop” arrangement, pumping groundwater through the unit.

A United States Environmental Protection Agency study has found that GHPs have the potential to significantly reduce fossil fuel consumption and corresponding green house gas emissions. The reductions in fossil fuel use have been estimated to be as much as 44% compared with air-source heat pumps, and as much as 72% compared with electric resistance heating and standard air conditioning equipment (GAO, 1994).

10.3 Space Heating and District Heating

Geothermal space heating is extensively used in Europe (particularly Iceland and France), the USA, China, Japan and Turkey. The installations in the USA are primarily individual building heating systems, whereas the other countries have extensive district heating systems. In Victoria, geothermal water is used to heat municipal buildings in Portland.

For space heating, hot geothermal water is either circulated directly through the buildings or is used as a heat source for a separate closed-loop heating system, depending on available temperature, flow and water quality.

Space heating and district heating are likely to be more economically attractive in areas where ambient temperatures are low for a substantial proportion of the year. In much of Victoria it is unlikely that space heating would be required for more than a few months each year. Facilities such as hospitals have a more substantial heat demand, however, including hot water. Low-grade heat demand for a modern, integrated health-care facility would be in the range 3 to 4 kWth/bed. A wide range of resource temperatures can be used, but the preferred range would be 70-80°C.

10.4 Bathing and Swimming

Geothermal hot water is used extensively for hot springs, spas and municipal swimming pools. Depending on water quality and temperature, the geothermal fluid may be used exclusively, mixed with town water, or used as a heating medium for town water. Supplemental heating can be provided to boost final water temperature, where necessary.

The pool temperature for such applications ranges from around 25 to 40 °C. Geothermal fluid temperatures of between 40 and 60°C are commonly used.

The municipal swimming pool at Portland in Victoria has used 58°C geothermal water for heating since 1985. A spa complex to be fed by 47°C geothermal water is currently under construction on the Mornington Peninsula near Melbourne.




A fully-enclosed swimming pool complex might use between 0.5 MWth and 1 MWth to maintain comfortable temperatures in the water and enclosures, whereas an outdoor pool would probably require twice as much. Capital cost would depend to some extent on the suitability of the geothermal fluid for direct use. The requirement for a fresh or treated water supply would involve a heat exchanger and additional pumping costs.

10.5 Greenhouse Heating

Geothermal hot water is used for greenhouse heating in many countries to extend growing seasons, extend growing regions and reduce operating costs. Plants grown include vegetables, potted plants, flowers and tree seedlings.

Related agribusiness applications include soil warming, soil sterilisation (if water temperature is high enough), irrigation and animal husbandry.

Fluid temperatures typically range from around 35°C upwards, and are commonly in the 45-80°C range. Heat demands for greenhouses vary widely with literature references ranging from less that 0.5 to around 2.5 MWth/ha. This is likely to reflect the ambient conditions as well as the crops (i.e. the value and the sensitivity to temperature). Greenhouse construction and ventilation will also have an influence on energy consumption.

10.6 Aquaculture Pond Heating

As with swimming pool applications, aquaculture can either use geothermal hot water directly or as an indirect heating medium. Water quality is a key consideration in this respect and, as aquaculture has a very high water demand, the availability of fresh water may be a significant constraint. Some applications, such as abalone production, may be able to use seawater, with a relatively small increase in temperature.

The largest users of geothermal heat for aquaculture are China, Iceland, Georgia, Israel and Turkey. Species farmed in this manner include catfish, bass, eel, trout, tilapia, prawns, shrimp, pet tropical fish and even alligators.

The optimum water temperature varies with species, potentially allowing a wide range of resources to be used. Applications in the USA use water temperatures ranging from 16 to over 80°C. Energy demands are dependent on the required temperatures, but may run as high as 3 MWth/ha of pond area.

10.7 Industrial Uses

There is a wide range of potential industrial applications for geothermal heat, however world-wide heat consumption in this category is relatively low. One reason is that many industrial applications




cannot use the low grade heat that is most widely available. The preferred temperature of the fluid supplied to most industrial users is in excess of 100°C.

Examples of existing industrial uses of geothermal energy include concrete curing, beverage bottling, oil recovery, milk pasteurisation, leather processing, chemical extraction, carbon dioxide extraction, laundering, salt extraction, diatomaceous earth drying, pulp & paper processing, production of borate & boric acid and sewage sludge digestion.

The largest direct industrial use of geothermal energy is at the Kawerau, New Zealand, pulp and paper mills owned by Norske Skog and Carter Holt Harvey. This plant uses 280 t/h of steam at up to 10 barg for direct pulp and paper drying, raising of clean steam, water heating, condensate stripping and black-liquor evaporation, as well as for electrical generation.

10.8 Cooling and Air Conditioning

There are a number of installations around the world where geothermal fluid is used for cooling and air conditioning via absorption refrigeration systems. This has not found widespread application because the efficiency is low and costs are high when the fluid temperature is below 100°C and there are other, more attractive uses for hotter fluids.

10.9 Agricultural Drying

Drying and dehydration of agricultural products using geothermal energy is practised in a small number of countries. Current and past drying applications include timber, onions, lucerne, fruit, cereals, rice, seaweed and coconut meat. The required geothermal fluid temperatures vary between products and will also be directly related to drying time and/or drying equipment size. Typically air temperatures of 40-100° would be used.

10.10 Direct Use Economics

The bore yield data presented in Section 7 combined with limitations associated with typical deep well pumps suggests that a typical geothermal bore in the Otway or Gippsland Basin may be expected to produce water at a flow rate of about 30 L/s. This translates to an energy production rate of around 2.5 MWth. The following analysis assumes a nominal bore depth of 1000 m and a geothermal water supply temperature of 50°C. For applications such as drying, space and water heating etc, a typical discharge (rejection) temperature will be around 30°C, giving a useable thermal output of 2.5 MWth/well.

For a direct heat application relying on a single well (or a critical application relying on a small number of wells) there may be a need for some redundant well capacity. There may also be a requirement for additional wells for disposal of the discarded geothermal water. For the type of




application presented here, however, we have assumed that there is no requirement for redundant well capacity and that the spent warm water may be disposed of at the surface.

Direct geothermal use costs have been developed for installed capacities ranging from 2.5 to 10 MWth and are presented in Figure 20. This range of capacity will cover some of the medium-to-large scale applications listed above, but somewhat less energy might be used for industrial or institutional space heating. Capital and operating costs may be scaled to estimate the economics of smaller or larger installations.

The capital cost of a geothermal direct heat development is likely to be dominated by the cost of the wells. The nominal 10 MWth installation would require four production bores each delivering 2.5 MWth. At the estimated mid-range drilling cost of $550 000 for a nominal 1,000 m deep well, the drilling cost for a 10 MWth installation will be around $2.2M. The other significant cost components include heat exchangers, pumps, valves and piping. Where the geothermal fluid may be used directly (bathing/swimming, aquaculture) there will be no need for heat exchangers, but many applications will require transfer of heat to another fluid. Heat exchanger capital cost is roughly proportional to heat transfer surface area, which is in turn inversely proportional to the temperature difference between the two fluids. With relatively modest temperature differences, the cost of geothermal heat exchangers is quite high. A water-to-water heat exchanger of 10 MWth capacity is likely to cost around $120 000. A water-to-air heat exchanger, because of the greater heat transfer area, is likely to cost as much as $300 000.

Piping and pumping costs have been assembled for an installation that can use the heat relatively close to the production wells and we have allowed for 200 m of 100 mmNB piping for well connections and 200 m of 200 mmNB trunk piping, together with appropriate isolation and control valves etc. For a nominal installation of 10 MWth capacity, requiring four wells and either a water-to-water or a water-to-air heat exchanger, we anticipate a capital cost of between $2.5 and $3.5 million.

The operating costs for direct use of low-temperature geothermal heat are governed largely by the cost of pumping. We have estimated an electricity demand of 200 kWe at a retail cost of $0.15/kWh. With an annual capacity factor of 75% (6570 h/year) the cost of electricity will be nearly $200 000/year. Repairs and maintenance have been estimated to cost around 2.5% of a nominal capital cost of $3M. Capital charges at 10% and labour and administration expenses will bring the total annual cost to around $620 000/year.

The delivered cost of around 230 000 GJ per annum of thermal energy from a typical 10 MWth installation of this type would be around $2.7/GJ. The cost of energy increases by around 10% for the 2.5 MWth installation. The system economics, and hence the cost of energy, will also be sensitive to capacity factor as the fixed charges amount to around 65% of the total annual operating cost. Capacity factor can vary widely, depending on application.


Figure 20 Geothermal Energy Cost as a Function of Plant Capacity

2.50

2.55

2.60

2.65

2.70

2.75

2.80

2.85

2.90

2.95

3.00

2.5 5 7.5 10

Heating Capacity (MWth)

Cos

t of D

eliv

ery

($/G

J)




11. Existing Geothermal Applications

11.1 Electricity Generation Readily accessible geothermal temperatures in Australia are generally too low for economic generation of electricity. Accordingly there are few examples of geothermal electricity generation in Australia. There are however two examples of Organic Rankine Cycle engines (ORC) that have been developed by Enreco Pty Ltd at Birdsville and Mulka Station (refer to Figure 21 for locations).

