DOCSLIB.ORG

Geothermal System

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Geothermal System 55 EVOLUTION OF GEOTHERMAL SYSTEM Roger C. Henneberger Geothermal Institute, University of Auckland GEOLOGIC SETTING and petrographic study of hydrothermal The Ohakuri field, cut by the Waikato River, alteration at the now-extinct Ohakuri geothermal occurs in the western part of the Taupo Volcanic field has revealed a long history of activity which Zone, within the Maroa Volcanic Centre (Fig, 1). varied in nature lacation. Early flow of Hydrothermal activity took place within an area in neutral to alkaline chloride- type water through which the dominant rocks are a sequence of rocks now exposed was followed by extensive near- rhyolitic pyroclastics, informally termed the surface flow of acid- sulphate water, with minor Ohakuri Ignimbrite. The sequence consists of at hot- spring discharges, which fdrmed scattered least 150 m of nearly flat- lying, porous, pumice- sinters, comprising the last activity. High per- rich, massive, nonwelded ignimbrite flows, with meability of the porous host rocks facilitated minor cross- stratified ignimbrites and thin fluid movement, and regional hydrology may have units. The age of the sequence is unknown, but its significantly controlled flow patterns, whereas control by tectonic fractures appears to have been minor. in rock sealed by silicifica- tion was sustained by hydrofracturing which resulted in veining and local brecciation. Fluid temperatures probably did not exceed and were largely less than at the levels observed. The distribution of hydrothermal features suggests that upflow zones migrated northward and westward with time, and that the now-active Atiamuri geothermal system is probably descended from the fossil Ohakuri field. INTRODUCTION Hydrothermally tered rocks and hot spring deposits are exposed over an area of at least 15 near Lake Ohakuri, 25 north of Wairakei i n the Taupo Volcanic Zone (Fig. 1). These hydro- thermal features are the remnants of a now-extinct geothermal system which was similar to active thermal areas i n the region. Variable erosion of the altered rocks affords an opportunity to study the upper 100 to 150 m of such a system i n much more spatial detail than is possible in an active system. Mapping of surface geology and alteration types, along with petrographic investigation of I samples, allows reconstruction of a number of characteristics of the system, particularly its fluid composition and temperature and their variations through time, controls on fluid move- ment, and the duration of activity. This study shows that Ohakuri evolved over a long period, with significant changes i n the nature and location of Figure 1: Geology of Ohakuri and vicinity, modi- activity before the near- surface movement of fied after Grindley (1959). Young geothermal waters ceased. tephras (542,000 yrs) not shown. Rectangle indicates area of this study (Fig. 2). 56 Henneberger relationship to other volcanic units in the area HYDROTHERMAL ALTERATION indicates an age in the range of several hundred thousand to one million years Grindley, 1959; Hydrothermal fluids produced several types of Cole, 1979). Up to 10 m of fine- grained ash beds alteration in tne tuffaceous rocks now exposed. rest on the eroded surface of the Ohakuri Ignim- The different types can be distinguished in the brite in a small area on the north shore of the field and correlate with petrographic Waikat o River. distinctions determined by optical and X-ray Diffraction methods. Most of the alteration is A number of terrace-forming fluvial and pervasive, with alteration intensity and mineralogy lacustrine deposits flank the reflecting remaining constant over distances of up to 10 m or fluctuating river levels and periodic inundation by more. However, variations over smaller distances lakes since the inception of hydrothermal activity. (to as little as several are frequently At least five terraces are present, and or more observed where the original rock was inhomogeneous, of the older deposits have been altered by geother- in thinly bedded pyroclastics with varying mal water in the same manner as the ignimbrites. grain size distribution o r pumice content. The area is mantled by tephras which postdate Veining, which is common only i n intensely altered