April 2003

DOWEC Cost Model

Implementation

DOWEC-068

S.A. Herman

2 DOWEC-068

Acknowledgement

This report is issued within the framework of the DOWEC project, supported by the EETprogram of the Dutch Ministry of Economic Affairs.

Abstract

A computer model for the costs of energy of a 480 MW wind farm, is composed based on theconceptual design of the 6 MW offshore wind turbine. This report provides a description of theimplementation of the cost model into an Excel spreadsheet. The partners of the project haveprovided all data required for this model. When required, data provided by the project partnersis mentioned.BN : Ballast NedamECN : Energy research Centre of the NetherlandsLM : LM Glasfiber HollandNM : Neg-Micon HollandTUD : Technical University of DelftVOO : van Oord ACZ

FOREWORDThe report has been published as a confidential ECN report under number ECN-CX-02-048. Onrequest of our partners a very limited amount of confidential information has been removed forthis public version.

DOWEC-068 3

CONTENTS

LIST OF FIGURES 3

SUMMARY 4

1. INTRODUCTION 5

2. DESCRIPTION OF THE COST MODEL 52.1 General 52.2 Input Section 62.3 Trend Compilation Section 82.4 Calculation Section 92.5 Results Section 9

3. REVIEW OF RESULTS FROM THE COST MODEL FOR THE WIND FARMCONCEPTS 11

3.1 Baseline Design Concept 11

4. REFERENCES 17

APPENDIX A - WIND FARM COST ITEMS SUBDIVIDED INTO LEVELS 18

APPENDIX B - WIND FARM COMPONENTS 23

LIST OF FIGURES

Figure 1. Snapshot of the ‘input sheet’ of DOWEC cost model. .................................................. 6Figure 2. Snapshot of the ‘variables sheet’ of DOWEC cost model. ............................................ 6Figure 3. Example of power curve of the wind turbine used in the cost model. ......................... 12Figure 4. Contribution of level 1 wind farm components to the LPC cost calculation............... 12Figure 5. Breakdown at level 2 of the design costs..................................................................... 13Figure 6. Breakdown at level 2 of Hardware costs. .................................................................... 13Figure 7. Breakdown at level 2 of assembly, transport and installation costs. ........................... 13Figure 8. Breakdown at level 2 of yearly operation and maintenance costs. .............................. 14Figure 9. Breakdown at level 2 of retrofit and overhaul costs. ................................................... 14Figure 10. Breakdown at level 2 of decommissioning costs....................................................... 14Figure 11. Breakdown of Hardware - OWEC costs at level 3. ................................................... 15Figure 12. Breakdown of Installation costs at level 3. ................................................................ 15Figure 13. Breakdown of Decommissioning – Removal of structures costs at level 3............... 15Figure 14. Breakdown of OWEC nacelle costs at level 4. .......................................................... 16Figure 15. Breakdown of OWEC rotor costs at level 4. ............................................................. 16Figure 16. Wind Farm Components............................................................................................ 23

4 DOWEC-068

SUMMARY

The DOWEC project (Dutch Offshore Wind Energy Converter) is performed by a consortium ofthe industry and research institutes with the aim to develop a 6 MW offshore wind turbine readyfor testing onshore in 2004. The six partners in this EET programme subsidised project areBallast Nedam, Van Oord ACZ, NEG-Micon Holland, LM Glasfiber Holland, Delft Universityof Technology and the Energy research Centre of the Netherlands.

In order to calculate the cost of energy, a cost model has been developed based onestimations of costs made by all partners. The cost model is an Excel spreadsheet that compilesall expected wind farm costs and calculates the energy yield of the wind farm. The wind farmcosts depend among others on the type of wind turbine used, the number of turbines within thefarm and the location chosen. Therefore, all partners have chosen a baseline design as a startingpoint, which defines these characteristics for this purpose.

All identified wind farm costs are separated into five main groups, i.e. design, hardware,transport and installation, operation and maintenance, and decommissioning. Within thesegroups, several cost items were identified. Where possible, the project partners have providedthese cost items in a parametric form. In this way, minimisation of costs may be achieved and/orenergy cost trends could be extracted. For the calculation of some cost items like the cost of theelectric infrastructure, some simple engineering models have been developed and implementedin the cost model.

