SUB-REGIONAL WORKSHOP ON WIND ENERGY UTILIZATION

23-27 June 1997

Harald Scholzell SOPAC Secretariat

August 1997 SOPAC Miscellaneous Report 253

[3]

TABLE OF CONTENTS

Page

Introduction ..................................................................................................................... 4

Workshop Program .................................................................................................. 4

Wind Energy ................................................................................................................. 4

Wind Energy in the South Pacific ......................................................................... 6

The Cook Islands Project .......................................................................................... 6

Workshop Evaluation ................................................................................................... 7

Appendix 1 - List of Participants ............................................................................... 8

Appendix 2 - Workshop Programme ........................................................................ 9

Appendix 3 - Executive Summary on Wind Energy Project in the South Pacific ..... 10

Appendix 4 - Draft Feasibility Report on the Cook Islands Project .................... 11

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Introduction

As part of the Energy Counselling Project the Forum Secretariat is providing to the South

Pacific through its Energy Division, a sub-regional workshop was held at the Forum

Secretariat on the utilization of wind energy.

The course was presented by eight resource speakers: Mr. Paul Gipe, Paul Gipe &

Associates; Mr. Ian Piggin, Environmental Meteorological Consultants; Mr. Graham White,

Garrad Hassan Pacific Ltd.; Dr. Paul Ebert, Energy Technology and Environmental Branch

Western Power Corporation; Mr. Niels Vilsboll, Folkecentre for Renewable Energy; Mr. Jens

Carsten Hansen, RISO National Laboratory; Mr. Bruno Crux, SOPRONER Consults.

Fourteen participants from Cook Islands, Vanuatu, Niue, Tonga and Fiji and seven

observers attended the workshop. A list of all participants is attached as Appendix 1.

SOPAC's presence was justified through its continuing interest in assisting the member

countries assess resources for renewable energy.

Workshop Program

The workshop was a follow-up to a former workshop held in 1993 to implement a wind

resource assessment project with five participating countries (Cook Islands, Vanuatu, Niue,

Tonga and Fiji). The workshop was to evaluate and discuss the results of the-two year

project by providing a vast overview about the history, state-of-art and future development of

wind turbines accompanied with the basics of wind resource assessment and their statistical

evaluation. The workshop was completed by several case studies and applied presentations

of professional resource persons. The program can be found in Appendix 2.

Wind Energy

In Modern Physic term wind energy utilization results in the transformation of wind’s

horizontal kinetic energy into electric energy by wind turbines.

Wind energy was utilized thousands of years ago to drive simple water lifting devices for

irrigation purposes. In Northern Europe wind-driven mills have been used for centuries.

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Wind energy utilization began in the fifties with prototypes of all thinkable shapes and none

of which came close towards economical electrical energy production. This changed

dramatically with the first oil crisis in the early seventies leading to significantly higher energy

production costs for fossil energy fuels. Pioneered by fossil resource scarce Denmark and

investors in California, USA, wind energy changed its image from an ”alternative technology

for freaks” to a reliable and efficient way producing electric energy by environmentally benign

means. The latest push for the wind energy high-tech industry came from the German

government which introduced the “Energy Feeding Law”. The law secures wind-produced

energy prices and allows economic energy production through wind by internalizing external

costs for burning fossil fuels.

A crucial part in using wind energy is the assessment of the resource. At least an entire year

of anemometer measurements is necessary to predicting the yield. Experienced personnel is

required either for the location of the anemometer towers or the interpretation of the

measured data. The main output of assessment data is a mean wind speed at different

heights and its directional distribution over the year (wind-rose). Sophisticated software can

nowadays assist in extrapolating measured data from one location to another when the data

is to be considered representative for the new location. Once determined a suitable location

for wind turbines with a likely yield expressed in mean wind-speed and Energy Density can

be set. The sizing of the systems depends mainly on the specifications required by the

Electric Utility.

Today’s wind turbines are available from 100 W power output to 1.5 MW power output. Its

size ranges from small portable systems for battery charging purposes to gigantic turbines

with tower heights up to 60 meters and rotor diameters up to 50 meters with an overall

weight up to 25 tons. They can work as stand-alone systems for applications on sailing boats

and in remote villages with no grid connection. On the other hand they can be integrated in a

grid and substitute other electricity generators, i.e. diesel generators, whenever the weather

conditions allow that. They can be located at end-points of power grids as a “voltage

booster” to avoid high voltage drops due to long cables or they can be clustered to large

wind-farms with an power output of hundred’s of MW.

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Wind Energy in the South Pacific

To assess the wind resources in the South Pacific the Energy Division of the Forum

Secretariat as the executive organization initialized in 1993 an investigation program. The

program included gear purchase such as towers, anemometers, data logging devices and

Notebooks, training and consultancy for the five participating countries Cook Islands,

Vanuatu, Niue, Tonga and Fiji. The countries were commissioned to collect the data and

forward them to New Zealand for further evaluation. Data collection began in November

1994 and was fairly complete while data loss occurred only due to equipment failures in a

negligible magnitude.

According to the evaluation report Niue has the biggest wind resource with about 5.9 m/s

mean wind speed (which on the global scale is a relatively low value) followed by Fiji with a

mean wind speed of 5.7 m/s and the Cook Islands with about 5.5 m/s respectively. The

Executive Summary of the evaluation report is attached as Appendix 3.

Regarding general applications of wind turbines in the South Pacific Small Island Countries

(SIC) their use in big wind farms is unlikely due to the high initial investment costs and the

often fragmented geography. More promising seems their use in hybrid systems as planned

in Fiji where eight 750 kW together with solar panels and a back-up diesel generator are

going to be installed until October 1997 as a stand-alone system. On some main islands of

SIC's,e.g. Cook Islands, the use of medium size (~ 200 to 300 kW) wind turbines as

substitutes for diesel generator looks favorable and for small wind turbines e.g. in rural

electrification schemes or for water pumping purposes a range of applications is possible.

Therefore more interest should be shown in assessing the resource. Consequently the

decision of the Forum Secretariat to follow-up the initiated project is commendable.

The Cook Islands Project

The Danish Government is considering the installation of a 200 - 300 kW wind turbine on

Rarotonga, Cook Islands through the Pacific-Danish Environmental Education & Action

Programme. The wind-turbine would be a sub-station in the existing grid and major savings

off the use of diesel fuel are expected. A feasibility study was carried out by the Danish

Consultant Jens Carsten Hansen. The study found four promising sites in the north-eastern

part of Rarotonga. Although simulation analysis concerning mean wind-speed and energy

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density look favorable some concerns about the siting still persist, especially the lack of good

access roads, the size of the disposable area, the geo-technical constraints and the

environmental impact of the entire project raised major concerns among the participants and

the consultants. It was therefore recommended that experienced consultants, if possible

regional agencies, should undertake further investigations on the above mentioned issues

before a final decision could be made. A draft feasibility report is attached as Appendix 4.

Workshop Evaluation

The Workshop organizers and presenters arranged a formal and informal evaluation of the

Workshop and of the need for future activities on the subject of wind energy especially the

follow-up of the already initiated assessment program.

It was generally agreed that the participating countries should continue with the

measurements. If possible and budgets permitting, they should change the location of the

measurements. The related costs would not be covered by the Forum Secretariat but

technical expertise could be provided.

Neither the measuring equipment nor the collected data belongs to the participating country.

Interested parties can have access to the data on request. No special fee would be charged

but variable costs would be covered.