the hydrothermal features now exposed. The rock, has produced similar small- scale variations of these, the Rotoehu Ash, imposes a minimum age of which a r e visible as alteration haloes. Transi- 42,000 years on the bulk of the hydrothermal tions between types are usually gradual, occurring activity (Vucetich and Pullar, 1969). over distances of at least 10 m, but are locally sharp, particularly where later alteration over- Ohakuri lies on the southwest extension of the prints an earlier event. northeast- trending Ngakuru Graben, and also within the northwest-trending Maroa Graben proposed by Table 1 summarizes the characteristics of the Modriniak and Studt (1959). Tectonic deformation various alteration types. The most intense in the area is weak, but minor NE-trending faults alteration converted the tuffs to a quartz + have been identified, and several adularia + sericite (illite and similar sheet lineaments seen on aerial photographs appear to silicates) pyrite assemblage, with minor amounts correspond to zones of more concentrated altera- of chlorite, clinoptilolite and leucoxene. Quartz, tion. The setting of Ohakuri is similar to those the most abundant hydrothermal mineral, replaces of the Orakeikorako and Atiamuri thermal areas, virtually all vitric components and often fills both of which also flank the Waikato River within cavities left by the leaching of primary grains. the Maroa Volcanic Centre and the inferred Maroa Plagioclase is replaced by adularia, with minor Graben. amounts of sericite and rare apatite, and frequently is partially leached. TABLE 1: Summary of hydrothermal alteration types at Ohakuri Alteration Type Quartz - Adularia Zeolite Kaolinite Hot Spring Deposits Alteration Minerals Quartz -- Cristobalite Adularia Illite - - Chlorite Clinoptilolite Mord e n i te Mon tmorillonit e - - Kaolinite Alunite Pyrite ---- Hematite - - - - - - - -. - - - - -- - - e - - - - Leucoxene Apatite Veining Common; l o c a l l y R a r e Sparse but Rare intense locally intense Probable Water Neutral - alkaline Neutral - alkaline Acid - sulphate ? Mixed chloride chloride chloride and sulphate? meteoric?) Deduced Water 100 - 200 50 - 100 50 - 100 -100 Temperature 57 Henneberger 0 33°C Figure 2: Distribution of alteration types, Ohakuri area. Kaolinite alteration is locally discontinuous. Temperatures of wells (depths 40 - 60 were measured February 1982. Veins of quartz and quartz + pyrite which vary Quartz- adularia alteration forms a central i n thickness fom microscopic to several cm are zone i n the southern portion of the area (Fig. 2) common i n zones o f quartz- adularia alteration. which grades both upward and outward into a zone of Zoning within veins, and crosscutting relationships less intense zeolite- type alteration (Table 1). between veins, indicate that a number of distinct This latter type is characterized by weaker silici- episodes of quartz and quartz + pyrite precipita- fication, little to no veining, and less dense tion took place. As many as four such episodes can rocks. Mordenite, montmorillonite and cristobalite be recognized i n single outcrops. Successive a r e the most abundant hydrothermal minerals, and generations veins follow a progression from plagioclase is fresh or only partially replaced by extremely thin mm) fillings with broad haloes sericite + adularia. The zeolite zone grades into to thick cm) veins without haloes. Many o f t h e fresh rock, i n places through a narrow (10 - 50 m thickest veins contain angular clasts of wallrock, wide) zone i n which the only alteration is leaching and appear to be gradational with hydrothermal of pyroxene and amphibole crystals. breccias present at several locations. These breccias consist of angular and rounded clasts in a Zeolite and quartz- adularia alteration types quartz pyrite matrix, and range from about 1 m to extend from Ohakuri dam at least 2.5 km to the several tens of meters i n thickness. The breccias towards Atiamuri. Though lack of exposure prohi- and most veins are thought to be the product of bits tracing the zones further, the trend of the violent hydrofracturing with subsequent infilling mapped alteration indicates that the active by mineral precipitation Grindley and Browne, Atiamuri system is contiguous with, and very likely 1976). descended from, the Ohakuri system. Such