The total wind farm investment costs together with an estimation of the wind farmenergy yield, have lead to the obtention of a “Levelised Production Cost” of energy (LPC-value), which is an indication of the cost value of energy. The calculation of the LPC is basedon economic parameters like inflation rate, and it is derived considering the estimated(economic) lifetime of the wind farm. The results of the cost model are, besides the LPC value,a breakdown of costs separated into the defined main groups and in lower levels. Thesebreakdowns are presented as pie- and bar diagrams.

The cost model is a helpful tool for the study of variations to the wind farm concept,variations to cost items (also called ‘one-dimensional variations’) and parametric variations. Allthese variations aim to identify promising concepts or changes to the baseline design, whichmay be subjected in the future to further study. This report refers to the implementation of thedeveloped cost model. The variations to the baseline performed with the cost model are reportedseparately (ref. [1]).

DOWEC-068 5

1. INTRODUCTION

The objectives of DOWEC Work Package 1 Task 18 “Overall Cost Modelling” are:- To determine the cost price for identified concepts based on the “Levelised Production

Costs” (LPC);- To set up targets for the chosen concept design;- To develop a cost model suitable for evaluation of the identified concepts, including trends

for the main design parameters.

This report deals with the first and the third of the three objectives mentioned. The evaluation oftrends based on the cost model is discussed in reference [1].

To calculate the LPC costs of the different concepts, a cost model is developed. Thecost model builds the costs up at component level. For each component, a cost trend is given inthe form of a formula based on input variables. In some cases the cost item is given by a fixedlump sum and is not based on a formula. The industrial partners have provided the trends.

In chapter 2 the set-up of the cost model is presented and in chapter 3 some results aregiven.

2. DESCRIPTION OF THE COST MODEL

2.1 GeneralThe cost model is an Excel workbook that incorporates formulas for cost prediction of thefollowing wind turbine concepts:- Baseline design concept;- Alternative power regulation concepts;- Telescopic tower wind turbine;These concepts have been defined within the DOWEC project as result of a concept variationstudy, reported in reference [1]. For each of these concepts, a cost breakdown into a componentlevel is incorporated. A formula or a fixed lump sum gives each cost item. The user suppliesvalues for the main design parameters of the formulas.

The wind farm cost items are subdivided into six main groups. All cost items of thesegroups are summarised and levelised to year “zero”. The procedure as presented in [2] is thebasis for the calculation of the levelised cost of energy. A complete list of the cost items of allgroups is presented in Appendix A. The six main groups mentioned above are presented in thelist below:

- Wind farm design costs;- Hardware costs;- Assembly, transport and installation costs;- Yearly operation and maintenance costs;- Overhaul and retrofit costs;- Decommissioning costs.

The cost model’s workbook consists of four sections:a. Input section;b. Trend compilation;c. Electric costs and energy calculation section;d. Results section.

In the following paragraphs, the structure of these sections is presented.

6 DOWEC-068

2.2 Input SectionThere are two kind of variables defined within the DOWEC cost model: user input variables anddefinition parameters.

User input variables are used to define the dimensions and the kind of turbines presentof the wind farm. Figure 1 gives a snapshot of the user input variables defined within the costmodel of DOWEC.

FARM PARAMETERSDescription of wind farm Name Value unitNumber of OWECs in the farm Nowec [-]

ENVIRONMENTAL PARAMETERSDescription of environment Name Value unitWater depth WD [m]Distance to the grid connection Dgrid [km]

TURBINE PARAMETERSDescription Name Value unitRated power of each OWEC Prated [MW]Rotor diameter Drotor [m]Hub height / Mast height (MSL) Hhub [m]

CONCEPT TYPE1. Baseline Design 3 blades, monopod, geared drive train

Figure 1. Snapshot of the ‘input sheet’ of DOWEC cost model.