Figure 21 Location of geothermal plants in Australia (from Burns et al 2000)

Mulka Cattle Station is located on the Birdsville Track in northern South Australia. A 15 kW ORC engine was constructed and installed in 1986 with funding provided by the South Australian Government. The plant uses water from a deep bore tapping the aquifers of the Great Artesian Basin. The bore, originally drilled in 1904, is approximately 1300 m deep and produces about 10 L/s of water at 86°C. After use as a heat source for the ORC plant the geothermal water was further cooled and used in the ORC condenser before being used for stock watering purposes.






Commissioned in 1986, the ORC plant operated continuously for about three and a half years before the property was sold. It is believed to be the first operational geothermal power plant in Australia. Rated at 15 kW, the ORC plant output declined to about 10 kW during the summer when high ambient temperatures reduced the plant efficiency. The gross electricity conversion efficiency was 8% with a net 6% obtained when parasitic loads were accounted for (Burns et al, 2000).

Following the successful demonstration of small scale electricity generation at Mulka Station, Enreco Pty, Ltd, installed a similar but larger plant in the town of Birdsville (population 100) in western Queensland. The plant was funded by the National Energy Research and Demonstration Council, an agency of the federal government. Hot water is supplied to the plant from a 150 mm diameter bore drilled to a depth of 1220 m in the Great Artesian Basin. The bore had been flowing under artesian pressure for 45 years prior to the installation of the ORC plant. Its production rate is approximately 27 L/s at a temperature of 98°C and a shut in wellhead pressure of 1215 kPa. The water is cooled to about 80°C in the ORC heat exchangers and is used in the Birdsville town water supply after use in the plant.

The ORC plant commenced operation in 1992. Rated at 150 kW it achieved only a modest net output of about 60 kW and an average parasitic load of almost 40 kW. Following substantial plant modifications in 1999, including the replacement of Freon (R114) by the more environmentally acceptable isopentane, the plant was returned to operation in June 1999 and has been operating successfully, albeit at low efficiency, since that time (Burns et al, 2000). Gross plant output is still well short of the rated plant output of 150 kW and overall conversion efficiency is about 6%.

The town’s peak electricity demand has been estimated as about 250 kW. The ORC plant is able to meet the town’s power demand at night and during the winter and it works in combination with a conventional diesel generator at other times. It is understood that the ORC plant has reduced the town’s diesel consumption by about 160,000 Litres per year representing an annual fuel saving of $135,000 and a reduction of about 430 tonnes of greenhouse gas emissions each year. The capital cost of the low temperature ORC units has been estimated at about $4000/kW increasing to about $6000 - $7000/kW after production bore refurbishment, water reticulation and civil works are included3.

3 http://www.epa.qld.gov.au/publications/p00834aa.pdf/Birdsville_geothermal_power_station.pdf




11.2 District heating in Portland4 The geothermal resources in the city of Portland have been used to heat a public swimming pool and a number of buildings in the city since the early 1980’s. A description of the installed heating facilities and an assessment of the total available energy are presented by King et al.1987 a summary of which is presented in the following paragraphs.

Deep groundwater bores, currently owned and operated by Portland Coast Water for the purpose of municipal water supply for the city of Portland, produce groundwater at temperatures between 57 and 60°C. Before reticulation in the city water supply the water is cooled in forced draught cooling towers. Water is extracted from the aquifers of the Dilwyn Formation of the Wangerrip Group at depths ranging between 1200 and 1400 m. King et al (1987) report that in 1985 there were seven existing deep bores including four production and two observation bores and one that had been abandoned.

Water produced from Portland 14 (also known as the Henty Park Bore) is used for geothermal heating purposes. Drilled in 1982, Portland 14 free flows under artesian pressure at approximately 90 L/s from a production interval between 1254 and 1365 m below ground level. In 1985 it delivered about 22 L/s of hot water to a number of heat exchangers to heat the city’s swimming pool complex, arts centre, civic centre, municipal offices (now occupied by the Glenelg Shire Council) and elderly citizen’s centre (King et al, 1987). The estimated cost savings associated with the use of geothermal energy for heating in 1985 was approximately $120,000 per year (King et al, 1987).

Since publication of King et al, 1987, the geothermal space heating system has been expanded to incorporate more municipal and private buildings. The geothermal heat is now used in the following buildings:

Portland and District Hospital

Police Station

Fawthrop Centre

Public Swimming Pool Complex

Municipal Offices

CEMA Arts Centre

Civic Hall

Library

4 Much of the current information presented in this section was kindly provided by Stuart Ferrier of Glenelg Shire Council and Ian Bale of Portland Coast Water.

Geother

SINCLAIR KNIGHT

C:


MERZ


Water is pumped from the production bore through a 225 mm diameter supply line connecting all of the utilisation sites. At each facility water is extracted from the main via 50 mm and 100 mm diameter offtakes. After heat is removed from the water in the heat exchangers it is pumped into a return line that parallels the main distribution pipe and the used geothermal water is piped back to the Henty Park production bore site where it is cooled further in forced draught cooling towers. The layout of the hot water reticulation system is shown in Figure 22.

The system is believed to currently use 60 – 70 L/s of hot water (~58°C) extracted by the Henty Park Production Bore. Unfortunately the production rates and temperatures are not being monitored and hence details of the geothermal water flow and temperature are only estimates.

Maritime Discovery Centre.

State Emergency Services Offices

Richmond Henty Hotel

Tourist Information Centre


Figure 22 Layout of the Portland Geothermal District Heating System (courtesy of Glenelg Shire Council)




Table 19 Details of Heating Facilities Included in the Portland Geothermal District Heating Scheme (information courtesy Glenelg Shire Council)

Location Heat Exchanger Use

Nominal Capacity (kW)

Primary – Geothermal Side Secondary – Building Side

Temp. In (°C) Temp. Out (°C) Design Flow (L/s)

Temp. In (°C) Temp. Out (°C)

Process Heat Transfer VT40

Space Heating 625 54 40 10.7 34 49

Process Heat Transfer VT40

Space Heating 625 54 40 10.7 34 49Portland Hospital

Process Heat Transfer VT4P

Domestic Hot Water

105 54 40 1.8 15 45

Alfa-Laval Clone P01

Pool Heating N/A N/A N/A N/A N/A

Alfa Laval Clone P22

Domestic Hot Water

N/A N/A N/A N/A N/A


Domestic Hot Water

N/A N/A N/A N/A N/A


Space Heating N/A N/A N/A N/A N/A

Richmond Henty Hotel


Space Heating

300

N/A N/A N/A N/A N/A

Police Station Alfa Laval P22-HBL

Space Heating 56 51 41 1.4 32 47

Fawthrop Centre SWEP B45 Space Heating 50 51.7 N/A N/A N/A N/AMunicipal Offices Alfa Laval

P22-HBL Space Heating 200 N/A N/A 4.8 N/A N/A

CEMA Arts Centre Alfa Laval P22VL

Space Heating 74 51.4 42.1 1.9 28.5 49

SES Offices Alfa Laval P22VL

Space Heating 68 57.3 41.9 1.7 28.5 49



Geother

SINCLAIR KNIGHT

C:


MERZ


Alfa Laval P2VXL

Pool Heating (indoor)

333 51.7 40.8 7.3 26 43.7

Alfa Laval P2VXL

Pool Heating (outdoor)

333 51.7 40.8 7.3 26 43.7

SWEP G30 Pool Heating (Spa)

91.4 56 46 2.2 38 44.3

SWEP G30 Space Heating (Change Room)

30 59 44 0.48 40 55

Swimming Pool Complex

SWEP G65 Space Heating (Main Room)

442 59 44 7.1 40 55

Civic Hall/Library/ Tourist Information Centre

Alfa Laval P22-HBL

Space Heating 245 51.5 38.4 4.48 28.5 48

Maritime Discovery Centre

N/A Space Heating 26 N/A N/A 0.8 N/A N/A

Total 3600 70




Details of the heat load at each of the facilities connected to the system are presented in Table 19. Few of the facilities are metered for their use of the geothermal water and hence much of the data included in Table 19 are based on design loads. Actual loads are expected to be significantly lower than indicated in the table. This conclusion is supported by an analysis of the available heat calculated from the measured temperature drop between the production bore (58°C) and the return water (56°C) and the estimated geothermal water production rate. This calculation suggests that the heat being extracted from the geothermal water is on average 580 kW being substantially below the design figures included in Table 19 (Energy and Thermal Services, 2002). The value of the existing system calculated in terms of the savings in alternative heating has been estimated to be as much as $300,000 per year. This figure is however based on design heating loads and may therefore be an overestimate of the actual saving.

The production bore is owned and operated by Portland Coast Water and the Glenelg Shire Council pays an annual fee for continued use of the geothermal water. The shire council in turn charges the non-municipal users on the basis of metered and assumed usage at a rate that is tied to the price of gas.