a 58 by resistivity mapped and possibly extending farther north and anomaly-patterns (Dawson et al, 1981) and by the west (Fig. A period of erosion presence of warm water wells at the western margin followed near- surface flow of acid- sulphate of the Ohakuri area (Fig. 2). waters, cohdensed from steam and oxidized produced by boiling of chloride water at depth, A third type of alteration, dominated by which altered fresh and previously altered rocks to kaolinite plus variable amounts of c kaolinite type. The main zone for the deep hematite and local alunite (Table affected both chloride water was north of that for the earlier fresh rocks and rocks previously altnred to zeolite phase, with shallow fluids flowing southward toward and quartz- adularia types. of kaolinite type the Waikato River, then following approximately its are bleached white and mainly converted to kaolin- present course (Pig. 3B). ite or kaolinite + cristobalite. been leached away, and the rock usually has a low The presence of
Load more

Recommended publications
  • Strong Iwi Involvement in River Clean-Up Projects
    DECEMBER 2018 A newsletter from the Strong iwi involvement in MESSAGE FROM river clean-up projects THE CE It has been a busy end of year for THE WAIKATO RIVER AUTHORITY HAS ANNOUNCED $6 MILLION FOR RIVER the WRA. We completed our 8th CLEAN-UP PROJECTS IN ITS JUST COMPLETED FUNDING ROUND, WITH MORE funding round and it was great to THAN A THIRD OF THESE PROJECTS BEING IWI LED. see projects successfully lifted from the Restoration Strategy Overall, a total of 38 projects have been The largest project to be funded this year that Environment Minister funded in 2018. is a continuation of the Waipā Catchment Parker launched earlier this year. Authority Co-chairs Hon John Luxton and Plan implementation which will involve Our advocacy for the Vision & Roger Pikia, say a feature of the funding working with approximately 70 farmers Strategy has been pursued across round has been a close alignment with the and landowners within identified priority a number of fora. We held our Restoration Strategy for the Waikato and catchments. The $1.6 million of funding AGM on the back of publishing Waipā rivers and the strong participation will work towards reducing sediment our 2017/18 Annual Report. We of River Iwi. levels going into the Waipā River and its have also received positive media tributaries. Sediment from the Waipā “In recent years there has been a clear coverage across several articles River is a major factor in reducing the trend for successful projects to reflect in as many weeks. One of these water quality in the lower Waikato River.
    [Show full text]
  • Waikato River Adare Flood Hazard Report
    The Adare Limited Company Limited Waikato River Adare Flood Hazard Report 17 May 2018 Prepared by Awa Environmental Limited for The Adare Company Limited The Adare Limited Company Limited Waikato River Adare Flood Hazard Report Project No. J000098 Document title Waikato River Adare Flood Hazard Report Document number 03 Version number 03 Date 17 May 2018 Project manager Craig Martell Author TonyTrueman Awa Environmental Limited 115 Tory Street, Te Aro, Wellington 6011, Phone:+64 04 455 0990 www.awa.kiwi Document History Version Date Description Author Reviewed 1 02/11/2017 Review TonyTrueman Craig Martell 2 29/03/2018 Preliminary Issue Tony Trueman Tony Trueman 3 17/05/2018 Review Tony Trueman Tony Trueman COPYRIGHT: The concepts and information contained in this document are the property of Awa Environmental Ltd. Use or copying of this document in whole or in part without the written permission of constitutes an infringement of copyright. iii The Adare Limited Company Limited Waikato River Adare Flood Hazard Report Contents Contents ................................................................................................................................................. iv 1 Introduction .................................................................................................................................... 1 2 1% AEP River Flooding Assessment ................................................................................................ 2 2.1 1% AEP Flood Hazard Extent ..................................................................................................