Definition parameters, provided by the project partners, are variables that define the‘intelligence’ of the cost model. They are defined within the several estimation formulas for thecalculation of all cost items. The value of these parameters for the baseline is:Nowec = 80 [-]WD = 23 [m]Dgrid = 60 [km]Prated = 6 [MW]Drotor = 129 [m]Hhub = 91.4 [m]

In addition, more engineering and economic parameters are defined into this section. Figure 2gives a snapshot of the user input variables defined within the cost model of DOWEC.FARM PARAMETERS TURBINE PARAMETERSDescription of wind farm Name Value unit Description Name Value unitNumber of cable platforms Ncplat [-] Turbine availability Avail_turb [-]Electric infrastructure efficiency Einf_elec [-] Max power coefficient 3 blades cp_max_3 [-]Aerodynamic farm efficiency Array_eff [-] Max power coefficient 2 blades cp_max_2 [-]Farm availability Avail_farm [-] OWEC Tower diameter at top Dtower_top [m]Distance of hor. Drilling Ddrill [m] OWEC Tower diameter at bottom Dtower_bott [m]Intensity of turbulence Tint [-] OWEC Tower wall thickness (mean) wt_tower [m]Number of turbine groups Ngroup [-] OWEC Tower unit cost Ctower [€/kg]Voltage of cable to shore HVac [kV] OWEC Platform costs Cplatf [€/kg]Mean relative dist. between turb. Dturb [-] Gearbox test costs Gear_test [€/MT]

Gearbox mass Gear_mass [MT]ENVIRONMENTAL PARAMETERSDescription of environment Name Value unit FOUNDATION PARAMETERSCut-in wind speed Vcutin [m/s] Description Name Value unitReference mean wind speed Vwind [m/s] Monopod diameter (if present) Dmonop [m]Cut-out wind speed Vcutout [m/s] Monopod wall thickness wt_monop [m]Percentage of waves < 1.0 [m] Waveper [%] Monopod unit cost Cmonop [€/kg]Weibull shape factor wind Kweibull [-] Depth of piles in the seabed L_pile [m]

Coating costs Ccoating [€/m2]Transition piece diameter Dtrans [m]Transition piece wall thickness wt_trans [m]Transition piece total length Ltrans [m]

ECONOMIC PARAMETERS Transition piece unit cost Ctrans [€/kg]Description Name Value unit Diameter of scour protection Dscour [m]Inflation rate Rinfl [-]Nominal rate (annual rate) Rintr [-]Lifetime of OWECs Lifetime_design [yr] CONSTANTSEeconomic Lifetime Lifetime_econ [yr] Description Name Value unitYears between R&O periods Nro [yr] Steel density Rsteel [kg/m3]

Figure 2. Snapshot of the ‘variables sheet’ of DOWEC cost model.

DOWEC-068 7

The default value of these variables have been chosen as follows:FARM PARAMETERSDescription Name Value unitNumber of cable platforms Ncplat 0 [-] Between 0 and 60 km from the coast, no cable

platforms are required [ECN, NM]Electric infrastructureefficiency

Einf_elec 0.98 [-] Data provided by experts [ECN, NM, TUD]

Aerodynamic farmefficiency

Array_eff 0.917 [-] On basis of estimations made by ECN

Farm availability Avail_farm 0.985 [-] On basis of estimations made by ECNDistance of hor. Drilling Ddrill 500 [m] Data estimated by experts [VOO] and used for

calculation of cable installation costsIntensity of turbulence Tint 0.15 [-] Data estimated by experts [LM] and used for

calculation of blade manufacturing costsNumber of turbine groups Ngroup 10 [-] Data used for the calculation of cost of

electrical infrastructure in the wind farmVoltage of cable to shore Hvac 150 [kV] Data used for the calculation of cost of

electrical infrastructure in the wind farm[ECN, NM]

Mean relative distancebetween turbines

Dturb 8 [-] Relative distance between the turbines. It isthe result of the mean value between thedistance in a row and between the rows of arectangular-shaped wind farm layout.

ENVIRONMENTAL PARAMETERSDescription Name Value unitCut-in wind speed Vcutin 3 [m/s] Data taken from reference [6]Reference mean windspeed

Vwind 9.2 [m/s] Data taken from reference [8]

Cut-out wind speed Vcutout 25 [m/s] Data taken from reference [6]Percentage of waves < 1.0[m]

Waveper 66.5 [%] Data estimated by experts [VOO] and used forcalculation of cable installation costs

Weibull shape factor wind Kweibull 2.08 [-] Data taken from reference [8]

ECONOMIC PARAMETERSDescription Name Value unitInflation rate Rinfl 0.03 [-] Estimation based on observations in the

Netherlands the past 5 years.Nominal interest rate(annual rate)

Rintr 0.08 [-] Although reference [5] mentions 5% nominalrate, a value of about 8% appeared to be morerealistic at the time of this writing.