The Workshop was well received and covered the areas of expertise required by many of

the participants for future schemes or in-country scheme proposals.

SOPAC's involvement in this aspect of energy generation, the continuing links with the

Energy Section of the Forum Secretariat, and the collaboration with member country staff

were the major benefits. It should be recognized that SOPAC's involvement in the future in

wind-energy projects is expected.

The Course Manual is located in the SOPAC Library for future reference.

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Appendix 1 - List of Participants

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..

-= FORUM SECRETARIAT

~ Energy Division, -~-

WIND ENERGY UTILIZATION WORKSHOP-~

Forum Secretariat Headquarters .-

--Suva23- 27 June 1997 -

--LIST OF P ARTICIP ANTS

COOK ISLANDS

Mr Tomavao Wichman Mr David Akaruru Mr Rino Tangi MarekoRenewable Energy Manager Energy Ofncer Technical OfficerMinistry of Energy Ministry of Energy Te Aponga Uira Tumu-Te-PO Box 2104 PO Box 129 VarovaroRarotonga Rarotonga PO Box 112 -Cook Islands Cook Islands RarotongaPhone: (682) 29998 Phone: (682) 24 484 Cook IslandsFax: (682) 29 998 Fax: (682) 24 485 Phone: (682) 20 054e-mail: twichman @ gate Fax: (682) 21 944

Polly.co.ck

FIJI

Mr Rakesh Singh Mr Noa Seru Mr Deepak Sa11aySenior Technical Officer Scientific Officer DSM EngineerDepartment of Energy Department !;?fEnergy Fiji Electricity AuthorityPrivate Mail Bag Private Mail Bag SuvaSuva -Suva FijiFiji Fiji Phone: (679) 664 555 -

Phone: (679) 386 355, Phone: (679) 386 355 Fax: (679) 664 787Fax: (679) 386 301 -Fax: (?79) 386 301

-Mr Mohammed YunusSenior EngineerPublic Works DepartmentPrivate Mail Bag -Suva --

FijiPhone: (679) 312277 .,.Fax: (679) 301198

- ---

, -.~, ---

-

NIUE

Mr Speedo Retutu Ms Gloria Talagi Mr Paul Johnson -

Network Manager' Assistant Economist General ManagerNiue Power Corporation Department of Economics Niue Power CorporationBox 198 and Development- Premiers Box 198 ,Alofi Dept. Alofi -

Niue Alofi NiuePhone: (683) 4119 N-iue -Phone: (683) 4119Fax: (683) 4385 Phone: (683) 4148 Fax:: (683) 4385 -

Fax: (683) 4148 e-mail: pjay@ voyager.co.nz--

TONGA

Mr Solomone Niusini Mr Tevita Tukunga Mr Talanoa ' Aholahi

Chief Generation En~ineer Energy Officer Energy TechnicianTonga Electric Power Board Energy Planning Unit Energy Planning UnitP.O Box 47 Ministry of Lands, Survey Ministry of Lands, SurveyNuku'alofa and Natural Resources and Natural ResourcesTonga Box 5 Box 5Phone: (676) 23311 Nuku'alofa Nuku'alofaFax: (676) 23632 Tonga Tonga -

Phone: (676) 23611 Phone: (676) 23611Fax: (676) 23216 Fax: (676) 23216

VANUATU -

Mr Moli JanjeaRural Energy OfficerMinistry of NaturalResources ...

-Private Mail Bag 067 --Port-Vila -'

VanuatuPhone: (678) 23584Fax: (678) 23586 --

RESOURCE SPEAKERS -

Mr Paul Gip~ Mr Ian Piggin Mr Graham WhitePaul Gipe & Associates Enviromet Meteorological Director

-208 S. Green St., #5 Consultants GarradHassan Pacific LtdTehachapi 31 Rothesay Avenue -PO Box 44 -157:CA 93561 East Malvem PT. ChevalierUSA Victoria 3145 AucklandPhone: (1805) 822 9150 Australia New ZealandFax: (1805) 822 8452 Phone: (613) 9572 2587 Phone: (649) 849 6600

Fax: (613) 95718939 Fax: (649) 849 6200

e_-mail: white@gh-, pacific.co.nz -

-

Dr Paul Ebert Mr Niels Vilsboll Mr Jens Carsten HansenEnergy Technology.-and Mechanical Engineer Senior ScientistEnvironment Branch Folkecentre for Renewable Riso National Laboratory -

Western Power Corpbration Energy PO Box 49363-365 Wellington St Kammersgaardsvej 16, DK-4000 RoskildePerth Sdr.Ydby Denmark-WA 6000 DK- 7760 Hurup~Thy Phone: (45) 46 77 4677Australia Denmark --Fax: (45) 46 77 5083Phone: (61) (8) 93264600 Phone: (45) 97956600 -e-mail:Fax: (61) (8) 93264600- Fax: (45) 97956565 carsten.hansen@risoe.dke-mail: paul.ebert -

@wpcorp.com.au --

Mr Bruno Crux Mrs Veronique SchmittTechnical Project Manager / Interpreter / TranslatorTechnical Project Engineer- SOPRONERSOPRONER 98846 Noumea Cedex

: 98846 Noumea Cedex New Caledonia

New Caledonia Phone: (687) 283480Phone: (687) 283480 Fax: (687) 288344FaX: (687) 288344

OBSERVERS

Zane Murray Mr Partrick Amini Miss Vandana NaiduSales Manager Executive Director Physics Technology andDesignPower NZ Ltd Pacific Power Association Energy TeamWellington Suva USPNZ Fiji FijiPhone: (644) 495 8659 Phone: (679) 306 022 Phone: (679) 313 900Fax: (644) 471 2224 Fax: (679) 302 038 Fax: (679) 314 007e-mail:- --

murrayz@designpower.co.nz

Mr Ed Burke Mr Harald Scholzel Mr Leonard GreerProject Manager Hydraulic Engineer PICHTR -

SOP AC -WASP SOP AC -WASP 2800 Woodlawn DrivePrivate Mail Bag Private Mail Bag Suite 180Suva -Suva HonoluluFiji -Fiji Hawaii 96822-1843Phone: (679) 381 377 Phone: (679) 381 377 USA -Fax: (679) 370 040 -Fax: (679) 370_040 Phone: (808) 539 3852 ..;;

e-mail: harald@sopac.org.fj -Fax: (808) 539 3899http://www.sopac.org.fj/wasp e-mail:

lsgreer@ilcaikala.pichtr.htdc.org

--c

,

;-;~ ~

Mr David Saouzanet --.

SPIREP.D Box 11530 -

98709 Mahina -TahitiFrench PolynesiaPhone: (689) 48 2020 -

Fax: (689) 4828 17 -

FORUM SECRETARIAT --

Mr Dick Goldberg Mr Solomone Fifita Mrs Melania TunidauDirector Adviser Divisional Assistant (Admin)Energy Division Energy Division Energy DivisionForum Secretariat Forum Secretariat Forum Secretariat

-Private Mail Bag Private Mail Bag Private Mail BagSuva ~ Suva Suva

Fiji Fiji FijiPhone: (679) 312600 Phone: (679) 312600 Phone: (679) 312600Fax: (679) 303 828 Fax: (679) 303 828 -Fax: (679) 303 828

e-mail: di ck@forumsec.ngo.fj

Miss Hamida RazaDivisional AssistantEnergy DivisionForum SecretariatPrivate Mail Bag .,.