    [Show full text]
  • Waikato District Council
    WAIKATO DISTRICT COUNCIL Report and Decisions of the Waikato District Plan Hearings Panel REPORT 2 Ohinewai Rezoning 24 May 2021 Commissioners Dr Phil Mitchell (Chair) Mr Paul Cooney (Deputy Chair) Mr Dynes Fulton Mr Weo Maag Page | 1 Decision Report 2: Ohinewai Rezoning Report and Decisions of the Waikato District Plan Hearings Panel Page | 2 Decision Report 2: Ohinewai Rezoning Report and Decisions of the Waikato District Plan Hearings Panel TABLE OF CONTENTS 1 Introduction ................................................................................................................................... 5 2 The APL submission ...................................................................................................................... 9 3 Statutory and planning framework ............................................................................................ 15 4 Site suitability and physical characteristics ............................................................................... 18 5 Three Waters Infrastructure ...................................................................................................... 20 6 Natural hazards ........................................................................................................................... 24 7 Transport and traffic ................................................................................................................... 26 8 Economic effects .........................................................................................................................
    [Show full text]
  • Geothermal Power Development in New Zealand - Lessons for Japan
    Geothermal Power Development in New Zealand - Lessons for Japan - Research Report Emi Mizuno, Ph.D. Senior Researcher Japan Renewable Energy Foundation February 2013 Geothermal Power Development in New Zealand – Lessons for Japan 2-18-3 Higashi-shimbashi Minato-ku, Tokyo, Japan, 105-0021 Phone: +81-3-6895-1020, FAX: +81-3-6895-1021 http://jref.or.jp An opinion shown in this report is an opinion of the person in charge and is not necessarily agreeing with the opinion of the Japan Renewable Energy Foundation. Copyright ©2013 Japan Renewable Energy Foundation．All rights reserved. The copyright of this report belongs to the Japan Renewable Energy Foundation. An unauthorized duplication, reproduction, and diversion are prohibited in any purpose regardless of electronic or mechanical method. 1 Copyright ©2013 Japan Renewable Energy Foundation．All rights reserved. Geothermal Power Development in New Zealand – Lessons for Japan Table of Contents Acknowledgements 4 Executive Summary 5 1. Introduction 8 2. Geothermal Resources and Geothermal Power Development in New Zealand 9 1) Geothermal Resources in New Zealand 9 2) Geothermal Power Generation in New Zealand 11 3) Section Summary 12 3. Policy and Institutional Framework for Geothermal Development in New Zealand 13 1) National Framework for Geothermal Power Development 13 2) Regional Framework and Process 15 3) New National Resource Consent Framework and Process for Proposals of National Significance 18 4) Section Summary 21 4. Environmental Problems and Policy Approaches 22 1) Historical Environmental Issues in the Taupo Volcanic Zone 22 2) Policy Changes, Current Environmental and Management Issues, and Policy Approaches 23 3) Section Summary 32 5.
    [Show full text]
  • Mathematical Modelling of Wairakei Geothermal Field
    ANZIAM J. 50(2009), 426–434 doi:10.1017/S1446181109000212 MATHEMATICAL MODELLING OF WAIRAKEI GEOTHERMAL FIELD MALCOLM A. GRANT1 (Received 1 November, 2008; revised 22 April, 2009) Abstract Mathematical modelling of Wairakei geothermal field is reviewed, both lumped- parameter and distributed-parameter models. In both cases it is found that reliable predictions require five to ten years of history for calibration. With such calibration distributed-parameter models are now used for field management. A prudent model of Wairakei, constructed without such historical data, would underestimate field capacity and provide only general projections of the type of changes in surface activity and subsidence. 2000 Mathematics subject classification: primary 86A99. Keywords and phrases: geothermal, reservoir modelling, Wairakei, review. 1. Introduction Wairakei geothermal field is located in the North Island of New Zealand, in the Taupo Volcanic Zone. In the late 1940s there was one geothermal field developed for electrical generation in the world, Laraderello in Italy. This example, and a looming electricity shortage, led to the decision to develop Wairakei for power generation. The first drilling showed a field markedly different from Larderello, as it was full of hot water rather than the expected steam. The subsequent development had a large element of exploration, and there was a significant scientific effort to understand the physical nature of the field. The power station was built by 1958, but research continued thereafter, and to the present day. Part of this effort was mathematical modelling. As pressures drew down with exploitation, it was discovered that the drawdown at depth was extremely uniform across the entire field, so that a single pressure history described this drawdown.