Lifetime of OWECs Lifetime_design 20 [yr] Data taken from reference [5]Economic Lifetime Lifetime_econ 20 [yr] Data taken from reference [5], although very

often a return of investment within 15 years isexpected.

Years between R&Operiods

Nro 4 [yr] Assumption: every 5 years a major overhauloccurs.

TURBINE PARAMETERSDescription Name Value unitTurbine availability Avail_turb 0.981 [-] Data obtained during analysis of maintenance

aspects of DOWEC [10].Max power coefficient 3blades

cp_max_3 0.495 [-] Data taken from reference [6]

Max power coefficient 2blades

cp_max_2 0.470 [-] Data taken from reference [1]. Used only forconcept variations.

OWEC Tower diameter at Dtower_top 3.5 [m] Data taken from reference [6]. Used for tower

8 DOWEC-068

top cost calculation.OWEC Tower diameter atbottom

Dtower_bott 6.0 [m] Data taken from reference [6]. Used for towercost calculation.

OWEC Tower wallthickness (mean)

wt_tower 0.04 [m] Data taken from reference [6]. Used for towercost calculation.

OWEC Tower unit cost Ctower 2.5 [€/kg] Assumption for mean price of material,including welding, etc.

OWEC Platform costs Cplatf 3 [€/kg] Assumption for mean price of material,including welding, etc.

Gearbox test costs Gear_test 25 [€/MT] Assumption for mean price of testingpremises, etc.

Gearbox mass Gear_mass 65 [MT] Data provided by experts [NM]. Used forestimation of Gearbox test costs.

FOUNDATION PARAMETERSDescription Name Value unitMonopile diameter (ifpresent)

Dmonop 6.0 [m] Data taken from reference [9]. Used formonopile cost calculation.

Monopile wall thickness wt_monop 0.06 [m] Data taken from reference [9]. Used formonopile cost calculation.

Monopile unit cost Cmonop 2.25 [€/kg] Assumption for mean price of material,including welding, etc.

Depth of piles in the seabed L_pile 30 [m] Data taken from reference [9]. Used formonopile cost calculation.

Coating costs Ccoating 3.0 [€/m2] Assumption for mean price of coating works.Transition piece diameter Dtrans 6.0 [m] Data taken from reference [9]. Used for

monopile cost calculation.Transition piece wallthickness

wt_trans 0.06 [m] Data taken from reference [9]. Used formonopile cost calculation.

Transition piece totallength

Ltrans 17.5 [m] Data taken from reference [9]. Used formonopile cost calculation.

Transition piece unit cost Ctrans 2.5 [€/kg] Assumption for mean price of material,including welding, etc.

Diameter of scourprotection

Dscour 25 [m] Assumption used for calculation of cost ofJ-tubes for electric cabling.

CONSTANTSDescription Name Value unitSteel density Rsteel 7850 [kg/m3] Known value.

2.3 Trend Compilation SectionThe cost items of the six groups are compiled in this section. Every cost item is defined by aformula or by a (fixed) lump sum. The formulas or lump sums have been provided by theDOWEC partners. In some cases they are specifically determined for the offshore locationand/or for the concept considered. Each concept includes (where necessary) its own costformulas. The concept type choice is user input.

The difference between “Yearly operation and maintenance costs” and “Overhaul andretrofit costs”, is the interval of time at which the maintenance occurs. Overhaul and retrofitcosts are also costs of Operation and maintenance, but they are realised every four to five yearsinstead of yearly. In the cost model, the interval of time at which retrofit costs are included isuser’s input. It has been assumed that overhaul and retrofit occurs every 5 years. Therefore, alump sum has been reserved for the whole operation.

The components of the wind farm in the cost model are grouped into four levels. Thedefinition of these levels is given in [2]. Each consecutive level includes a subdivision of thecomponents of the previous (lower) level. See also Appendix A for more details.

DOWEC-068 9

2.4 Calculation SectionSome calculations are also performed in the spreadsheet:- The annual energy output of the wind turbine is calculated based on three factors: (1) the

power curve, (2) the given average annual wind speed and (3) the value of the Weibull’sShape factor for the considered offshore location. For this calculation, the air density isassumed constant and equal to 1.225 [kg/m3]. The air density is not user input. The choiceof the power curve to be used is coupled to the design concept considered.