Glenelg Shire Council maintains the reticulation system and has a programme in place for the upgrade and replacement of the ageing asbestos cement delivery and return pipes. They are also progressively adding instrumentation to the system including water meters, with the intention of obtaining more accurate estimates of water usage.

The geothermal production bore (Portland 14) is operated and maintained by Portland Coast Water. As part of their on-going maintenance and asset management plans Portland Coast Water had the Henty Park Bore surveyed in the year 2000 in order to investigate the condition of its casings. The principal results are summarised below (SKM, 2000):

Minor failures in and around the screens between 1200 and 1300 m were identified as potential sites of imminent major failure that could compromise both water quality and bore yield.

The majority of the casing was classified as having up to 30% metal loss.

In the absence of repair or refurbishment a major bore failure was expected within five years of the survey date.

As a result the following four options have been identified for the refurbishment of the Henty Park bore (SKM, 2003):

Option 1 – Partially reline the bore by installing a stainless steel screens within the existing screens from 1050 m depth to hole bottom.

Option 2 – Totally reline the bore from the surface to bottom hole using a combination of fibre glass casing and stainless steel screen. Grout the casing in place from the surface to 1150 m depth.

Option 3 – Partially reline the bore from 1000 m to 1300 m depth and seal the hole below 1300 m depth. Perforate the existing casing at the depth intervals adjacent to sands at 1040-1060 m and 1100-1160 m.




Option 4 – Totally reline the bore from the surface to 1300 m depth with fibre glass casing and stainless steel screens. Seal the hole below 1300 m depth. Grout the new casing in place from the surface to 1150 m depth.

These options are currently being evaluated by both Portland Coast Water and the Glenelg Shire Council and negotiations are under way regarding the on-going funding and ownership of the Henty Park production bore.

While the benefits of the geothermal heating scheme are widely accepted there are a number of issues that have recently arisen that have caused concern as to how the system is being operated. Originally the returned, partially cooled geothermal water was pumped into the city’s municipal water supply following additional cooling in forced draught cooling towers located at the Henty Park site (refer to Figure 25). Concerns were raised as to the risk of cross contamination of the geothermal water from possible leaks in any of the individual heat exchangers connected to the system. The potential for leaks to impact adversely on the water quality of the town water supply is heightened by the fact that the secondary waters are often chemically dosed to avoid chemical and biological fouling in the heating water circuits. In the face of these concerns, combined with the fact that the quality of water produced by the Henty Park bore is currently inferior to that of water obtained from the other town water supply bores, Portland Coast Water has decided that it is no longer desirable to use the returned geothermal water in the city’s water supply. As a result the returned and cooled geothermal water is now discharged to the ocean via a nearby surface channel. The resultant wastage of the water resource has been highlighted as a negative effect associated with the scheme.

Furthermore, the current operating regime requires that the used geothermal water be cooled before it is discharged to surface waters and to waste. The operation and maintenance of the cooling towers at the Henty Park site are additional and undesirable costs that are currently borne by Portland Coast Water.

Both Portland Coast Water and the shire council are attempting to address these issues and a number of consultants’ studies have been commissioned to identify the optimal operation of the system that maximises the use of the geothermal water and reduces overall operating costs. It is generally recognised that modifying the system so that the used geothermal water is suitable for subsequent use in the town’s water supply is a key objective that would help to alleviate many of the negative effects. Options under current consideration include:

The installation of a single centrally located heat exchanger that can be carefully monitored and maintained. This proposal would potentially reduce the possibility of cross contamination from leaks in the heat exchangers,

Modifying the bores production interval to help improve quality of the water produced by the Henty Park Bore,

Optimisation of the water production rates to ensure that excess water is not unnecessarily pumped through the geothermal heating system.

It is to be hoped that these issues can be resolved in the near future so that the scheme can operate in a manner that minimises the adverse effects and provides benefits to all parties. Such a


resolution would help ensure that the scheme maintains its position as a flagship for alternative energy use in Victoria and highlights the potential and largely untapped value of the geothermal resources of the Otway Basin.

Figure 23 Construction Details of the Henty Park Geothermal Production Bore

20.90

SCREEN 25.75 m

SCREEN 17.45 m

SCREEN 8.30 m

SCREEN 20.60 m

THICKNESS

CONSTRUCTION-SCHLUMBERGER SURVEY

DETAILS UNKNOWN1385 REDUCING

SUMP

88376 21/82/214

PORTLAND

WATER IDPORTLAND COAST

NUMBERGDB BORE

NUMBERPARISH BORE

NUMBERRIG SEQUENCE

CONSTRUCTION RECORDS

FROM (m) TO (m) OD (mm)

WALL

THICKNESS

(mm) FROM (m) TO (m) OD (mm)

WALL

(mm)

106

ASSUMED THICKNESS FROM API TABLES

9.65

1.10 LINER PIPE 1.10

0.0 106 339.725 0.0

1254.45

8.9

PARKHENTY

PORTLAND

SCHLUMBERGER SURVEY DID NOT ACCESS PAST 1368m

CASINGSURFACE

20.9 508 20.9 508 LINER PIPE

339.725 9.65

1161106 1196 273.05 12.6 104.5 273.05 12.6

SWEDGENo. 1 CASINGWELL LINER

1161 1255.5

No. 2WELL LINERTOP OF SEAL

1366.5 1385 168.3 8.91366.5 1385 168.3

1275.05 1255.5 12768.9 8.9219 219

1291.47 1299.77 1292.5 1301

1307.78 1325.23

1339.25 1340.5 1366

1309 1326.5

1365

DRAWING NOT TO SCALE

0.0 N.S.

(13.375") API339.725 DIA.

(10.75") API273.05 DIA.

(8") PLAIN API (?)203 DIA.

(6.6") APISUMP 168.30DIA.




Figure 24 Henty Park Production Bore Wellhead




Figure 25 Henty Park Cooling Towers

With regard to the state of the geothermal resource in Portland, it is of interest to know whether there are signs that the resource is stressed and whether the extraction of hot water is sustainable. To fully answer these questions it would be necessary to establish a detailed temperature and water level monitoring programme aimed at identifying and tracking changes in aquifer pressure and temperature. Unfortunately, no such programme has been established for monitoring changes in resource temperature and in particular, there are no baseline data against which recent observations can be compared. Notwithstanding the absence of any quantitative temperature monitoring of the resource and the produced water, there are no qualitative or anecdotal signs of thermal decline despite many decades of groundwater extraction (deep groundwater was first used for the town’s water supply in the late 1950’s).

Water levels in the aquifer are measured in a number of monitoring bores that are included in the state groundwater observation bore network. Records of water level from two observation bores, Portland 8 and Portland 10 are shown in Figure 26. Both bores are located near the Bald Hill production bores and tend to reflect local changes in water level that are strongly influenced by the extractions from the nearby production bores. Water levels have declined since 1970, with a marked drawdown observed since 2001. This rapid decline is most likely caused by increased water demand during the drought of the late 1990’s and early 2000’s (Portland is the only city in Victoria not to have applied water restrictions during drought). While the recent drawdown in water levels measured in Portland 8 and Portland 10 appear to be quite dramatic, the aquifer is extremely deep and a further decline of many tens or even hundreds of meters in head can be




sustained. It may be concluded that the resource is not under serious stress at present. Given the large area over which geothermal waters can be extracted and the relatively small level of development to date, there is a huge potential for expanding and further utilising the geothermal resources of Portland and of the Otway Basin in general.

Figure 26 Water Level Observations in the Portland Geothermal Aquifer

0

5

10

15

20

25

1968 1973 1978 1983 1988 1993 1998 2003 2008

Wat

er L

evel

[mA

HD

]

Portland 8Portland 10

11.3 Geothermal heat pumps the New AGSO Building5 The Australian Geological Survey Organisation (AGSO) is one of the seven Groups comprising the Commonwealth's Department of Primary Industries and Energy (DPIE). In early 1995 Parliament approved the construction in Canberra of a new purpose-built building for AGSO, with a budget of $105 million (at December 1994 prices). Because DPIE has carriage of the Commonwealth's energy policies, the design brief for the new building sought to demonstrate an appropriate, pragmatic response to Ecologically Sustainable Development (ESD) design principles. The complex has been acclaimed for its Environmentally Sustainable Design (ESD) strategies, the outstanding feature of which, appropriately for a geological survey organisation, is the largest geothermal-based air conditioning system yet to be installed in Australia. Construction of the AGSO building commenced in April 1996 and was completed in December 1997, about four months ahead of schedule. The building includes both offices and laboratories

5 Information in this section was kindly provided by John Coffey, of Davis Langdon (formerly of Bassett Consulting) and Stephen Read of Geoscience Australia.




and, together with an adjacent support building, has a total floor area of 40,000 m2. The AGSO GHP system developed by Bassett Consulting Engineers is an electrically powered system that capitalises on the Earth's moderate temperature (around 17°Celsius) at a depth of up to 100 metres beneath the building site. Water is circulated through a "geothermal field" comprising heat exchange loops immersed in groundwater in 350 bore holes (each 100 metres deep) in front of the AGSO building (refer to Figure 27 and Figure 28). The bore field consists of four distinct sectors within which bores are arranged in a rectangular grid at spacing of approximately 4.5 m. The entire borefield covers an area of about 6000 m2. In winter the circulating water collects heat from the earth and carries it through the system into the building. In summer the system reverses and extracts heat from the building and transfers it back to the geothermal field. The borefield effectively acts as a water-to-groundwater heat exchanger.