    [Show full text]
  • A Study of Some Effects of the Wairakei Geothermal Power Station Upon the Waikato River
    TANE 21, 1975 A STUDY OF SOME EFFECTS OF THE WAIRAKEI GEOTHERMAL POWER STATION UPON THE WAIKATO RIVER by G.J. Cox*, Sally M. Naylor f, and D.E. Thomson ft SUMMARY The effects of heated discharges from the Wairakei Geothermal Power Scheme upon the Waikato River have been investigated. Water temperature, oxygen content and mercury concentration were measured at a number of points above and below the station and aquatic life was studied (the data on the flora has yet to be fully analysed and can thus only be described briefly here). Marked local effects on both the aquatic life and paramaters of water quality were observed. However, although further investigation is warranted, particularly of the discharge rates of heavy metals such as mercury, the scheme does not appear to contribute significantly to the pollution of the Waikato River. INTRODUCTION A number of reports dealing with various aspects of the Wairakei Geothermal Power Station and its effects on the Waikato River have been published since the station became operative in the late 1950's. This work has recently been summarised by Axtmann1 who included a number of New Zealand Electricity Department reports in his references. However certain topics such as thermal mixing and the effects of the outputs from both station and bore fields on the aquatic life, have been virtually ignored. It was chiefly to provide some information on these that the present study was initiated. The study was confined to a single week in the mid-winter (11 to 16 August) of 1974. The power station-bore complex has two outlets into the Waikato River, the more obvious one being the discharge of cooling water used to condense the stream which is used to drive the powerhouse turbines.
    [Show full text]
  • Meremere Roading Cases Tudy
    1 Reference: Harmsworth, G.R. 2005: Roading Case Study: Transit New Zealand and Ngati Naho, Meremere œ Springhill Road. Contract to Opus International Consultants New Zealand Ltd. 6 pp. FRST programme: Roading enhanced by M,ori values and Knowledge (OPSX0301) http://www.transportco2.org.nz/ FRST programme: Roading enhanced by Mori values and knowledge Case study: Transit New Zealand and Ngati Naho, Meremere œ Springhill Road Garth Harmsworth, Landcare Research [email protected] Background Construction on a 100-m section of the Waikato Expressway (major 4-lane highway), between Mercer and Longswamp, was temporarily stopped in 2002 while a solution was sought between the parties, Transit New Zealand (Transit) and the local hap> Ng,ti Naho, regarding a significant cultural "taniwha" (a M,ori mythological creature) and wetland site. The issue was widely publicised nationally and internationally in 2002 when it came to the attention of the media. The small wetland and culturally significant site (~30 m by 20 m) was located between the existing road and the Waikato River, adjacent to the planned Expressway. Transit NZ had also identified the vicinity as having —higher environmental value than adjacent land“ (Transit New Zealand 2002b) and there was a spring feeding a small remnant of kahikatea trees ( Podocarpus dacrydiodes ) œ a fact never presented by the media. —While a lot of the area we are working on is in swamp, this section over about 30 metres appears to be a spring which may be significant for a large stand of kahikatea trees, which need to be protected“ (Transit New Zealand 2002b), —The discussions to date with Ngati Naho had focussed on how the Expressway could be constructed past this section in a manner which preserved the nature of the site“ (Transit New Zealand 2002b).