- The costs of the electric infrastructure are calculated in the cost model in accordance with[3], based on trends delivered by the partners. This analysis results in an optimal value ofthe medium voltage of the cables based on the predicted electric power to be transported.The number of cables used is also a result of this analysis.

2.5 Results SectionThe result section summarises the costs results obtained from the different levels and calculatesthe levelised production costs LPC according to [4]. In this section some economic parametersare calculated (discount rate, annuity) and the different periods related to the phases of the windfarm construction are defined. The periods assumed are based on an economic lifetime:- Wind farm design in the first year;- Delivery of hardware components distributed over the 2nd and 3rd year;- Installation of components distributed over the 3rd and 4th year;- Start of production in the 4th year, equals year “zero”;- Operation and maintenance works (and costs) every year between year zero and the last

year (= year zero + economic lifetime);- Retrofit and overhaul costs every 5 year between year zero and the last year;- Salvage in the last year.The economic lifetime of the wind farm is input for the cost of energy calculations. The costs ofretrofit and overhaul are added every time after a certain number of years. This number is alsouser’s input.

In the results section the levelised production costs of energy are given as the price in[€ct/kWh]. The contributions of the different groups are presented as a “Pie-chart”. Other resultsare the breakdown of the costs at each level. These results are presented comparatively, as apercentage of the contribution of each level to the LPC.

The annual energy gross from the wind farm (delivered at shore) is also a part of theresults. This energy includes all considered efficiencies and the calculated load factor for thewind turbine.

10 DOWEC-068

DOWEC-068 11

3. REVIEW OF RESULTS FROM THE COST MODEL FOR THEWIND FARM CONCEPTS

This chapter presents a brief overview of the results from the cost model for the wind farmconcepts. For detailed information on the design of each wind farm concept, see reference [5].For the calculation of the LPC of any considered concept, the following parameters are used:Technical lifetime 20 yearsEconomic lifetime 20 years

Wind Farm ComponentsA wind farm as defined in the cost model, is subdivided into five main components. A schemeof these components is shown in Appendix B.- 1x Measuring Station (Metmast);- Wind turbines;- Electric Power Collection System, consisting of electric cables and components between

turbines and Central Platform;- 1x Central Platform, whereon the Transformer Station is mounted;- Transmission System to Shore, consisting of a Transformer Station, Transmission cable and

optionally Cable Platforms to mount capacitors needed to control the reactive powerbetween the electric current and the electric voltage for alternating current. No cableplatforms are needed for distances less than 100 km from the coast.

3.1 Baseline Design ConceptThis concept consists of 80 wind turbines of rated power of turbine equal to 6 MW (Wind farmsize = 480 MW). The turbines are 3-bladed and have a monopile as foundation. For thecalculation of the operational and maintenance costs, a wind turbine availability of 98.1% hasbeen assumed, based on an ‘onshore’ failure rate of 2.28 times a year (blade tip failure has beenneglected because no blade tip brake is present) [11]. The influence of an ‘offshore’ failure rateof 1.55 times a year is analysed in [1] under the one-dimensional variation called “Low FailureRate and Redundancy”.

OWEC components:- Monopile foundation in seabed up to 15 [m] above sea bottom;- Transition piece placed over foundation extended up to +9 [m] above MSL level;- Turbine tower from top of transition piece up to yaw bearing;- Nacelle including the drive train, main shaft, hub and Rotor.

Assumptions:- Installation of 40 turbines in a year as a maximum;- Installation using special installation vessel (Svanen) and installation Jack-up (Buzzard);- Cable installation between 1.0 [m] and 2.0 [m] burial depth;- Percentage of waves <1.0 [m] equals 66.5% (used for cable installation and scour protection

costs).

The power curve of the 6 MW turbine used in the cost model is calculated in accordance with[6]. The power curve derived for the baseline is given in Figure 3.

12 DOWEC-068

P-V Curve of wind turbine

0

1000

2000

3000

4000

5000

6000

7000

0.00 5.00 10.00 15.00 20.00 25.00 30.00

Wind speed [m/s]

Rat

ed p

ower

[kW

]

Data

Figure 3. Example of power curve of the wind turbine used in the cost model.

ResultsThe calculated total energy delivered by the wind farm of the baseline design is approximatelyequal to 25.7 106 kWh per year, corresponding to a turbine load factor of 49%. The actualisedcosts of the wind farm related to the first production year (considering only the discount rate)are approximately equal to 1,200 M€. The levelised costs per year (considering the annuity forthe given economic lifetime) are approximately equal to 90 M€. From these values, it followsthat the LPC of the considered wind farm approximates 5.30 €ct/kWh.