Water is pumped to and from the borefield by circulating pumps located in the lower-ground level of the building (refer to Figure 29) through a series of headers and then through 350 individual high density polyethylene pipes each inserted in an individual bore hole (see Figure 30). The circulating water is either heated or cooled, depending on the season, as it flows down and then back up the bore hole. The water pipework between the building and the bore field is buried to an average depth of 1200 mm. The entire geothermal loop and geothermal water pipework are freeze protected to -6°C by the use of methanol as an anti-freeze solution.

Figure 27 Schematic Layout of the AGSO Building and its Surrounds




Figure 28 The Borefield Has been Restored to Lawn and Garden (Photo Courtesy John Coffey, Davis Langdon)

Inside the building there are 200 water-to-air heat pumps, each serving up to four perimeter offices or eight interior offices (shown in Figure 31). The heat pumps are housed in cabinets that form partitions between rooms and work spaces and are effectively integrated in the interior office design (refer to Figure 32). Each of these systems is independent of the others and can be switched off during office hours if they are not in use. They can also be switched on individually after hours as required. The heat pump units contain a sealed refrigerant circuit including a refrigerant compressor, bi-directional thermal expansion valve, finned refrigerant coil, reversing valve and a co-axial water-to-refrigerant heat exchanger. The water-to-refrigerant heat exchanger comprises convoluted copper inner tube and cupro-nickel outer tube.

The decision to use a GHP system in the AGSO building was based on a life-cycle cost comparison of the system with conventional Variable Air Volume (VAV) air conditioning systems, and VAV systems with chilled water storage. The analysis found that the GHP system had the lowest net present cost while the VAV system with chilled water storage had the highest (Williams, 1997). In addition to net present cost savings, other advantages of the GHP system to AGSO include:

reduced annual energy consumption and therefore, reduced usage of non-renewable energy resources (~340 MJ/m2 per annum for the GHP system versus ~400 MJ/m2 per annum for a VAV system and ~415 MJ/m2 per annum for a VAV system with chilled water storage),

reduced peak energy demand which reduces maximum-demand electricity charges (and ultimately the sizes of power station requirements),

greater after hours flexibility as units can be left off in areas which are unoccupied,




less redundancy due to the configuration of the GHP system and the lower need for "standby" capacity,

less outside equipment and consequential corrosion,

reduced risk of major breakdown of costly central plant items,

increased plant warranties,

elimination of cooling tower water treatment and corrosion, thereby removing the risk of Legionnaires Disease (Williams, 1997).

It has been claimed that the building is performing 30% below the normal electrical energy consumption for Commonwealth office buildings. The total building energy consumption appears to be about 67% electricity and 33% gas split. The all-electric energy consumption of the central services and power and lighting of the office component represents 527 MJ/m2 year. This is 16% less than the Commonwealth Government target figure of 625 MJ/m2 year for a building of this size and population. Translating the reported energy consumption figures into greenhouse gas emissions (GGE) as used by SEDA’s (Sustainable Energy Development Authority) NSW Building Greenhouse Rating Scheme, this calculates as CO2 emissions of about 138 kg/m2 year. This represents an excellent result, (just short of a five star rating of 125 kg/m2 year) achieved without having to compensate by using the “Green Power” option of buying electricity generated from renewable sources (Johnston, undated).

Figure 29 Water Circulation Pumps (Photo courtesy Stephen Read, Geoscience Australia)




Figure 30 Banks of Small Diameter Pipes Transfer Water and Heat Between the Bore Field and the Heat Pump Units (Photo courtesy Stephen Read, Geoscience Australia)




Figure 31 Geothermal Heat Pump Installation (Photo courtesy Stephen Read, Geoscience Australia)




Figure 32 Geothermal Heat Pumps Housed in Cabinets Inside the Buildings (Photo Courtesy John Coffey, Davis Langdon)






12. Environmental Effects of Geothermal Use

12.1 Resource Depletion Geothermal energy is often classified as a renewable or sustainable energy source and by most measures this classification is appropriate. However under short term, high intensity utilisation scenarios it is possible to deplete the geothermal resource both in terms of energy and water reserves. The sustainability of the resource becomes evident once the fluid extraction ceases and both the energy and fluid reserves naturally replenish and pre-exploitation conditions can be re-established given sufficient recovery time. During the exploitation phase there are a number of potential environmental effects associated with the extraction and disposal of the geothermal fluids. Perhaps the most damaging effect associated with the development of high enthalpy geothermal systems is the decline in activity and intensity of the geothermal discharge features that are often valued as a tourist attraction. The development of the Rotorua geothermal field in New Zealand provides a good case study of such effects.

The renewability of geothermal resources has been clearly demonstrated in Rotorua, New Zealand, where a shallow hot water resource has been exploited since the 1920’s for district heating and bathing purposes. Many Rotorua residents take advantage of the underlying geothermal fluids by drilling shallow wells (20-200 metres depth) to extract hot water. These fluids are used for domestic and commercial heating, with some of the largest commercial users being Government Department offices, hospitals and major tourist hotels. The extractive geothermal users coexisted for many years with a thriving tourism industry based on the spectacular geothermal springs, fumaroles and geysers that are fed by the geothermal resource. During the period 1967 to 1986 borehole numbers increased dramatically. By 1986 over 1150 wells had been drilled in the city to tap the shallow geothermal resource. Coincident with the increased extractions the natural geothermal features and the tourist attraction reached a crisis point as a significant decline in activity led to the demise of a number of geysers and a significant reduction in overall energy discharge. In an effort to reverse this trend, the central government instigated a bore closure programme in 1987-88 which resulted in 106 wells within a 1.5 km radius of the geysers being cemented. A royalty charging regime for all remaining wells resulted in a further 120 wells being shut outside the 1.5 km radius. This regulatory programme was met with much animosity and opposition from the local community. However within 10 years of the start of the recovery program water levels recovered, flows of hot springs increased and several extinct geysers began to erupt again. Problems have arisen where long extinct fumaroles and springs have been re-activated in locations that had been built on causing damage to private gardens and houses. Although some failed geysers have shown no signs of recovery to date, the program has nevertheless delivered significant success in the recovery of the geothermal reservoir.

In the case of high enthalpy geothermal systems used to generate electricity, the geothermal fluid extraction system is typically designed or sized to maintain full steam supply to the power plant for a 25 or 30 year plant life cycle. Under these conditions the reserves of heat and water are expected to be severely depleted at the end of the plant life. Potential environmental effects that may arise during the period of intense extraction are summarised below.




12.2 Venting of Gases. Geothermal fluids contain dissolved gases, mainly carbon dioxide (CO2) and hydrogen sulfide (H2S), small amounts of ammonia, hydrogen, nitrogen, methane and radon, and minor quantities of volatile species of boron, arsenic, and mercury. As the geothermal fluids are brought to the surface they undergo rapid depressurisation with the associated liberation of many of the dissolved non-condensable gases. Toxic gases are generally present in such small amounts as to represent an insignificant risk to the local environment. The principal environmental concern related to high enthalpy geothermal developments is the liberation of CO2 into the atmosphere and subsequent effect on climate change. This effect is, however, small compared to other energy sources that rely on combustion of fossil fuels. This point is discussed in more detail in Section 12.6.

Hydrogen sulphide emissions from geothermal fluids do not contribute to acid rain or global climate change but do create a sulphur smell that some people find objectionable and are toxic at high concentrations. The range of H2S emissions from geothermal plants is 0.03–6.4 g/kWh. The removal of H2S from geothermal steam is mandatory in the United States. The Stretford process, which produces pure sulphur and is capable of reducing H2S emissions by more than 90% is the most commonly used control method. More recently developed techniques include burning the hydrogen sulphide to produce sulphur dioxide, which can be dissolved, converted to sulphuric acid and sold to provide income.

With regard to the development of the low temperature geothermal resources of Victoria, there is effectively no discharge of gas associated with the recovery and use of the warm water. Accordingly there is no chance of air pollution or greenhouse gas emissions associated with the development of geothermal resources in Victoria. This conclusion can also be extended to include any possible future development of deep hot dry rock resources. The hot dry rock process involves a negligible extraction or recovery of in-situ geothermal water and hence issues associated with the venting or release of gases included in these fluids are not relevant.

12.3 Noise Noise occurs during exploration drilling and construction phases. Table 20 shows noise levels from these operations can range from 45 to 120 decibels (dBa). For comparison, noise levels in quiet suburban residences are on the order of 50 dBa, noise levels in noisy urban environments are typically 80–90 dBa, and the threshold of pain is 120 dBa at 2,000–4,000 Hz. Site workers can be protected by using appropriate personal safety equipment. With best practices, noise levels can be kept to below 65 dBa, and construction noise should be practically indistinguishable from other background noises at distances of one kilometre. Operating geothermal plants (e.g.geothermal power plant) have relatively low noise emission levels.