    [Show full text]
  • Notes on the Early History of Wairakei
    Proceedings 20th Geothermal Workshop 1998 NOTES ON THE EARLY HISTORY OF WAIRAKEI R.S. 11Fiesta Grove, Raumati Beach, New Zealand SUMMARY These notes outline the major circumstancesand events influencing the decision to investigate the resources of New Zealand, together with problems faced in the early days of the development of They cover the period fiom 1918when the first suggestion for the investigationof the resource appeareduntil early 1953when Wairakei's development began in earnest. 1. INTRODUCTION would be more economical than the further use of water." 1924) 1.1. Early Interest in the Resource Eighty years ago, on 2 February, 1918, the Coincidentally, in 1925, a 250 generator was Masterton Chamber of Commerce requested the operating at the Geysers. However, no further Minister of Public Works to enquire into the development was being carried out because of the utilization of thermal energy for industrial and competition hydro and natural gas. other purposes, pointing out that the Italians were 1980). In other words, although now generating electrical energy fiom thermal districts the intensively developed geothermal field and were using it for lighting, and in the world, the Geyser's early development was munitions manufacture with great success. inhibited for much the same reasons as was New 1918). However, another four decades passed Zealand's. before New Zealand could say with some truth that it was using electricity fiom thermal The literature from this period is district "with great success". sparse, but one publication of significance is Geological Survey Bulletin 37. (Grange, 1937). Among a number of similar suggestions which This is the first detailed description of the geology appeared over the next two decades, perhaps the of the Zone and made an most unusual New Zealand's High important contribution to the subsequent Commissioner in London.
    [Show full text]
  • Historic Overview - Pokeno & District
    WDC District Plan Review – Built Heritage Assessment Historic Overview - Pokeno & District Pokeno The fertile valley floor in the vicinity of Pokeno has most likely been occupied by Maori since the earliest days of their settlement of Aotearoa. Pokeno is geographically close to the Tamaki isthmus, the lower Waikato River and the Hauraki Plains, all areas densely occupied by Maori in pre-European times. Traditionally, iwi of Waikato have claimed ownership of the area. Prior to and following 1840, that iwi was Ngati Tamaoho, including the hapu of Te Akitai and Te Uri-a-Tapa. The town’s name derives from the Maori village of Pokino located north of the present town centre, which ceased to exist on the eve of General Cameron’s invasion of the Waikato in July 1863. In the early 1820s the area was repeatedly swept by Nga Puhi war parties under Hongi Hika, the first of several forces to move through the area during the inter-tribal wars of the 1820s and 1830s. It is likely that the hapu of Pokeno joined Ngati Tamaoho war parties that travelled north to attack Nga Puhi and other tribes.1 In 1822 Hongi Hika and a force of around 3000 warriors, many armed with muskets, made an epic journey south from the Bay of Islands into the Waikato. The journey involved the portage of large war waka across the Tamaki isthmus and between the Waiuku River and the headwaters of the Awaroa and hence into the Waikato River west of Pokeno. It is likely warriors from the Pokeno area were among Waikato people who felled large trees across the Awaroa River to slow Hika’s progress.
    [Show full text]
  • Proc. 7Th NZ Geothermal Workshop 1985
    87 Proc. 7th NZ Geothermal Workshop 1985 ALTERNATIVES TO REIN,JIECTION IN WAIRAKEI H Peter Rothbaum Chemistry Division, DSIR ABSTRACT is required". The high cost of re-injection of geothermal Other-environmental effects from geothermal discharge waters is largely due to their silica discharges are raising the temperature of the deposition potential. One should ask if reinjection Waikato river by about 0.5OC, and discharging some of Wairakei discharge waters is really necessary to mercury from geothermal condensates. The mercury solve any environmental problems due to arsenic, concentrations in the Waikato River are generally hron, lithium, mercury or waste heat. below 0.02 mg/t, well below the 1 mg/t limit for Alternative strategies are: mercury in potable water, recommended by WHO. Nevertheless, mercury accumulating in the sediments Doing nothing, and continuing discharging appears to result in unacceptably high mercury the geothermal waters from Wairakei into concentrations in some fish in the Waikato River. the Waikato River. (Weissberg and Rohde, 1978). Chemical treatment to 'remove arsenic together with prevention of silica scaling It is sometimes claimed (Itoi et al., 1984) that and removal of waste heat. A successful reinjection will remove most environmental problems pilot plant will be de'scribed which achieves as well as recharging the geothermal field. However, these aims by a method particularly suitable some authorities believe that reinjection cools a to Wairakei waters. ' Alas-boron and lithium geothermal field in the short term. In addition remain. reinjection of discharge water will obviously not remove mercury der'ived from condensate. Overseas A more controversial suggestion involves experience has shown that the main problems of chemical treatment of Wairakei waters as in reinjection are associated with.the silica deposition No.