SuvaFijiPhone: (679) 312600Fax: (679)_303 828 ...

.;

--

.

",...

~

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Appendix 2 - Workshop Programme

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..FORUM SECRETARIAT --

~~ .SUB-REGIONAL WIND ENERGY WORKSHOP

DRAFT PROGRAMME(Forum Secretariat, Suva: 23-27 June, 1997)

Monday, 23 June -

8.30 -9.00 -OPENING -

WORKSHOP INTRODUCTION

RESOURCE ASSESSMENT9.00 -10.30 : The basics of resource assessment (Ian Piggin)

: Site Selection (Ian Piggin)~ : Equipment, installation, relocation (Ian Piggin)

10.30 -11.00 MORNING TEA11.00 -13.00 : Equipment maintenance & calibration (Ian Piggin)

: Results of Wind and Solar monitoring (Ian Piggin): Data acquisition and analysis (Ian Piggin)

13.00 -14.00 LUNCH14.00 -15.00 : Quantification of sites wind speed (Graham 'White)15.00 -15.30 : AFTERNOON TEA15.30 -17.00 : Wind resource estimation and siting of wind turbines (lens

Carsten Hansen)

Tuesday, 24 June INTRODUCTION TO AND THE FUNDAMENTALS OFWIND ENERGY (Paul Gipe)

8.30 -9.30 : Overview -Wind Energy Comes of AgeWorldwide status, benefits, impacts, mitigation and

compatibility.9.30 -10.30' : Fundamentals of Wind Energy

;. Power in the wind, wind speed, and annual energy output.

Speed distributions, wind speed and height, andanemometers.

10.30 -11.00 MORNING TEA11.00 -11.30 : Estimating annual energy output11.30 -12.00 : Introduction to Wind Technology

Wind Energy conversion devices, HA WTs & V A WTs, andcontrols. .

12.00 -13.00 : Medium-sized Wind Turbine Drive Trains. Conventional,int~grated, and direct drive trains.

13.00 -14.00 LUNCH14.00 -15.00 : Wind Energy Development in Denmark

small wind power systems and the NGOs (Niels Vilsboll)15.00 -15.30 AFTERNOON TEA15.30 -17.00 ..Large machines/ wind farms -status and development

(lens Carsten Hansen)

Wednesday, 25 June FORMS OF WIND ENERGY GENE~TION (Paul Gipe)8.30 -9.30 : Small Wind Turbines

Distributed wind systems, micro and small wind turbines.Overspeed. controls, blades, and generators

9.30 -10.30 : Towers and installation of small wind turbinesCyclone proof towersSmall wind turbine drive trains

-10.30 -11.00 MORNING TEA: IJ-,iJO -12.00 : Form of Generation

Remote Pow-er Systems, electrification, and interconnection12.00 -13.00 : NZ case study: Small Wind Turbine for RAPS (Graham

-White) -

13.00 -14.00 : LUNCH14.00 -15.00 : Wind Energy Economics: a balancing act (Paul Gipe) -

Price, cost of energy, economics15.00 -15.30 AFTERNOON TEA15.30 -16.00 : Elements of a wind plant. Spacing.16.00 -16.30 : Wind energy and the human environment -

Noise, birds, occupational hazards, and maintenance16.30 -17.00 : Conclusion: Wind energy comes of age. Wind works.

Thursday, 26 June PRACTICAL EXERCISES8.30 -9.30 : Demonstration of the WAsP software (lens Carsten

Hansen)9.30 -10.30 : Wind analysis practical exercise (Ian Piggin)10.30 -11.00 MORNING TEA11.00 -13.00 : Wind analysis practical exercise (Ian Piggin)13.00 -14.00 : LUNCH14.00 -15.00 : Maintenance practical-exercise (Ian Piggin)15.00 -15.30 : AFTERNOON TEA15.30 -17.00 : Maintenance practical exercise cont'd (Ian Piggin

Friday, 27 June CASE STUDIES & WORKSHOP CLOSING8.30 -9.30 : Wind energy in island grids: Experienc~s from Cape Verde

(lens Carsten Hansen)9.30 -10.30 : A grid connected wind turbine on the small Brazilian island

of Fernando de Noronha (Niels Vilsboll)10.30 -11.00 MORNING TEA11.00 -12.00 : The findings of the feasibility -study on the Pacific-Danish

Environmental Education & Action Programme (lensCarsten Hansen)

12.00 -13.00 : The New Caledonian Wind Power Experience (Bruno Crux& Veronique Schmitt)

13.00 -14.00 LUNCH14.00 -15.00 : Western Power's Ten Mile Lagoon Wind Farm (Dr Paul R

Ebert)15.00 -16.00 : General discussions on the future direction and priority for

~ --regional wind power activities (FSED, Resource People &

participants): Workshop Conclusions, Recommendations & Evaluation

~: Closing (FSED)

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Appendix 3 - Executive Summary on Wind Energy Project in the South Pacific

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EXECUTIVE SU1\tli\fARY

Following e~pressions of interest frOln several Forum Island Countries for assistance ina.ssessjng their wind resource, the Forum Secretariat In.itiated the Southern Pacific Wind andSolar Monitoring Proj~t in 1993. The 'goal of this project was to e.5tablish, at a suitable .'Jite ine.ach participating country. a wind and solar radiation monitoring system for evaluating thepotenti.al of wind power far main grid electricity generation, and to record and analyse wind andsolar energy data for a period of two years. The five coun.tries were Cook Islands ~1Rarotonga). Fiji (on Viti Levu), Niue. Tonga (on Tongampu) and Vanuatu (on Efate). ~

A reconnaissance visit was made to e~h country in November and December 1993. to identifyMd rank possible sites and select the optimum one for monitoring the wind resource. Factorsconsidered in making the decision were anticipated wind regime. exposure, topography,accessibility, available area, ground conditions, security trom vandalism. and proximity topower grid as well as nearby residences.

Organisation of leases for all the preferred sites, and fabrication and testing of the custom-madedata loggers took a1most one year. so installation was not undcrtakcn until November andDecember 1994. Each country was visited for six to nine days tQ insW1 all equipment and trainpersonnel in procedmes for operating and maintaining the j.nstroments as well as downlo3dingand analysing the collected data. -

Followmg pre-deployment calibration in a wind tunnel. heavy duty anemometers wel'e installedon towers at a height of 10 m (as well as 21 m on Fiji). Calibration of the anemometel"S in theSaine wind tunnel after deployment vcrificd the accuracy of the sensors throughout themonitorjng period. and ensUfed confidence in the recorded wind speed data. Silicon cellpyranomcters were also moUnled near the top of the tower, on an arm long enough to preventthe anemometer on top from casting a shadow over the sensor at the sumrner solstice. The dataloggers record hourly values of average, maXImum, mi.11imwn and standard deviation of windspeed, average and standat"d de"liation of wind direction. and hourly ti>tals of solar radiation.T~ data logger and tile batteries which power it are housed inside an ins-rrumeD.t 5heIter. whichis bolted to a concrete pad _near the base of the tower on Efate, Niue, Tongatapu and Viti Levu,and to the tower on Rarotonga. I

The towers and anemometers have been chosen to withstand-the corrosive coastal envil"Onmentas well as c~clonjc winds (up to 70 m/s).