Table 20 Geothermal Exploration and Construction Noise Levels

Operation Noise Level (dBa)

Air drilling 85–120

Mud drilling 80

Discharging wells after drilling (to remove drilling debris) Up to 120

Well testing 70–110

Diesel engines (to operate compressors and provide electricity) 45–55

Heavy machinery (e.g., for earth moving during construction) Up to 90

12.4 Disposal of Wastewater When brought to the surface, high temperature geothermal fluids exploited for electricity generation typically comprise a mixture of water (or more specifically brine) and steam. The electricity generation process involves the separation of steam from the brine and/or the extraction of heat from the brine. The waste brine must then be disposed of in a manner that avoids the contamination of surface and underground water resources. High temperature geothermal brines typically contain high concentrations of dissolved salts and include relatively high concentrations of heavy metals including arsenic. The heat depleted waste brines are typically returned to the geothermal reservoir by injection into deep bores. This method of disposal has proven to be highly effective in avoiding the harmful impacts of surface disposal of the brines and in prolonging the life of the resource by counteracting the effects of mass depletion and associated resource decline.

The chemical characteristics of the geothermal waters of Victoria are benign and the water is used extensively, after cooling, for municipal water supply. Accordingly it may be concluded that there is no risk of negative effects associated with the extraction, use and disposal of the geothermal waters available in Victoria. In terms of any possible future developments of the deep hot dry rock resources of Victoria, the water injection and discharge cycle used in such developments essentially forms a closed circuit with there being no waste water produced.

12.5 Land Subsidence The large scale extraction of geothermal waters and the associated decline in subsurface pressures in the geothermal reservoir and overlying strata can sometimes give rise to land subsidence. The most famous and most dramatic example of geothermally induced subsidence is that observed at the Wairakei Geothermal Field in New Zealand. Geothermal developments at Wairakei commenced in the early 1950’s and in 1956 subsidence of 76 mm was measured in an existing benchmark. Since then the rate at which geothermal fluids are extracted from the reservoir has increased and the associated levels of subsidence observed over the field have also increased. A number of small subsidence centres (termed “subsidence bowls”) have been identified. One of the




earliest observed bowls displayed a peak subsidence rate of 450 mm/year in the 1970’s. Subsidence rates have since reduced somewhat, however the overall magnitude of the total subsidence at this location currently exceeds 15 m (Lawless et al, 2003).

Effects of the subsidence in the Wairakei region have fortunately been restricted to small regions of rural land between the original steamfield and the power station. Observed impacts have included:

The creation of a pond about 1 km in length and 6 m in depth in what was originally a fast-flowing stream,

Cracking of both a nearby highway and the main waste water drain on the site,

Compressive buckling and tensile fracturing of steam pipelines, and

Fissures in surroundings fields.

As geothermal fluid extraction continues and the subsurface depressurisation of the resource intensifies and widens, there are concerns that new subsidence bowls will form in the nearby town of Taupo with serious consequences to existing infrastructure and buildings.

The experience of subsidence at Wairakei has not been repeated elsewhere. The principal reason for this is the fact that the net mass withdrawal of fluids at Wairakei far exceeds that at any other geothermal field. This is partially because Wairakei is a large power plant that has been generating electricity for a long time, and that Wairakei is perhaps the only major geothermal development in which waste water is not returned to the reservoir through reinjection. (Partial reinjection of spent geothermal brines has recently been introduced). Consequently subsidence levels measured at other geothermal fields are typically one or two orders of magnitude less than those observed at Wairakei. It is generally accepted that appropriate field management, including reinjection of wastewater into the reservoir, can effectively prevent the onset of potentially catastrophic land deformation processes.

The possibility that development of the geothermal resources of Victoria will lead to damaging subsidence is considered to be extremely small. Even under the most optimistic assumptions as to the future demand for geothermal energy in Victoria, geothermal water extraction rates and associated depressurisation of the aquifers are unlikely to reach the levels required for significant subsidence to occur. This conclusion is based on expectations and understanding of the likely future demand for geothermal water for heating and other applications. The conclusion does not relate to mine dewatering activities currently being carried out in the Loy Yang and Morwell open cut coal mines in the Latrobe Valley. Large volumes of geothermal water are being pumped out of these mines in order to reduce groundwater pressures beneath the open cuts to help control the vertical movement of the pit floor. To date, as a result of dewatering activities and mining operations, there has been subsidence at Morwell of up to 2 metres6.

6 (www.audit.vic.gov.au/old/sr24/ags2409.htm).

http://www.audit.vic.gov.au/old/sr24/ags2409.htm)


12.6 Environmental benefits Geothermal power provides significant environmental advantage over fossil fuel power sources in terms of air emissions because geothermal energy production releases no nitrogen oxides (NOx), no sulfur dioxide (SO2), and much less carbon dioxide (CO2) than fossil-fuelled power. The reduction in nitrogen and sulphur emissions reduces local and regional impacts of acid rain, and reduction in carbon dioxide emissions reduce contributions to potential global climate change. Geothermal power plant CO2 emissions can vary from plant to plant depending on both the characteristics of the reservoir fluid and the type of power generation plant. Binary plants have no CO2 emissions, while dry steam and flash steam plants have CO2 emissions on the order of 0.05 kg/kWh, less than one tenth the CO2 emissions of coal-fired generation.

The relative amounts of greenhouse gas emissions for various fuels are shown in Figure 33. Indeed, geothermal steam plants can be designed so that no gases are emitted into the atmosphere provided that the non-condensable gases are compressed and re-injected into the geothermal reservoir with the waste brine. This technique is being tried for the first time at geothermal power plants in the Coso Geothermal Project in California, USA.

Figure 33 Carbon Emissions from Energy Production by Fuel (DiPippo, 1988)

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The use of Victoria’s geothermal resources provides a clear environmental benefit in that useful energy is gained without any greenhouse gas emissions. This benefit applies equally to direct uses, binary plant electricity generation and hot dry rock electricity generation. By way of example, the Portland district heating scheme described in Section 11.2 contributes no greenhouse gases to the atmosphere and avoids the consumption of energy derived by the combustion of fossil fuels.




Geothermal power plants require relatively little land and do not require damming of rivers or harvesting of forests, and there are no mineshafts, tunnels, open pits, waste heaps or oil spills. An entire geothermal field uses only 0.4 to 3.2 hectares per MW versus 2 to 4 hectares for nuclear plants and 7.6 hectares per MW for coal plants.

Geothermal plants can be sited in farmland and forests and can share land with livestock and local wildlife. For example, the Hell’s Gate National Park in Kenya was established around an existing 45 MWe geothermal power station, Olkaria I. Land uses in the park include livestock grazing, growing of foodstuffs and flowers, and conservation of wildlife. After extensive environmental effects analysis, a second geothermal plant, Olkaria II, was approved for installation in the park in 1994, and an additional power station is under consideration.




13. Conclusions Geothermal temperatures in Victoria appear to define a geothermal gradient that is, on average, between 3 and 4ºC per 100 m of depth. This gradient is only slightly higher than the international average geothermal gradients observed in volcanically inert areas. The feature of the geothermal systems of Victoria of most interest is that highly productive aquifers in the unconsolidated basin sediments at depths of up to 1000 m, provide uniformly high productivity of geothermal bores. Such highly productive porous media type aquifers at these depths are relatively rare. Accordingly, the targeting of geothermal bores in Victoria requires an appreciation of the location and thickness of the sedimentary sequences within the basins as well as an understanding of prevailing geothermal temperatures.

Available data sets have been used to define the geothermal temperatures and unconsolidated sediment regions at various depths in the Gippsland Basin. A similar assessment of the other two major basins (i.e. the Otway and Murray basins) will require additional data compilation and mapping of the top of the basement rocks in these basins. Geothermal developments in the regions of bedrock outcrop will be less attractive because of the relative difficulty in obtaining good water production from the fissures, fractures and joints in the basement rocks.

In regions where there are little or no measured temperature data, geothermal temperatures have been estimated on the basis of calculated and assumed thermal properties of the rocks and heat flows. Calculated data have been used to augment measured temperature data to prepare the maps of geothermal temperatures presented in this report.

The temperature of the geothermal waters that are easily accessible from the unconsolidated sediment aquifers in the deep basins can be used in a number of applications. Applications such as space heating including the heating of greenhouses, bathing (both in spas and heated swimming pools), aquaculture pond heating and agricultural drying can be achieved with the hot water available within 1000 m of the surface. Existing facilities in Portland and elsewhere in the Otway Basin have demonstrated that many of these applications of geothermal heat are feasible.

The temperature of geothermal water within 2000 m of the surface in Victoria is not sufficiently high for generating electricity in a conventional steam turbine. Organic Rankine Cycle and Kalina Cycle® electricity generation technologies could possibly be applied in Victoria. However the expected plant efficiencies at temperatures less than 100ºC are so low that such developments are unlikely to be economic. Similarly, it is expected that the depth to which bores would have to be drilled to encounter temperatures required for electricity generation from a “Hot Dry Rock” development would make this type of development economically unattractive in much of the state. Local thermal anomalies in the Gippsland and Otway Basins may however represent potential targets for future Hot Dry Rock exploration.