    [Show full text]
  • Waikato River & Hydro Lakes
    Waikato River & Hydro Lakes Image Josh Willison E A S T E R N R1 E G I O N Waikato River Fishery The Waikato River flows out of Lake Taupō, through the central north island and Waikato regions before joining the sea south of Auckland at Port Waikato on the west coast. It is the longest river in NZ at about 425 km in length. A considerable length of the Waikato River flows within the Eastern Fish & Game region, and that portion also contains 5 hydro lakes. The Eastern region starts below Huka Falls near Taupō and ends just below Lake Maraetai. The river and its hydro lakes offer a huge amount of angling opportunity and many parts seldom see an angler. There are opportunities for trolling, fly and spin fishing, and bait fishing is also permitted on the Waikato River and its lakes. In summer when water temperatures rise excellent fishing can be had at the mouths of tributary streams where fish tend to congregate seeking cooler water conditions. As well as holding rainbow and brown trout the river and hydro lakes also contain other fish species in various areas including pest fish such as Rudd and carp and in some places catfish. If any of these species are caught anglers should kill them and dispose of them carefully and never transfer them to other waters. As the river and its lakes are used for hydro-power generation the water levels can fluctuate dramatically and without warning and due to this care is needed when on and around the river.
    [Show full text]
  • Te Mihi Power Station Contact Energy | Investor Day | 6 November 2018 6 November 20181 Disclaimer
    2018 Investor day Te Mihi Power Station Contact Energy | Investor day | 6 November 2018 6 November 20181 Disclaimer This presentation may contain projections or forward-looking statements regarding a variety of items. Such forward-looking statements are based upon current expectations and involve risks and uncertainties. Actual results may differ materially from those stated in any forward-looking statement based on a number of important factors and risks. Although management may indicate and believe that the assumptions underlying the forward-looking statements are reasonable, any of the assumptions could prove inaccurate or incorrect and, therefore, there can be no assurance that the results contemplated in the forward-looking statements will be realised. EBITDAF, underlying profit, free cash flow and operating free cash flow are non-GAAP (generally accepted accounting practice) measures. Information regarding the usefulness, calculation and reconciliation of these measures is provided in the supporting material. Furthermore, while all reasonable care has been taken in compiling this presentation, Contact accepts no responsibility for any errors or omissions. This presentation does not constitute investment advice. Contact Energy | Investor day | 6 November 2018 2 Agenda 1 Wholesale James Kilty 2 Geothermal advantage Mike Dunstall 3 Geothermal options James Kilty 4 Closing remarks and Q&A Dennis Barnes Contact Energy | Investor day | 6 November 2018 3 Wholesale – James Kilty Contact Energy | Investor day| 6 November 2018 Wholesale James Kilty – Chief Generation and Development Officer 1 Environment and strategy 2 Organising for success 3 Wholesale market outlook Contact Energy | Investor day | 6 November 2018 5 About Contact * - All figures as at June 30 2018 Contact Energy | Investor day | 6 November 2018 6 Sustainability is business as usual Sustainability is about integrating diverse interests into our strategy to ensure long term People value creation.
    [Show full text]