Data is down]oaded from the loggers at regular intervals using a laptop computer-Results from --monitoring for two yeaJ:S are summMised below. -

Wind data recovery w~ 100% on Cook Islands and Niue and 97 -98% on Fiji. Data loggermalfunctions were respoMible for the loss of more than 10% of data on Tonga, and operationaJproblems resulted .in the loss of 17% of data for Vannatu!-

Winds in all countries were predominantly from the northeast, east and southeast, with their Joccurrence being 85% on Fiji, 80% on Niue, 75% on Tonga and Vanuatu an

'M

..D RAFf

The fas~t gust recorded in anycounny during 1995 and 1996 ~'aS 25 m/s at Rarotonga. whe:nit was influenced by a low pressure, cell on 9 April 1995. The highest hourly and dailyaverages were 17.7 DJ/s and 14.0 m/s at Rarotonga on the same day. The fastest monthlyaverage speed was 8.4 rn/s at 21 m on Fiji in August. Dwing extendcd monitoring on Fiji.Tropical Cyclone "GavIn" tracked north of Viti Levu on 7 March 1997. On this day. at 10 mand 21 m respectively at Vunatovau, the fastest gUSt5 were 42 m/s and 34 mis, the highesthourly mmges were 22.8 and 22.5 mis, and the daily averages were 13.8 m/s and 14.3 mls.

Comparison of wind speed data during 1995 and 1996, with long-term averages for the airportsat Rarotonga, Nadi on Viti Levu. Fua'amotu on Tongatapu and Bauerfield on Efate. indicatethat s~ throughout the region in 1995 a1ld 1996 were generally slower than average, beingfaster only in the months oflanuary, August and September in 1995 and June and October jn1996. The annual average for tWo years was_lower thAn the six-year average by about 5% atRarotonga and Bauerfield, 7% at Nadi and 10% at Fua'amotu. This suggests that long-termannual average speeds could be 5 -10% faster than the averages recorded. and wind energyfluxes might be 15 -25 % higher.

Calculated annual averages of wind energy flux: at 10m were 220 W 1m 2 for Niue, 190 W 1m2for Fiji. 180 Wlm2 for Cook Islands, 120 W/m2 for Vanuatu and &0 W/m2 for Tonga. Thevariability in ro m wind energy flux, the coefficient of variation (equal to the standard deviationdivided by the mean, expressed as a percentage) was high, increasing from 44% on Tonga to46% on Cook Islands. 48% on Niue, 50% on Fiji (10 .m) and 57% on Vanuatu.

The annual average daily solar radiation was more man 4800 Wh/m2 on Fiji and 4600 Wh/m.2on Vanuatu. 4600 Wh/m2 on Niue, more than 4500 Whlm'- on Tonga, and 4200 Wb/m2 onCook Islands. Data losses on Fiji, Tonga and especially Vanuatu, added a measure ofuncertainty to their calculated annual averClges. -

In tenns of wind resource, two years of monitoring showed Niue to be the best site forharvesting wind energy sjnce it.~ average wind speed and energy flux- were highest and itsenergy t1n~ was dIe fairly consistent throughout the year; Fiji aDd Cook Islands werc next bestfollowed by Vanuatu and Tonga. Further wind prospecting may indicate better wind resoUrcesat other sites in these colmtries.

[11]

Appendix 4 - Draft Feasibility Report on the Cook Islands Project

[MR253 - Scholzel]

.

Dra )11 -Alme.\" -I

ANNEX 4: Technical analysis. Raroton2:a

1. Methodology

a--A wind farm feasibility study should typically involve

a) wind farm site selectionb) analyses and assessment of all relevant aspects on a sketch design level sufficient to establish

whether the project is technically feasible and sustainable as well as to make estimates ofinvestment budget and wind energy production

c) an evaluation and recommendations

This study will analyse the proposed demonstration wind turbine and recommend on the size ofwind farm capacity that can be installed in the power system. The comparison of candidate sitesdoes not require the full detailed analysis of all aspects. Conclusions regarding site selectionis drawn from a subset of criteria and analyses sufficient for the relative comparison betweensites. The sketch design and feasibility study is carried out for the selected wind farm site

only. :c-

The study will go through the three main aspects ~riefly described below:

.Identification and selection of wind farm site:0 Availability of land, human resources and infrastructure0 Wind resources0 Power system interconnection and operation0 Adaptation to the national and local development, physical surroundings and planning0 Suitability for project objectives

.Analyses and assessments:0 Wind resources and physical characteristics -data, extrapolation, analyses, statistics0 Wind turbine structural loading and safety -standards and requirements0 Wind turbines -types, sizes and design0 Electricity demand and load forecasts0 Wind farm sizing WId power system configuration0 Wind farm layout0 Wind farm energy production estimation0 Electric grid connection -standards and requirements0 Power system operation and control system communication0 Environmental impact -visJ,lal, noise, wildlife, fuel savings, emissions (CO2, Nax, SO2,..)0 Physical planning -existing and new requirements for the site.and-surrotmdi_ng land0 Requirements'in general of nearby installations -e.g. airpo,rtsi obstacle limits -

0 Electromagnetic interferencea Climate in general.. temperature, humidity, etc., and its impact on design requirements

e.g. regarding corrosion protection, cooling, tropicalisation, etc. -;0 Soil conditions0 Access to site0 Erection -facilities, conditions, need for landscaping0 Operation and Mainten~ce

? Dra Feasihr7iIV Re rt -Armex -I

.Evaluation and recommendations:a Compatibility with project objectivesa Locaf physical planning aspectsa Potential energy production from wind farma Environmental impacta Economic and financial consequencesa Sustainability of the projecta Project risks and uncertainties

2. Candidate sites

Coastal

The candidate sites for installation of wind turbines are the coastal plane on the east coast ofRarotonga -between the meteorological measurement station at Ngatangiia and Pue, which willbe the coastal locations expected to have the highest wind speeds in periods with winds from theprevailing wind directions.

iv/ountain slopes..

Candidate sites on mountain slopes well exposed to winds from prevailing east and southeastwinds have been identified as indicated in figure 1.

Figure 1 Digitized map of Rarotonga with hight contours and indication of candidate sites forthe demonstration wind turbine.

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3 Draft Feasibilty Report - Annex 4

3. Availability of land, human resources and infrastructure

Land

Most of Rarotonga is covered with natural forest or cultivated land with many trees and palms. Furthermore, the density of habitation is very high in the coastal plane and the population is growing rapidly. Practically nobody live in the mountains.

Wind farm sites must be chosen so that they do not interfere with any other future development with a higher priority and/or potential higher value for the country the next 20 years.

A wind turbine of the 200 - 300 kW size would require a safety and noise buffer zone of some 150-300m around it, within which no habitation, hotels, hospitals, schools, offices or other noise sensitive activities should be located. Furthermore, unobstructed wind flow at least from the prevailing E and SE wind directions is essential in order to obtain the highest annual wind energy production. Restrictions in the future use of neighboring land may be necessary, ensuring that no or little trees or major buildings are found within 2-5 km to E and SE. For sites on mountain hilltops or ridges, this restriction will not apply to the same degree as long as no obstacles exist on the hilltop itself, since the wind turbine rotor will be in a quite elevated position compared to any surrounding obstacles in the nearby valleys. The surrounding land in both flat coastal plane and in mountains can be used for any purpose that does not obstruct the wind flow, including agriculture with low crops and gazing of cattle.