Experience to date in using geothermal energy in Australia is reasonably limited. Small scale binary cycle geothermal plants have been successfully demonstrated in remote areas of South Australia and Queensland using hot water from the Great Artesian Basin. In Victoria, an extensive district heating scheme in the city of Portland has been operating continuously since the early




1980’s and has resulted in substantial saving in heating costs for the Glenelg Shire Council and several private and public sector users of the resource.

No significant adverse environmental effects have been identified that may hinder the future use of the low temperature geothermal resources present in Victoria. Conversion to geothermally based space and water heating in Victoria will reduce the amount of greenhouse gas emissions by removing dependence on combustion based heating or on electricity derived from burning fossil fuels.




14. References Burns, K. L., Weber, C., Perry, J. and Harrington, H. J., 2000. Status of the Geothermal Industry in Australia. Proc. World Geothermal Congress, Kyushu – Tohoku, Japan, May 28 – June 10, 2000.

Cull, J.P. Heat flow and geothermal energy prospects in the Otway Basin, SE Australia. Search, 10 (No 12), 429-433, (1979).

Cull, J.P. An appraisal of Australian heat flow data. Bureau of Mineral Resources Journal of Australian Geology and Geophysics, 7, 11-21, (1982).

Cull, J.P. Cultural changes to ground temperature and geothermal gradients. Search, 14 (No 3-4), 101-103, (1983).

Cull, J.P. 1982. An appraisal of Australian heat-flow data. BMR Journal of Australian Geology and Geophysics, 7, 11-21.

Cull, J.P. 1979. Heat flow and geothermal energy prospects in the Otway Basin, SE Australia. Search, 10, 429-433.

Cull, J.P. 1983. Cultural changes to ground temperature and geothermal gradients. Search, 14, 101-103.

Cull, J.P., O’Reilly, S.Y., and Griffin, W.L. 1991. Xenolith geotherms and crustal models in eastern Australia. Tectonophysics, 192, 359-366.

DiPippo, R. 1988. Geothermal Energy and the Greenhouse Effect. Geothermal Hot Line Vol 18 Issue 2.p 84-85.

DiPippo R., 1999. Small Geothermal Power Plants: Design, Performance and Economics, GHC Bulletin, June 1999.

Energy and Thermal Services, 2002. An Energy Consumption Study for the Glenelg Shire Geothermal Water Supply System. Report prepared by Energy and Thermal services Pty, Ltd. and Earth Tech Pty Ltd. For the Glenelg Shire Council, June 2002.

Ewart, A. 1989. Fractionation, assimilation, and source melting: a petrogenic overview. In Intraplate Volcanism in Eastern Australia and New Zealand (Johnson R.W, editor). Cambridge University Press.

Gray, D.R., Foster, D.A., and Bierlein, F.P. Geodynamics and metallogeny of the Lachlan Orogen. Australian Journal of Earth Sciences, 49, 1041-1056, (2002).

Gray, D.R., and Cull, J.P. 1992. Thermal regimes, anatexis, and orogenesis: relations in the western Lachlan Fold Belt, southeastern Australia. Tectonophysics, 214, 441-461.

Gill, E.D. (1972). Eruption date of the Tower Hill volcano. Vic.Naturalist, 89, 188-192.




Gloe, C.s., Barton, C.M., Holdgate, G.R., Bolger, P.F., King, R.L., and George, A.M., 1988. Brown Coal. In Geology of Victoria, Douglas & Ferguson (eds), Geological Society of Victoria, 498-511.

Johnson, L. undated. Article written by L Johnston http://www.fourhorizons.com.au/lindsay/ar_articles/ar_71.pdf).

Johnson, R.W. 1989 (editor). Intraplate Volcanism in Eastern Australia and New Zealand. Cambridge University Press.

King, R.L., Ford, A.J., Stanley, D.R., Kenley, P.R., and Cecil, M.K., 1985. Geothermal resources of Victoria a discussion paper. Dept of Industry Technology and Resources and the Victorian Solar Energy Council. ISBN 0 7241 3908 7

Lawless, J. Wataru, O. Terzaghi, S, White, P. and Gilbert, C. 2003. Two Dimensional Subsidence Modelling at Wairakei-Tauhara, New Zealand. International Geothermal Conference, Reykjavik, Sept. 2003.

Lister, G.S., and Etheridge, M.A. 1989. Detachment models for uplift and volcanism in the Eastern Highlands and their applications to he origins of passive margin mountains. In Intraplate Volcanism in Eastern Australia and New Zealand (Johnson R.W, editor). Cambridge University Press.

McDougall, I., Allsopp, H.L., and Chamalaun, F.H., (1966). Isoptopic dating of the New Volcanics of Victoria, Australia, and geomagnetic polarity epochs. J.Geophys. Res., 71, 6107-6118.

Purss, M.B., and Cull, J. (2001). Heat-flow data in western Victoria. Australian Journal of Earth Sciences, 48, 1-4.

Sass, J.H. 1964. Heat-flow values from Eastern Australia. Journal of Geophysical Research, 69, 3889-3893.

Sass, J.H., and Lachenbruch,A.H. 1979. Thermal regime of the Australian continental crust. In: McElhinney, M.W. (Editor), The Earth – its Origin, Structure and Evolution. Academic Press, London, 301-352.

Sawka, W.N., and Chappell, B.W. 1986. The distribution of radioactive heat production in I and S-type granites and residual source regions: implications to high heat flow areas in Lachlan Fold Belt, Australia. Australian Journal of Earth Sciences, 33, 107-118.

SKM, 2000. Portland Coast Water Town Water Supply Bore Asset Inventory. Casing Condition and Risk Assessment of Henty Park. Prepared by Sinclair Knight Merz, August 2000 WC01189.

SKM, 2003. Henty Park Bore. Bore Condition and Remediation Potential. Prepared by Sinclair Knight Merz WCP4205.

Spassov, E., Kennett, B., and Weekes, J. 1997. Seismogenic zoning of southeast Australia. Australian Journal of Earth Sciences, 44, 527-534.




Williams, N., 1997. Energy For Ever: Technological Challenges for Sustainable Growth. Academy Symposium, November 1997. Mother Earth – A Source of Sustainable Energy? (http://www.atse.org.au/index.php?sectionid=542)

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Appendix A Compilation of all Measured Temperature Data

Bore Temperature © Depth (m)

VIC Grid Easting

VIC Grid Northing Basin

PANYYABYR 00005 17 13.7 2263696.057 2435001.494 Otway PANYYABYR 00004 17 29.6 2259016.342 2430216.708 Otway MOUTAJUP 00004 18 30 2260484.894 2428282.486 Otway DUNKELD 00004 18 42 2260809.171 2420564.328 Otway PANYYABYR 00002 17 51 2260357.096 2439614.246 Otway BARONGAROOK 00066 25 59 2381505.946 2340100.26 Otway ALBERTON WEST 00182 19 60.9 2635302.698 2317638.344 Gippsland MULLUNGDUNG 00003 21 71.6 2660728.15 2347878.489 Gippsland MOORBANOOL 00016 21 76.2 2368637.212 2329102.429 Otway ARCADIA 00001 21 79.3 2537717.658 2552079.701 Gippsland ARCADIA 00005 30 82.3 2538581.515 2549046.707 Gippsland BARONGAROOK 00059 14 85 2376826.293 2337111.912 Otway DUNNAWALLA 00010 19 85 2338837.245 2398737.201 Otway EILYAR 00002 27 86.9 2313349.297 2405012.739 Otway WILLUNG 00178 23 93 2656681.891 2349832.139 Gippsland HAZELWOOD 1095 32 101 2618694.488 2357660.945 Gippsland GEELENGLA 00010 20 103.6 2335180.147 2388274.855 Otway HAZELWOOD 1301 34 105 2619487.616 2358160.476 Gippsland LIGAR 00001 17 105.2 2317194.298 2389910.195 Otway LOY YANG 1261 28 116 2637988.772 2359549.983 Gippsland YARRAGON 00008 49 120 2609668.57 2371466.743 Gippsland YARRAGON 11 19.1 120 2609635.093 2371458.023 Gippsland HAZELWOOD 1096 46 122 2620364.153 2358535.158 Gippsland LOY YANG 713 28.3 124 2638376.204 2361261.985 Gippsland SALE 00019 26 125 2680175.352 2375150.593 Gippsland COONGULMERANG 00024 24 128 2711467.183 2394980.337 Gippsland LOY YANG 1302 24.8 130 2638250.014 2360262.96 Gippsland DUNNAWALLA 00009 21 136 2339795.402 2400931.439 Otway MOORMURNG 00016 22 141.75 2723276.225 2405499.154 Gippsland VITE VITE 00002 22 144.8 2342034.255 2408278.412 Otway LOY YANG 01261 26 145 2637989.258 2359555.889 Gippsland YEERUNG 00011 21 150 2693411.2 2391708.723 Gippsland MARYVALE 2230 56.6 152 2621584.171 2359724.121 Gippsland MULLUNGDUNG 00009 16 155 2662985.666 2343370.771 Gippsland MARYVALE 2109 57.1 155 2622322.572 2360002.67 Gippsland BOODYARN 00012 12 166 2653983.4 2340677.358 Gippsland MARYVALE 2159 53.8 169 2621957.993 2360600.797 Gippsland HAZELWOOD 1330 48.8 169 2621109.246 2359554.066 Gippsland ALBERTON WEST 00197 27 170.6 2643353.925 2318447.103 Gippsland NARRACAN 3558 25.3 173 2616626.186 2360354.609 Gippsland TONG BONG 00172 22 173.7 2645717.99 2358258.613 Gippsland WILLUNG 168 30 174 2648811.435 2355144.428 Gippsland




