University of Glasgow

Faculty Engineering

Feasibility Report for Wind Turbine on the Isle of Cumbrae

Integrated System Design Project

Team Members

• Project Manager: Ikenna Ejiofor • Engineering Manager: Ali Mohammed Adil • Planning Manager: Yadan Rao • Financial Manager: Qing Peng • Quality Manager: Saeed Al Amri • Construction Manager: Sundeep Kumar • Operation and Maintenance Manager: Sajal Thakur • Environmental Manager: Arinze • Health and Safety Manager: Gao

Submitted By: Team 2 Supervised By: Professor Ross Wilson

University of Glasgow 2010 Faculty of Engineering

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ABSTRACT

This paper describes a feasibility study for wind turbine project on the Isle of Cumbrae, discusses its system designs and evaluates the possibility for undertaking such a large scale project which may be capable of offering long term benefits to the company, the denizens of the Island and also the environment.

Based on the presently available published literature, the feasibility study performed in the report takes into account environmental, ecological and financial aspects and an extensive amount of subjective evaluation that leads to the recommendations and a potential design for the wind turbine which. The health and safety and environmental considerations were produced as a part of the design process. Also, the Construction plan, Quality Assurance plan and the Cost and Income estimations are produced. Systems Engineering principles and methodologies along with some management principles have been used to arrive at a design and to complete the feasibility study for this project. This project concludes that building this wind turbine will be useful for the environment, feasible financially and can be further evaluated based on public opinion.

The project assesses different aspects involved qualitatively and quantitatively.

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TABLE OF CONTENTS Section Description page List of Figures 4 List of Tables 5

1. INTRODUCTION 6 1.1. History of Wind Energy 6 1.2. U.K. Wind Energy 6 1.3. Power from the Wind 7 1.4. Isle of Great Cumbrae 7

2. PROJECT OVERVIEW 8 2.1. Purpose and Scope 8 2.2. Report Organization 8

3. SITE SELECTION 10 3.1. Wind Speed 10 3.2. Noise 11 3.3. Environmental Impact 11

3.3. 1. Wildlife Impacts 11 3.3. 2. Impacts on Historical, Archaeological & Cultural 12 3.3. 3. Visual & Aesthetic Impacts 12 3.3. 4. Environmental Interference 12 3.3. 5. Sore conclusion 12

3.4. Accessibility 12 3.5. Smart Analysis 13

4. TURBINE STRUCTURE SELECTION 14 4.1. Cost-benefit Tradeoffs 14 4.2. Design Standard 14 4.3. Demand on the Isle of Great Cumbrae 15 4.4. Access to Transmission Lines & National Grid 15 4.5. Decision Point 15

5. TURBINE SYSTEM DESIGN 17 5.1. AERODYNAMIC SYSTEM 17

5.1. 1. Wind Use & Wind 17 5.1. 2. Rotor Design 18

5.2. MECHANICAL SUBSYSTEM 19 5.2. 1. Yaw System 19

5.2.1.1. Yaw Bearings 19 5.2. 2. Pitch System 21

5.2.2.1. Pitch Control 21 5.2.3. Operating conditions and bearing dimensions 22

5.2.3.1 .Bearing Load 22 5.2.3.2. Brake System 22

5.2.4. Gearbox for wind turbine 23 5.2.4.1 . Types of Gearbox 23 5.2.4.2 . Advantage of Planetary Gearbox 23 5.2.4.3 .Materials Used 24 5.2.4.4. Gear box specifications 24

5.2. 5. Shaft 25

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5.3. ELECTRICAL SUBSYSTEM 25 5.3. 1. Realistic Calculation 27 5.3. 2. Grid Connectivity 28 5.3. 3. Connectivity Scheme 29 5.3. 4. Technical Specification 31 5.3. 5. Protective equipment 32

5.4. CONTROL SUBSYSTEM 32 5.4. 1. Control System Definition 33 5.4. 2. Cut-in & Cut-out Wind Speed 33 5.4. 3. Summary 33 5.4. 4. SCADA System 33

5.4.4.1. Communication Media 33 5.4. FOUNDATION SUBSYSTEM 34

5.5. 1. Construction of Foundation 34 5.5. 2. Foundation Design 35

5.6. TOWER LAYOUT 36 6. ENVIROMENTAL IMPLICATIONS 37

6.1. Proposed Development 37 6.2. Environmental Impact Assessment 37 6.3. Lifecycle Assessment 40 6.4. Energy Balance 40 6.5. Sustainability 41 6.6. Wind turbine Disposal & Cost 42