Land in the coastal plane is a scarce commodity needed for habitation, agriculture and tourism. Furthermore, any wind turbine placed near to the sea will be exposed to a highly corrosive environment which will mean high costs for corrosion protection and/or shorter lifetime of equipment. Considering the area of land needed, the Team recommends to investigate other possibilities carefully before considering building any wind turbine or wind farm in that area.

In the mountain areas, the Ministry of Works, Environment and Physical Planning (MOWEPP) informs that land can be made available, although also here land may be private and land acquisition is a complicated and lengthy process and land availability is subject to project approval by Cook Islands Environment Service based on a positive result of the Environmental Impact Assessment required.

A preliminary assessment has been made by the MOWEPP and the Ministry of Energy which confirms in letter of 13 June 1997 that land at the proposed candidate sites - A, B1 and B2 - in the mountain slopes can be made available for the project.

These sites seem rather small in size and the number of wind turbines that can be accomodated in each site is limited. Choosing a site with a view to the possibilities for future expansion of the

wind farms would point at one or two mountain ridges at somewhat higher elevations. These areas’ accessibility etc. have not been analysed, but a land-owner has expressed to the Team the

willingness to make land in one of these areas available.

All in all, suitable land seems to be available in either the lower or the higher elevations of the slopes to the NE in Rarotonga. The Team recommends that the feasibility study is carried out assuming availability and accessibility of the slopes in the lower elevations only, i.e. sites A, B1 and B2.