TARIPTA 00046 35 179.8 2506166.401 2588509.835 Gippsland HAMILTON SOUTH 00003 20 182.9 2244480.397 2410989.041 Otway MARYVALE 2263 47 187 2621823.277 2360146.342 Gippsland YARRAM YARRAM 00015 26 189.1 2646033.083 2323320.003 Gippsland NARRACAN 3470 33 194 2616694.649 2361978.242 Gippsland NARRACAN 3280 26 196 2616628.102 2360350.566 Gippsland STRATFORD 00019 29 198.1 2681695.509 2401563.273 Gippsland HOLEY PLAINS 188 23.4 199 2667310.932 2365092.917 Gippsland COOLUNGOOLUN 94 24.3 212 2673622.755 2361830.023 Gippsland NARRACAN 3473 37.2 215 2618401.597 2360695.207 Gippsland LOY YANG 1122 31.2 218 2637230.904 2361758.521 Gippsland COOLUNGOOLUN 00096 25 220 2673609.598 2361854.947 Gippsland ROSEDALE 00322 47 221 2659064.533 2368673.496 Gippsland NARRACAN 3284 25.2 223 2614468.808 2365923.015 Gippsland MURROON 00029 27 225 2397028.475 2339396.796 Otway YATCHAW WEST 00002 25 228.8 2249693.218 2403173.916 Otway COOLUNGOOLUN 00094 28 231 2673622.267 2361832.476 Gippsland MURROON 00028 25 232 2392972.635 2345063.613 Otway YARRAM YARRAM 08002 31 234.8 2644384.277 2325047.9 Gippsland LOY YANG 1159 42.9 236 2637394.722 2362596.635 Gippsland WILLUNG 00179 30 249 2658349.729 2349334.239 Gippsland LOY YANG 1184 37 250 2636008.347 2360872.742 Gippsland WINNINDOO 45 33.8 250 2653124.184 2384366.128 Gippsland LATROBE 00045 26 263 2341679.136 2312550.833 Otway YAUGHER 00021 35 265.2 2376475.668 2328589.933 Otway HOLEY PLAINS 174 22 277 2667298.859 2368324.38 Gippsland MARYVALE 2291 48 285 2620183.657 2362010.329 Gippsland ALBERTON EAST 10003 35 287 2646433.199 2317788.089 Gippsland LATROBE 15002 20 299 2345918.747 2316162.492 Otway YINNAR 122 40.5 300 2617727.376 2351083.884 Gippsland BOODYARN 00006 21 305 2654657.251 2334357.583 Gippsland WILLUNG 00182 23 305 2648430.835 2352958.973 Gippsland YEO 00023 25 307 2387660.712 2348735.178 Otway WORANGA 00016 29 310 2649379.953 2327369.315 Gippsland CRESSY 20001 27 310.5 2381670.692 2379782.264 Otway POLIAH SOUTH 20001 27 311 2369480.019 2380788.339 Otway INGLEBY 1 31 326 2394810.351 2353558.423 Otway DENISON 54 36 329 2653375.431 2384417.869 Gippsland BOODYARN 00004 18 333 2659077.051 2338349.548 Gippsland STRADBROKE 51 21.9 335 2663451.204 2353015.517 Gippsland LOY YANG 1185 45.4 339 2636477.601 2362052.638 Gippsland IRREWILLIPE 00016 20 347.3 2363493.331 2337924.951 Otway WIRIDJIL 00003 27 348 2344861.208 2322128.654 Otway TRARALGON 377 36 350 2632826.953 2358167.114 Gippsland NALANGIL 1 25 362 2363584.761 2347997.448 Otway MUMBANNAR 00006 18 365.7 2159942.551 2393921.688 Otway WULLA WULLOCK 00004 23 365.8 2680695.323 2356041.515 Gippsland WILLUNG 196 29.5 369 2654622.451 2358696.474 Gippsland




MURROON 00027 33 369.1 2394610.612 2339799.483 Otway ALBERTON EAST 00003 38 370.9 2646475.669 2319603.069 Gippsland TRARALGON 256 45.9 383 2631780.667 2357667.891 Gippsland COLAC 00010 37 384 2377161.941 2350263.215 Otway MILDURA WEST 1 44 429 2170154.714 2766721.931 Murray SOUTH CARAMUT 1 36 430 2278463.545 2385808.718 Otway HAZELWOOD 1320 51 434 2621603.319 2355954.13 Gippsland PALPARA 00004 28 445 2146077.403 2384336.762 Otway COLONGULAC 00012 38 450 2331798.289 2360750.683 Otway TANDAROOK 00002 34 454 2337687.333 2349397.625 Otway TONG BONG 182 26 461 2642904.071 2357222.552 Gippsland TULLICH 1 34 464 2160008.329 2435033.112 Otway WORANGA 00015 35 470 2646431.825 2327643.905 Gippsland MARYVALE 00942 65 500 2626659.834 2367895.784 Gippsland WAARRE 15003 32 501 2337534.391 2315602.453 Otway TONG BONG 00182 34 515.1 2642902.772 2357230.358 Gippsland TONG BONG 176 41.5 517 2645685.767 2359863.707 Gippsland MARYVALE 8001 70 524 2626225.673 2368529.732 Gippsland STRATFORD 00017 36 525 2684077.348 2391619.454 Gippsland PAARATTE 00002 31 548 2325744.988 2318505.85 Otway BOOLA BOOLA 1 63.8 558 2627244.141 2372302.636 Gippsland HOMERTON 00004 33 575.6 2212163.691 2367149.403 Otway PAARATTE 08011 25 576 2323284.362 2327138.53 Otway TRARALGON 286 62.5 582 2635010.018 2366946.959 Gippsland BAIRNSDALE 6 58.9 584 2736529.937 2396045.761 Gippsland ROSEDALE 307 52 585 2651491.392 2369189.686 Gippsland MURROON 00024 39 590 2392815.827 2341708.467 Otway GLENAULIN 00002 33 592.5 2188288.351 2382574.98 Otway HAZELWOOD 1333 56 594 2625514.936 2358500.046 Gippsland MURROON 00023 39 598 2393123.292 2341912.287 Otway MILDURA WEST 2 50 598 2158898.31 2766345.23 Murray NARRAWONG 00016 31 613 2209830.495 2364258.352 Otway CODRINGTON 00001 35 629 2232312.122 2355325.775 Otway ARDONACHIE 00002 30 630.9 2224472.893 2384502.257 Otway PENINSULAR HOTSPRINGS 47 637 2481050.193 2347379.253 Otway WANWIN 00001 26 657.15 2162688.001 2385834.869 Otway PAARATTE 00004 66 658.5 2326988.587 2325717.38 Otway YANGERY 00001 40 673 2270088.721 2352256.929 Otway WINNINDOO 46 65 679 2651687.098 2375860.972 Gippsland BELFAST 00013 43 685 2256315.066 2342957.519 Otway COBBOBOONEE 00005 34 700 2185385.241 2372513.467 Otway ROSEDALE 00307 51 702 2651491.539 2369191.848 Gippsland KOROIT 00010 36 707.4 2265040.38 2346207.47 Otway LOY YANG 2390 62 715 2644284.896 2368209.981 Gippsland GUNAMALARY 2 60 718 2153894.156 2678301.317 Murray HOTSPUR 00001 25 740 2199182.94 2393081.578 Otway NEPEAN 00038 45 759 2484660.461 2345084.334 Otway LOY YANG 01675 65 790 2643005.085 2367953.742 Gippsland