The contribution of the level 1 wind farm components to the LPC value, are shown inFigure 4.

Break-down of Wind Farm Costs

Assembly, Transport and Installation

11%

Yearly Operation & Maintenance

27%

Decommissioning1%

Retrofit & Overhaul7%

Wind Farm Design1%

Hardware (including transport onshore)

53%

Figure 4. Contribution of level 1 wind farm components to the LPC cost calculation.

The costs of each level 1 component are broken-down into level 2. The following figures givethe relative contribution of the level 2 components to the LPC. These figures read as follows: iffor instance the design costs represent 1% of the LPC and the management costs at level 2 are

DOWEC-068 13

about 17% of the design costs, then the contribution of the management costs to the LPC isapproximately 0.01 x 0.17 = 0.17% of LPC.

Break-down of Design Costs

0%5%

10%15%20%25%30%35%40%

Manage

ment

One-of

f Insu

rance

Prem

ium

Feasib

ility

Site Ass

esmen

t

Acquis

it ion

Engine

ering

Figure 5. Breakdown at level 2 of the design costs.

Break-down of Hardware Costs

0%10%20%30%40%50%60%70%80%90%

Manag

emen

t

Measu

ring T

ower

OWEC

Electric

Coll

ectio

n Sys

tem

Centra

l Plat

form

Trans

mission

Sys

tem to

Shore

Purcha

sed A

uxilia

ry Equ

ipmen

t

Onsho

re Tran

sport

Pre-as

sembly

Onsho

re Prem

ises

Figure 6. Breakdown at level 2 of Hardware costs.

Break-down of Assembly, Transport and Installation Costs

0%5%

10%15%20%25%30%35%40%45%

Manage

ment

Assem

bly O

nsho

re

(De)m

obilis

ation

Cos

ts

Transpo

rt Offs

hore

Offsho

re Stor

age

Assem

bly O

ffsho

re

Instal

lation

Seabe

d Prep

aratio

n / Sc..

.

Commiss

ioning

Figure 7. Breakdown at level 2 of assembly, transport and installation costs.

14 DOWEC-068

Break-down of Yearly Operation and Maintenance Costs

0%

5%

10%

15%

20%

25%

30%

Manage

ment

Preven

tive M

ainten

ance

- Crew

s

Preven

tive M

ainten

ance

- Equ

ipmen

t

Preven

tive M

ainten

ance

- Spa

re Part

...

Correcti

ve M

ainten

ance -

Crew

s

Correcti

ve M

ainten

ance -

Equipment

Correcti

ve M

ainten

ance -

Spare Part

...

Annua

l Insu

rance

Premium

Admini

strati

on (S

ales,

Distrib

ution

, etc)

Figure 8. Breakdown at level 2 of yearly operation and maintenance costs.

Break-down of Retrofit and Overhaul Costs

0%20%40%60%80%

100%120%

Manage

ment

Preven

tive M

ainten

ance

- Crew

s

Preven

tive M

ainten

ance

- Equ

i...

Preven

tive M

ainten

ance

- Spa

re...

Correcti

ve M

ainten

ance -

Crew

s

Correcti

ve M

ainten

ance -

Equip...

Correcti

ve M

ainten

ance -

Spare...

Figure 9. Breakdown at level 2 of retrofit and overhaul costs (actually a lump sum).

Break-down of Decommissioning Costs

0%

20%

40%

60%

80%

Manage

ment

(De)m

obilis

ation

costs

Remov

al of

Structu

res

Transpo

rt to S

hore

De-ass

embly

Figure 10. Breakdown at level 2 of decommissioning costs.

DOWEC-068 15

Furthermore, the most important contributions to the LPC at level 3 are also given in the nextfigures. The level 1 wind farm components Design, Yearly O&M and Retrofit and Overhaul donot have a level 3 decomposition.

Hardware - OWEC

0%

10%

20%

30%

40%

50%

Supportstructure

Nacelle Rotor

Figure 11. Breakdown of Hardware - OWEC costs at level 3.

Assembly, Transport and Installation - Installation

0%10%20%30%40%50%60%70%

MeasuringTow er

OWEC ElectricCollectionSystem

CentralPlatform

TransmissionSystem to

Shore

Figure 12. Breakdown of Installation costs at level 3.