~

~~~

4 Draft Feasibilty Report - Annex 4

The feasibility study Team recommends that further analyses are made regarding the sites in higher elevations (site C) before the project implementation is started.

Procedure for obtaining an agreement with the land-owner of the chosen site should be allowed for in the project time schedule during project implementation.

The cost of land acquisition, access road and landscaping of the site has been estimated by the Ministry of Works as input to the economic analysis of the feasibility study.

Human resources, local works and O&M

The Team has found that human resources with the necessary skills and experience for undertaking project - implementation as well as operation and maintenance of the demonstration wind turbine exist very few other places than in the electric utility - Te Aponga - which given the necessary training can draw on the experience from similar machinery in the power station. A few other major private and public undertakings existing in Rarotonga today would possess the necessary background, e.g. Ministry of Works.

Contractors for construction works exist. It has been indicated that Te Aponga might undertake the electric works themselves if the job were be undertaken today, but whether this will be the situation after privatization is not known. Civil works would have to be carried out by sub-contractors - private and/or the Ministry of Works. Ready made concrete would be brought to the site in mixing plants’ trucks.

Infrastructure

Harbor facilities allow for landing 40' open top containers. These will probably have to be reloaded to minor trucks in the harbor in order to be able to go by the on the access road to a mountain site.

Information and documentation of available crane capacity (Make, type, carrying capacity in tm and maximum lifting height) has been requested. No clear answer as to the available crane capacity has been obtained yet. If crane capacity is not sufficient for erection a self- erecting wind turbine with the necessary additional equipment both for erection and for handling of major items during maintenance will have to be procured, which means a significant additional investment.

Roads in Rarotonga are mainly in the coastal plane, where roads are available and access is easy all around the island. The critical part for transportation of equipment would be to construct a road up to slopes of a mountain to one of the sites A, B1, B2 or C. It has been confirmed by the Ministry of Works in letter of 13 June 1977 that a road with a maximum inclination of 1:9 can be constructed to any of these sites, and that the minimum curvature will be enough to enable that the cranes and trucks available in Rarotonga can drive to any of the sites. The Team finds that some further specifications of the roads and indication of the routing are needed in order to understand and describe in a tendering process to potential bidders the exact working conditions that a wind turbine supplier will meet in Rarotonga. Detailed specifications will influence the price.

Draft Feasibility Report - Annex 4 5

4. Environmental Impact Assessment (EIA)

For any project in Rarotonga, an EIA shall be carried out, ensuring that valuable, rare and endangered species of animals (incl. migratory animals) and plants of the natural forest are protected and conserved as well as protection against and control of soil erosion, all in accordance with the Rarotonga Environment Act 1994-95, established 31 July 1995 to provide for the conservation and management of the environment of the island of Rarotonga in a suitable manner. Part II, Environmental Impact Assessment, states that no project shall be undertaken which is likely to significantly affect the environment except in accordance with a project permit. Such a project permit is needed for this project. Filled in project application forms with an attached Environmental Impact Assessment report, setting out details as specified in sub-section 3, have to be forwarded to the Cook Islands Environment Service.

It is assumed that the EIA is to be carried out by a Cook Islands consultant or authority as a local contribution to the project financed by the Cook Islands. The EIA shall in addition to the above be approved by the Danish consultant assigned by the Danish Government for the supervision of the project implementation. The Danish consultants obligation is to ensure that Danish Government requirements and policies in this respect are satisfied.

5. Power System

The electric 11 kV transmission network runs around the island in the coastal plane (70 mm2 AI) and across the island from the power station to the south coast (150 mm2 A1). The network is operated as a radial grid, which is open in two points in the southern part of the island. A number of substations are available as connection points for a wind turbine. The distance from any of the proposed sites to such a connection point is of the order of 1 km, and the maximum distance between the wind turbine and the power station would be less than 10 km.

Preliminary analysis of the power system on Rarotonga indicates that a single wind turbine of a size between 200 kW and 300 kW can be connected to the grid at one of the existing sub- stations or switches without any need for network reinforcement. The voltage increase from the power station to a 300 kW wind turbine equipped with capacitors for 100% compensation of the reactive power consumption and connected via a 10 km long 3 x 70 mm2 A1 cable would be approximately 1 % at maximum wind power output if there were no load on that radial.

The detailed design of the connection at the sub-station will depend on the site and the actual sub-station chosen, since they are different. Sketches and suggestions have been provided by Te Aponga.

The daily load pattern is shown in Figure 2. The minimum load during normal operation on Rarotonga is approximately 1300 kW, occurring in the early morning. The peak load is about 3000 kW in week-days and somewhat lower during weekends.

A list with a brief specification of the power stations diesel gen-sets is shown in Table 1. ~

rt -A/me.\" -I

Table 1 Diesel gen-.,;ets in Te Aponga power station -Rarotonga -capacity and .5tati.,;tic.\'of April/997 .

Eng. year capacity average availability capacity factor load factorNo. commis- nominal/de-rated specific fuel May97 May97 May 97

sioned (kW) consumption (\vhile in senice) (in the pcrilXi)

(VkWh)1 Duvant- 1991 2100/2000 0.260 77% 70% 40%

Crepelle2 Duvant- 1991 2100/2000 0.260 81% 70% 32%

Crepelle3 Mirrless- 1990 1700/1600 0.271 94% 56% 10%

Blackstone4 Lister- 1979 600/500 0.271 99% 62% 25%

Blackstone5 Lister- 1979 600/500 0.271 99% 80~o 28%

Blackstone

Engine No.1 or 2 is run as base-load units. Next unit is started at 1800 kW leaving a spinningreserve of 10% of the capacity. Technical minimum load of the engines is estimated to be 25-30%. Running-in of machines starts at 20%, i.e. 400 kW.

At the minimum load of 1300 kW, a 300 kW wind power output would reduce the load onthe largest diesel to 1000 kW, which is welt above its technical minimum load. Theoperational strategy for the diesel power plant should be modified to take into account thatpart of the load is supplied from wind which could drop out. The number of operation hoursof some of the minor gen-sets might be reduced due to the wind power contribution.

F the week in A ril1997

Kilowatts Generated April 97

3000

25001=-- -Saturday 1

2000 '-Sunday

~ -~ndaycu I~ 1500 I Tuesday.9. I~ i-Vl.Ednesday

1000 i i-:- -Thursday I

!. ...Frida y500 ' I

0

~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~O;';NM",tiJcijr:.:cXia;o;';NM",tiJcijr:.:cXia;o;';-NM

~ ~ ~ ~ ~~ ~ ~ ~ ~ N N N N

Time .-

-/'..

At present there is a slight over-capacity of diesel generators on Rarotonga and because ofeconomic recession the load i~ not expected to grow significantly in the nearest future. Newcapaciy would not be expected before year 2005. It must be expected that this fact \:ViII havean adverse effect on the capacity value -of a new wind turbine connected to the grid.However, some of the existing gen-sets have experienced serious operational problemsaffecting their status as firm c,!!pacity.

D rt-A/1/rex.J

6. Site descripti°!1' analysis and site selection

Together with representatives from the local Ministry of Energy the Team has surveyed thefrrost promising locations for establishment of wind turbines.

The candidate sites areA: lower part of slope to the north from Oroenga (elevation app. 100 m)B 1: lower part of slope from Ikurangi east ofPue stream pointing towards Upper Tupapa-sub-

station (elevation app. lOa-125m)B2: lower part of slope from lkurangi east of Pue stream pointing towards Tamure sub-station

(elevation app. lOa-125m)C: upper part of slope from lkurangi west ofPue stream (elevation app, ISO-200m)D: coastal plane near Ngatangiia on the rocky coast about 5m above mean sea level

The locations of the sites are shown in Figure 1.

Table 2 COMPARISONOFCANDIDA1ESI1ESFORDEMONS1R4770NWlND TURBINEA HI H2 C D

Land Partly covered v.ith Fern, no forest Covered by natural Covered by natural pahn trees close by tonatural forest, but Limited space in forest forest W and NW and seanearby forestry sloping narrow ridge Limited space Seemingi.'"' more space directly to E and SELimited space Acquisition possible Acquisition possible Acquisition possible Limited space in area

Acquisition possible presently being

developedPossibly floodingdurin~C\'clones

Access possible, estimated possible, estimated possible, estimated not known if it is easy -practically nocost incl. land cost incl. land cost incl. land possible at prices costsCl$140,000 C1$ 1 75,000 C1$222,000 comparable to A, B1

and B2Grid and connection to existing connection to existing connection to existing connection to existing connection to existingCMCS grid at Upper Tupapa grid at Tamure v.ith grid at Tamure v.ith grid at Tupapa or grid at Turangi v.ith

v.ith less than 1 !an less than 1 !an less than 1 !an closer to town v.ith less 200/300 m extensionextension extension extension than 1.5 !an extension

Operation & special access road special access road special access road special access road extra compared to A,Maintenance maintenance, less maintenance, less maintenance, less maintenance, less B1, B2 and C due to

corrosion than at coast corrosion than at coast corrosion than (It coast corrosion than (It coast corrosive environment, at coast