7. HEALTH & SAFETY PLAN 44 7.1. Accident and fatality rates 44 7.2. Community safety assessment 44

7.2.1. Wind turbine system protection 44 8. QUALITY ASSESSMENT PLAN 48 9. CONSTRUCTION PLAN 50

9.1. Site clearance 50 9.2. Access routes 51 9.3. Construction scheme 51

10. FINANCIAL FEASIBILITY OF WIND TURBINE 53 10.1. Cost estimation 53

10.1.1 Initial Capital Cost 53 10.2. Net Income 56

11. ECONOMIC ANALYSIS 58 11.1. Simple payback 58 11.2. Life cycle cost 58 11.3. Cash flow 58 11.4. Conclusion 59

12. SUMMARY AND RECOMMENDATION 60 Annexure 61-75 References 76-79

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LIST OF FIGURES: A typical spread footing foundation Annual wind speed at 80meters height at Isle of Cumbrae Braking system Connection point distance and position from site location Construction plan flowchart aerial view of site location Control mechanism for wind turbine Control schematic Delivery point view Final location Force components Gearbox Generator Global wind energy council 2007 press release on world resource use Inverter Low speed end and high speed end shaft Mechanical pressure vs. RPM standards Pitch system being required Power rectifier Primary locations based on high wind speeds Rectifier Report structure/flow chart Risk assessment due to icing conditions SCADA control Self serving portable toilet Sound power vs rated power The wind turbine control subsystem block diagram Tower schematic Turbine design schematic Turbine site across the road Wind rose for western Scotland Wind speed vs. power generated Yaw bearing being mounted Yaw bearing of typical 5MW turbine Yaw drive Yaw system mechanism LIST OF TABLES: Balance of station cost Cash flow over the life of the turbine Designing Labour cost Details of gearbox being used Electrical parts Existing rotor diameter from leading companies HP and gearbox ratio relationship

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Initial capital cost of wind turbine Maintenance scheduling (tentative) Net present value of net annual income Power and extractable energy values Removal scenario for materials SMART analysis: rating each site location Smart analysis: weighted analysis of site location Speed, RPM and shaft diameter relationship Summary of global values for renewable sources Turbine system cost V82- 1.65MW Wind speed and power Yaw bearing dimensions and materials properties Yaw bearing duty cycle

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1. INTRODUCTION

1.1. History of Wind Energy

The use of wind as a resource dates back to Persia in the 500 A.D. when it was used for grain grinding and water pumping (Early history through 1875, 2001). Since then its development and the investment in its research and procurement has been exponential. However, most of this technological advancement in the field took place after a period of stunted growth in the 1960’s due to availability of cheap petroleum. The depleting non-renewable sources brought wind back to the centre stage of research and its development was rapid (Early history through 1875, 2001).

1.2 UK Wind Energy

The Global Status Report in 2009 on Renewable Energies by Renewable energy policy network takes an optimistic stance towards growth in this sector when it is guided through policy driven, stable and predictable governmental strategies in spite of the recent global financial crisis (Global status report, 2009) and the Global Wind Energy Council purports this optimism by stating a 32% increase in the market of wind energy itself in the year 2006 in spite of supply chain difficulties (GWEC, 2007). Figure 1 shows capabilities of different nations.

With European counterparts making their presence felt in the wind industry, UK seemed to be lagging behind in 2007. However, the rise of wind energy acquisition drive via the 2010 target of 10% electricity generation from renewable by the government saw UK wind industry surpassing Denmark as reported by BWEA in its 2008 Annual Review. In 2008, UK was reportedly generating 3240MW worth grid connected wind energy (BWEA Annual report, 2008).

1.3. Power from the Wind

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Wind energy ranks second to solar energy in terms of extractable power per year as shown in Table 1. However, even with a high extractable energy value, wind energy is not without its share of disadvantages like the creation of drag or wind shear, turbulence it creates and most importantly its variability. As of now, the research positively stands capable of overcoming these hurdles and the technological know-how available is more than sufficient for dealing with extraction process.

1.4 Isles of Cumbrae

Regarded as Scotland’s most accessible Island (Cumbrea Tourist Association, 2009).Isles of Cumbrae (55° 45′ 7.2″ N, 4° 55′ 48″ W) is Island just 10 minutes by ferry to the west of Scotland’s Ayrshire coast. Millport is the only town situated to the south of the Island. The Island itself is 3.9 kilometres (2.4 mi) long by 2 kilometres (1.2 mi) wide, rising to a height of 127 metres (417 ft) above sea level at "The Glaidstone" - a large, naturally occurring rock perched on the highest summit on the island. The population on the Island according to 1991 census is 1434. However, for this report a population of 1830 is being assumed considering a 0.276% population growth (The world fact book, 2009).