Decommissioning - Removal of Structures

0%20%40%60%

80%100%120%

MeasuringTower

OWEC ElectricCollection

System

CentralPlatform

TransmissionSystem to

Shore

Figure 13. Breakdown of Decommissioning – Removal of structures costs at level 3.

Finally, for the sake of completeness, a breakdown at level 4 of the nacelle and rotor costs aregiven in the next figures.

16 DOWEC-068

Hardware - OWEC - Nacelle

0%

5%

10%

15%

20%

25%

30%

35%

Figure 14. Breakdown of OWEC nacelle costs at level 4.

Hardware - OWEC - Rotor

0%

20%

40%

60%

Blades Hub Pitch Control System

Figure 15. Breakdown of OWEC rotor costs at level 4.

DOWEC-068 17

4. REFERENCES

1. S.A. Herman; DOWEC Concept Variation Study. DOWEC-F1W2-SH-03-019/00-C. Energyresearch Centre of the Netherlands, Petten, January 2003.

2. M.B. Zaaijer; Overall Cost-Modelling of the DOWEC Lifecycle in a Wind Farm. DOWEC-F1W2-MZ-02-037/00-P; Technische Universiteit Delft, November 2001.

3. J.T.G. Pierik, M. Pavlovsky, J. Bozelie, P. Bauer and S.W.H. de Haan; Dowec ElectricalSystem – Baseline Design. ECN-C—02-021. Petten, February 2002.

4. M.B. Zaaijer; G.J.W. van Bussel; W. van den Broek; F. van der Hidde; Starting-point andMethodology of Cost Optimisation for the Conceptual Design of DOWEC. March 2000.

5. F. Goezinne; Terms of reference DOWEC. DOWEC-F1W1-FG-01-041/00-P. NEG-Micon,Bunnik, September 2001.

6. H.J.T. Kooijman, C. Lindenburg and D. Winkelaar; Modelling of the DOWEC 6 MW pre-design in Phatas IV. ECN-CX- 01-135; Energy research Centre of the Netherlands, Petten,January 2002.

7. L.W.M.M. Rademakers and H.Braam; O&M Aspects of the 500 MW Offshore Wind Farmat NL7. DOWEC-F1W2-LR-02-080/0. Petten, July 2002.

8. W. Bierbooms; Wind and wave conditions. DOWEC-F1W1-WB-01-047/C. Delft,November 2001.

9. J.C. Oud; DOWEC – Foundation Design Monopile. DOWEC-F1W2-TT-02-067/00-C.Ballast Nedam Engineering, Nieuwegein, May 2002.

10. L.W.M.M. Rademakers; Availability figures for the Reference DOWEC Turbine. Personalcommunication. Petten, February 2003.

11. H. Wisselink and A. Winnemuller; Estimation of Turbine Reliability figures within theDOWEC project. DOWEC-F1W1-HW-01-048/02-C. NEG-Micon, Bunnik, March 2002.

18 DOWEC-068

APPENDIX A - WIND FARM COST ITEMS SUBDIVIDED INTOLEVELS

Definition of groups:- D : Design- H : Hardware- I : Transport and installation- O : Operation and maintenance- S : Decommissioning

LEVEL 1 LEVEL 2 LEVEL 3 LEVEL 4D1 Wind Farm DesignD2 ManagementD3 One-off Insurance PremiumD4 FeasibilityD5 Environmental StudyD6 Technical FeasibilityD7 Social FeasibilityD8 Site AssessmentD9 EnvironmentalD10 GeophysicalD11 GeotechnicalD12 AcquisitionD13 TenderingD14 QuotationsD15 ContractD16 EngineeringD17 DesignD18 CertificationH1 Hardware (including transport onshore)H2 ManagementH3 Measuring TowerH4 Support StructureH5 FoundationH6 TowerH7 PlatformH8 Access FacilitiesH9 Lifting Equipment

H10 OtherH11 Measurement SystemH12 HutH13 Measurement EquipmentH14 ComputersH15 OtherH16 OWECH17 Support structureH18 FoundationH19 TowerH20 PlatformH21 Access FacilitiesH22 Lifting Equipment