Physical not knO"ll if forestry no known conflict v.ith no known conflict v.ith no known conflict v.ith probably conflict v.ith

planning may e:'.-pand planning planning, except for its planning development v.ithin the-closeness to the coming 20 years

centerline of the airportrunway and the beaconstation

Wind and 900 MWhi)' 760MWhiy 830MWhiy 860MWhi)' 570MWh/y -

energy lUlcertainties are large lUlcertainties are large lUlcertainties are large ~es are large lUlcel"tainties due toproduCtion ,- nearbv pahn treesEnvironmental Some valuable trees No valuable trees Some valuable trees ' Probabi)-valuable trees No valuable trees -

impact Visible east of the Visible east of the Visible north and east Visible north and east Some visual impactisland island of the island of the island Less reduction in

--Reduced emissions Re(fuced emissions Reduced emissions RechIced emissions emissions than A, B

--.and CEconomvSustainabilitv -

Risks

8 Draft Feasibility Report - Annex 4

Unless more information regarding site C can be provided, it is the opinion of the feasibility study Team that the B 1 site should be selected due to its . seemingly favorable wind conditions according to the WAsP modeling based on the

Ngatangiia data . little environmental impact due to the fact that no valuable trees occupy this land . nearby grid interconnection point exists . no alternative uses of the land and thus low opportunity costs (price or rent) of land, although

construction costs seem high . little or no present or future obstacles to the wind . no consequences of noise from the wind turbine . Visual impact less than in B2, C and D . no interference to any planned future development of towns or other physical planning . low human risks to structural damage or failures of wind turbine (large safety distances)

However, because a mountain site is chosen with a rather complex wind flow, it is recommended that wind measurements are made as soon as possible by FSED and the Ministry of Energy to verify the assumed wind resources. Such measurements should be carried out in site B 1 unless more information provided before the initiation of the measurements points at site C as the most promising site, in which case the site selection conclusions and thus the site for additional measurements may be changed,

~

7. Climate and wind resource assessment

7.1 General

The island of Rarotonga is the main island in the Southem Cook Islands in the South Pacific Ocean at latitude 21'14'S and longitude 159'47'W. The Southern Cook Islands being on the equatorial side of the subtropical high-pressure systems at 25-30'S and south of the equatorial trough with a relative low-pressure, is in a trade wind climate for most of the year. The climate of the Southern Cook Islands is e.g. described in Thompson’. General descriptions of the regional climatology of the trade winds and the tropical climates can be found in the literature about world climatology as e.g. in Lockwood.

The trade winds are known for their extreme constancy in speed and direction - more so than in any other climate zone. The weather in the Southern Cooks is largely dependent on the position of the South Pacific Conversion Zone (SPCZ). It has a dry (May-Oct) and a wet (Nov-Apr) season. During the dry season the SPCZ is north of the island and the winds are predominantly the south-east trade winds. In the wet season, the SPCZ can lie over the island group bringing different types of weather with heavy rain and tropical cyclones. Thompson’ states that the annual average wind speed over the sea is 13 knots (6.7 m/s). It is however not explained how this number has been arrived at, and it is not clear in which height above sea level this is valid, although it must he expected to refer to standard meteorological height of 10 m. The corresponding annual average wind speed found by extrapolating wind data measured by the South Pacific Wind and Solar Monitoring Program (SPWSMP) to open sea is 6.0 m/s before any correction to climatological average level has been made, which seems

C.S. Thompson “The Climate and Weather of the Southern Cook Islands”. N.Z. Met. Serv. Misc. Publ. 188(2), ISSN 0110-6937 John G Lockwood “World Climatology, An environmental approach”, Edward Arnold Publishers Ltd, 1974.

10 Draft Feasibility Report - Annex 4

Programme recorded 40 m/s gusts and maximum hourly average wind speed of 22 m/s.

Preliminarily, it is concluded regarding extreme maximum wind speeds, that a 50 year gust value of 125 knots seems on the safe side for Cooks as design wind speed, but further analysis will be made, both with respect to the extreme statistics used and with respect to extrapolation to mountain sites and to to heights of 50-50 m agl of gust values measured in 10 m height agl in a flat airport site.

General statistics oftemperature and rainfall recorded at Rarotonga Airport are shown in Table 5

Table 3 General statistics of temperature and rainfull recorded at Rarotonga Airport Annual average temperature 25'C Range of monthly average temperatures 24 - 28'C Measured total range of temperatures 8.9 - 33.6'C Annual average rainfall 2000 - 4500 mm Extreme hourly rainfall >25 mm Extreme 24 hour rainfall (return period: 20 y) 277 mm

> 15 per year Days of thunder and lightning

Risk of soil erosion at heavy rainfalls is a major concern in Rarotonga as can be seen from the Rarotonga Environment Act 1994-95.

The climate in the region is rather corrosive near the ocean particularly on the east and south coast due to the contents of salt in the air carried by the wind and the high annual average temperature. The corrosion gets less severe when moving inland some kilometers in the direction of the wind and further when moving to sites on hills and mountains, since the amount of salt in the air carried to such places will be less than at the coast at sea level. The corrosion problem can be handled by proper design of equipment and maintenance.

7.2 Wind energy resources

Data

The Team has reviewed the meteorological data available from Rarotonga with assistance from the local Meteorology Office, supplying data and information in report form on the general climatology of the Southern Cook Islands, particularly for Rarotonga

Another source of information and data is the Southern Pacific Wind and Solar Monitoring Project (SPWSMP), from which both the First Annual Report 1995 and the original files of measured data from 1995 and 1996 have been supplied from the FSED. The data from the SPWSMP have been measured at Ngatangiia on the east-coast of Rarotonga less than 10 m from the coastline - a site that is well exposed to all easterly wind sectors. Measuring height was 10 m above ground level (agl). Data recovery was 100%.

The airport met-station is located in the north-west part of the island and is thus somewhat sheltered from south-east winds by the mountains. Measuring height here is also 10 m agl.

~

.

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Due to its better exposure to the prevailing winds, the wind resource assessment has beenbased on SPWSMP data. Data trom the airport from 1995 have been compared with long-term averages in the First Annual Report 1995 of the SPWSMP. The year 1995 had 5 %lower annuah¥erage wind speed in Rarotonga airport than the 5-year long-term averagerecorded. When making the wind resource assessment, data for 1995 should be corrected by afactor of 1.05. This analysis is not yet available tor 1996. The data will be corrected toclimatological average in the final analysis.

Statistics of recorded data are shown in Figures-4 and 5.

Figure"" Wind rose, Ngatangiia data 10 m ag11995-96

N

..W i E

I

S

Figure 5 Wind speed distribution, Ngatangiia data 10 m ag11995-96

.15

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I". ..U ':: ~~ r0" sf-~ ~ -

-L.. -+

I , :'r..'

"OSlO IS 20

Wi"d speed ms-' -

-

,

-

? D/i Jrt -AJ1/lex -+'

Wind re.50urce asse.5.5ment

Estimation of the wind energy production potential at a given site in Rarotonga -aseverywhere in the world -should in principle be done using the Wind Atlas method3 orsimilar. This implies extrapolation of nearby representative-wmd statistics from a highquality wind measurement station taken at a topographically simple site for aclimatologically long enough period to the potentially interesting wind farm site.

A calculation of the wind energy potentials at the candidate sites has to be made us-ing theW A sp4 program, which is a computer software tool modeling wind in accordance with the -Wind Atlas method.

Input data are time series of hourly average wind speeds and wind directions from theNgatangiia (SPWSMP) as well as description of the surface roughness and orography of theisland as well as any Qbstacles or sheltering trees nearby points of interest. Figure 1 shows thedigitization of the Rarotonga orography used in the modeling with an indication of thelocation of wind turbine candidate sites and measurement station.

The result of the wind atlas analysis for the north-east part of Rarotonga is shown in Figure 6.The expected annual average wind speed at 30 m above ground level is shown in color codeson top of the height contour lines of the NE part'" of Rarotonga where the candidate sites are.The color codes are normalized values of wind speeds, where the common normalization isdone on an (in this connection) arbitrarily chosen value, which enables comparison betweenthe sites.

The estimated annual average wind speed distributions at the candidate sites as used in thispreliminary feasibility study report are shown in Table 4, which gives values of estimatedannual average wind energy resources at 30 m height above ground level (agl) in terms of theannual average wind speeds Umean and the Weibull probability density distribution scale and

shape parameters (A, k).

Table 4 Estimated wind energy resources at a height of 30 m agl- annual average windspeed {Umean)and Weibull scale and shape parameters (A, k)

Umean (m/s) Weibull- A (m/s) Weibull- kA ' 7.5 8.5 1.95

_B1 6.8 7.7 2.11B2 7.1 8.0 1.93C 7.2 -8.2 2.04Ngatangiia met site 6.1 6.9 2.22

-~":', ~

3 "European Wind Atlas", Rise National Laboratory, 1989, ISBN 87-550-1482-84 "Wind Atlas Analysis and Application Program (WASP)", Rise National Laboratory, 1993 -~

D/1 Jrt -Almer -I ..,

The details sector-by-sector, energy density in the flow and potential annual energyproduction is shown in Table 5.

Tahle 5 Preliminary e,\'timate ofwindre,\'ources at ite 81.+ +: Ngatangiia, 10m agl, 1995-96 191 6197 7:18 :I II ,