This report will demonstrate the value of building a wind turbine in the Isle of Cumbrae and show its significant benefits for the environment, and people. This project will also show that the wind turbine is financially feasible. There are four main parts; the first part is dealing about assessments of the wind speed and choosing the place and calculating the power requirements for the Island. The second part shows the chosen system and subsystem design. The third one is providing the construction and others project plan. Finally, cost and income estimations are considered to find the financial feasibility.

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2. PROJECT OVERVIEW

2.1 Purpose and Scope

Our team has been commissioned with the purpose of reporting the feasibility for a wind turbine on the Isles of Cumbrae. This exercise involves an investigation into a number of technical and non-technical issues which will be dealt with in detail here forth.

This feasibility report has been intended with certain aims that the team unanimously agrees upon in order to obtain maximum benefits from the project. Following is a description of these aims:

� Report is intended to keep the interest of the denizens of the Isles of Cumbrae as top priority. � Considering the ecological welfare for Isles of Cumbrae, the turbine will have to follow certain

standards in quality, environmental protection and health and safety when recommending the feasibility of the project.

� The report will undertake a discussion and analysis of the planning, construction, operation and decommissioning stages to establish the economy of the wind turbine while keeping the environmental and ecological protection of the Island and the interests of its people at heart.

In order to have a considerably correct measure of decisions and their implications, a set of assumptions are being considered. These help the team to establish an approximate measure of feasibility and make it easier to arrive at a logical decision in view of the dearth of literature regarding minute details that need essential consideration. A list of these assumptions is as follows:

� All calculations involved are all intended to provide a rough idea of the power obtainable and extractable. The measurements in the actual stages will reveal precise values of the entities being dealt with.

� The equipments and their specifications are kept as close as they can be to those that will actually be employed in the procurement and construction stages. No such compromise in costs will be considered and a more prudent approach will be taken for almost all costing.

� Present acceptable standards of environment and health and safety, following as much published guidelines available will be considered.

� All financial analysis will be kept down to the basics assuming a constancy of inflation. � In addition to these explicit assumptions, certain detailed assumptions will be implicitly

mentioned wherever they are being made in the report.

All in all, a prudent approach in all aspects involving decision making will be taken in the best interests of the company.

2.2 Report Organisation

In this section, a general idea of what is to follow is given. The structure is kept as simple as possible and is such that the approach to the final decision becomes clear implicitly.

The team has followed the flow chart below in arriving at the decision and hence the report is structured accordingly. The project aims were translated into a set of criterion which helped us arrive at the final decision on site of the turbine, primary design analysis including initial calculations dealing with available and procurable energy and costs involved in such a design. The design choice was made

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considering the cost and benefits of at least three design choices that will be explained further, and the particular reason for the final selection.

This has been followed up by further analysis of the energy calculations. Thereafter, design of each subsystem suitable and compatible to the calculated energy values in the secondary analysis is done with as much references that could be made to available literature. This particular analysis is supposed to be prudent and is to provide a logical but not accurate idea of how much energy will be produced. Each member on the team has made an analysis in the different aspects of the design system including the current costs sourced from the internet. Each system has been integrated to form the final layout design of the turbine including the site layout prior to construction phase (that includes transport and logistical specifics and costs) and that which will be included in the planning permission along with support statement and other related documents. Incorporated in the construction plan will be the quality, environment, health and safety directives and related costs incurred as a result. Thereafter, gross investments will be compared with gross revenue figures obtained from the follow-up or secondary revenue analysis to arrive at the financial feasibility in light of other important factors effecting feasibility of the wind turbine like public acceptance, environmental and health and safety impacts etc. A follow-through of the decision will be made in form of recommendations to the board of directors.

The report is intended to be simple in its construct so that its discourse is easily understood by anyone irrespective of knowledge of wind turbines. The annexure contains the analysis and calculations dealt by the team for the report. The decisions made and the difficulties faced during the project are mentioned along with the necessary information for understanding the decisions made.

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3. SITE SELECTION

In consideration of site, there are certain essential points that require to be ascertained before any logically supported statement can be made. Out of the most important points that need consideration is the wind statistics at the potential site. However, for any site, much of the metrological data from met stations is of little use in predicting the actual power in the wind (Nelson, V., 2009). Even when certain measurements methods like ‘wind atlas method’ may come handy; these predications cannot obviate on-site measurements that can only happen after approval of the planning permission (Garrad Hassan). A brief description regarding the various site selection considerations follows before the final decision analysis is presented:

3.1. Wind speeds

As mentioned earlier, wind is the fuel for the wind turbine which generates electricity. Its abundance is positive sign but the form (gusts or gales) in which this abundance prevails needs to be essentially known. Wind prediction strategies usually involve wind maps or atlases or sophisticated prediction software like Geographic Information System (GIS) like Digital Elevation Model (DEM) analyses terrains with relevance to wind energy prospecting (Nelson, V., 2009).