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LEVEL 1 LEVEL 2 LEVEL 3 LEVEL 4H23 OtherH24 NacelleH25 HousingH26 Drive TrainH27 Main ShaftH28 Gear SystemH29 BearingsH30 GeneratorH31 Electr. ConversionH32 Yaw SystemH33 MainframeH34 Computer and SensorsH35 Break-Coupling SystemH36 Electr. CableH37 Cooling SystemH38 MiscellaneousH39 RotorH40 BladesH41 HubH42 Pitch Control SystemH43 Electric Collection SystemH44 Power ConversionH45 Collection CableH46 Central PlatformH47 Support StructureH48 PlatformH49 OtherH50 Transmission System to ShoreH51 Cable PlatformH52 Transformer StationH53 Transmission CableH54 Power ConversionH55 Intermediate ComponentsH56 Grid ConnectionH57 Onshore Transformer StationH58 Purchased Auxiliary EquipmentH59 Onshore TransportH60 Pre-assemblyH61 Onshore PremisesI1 Assembly, Transport and InstallationI2 ManagementI3 Assembly OnshoreI4 Measuring TowerI5 OWECI6 Electric Collection SystemI7 Central PlatformI8 Transmission System to ShoreI9 Rent of Quay side

I10 Rent of Storage OnshoreI11 Testing OnshoreI12 Measuring EquipmentI13 OWEC Lifting EquipmentI14 Other OWEC Components

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LEVEL 1 LEVEL 2 LEVEL 3 LEVEL 4I15 Electric Collection SystemI16 Transmission System to ShoreI17 (De)mobilisation CostsI18 Transport OffshoreI19 Measuring TowerI20 OWECI21 Electric Collection SystemI22 Central PlatformI23 Transmission System to ShoreI24 Offshore StorageI25 Assembly OffshoreI26 Measuring TowerI27 OWECI28 Electric Collection SystemI29 Central PlatformI30 Transmission System to ShoreI31 InstallationI32 Measuring TowerI33 FoundationI34 TowerI35 Measurement EquipmentI36 OWECI37 FoundationI38 TowerI39 Nacelle & RotorI40 Access FacilitiesI41 Electric Collection SystemI42 Offshore Electric CablingI43 Cable Tie-inI44 Central PlatformI45 Transmission System to ShoreI46 Platform(s)I47 Transformer StationI48 Offshore Electric CablingI49 Cable tie-inI50 Grid ConnectionI51 Onshore Electric CablingI52 Onshore Transformer StationI53 Seabed Preparation / Scour ProtectionI54 Measuring TowerI55 OWECI56 Electric Collection SystemI57 Central PlatformI58 Transmission System to ShoreI59 Cable PlatformI60 Transmission CableI61 CommissioningI62 Measuring TowerI63 OWECI64 Electric Collection SystemI65 Central PlatformI66 Transmission System to Shore

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LEVEL 1 LEVEL 2 LEVEL 3 LEVEL 4O1 Yearly Operation & MaintenanceO2 ManagementO3 Inspection Subsea WorksO4 Preventive Maintenance - CrewsO5 Preventive Maintenance - EquipmentO6 Preventive Maintenance - Spare Parts & ConsumablesO7 Corrective Maintenance - CrewsO8 Corrective Maintenance - EquipmentO9 Preventive Maintenance - Spare Parts & ConsumablesO10 Annual Insurance PremiumO11 Administration (Sales, Distribution, etc.)O12 Retrofit & OverhaulO13 ManagementO14 Preventive Maintenance - CrewsO15 Preventive Maintenance - EquipmentO16 Preventive Maintenance - Spare Parts & ConsumablesO17 Corrective Maintenance - CrewsO18 Corrective Maintenance - EquipmentO19 Preventive Maintenance - Spare Parts & ConsumablesS1 DecommissioningS2 ManagementS3 (De)mobilisation costsS4 Removal of StructuresS5 Measuring TowerS6 OWECS7 Electric Collection SystemS8 Central PlatformS9 Transmission System to ShoreS10 Transport to ShoreS11 De-assemblyS12 Salvage

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APPENDIX B - WIND FARM COMPONENTS

TRANSFORMER STATION

ELECTRIC

CENTRAL PLATFORM

ELECTRIC

OWEC

MEASURING SYSTEM

CABLE PLATFORM

TRANSMISSION SYSTEM

COLLECTION SYSTEM

(OPTIONAL)

Figure 16. Wind Farm Components.

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