: +raro**** Height: 30.5 m a.g.l. :: ~ :: Sect Rch Input Obstacle Orography A k ,~ P% :' : 'I I

: 0: 1 O.O~ 00 0.0% 35.6% _90: 6.8 2.36 7.9 5.5 :: 30: 1 O.O~ 00 O.O,~ 13.6% -90: 6.1 2.78 5.2 2.3 :: 60: 1 O.O~ 00 0.0% 4.0% 20: 6.4 2.79 8.1 4.3 :: 90: 3 0.0'ii:. 00 0.0% 18.9% 110: 8.5 2.89 14.7 17.4 :: 120: 3 O.O~ 00 0.0% 44.4% 80: 9.8 3.24 23.1 38.6 :: 150: 3 0.0% 00 0.0% 52.7% _30: 8.4 2.55 14.0 16.4 :: 180: 1 0.0% 00 0.0% 34.9% -120: 5.8 2.48 4.4 1.7 :: 210: 3 0.0% 00 0.0% 6.9% -100 : -4.0 2.33 2.6 0.2 :: 240: 2 O.O~ 00 0.0% -1.1% 50: 3.3 1.75 3.2 0.2 :: 270: 3 0.0% 00 0.0% 22.7% 130: 4.9 2.20 6.1 1.4 :: 300: 4 0.0% 00 0.0% 42.3% 80: 6.7 1.30 4.6 4.1 :: 330: 2 0.0% 00 0.0% 48.9% -10: 8.5 1.65 6.2 7.8 :: :: M= 6.8 MIs E= 356. W/m2 P= 759.9 MWh/y 7.7 2.11 :+ +

..It should be noted that the sheltering palm trees 45 m to the NW of the measurement stationare modeled as obstacles for winds from NW. The effect these 30 m high trees may have onwind flow from SE in 10 m height agl at the met mast 45 m upstream from them is notmodeled. This is considered a main source of uncertainty.

Furthermore, the digitization at the sites includes only the height contour lines Om, 20m, 60m100m, 160m, 200m, 300m, 400m, 500m, and 600m. This needs to be improved near the sitesin question, where contours every 20m will be digitized and used in the final feasibility

analysis.

It is recommended to continue the measurements at Ngatangiia and carry out a comparisonbetween the Ngatangiia data and data from the proposed wind turbine site preferably forsome months in a windy, period sufficient to establish the correlation between the two sitesfor the prevailing wind directions.

The uncertainties of estimates are rather large. Further documentation will be provided by thecontinued wind measurements.

l ,.,." -

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Fi~ure 6 Annual avera,~e wind ,'ipeed'i in ]O.m a,,;?;1 at the north-ea.'itpart of!?aroton~a(contour lines of topography shown) -normali=ed value,'i afwind ,'ipeeds for campari,'ion.modeled using the H1 A'V P program with NKatan~iia wind data a.'i input

, ,7655500 :

1,4

7655000-

1.2

1.17654500-

1.0

0,97654000

0.7

7653500 0.4

relative

wind speed421000 421500 422000 422500 423000 0

8. Wind turbine type and design

General

The type and size of the demostration wind turbine should be based on and of similar quality asan approved type in accordance with the Danish regulations and requirements, i.e. class A or BDanish Type Approval for operation in the local climatic condition~ at~e selected site atRarotonga and for operation in the local power system. "

I' -

Safety reQuirements -

-

The wind turbines should be designed in accordaflce with the requirements of IEC 1400-1;International Standard fOF Wind turbine generator systems -Part 1: Safety requirements; firstedition 1994 (or any later version).

The Wind turbine class should be: I or S..

-

D rt -AllIle.t" -I

Based on the available data it is estimated, the basic design wind parameters (V ref, Vave , lave)at the proposed sites -in a height above ground level ot- 30 m should be assumed to be asspecified in Table 6. This is just a preliminary suggestion which will be analysed and revisedin the Final Report.- ---~

Table 6 Prelimina su g-e.s1ion.for de.s'ign wind parameter.\'V ref = 45 m/s

max ust of70 m/s)Vave = 8 m/s -

lave = 0.17

Data from local building codes from the region and further climatological expertise will beconsulted.

Extreme value analysis using a statistical approach as e.g. described by Lawson) will also becarried out based on the Nadi and Laucala Bay data from Fiji.

All in all it seems that extreme wind speeds at the selected sites in are within normal designwind speeds for wind turbines installed elsewhere in the world. The relatively largeuncertainty with which the V ref is given is, however, considered somewhat of a risk for theproject, so further studies of this matter than those conducted in the preliminary phase duringthe field visit to the region will be necessary.

Notes regarding design of wind turbine and project implementation

Emphasis should be given to.design wind speeds.corrosion protection.tropicalized and termite proof equipment.availability of crane decides whether "self-erecting" wind turbine type is needed.lattice or tubular tower dependent on erection method, transportation, protection of

equipment, price, and Visual impact.specification of site -particularly that area of land required for the erection work may be

limited.transportation to site may require special handling of blades.special hoisting and handling equipment for moving spare parts to and from the nacelle during

maintenance and repair should be considered.planning which takes intO-accQunt the time consuming land acquisition and road works

! ~

O&M--

-Special maintenance which would require a large crane may be costly and time consuming if """

crane capacity is not available in Rarotonga. Measures should be taken to avoid this problem.

~

ST. V. Lawson "Wind effects on buildings, Statistics and Meteorology", Applied Science Publishers Ltd, 1980. ,-

--,

16 Draft Feasibility Report - Annex 4

The lifetime of the wind turbines as well as the maintenance effort and costs necessary cannot yet be precisely determined. However, the site selected is expected to have climatic conditions so that normal estimates and procedures from other wind farms with similar wind conditions will apply.

9. Conclusions

Conclusions of the technical analysis can be summarized as follows:

Land

EIA

Land can be made available in candidate sites, but process may take several months. Valuable trees in candidate sites except B 1. Ngatangiia site has not been evaluated. Project has to be approved by the Cook Islands Environment Service in accordance with requirements of the Rarotonga Environment Act 1994-95. Approval needs EIA to be carried out by local consultant or authority in Cook Islands and approved by Danish consultant. A mountain site should be selected. B 1 is selected due to its favorable environmental impact. If access and land to C can be ensured at comparable cost to B1 and the environmental impact can be documented to be acceptable, the C site would be chosen, due to its seemingly larger size. As part of the documentation, the size of land available should be made clear. In conclusion, the project should be carried out on site B 1. If, however, the above documentation is provided for site C before any project activity is started - including the site measurements for verification of wind energy resources - site C should be preferred. The feasibility study is carried out assuming that the wind turbine is installed at site B1. The annual average wind speed in 30 m height above ground level is 6.8 m/s. Estimated annual wind energy production from a 300 kW wind turbine is: 700 MWh. The number is arrived at using a 300 kW Nordtank wind turbine allowing for 8% losses due to technical availability, transmission losses, soiling of blades, etc. The wind turbine shall be selected among pre-qualified Danish supplier through an invited tender. The size of the wind turbine shall be in the

The size of the wind turbine shall be decided as the one with the best offer measured according to tender evaluation criteria which give highest priority to cost of energy per kWh produced, but also include quality of equipment enabling operation and maintenance at the local conditions as well as the experience of supplier. Design wind gusts of 70 m/s - 50 year return period. Special equipment for erection and maintenance without use of a major crane is assumed in the investment budget. Corrosion protection in accordance with climate. Termite protection and tropicalization needed. It is assumed that access road and site can be made by local contractors with a maximum inclination of 1:9 Size of site is minimum 6 x 40 m plus a place to turn the crane and trucks. Design should be made to prevent soil

Site selection

Wind resources

Wind turbine and design requirements range 200-300kW.

Access roads and site layout

17 Draft Feasibility Report - Annex 4

erosion and land slides. The project is implemented by Te Aponga, coordinating all works, Local civil and electrical works are carried out by Te Aponga themselves or by private or public sub-contractors. Operation will be the responsibility of Te Aponga. The wind turbine will be supplied by a Danish wind turbine manufacturer with a wind turbine with a proven record of operation and a documented experience from similar projects. The wind turbine supplier will be a turnkey contractor responsible for . supply of a wind turbine with a Danish Type Approval (A or B) as well

as all other imported equipment with a 2 year liability period, including spare parts for 5 years operation and necessary special tools

. erection and commissioning of the wind turbine

. training in operation and maintenance

. a 2 year after sales service with 3 visits The implementation will be supervised by a Danish consultant with the

.

. to review EIA

.

.

.

.

Project implementation

responsibilities to prepare tender documents and contract

to review design of road and site to check supplies prior to shipment to witness tests in the factory and commissioning tests on site to certify payments to the Danish turnkey supplier

D 1rt -All/lex-l

10. Investment budget

The investment budget is estimated based on actual list prices in Denmark, intormationprovided in Cook Islands during the visit and prices known from similar projects. Table 7gives the investment budget assumed by the economic analysis of the teasibility study.

Description -Specification Unit price Quantity Total

kl"'J"Z$ kNZ$

Wind turbine turnkey contractWind turbine incl. winch and pully system 300 kW 500 1 500Transport, erection, installation, etc. 300 kW 40 1 40Spares & tools -30

Remote monitoring facilities 1 5Training in O&M 15

After sales service 40

Sub-total wind turbine turnkey contract 630

Local worksWind turbine foundation+support for erection reinf concrete and ballast 50 m3 20

Access roads and land ..1 kIn 175Cable incl. trenching and laying 11 kV / 3x70 mm2 Cu 50 800 m 40

Connection at switchgear 10

Sub-total local works 245

Desif(n and supervision -Danish consultanttendering and contractingreview ofEIA and design of road and site

supervisionSub-total Danish consultant 100

GRAND TOTAL (kNZ$) 975

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