BCL #62106 (PORT FAIRY) 43 770 2256314 2342908 Otway BELFAST 00004 41 800.4 2256344.832 2342747.363 Otway COBBOBOONEE 00002 57 806 2183231.98 2365766.928 Otway ECKLIN 00004 104 807 2313658.958 2344818.517 Otway ROSEDALE 301 50.5 817 2661060.493 2370218.87 Gippsland WANGOOM 00006 44 824.8 2278781.066 2342097.638 Otway TRARALGON 00286 65 840 2635009.837 2366954.457 Gippsland DENISON 00053 53 854 2666399.975 2375536.275 Gippsland NIRRANDA 08001 37 855 2304258.398 2327599.827 Otway DENISON 00057 55 872 2662747.609 2379793.788 Gippsland BOOTAHPOOL 08001 42 890 2329773.153 2325497.371 Otway WULLA WULLOCK 00004 40 895 2680695.323 2356041.515 Gippsland PAARATTE 08004 50 895 2324904.821 2320620.499 Otway WURRUK WURRUK 00013 47 900 2677006.63 2374319.012 Gippsland HOLEY PLAINS 185 38.2 904 2671406.28 2368735.336 Gippsland NARRAWATURK 00006 50 907 2313394.875 2327532.748 Otway BESSIEBELLE 08003 41 921 2227744.633 2366528.847 Otway TIMBOON 00005 36 921.4 2323932.677 2333293.592 Otway WANGOOM 00002 44 922.93 2281958.162 2344558.254 Otway TARRAGAL 00003 35 934 2190177.446 2343443.623 Otway SHAW 1 39 960 2241791.761 2358435.166 Otway MOUZIE 00001 43 960.5 2189425.093 2357235.359 Otway CURDIE VALE 1 58 964 2306932.587 2325219.158 Otway LINDON 2 40 970 2194366.984 2375935.29 Otway NIRRANDA 00008 62 982 2302982.894 2329846.376 Otway TREWALLA 00005 39 983.3 2191987.75 2346665.956 Otway SALE 13 65 995 2694520.978 2373994.038 Gippsland NARRAWATURK 08029 45 998 2318963.425 2325379.475 Otway HAZELWOOD 01395 58 1000 2620153.665 2356845.372 Gippsland HOTSPUR 1 58 1000 2198929.944 2393094.686 Otway ARDONACHIE 00002 39 1021.7 2224472.893 2384502.257 Otway ARDONACHIE 00002 39 1022 2224472.893 2384502.257 Otway PORTLAND 00002 50 1030 2203434.404 2346748.779 Otway WARRONG 00005 48 1034 2264109.564 2358319.892 Otway SALE 00013 52 1048.5 2694519.694 2374007.213 Gippsland SALE 00013 64 1049.76 2694519.694 2374007.213 Gippsland BENGWORDEN SOUTH 00006 50 1057.5 2713050.43 2379806.457 Gippsland PAARATTE 08001 53 1067 2323546.778 2327144.117 Otway DARTMOOR 00025 38 1100.88 2171585.642 2392032.127 Otway PRINCES 1 44.5 1150 2324650.926 2332720.223 Otway NARRAWONG 00013 53 1150 2211324.551 2355357.5 Otway PORTLAND 00008 32 1174 2203421.135 2341138.312 Otway PORTLAND 00013 57 1187 2203243.35 2340632.056 Otway OTWAY BASIN 08008 44 1210 2157178.27 2336381.298 Otway OTWAY BASIN 08008 44 1210 2157178.27 2336381.298 Otway PORTLAND 00010 30 1224 2203559.303 2341432.077 Otway BENGWORDEN SOUTH 00006 67 1225 2713050.43 2379806.457 Gippsland GREENBANKS 1 64 1226 2217075.77 2382067.085 Otway




SEAVIEW 1 44 1235 2337411.79 2322874.311 Otway BALANGEICH 1 59 1250 2293681.562 2360215.586 Otway BIG DESERT 1 41.7 1250 2156650.022 2671483.032 Murray TIRRENGOWA 1 74 1272 2354974.826 2345408.916 Otway FAHLEY 2 49 1300 2152827.691 2384308.952 Otway WILSON 1 54 1312 2161079.532 2388980.165 Otway HOMERTON 00003 50 1326 2216344.316 2368703.288 Otway NARRAWATURK 00002 56 1341.7 2314980.059 2320216.062 Otway PORTLAND 00014 60 1365 2203499.609 2344307.168 Otway BOOTAHPOOL 00002 55 1370 2253951.519 2351606.563 Otway MOCAMBORO 11 71.6 1370 2191850.449 2410940.248 Otway NAMGIB 1 50 1387 2329774.025 2325497.389 Otway VOGEL 1 51 1394 2328955.21 2327146.364 Otway PORTLAND 00003 59 1420.6 2202066.04 2345500.113 Otway HENKE 1 62 1430 2165676.315 2381833.707 Otway BESSIEBELLE 08002 48 1459 2231589.275 2361344.618 Otway KRAMBRUK 00013 60 1475 2382814.436 2301829.922 Otway IONA 1 57 1490 2328679.894 2323586.9 Otway SQUATTER 1 55 1500 2160167.391 2396274.675 Otway ARDNO 00002 52 1500 2145262.096 2406120.412 Otway PAARATTE 08008 55 1509 2327207.623 2325877.425 Otway CASTERTON 2 65.6 1524 2166833.536 2421312.165 Otway DRAJURK 08005 65 1526 2166831.772 2421312.095 Otway WARRACBARUNAH 2 75 1527 2395925.352 2369337.244 Otway PAARATTE 08007 62 1531 2321755.455 2325917.507 Otway GARVOC 1 67 1533 2314371.895 2351375.044 Otway YAMBUK 00002 55 1535 2242873.49 2347162.019 Otway KENTBRUCK 00003 57 1575 2174432.055 2368893.839 Otway NORTH PAARATTE 2 60 1580 2323309.757 2326028.509 Otway NARRAWONG 00016 63 1625 2209830.495 2364258.352 Otway TULLICH 1 57 1634 2160008.329 2435033.112 Otway GORAE 00002 53 1650 2204006.523 2359332.689 Otway GRUMBY 1 69 1660 2321734.709 2322218.817 Otway BOGGY CREEK 1 68.3 1672 2310342.913 2328629.647 Otway WANWIN 00003 72 1675 2164131.084 2382227.162 Otway GORAE 00005 55 1696.5 2195938.426 2354743.054 Otway MALANGANEE 00004 99 1719 2147139.318 2397190.567 Otway NARRAWATURK 08030 66 1763 2317514.125 2323792.879 Otway WALLABY CREEK 1 62 1763 2317515.868 2323792.918 Otway COBBOBOONEE 00005 53 1765 2185385.241 2372513.467 Otway WARRAIN 00007 62 1775 2158731.224 2375453.857 Otway HAWKESDALE 1 79 1775 2263078.55 2376836.158 Otway CALLISTA 1 63.8 1790 2311327.649 2335204.418 Otway PAARATTE 08006 82 1797 2322685.139 2322572.38 Otway NULLAWARRE 08001 63 1797 2307119.99 2335885.119 Otway ROWANS 1 67 1798 2307120.862 2335885.14 Otway OTWAY BASIN 08004 54 1805 2178238.76 2335079.476 Otway PORT CAMPBELL 1 82 1811 2322686.011 2322572.399 Otway




PAARATTE 08010 68 1814 2321733.838 2322218.798 Otway PURRUMBETE 1 77 1828 2343493.572 2347088.307 Otway FENTON CREEK 1 67 1835 2319818.561 2330173.529 Otway GORAE 00004 58 1843 2193210.214 2358875.334 Otway BUS SWAMP 1 82 1850 2164322.5 2435539.717 Otway WINDERMERE 1 81 1852 2238687.155 2359671.1 Otway WESTGATE 1A 66 1918 2315690.968 2335302.428 Otway WOOLSTHORPE 1 76 1971 2280604.847 2371208.048 Otway DIGBY 1 100 2088 2192405.643 2400631.87 Otway OLANGOLAH 1 72 2090 2404190.021 2314032.324 Otway BARTON CORNER 1 77 2100 2304077.671 2339034.483 Otway PINELODGE 1 77 2140 2167377.9 2385456.359 Otway PAARATTE 08011 82 2210 2323284.362 2327138.53 Otway BRAESIDE 1 81.1 2300 2323375.651 2327029.419 Otway HINDHAUGH CREEK 1 118 2370 2430285.907 2357928.192 Otway MCEACHERN 1 99 2380 2163625.793 2430847.112 Otway KILLARRA 1 101 2418 2256678.635 2364547.357 Otway PRETTY HILL 1 86 2477 2248388.964 2360414.095 Otway CASTERTON 1 82 2500 2176643.251 2425694.175 Otway PORT CAMPBELL 4 79 2596 2323547.649 2327144.136 Otway NIRRANDA 08005 86 2600 2310238.768 2325517.595 Otway CURDIE 1 86 2600 2310239.639 2325517.615 Otway GREENSLOPES 1 101 2608 2255607.797 2371179.241 Otway PORT CAMPBELL 2 87 2693 2324767.462 2339607.771 Otway TARALEA 1 116 2800 2255667.127 2360186.55 Otway NORTH EUMERALLA 1 110 2967 2227774.053 2366540.915 Otway DRUMBORG 08001 118 3011 2194361.167 2376046.152 Otway LINDON 1 118 3011 2194362.921 2376046.216 Otway ANGLESEA 1 115 3060 2430055.606 2343715.553 Otway JAN JUC 08241 115 3062 2430059.287 2343693.379 Otway EUMERALLA 1 97 3140 2231624.649 2361334.651 Otway FAHLEY 1 71 3211 2152809.499 2386863.295 Otway NAJABA 1A 102 3412 2154063.689 2392691.913 Otway FLAXMANS 1 109 3510 2305435.228 2325850.533 Otway FERGUSONS HILL 1 119 3540 2339935.262 2318592.246 Otway WINDERMERE 2 135 3592 2239411.644 2358916.347 Otway