In the present case regarding the site selection on Isles of Cumbrae, a total of five site locations were selected by inference from the Meteorological office (Met Office, 2010) and using the UK wind speed database (Renewable UK, 2010[2]). A list of all selected locations follows:

1. N1656 2. N1657 3. N1655(denoted 2 in figure 3) 4. NS 1555 (denoted 3 in the figure 3) 5. N1756 (denoted as 4 in the figure 3)

Figure 3 shows the choices made with an intention to investigate the locations on the Island that have high average wind speeds. As indicated, location 1 N1656 is the best place as it has high average values of wind speed for different heights. A set of rough calculations for estimation of extractable wind energy at each of the above locations is included in Annex 1. It briefly considers the acceptability of each particular location along with energy values.

Figure 3: Primary locations based on high wind speeds

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3.2. Noise

According to BWEA, a wind turbine farm at a distance of 350m away generates as much noise as noise from a flowing stream about 50-100 metres away(BWEA, 2009). However, this is not to say that measurements would not be done in the site assessment phase prior to construction as it would be a non compliance of the aims of the project.

Figure 4 (Klug, H., 2002) shows the extent of noise in dB that is produced from different power rated turbines. This plot can help in making crucial trade-offs when power vs. noise is being considered as the relation of power and noise arises from the operating conditions and hence, the choice of a wind turbine’s blade pitch setting and its rotational speed is a compromise between noise radiation and energy production (Klug, H., 2002). In other studies from a number of different countries like Sweden, Netherlands apart from UK, the recommendations that followed were to include cumulative noise impact evaluations within 35-45 Db for high frequency and 10dB for low frequency components in addition to potential shadow flicker and turbine visibility impacts (Minnesota department of health, 2009). The reduction in noise from the turbine is one of the ways of countering the problem. The extent of technological sophistication achieved in insulating the hub and shaping the blades has been of great aid in assuming the reduction of noise by similar appropriate measures like active noise reduction for gearboxes (Illgen, A., et al, 2007) and acoustically absorbing tiles usually secured to the walls of the hub (European patent EP0657647). In the SMART based decision making approach each site has been given a numerical measure to establish its position amongst others.

3.3. Environmental Impact

Impact of wind turbines on the environment in itself spans a number of topics. A verification program undertaken by U.S Department of Energy in association with EPRI discussed a number of environment related issues like wildlife impacts, and impacts on areas of historical, archaeological and cultural heritage, visual and aesthetic impacts (Green Mountain Project, 1997). Discussion of some relevant issues will now be in order:

3.3.1. Wildlife Impacts: The prediction is that these are limited or not at all. The locations chosen are far away from large animal habitation areas and also away from forests and hence the elimination of need to heavily de-forest will not have an indirect impact on the wildlife on the Island.

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3.3.2. Impacts on Historical, Archaeological and Cultural heritage: In view of avoiding conflicts with historical conservation societies, the sites at N1555 and N1756 are least appropriate on account of a war memorial in the vicinity of the former and the famous Glaidstone near the latter. Similarly, N1656 is located in the Golf course and hence unsuitable. Location N1655 isn’t suitable either as it is too close to the town of Millport that is bound to have adverse affects on the community including, noise and visual impact related health issues.

3.3.3. Visual and Aesthetic impacts: The analysis of these impacts is to some extent subjective and is therefore prone to variable assessments. In order to obtain a better insight, simulation mechanisms exist but face the problem of accurate representation of impacts of significant vertical structures. Colour photomontage and video photomontage are useful techniques and are likely to be used in the pre-planning phase of the project, in spite of both being limited by some problem in representation and public acceptance of results. Nevertheless, these are the extensively used techniques (Thomas, G.W., 1996).

3.3.4. Electromagnetic Introduction: A wind turbine can act as both transmitter and receiver of electromagnetic interference. Hence, its protection from its own radiation and from other forms that may be rare or limited in locations 1, 2 and 3 but not 4 and 5 must be considered. Critical elements that come under EM influence are the control systems under the hub and nacelle and the best way to protect these devices is by electromagnetic shielding. In order to ascertain the shielding effectiveness required, a sense of EMI strength needs to be calculated. One of the ways in which EMI may be minimised to avoid its effects on communication signals between hub and the base station is by using a GSM transmitter placed at the entrance, inside the cast iron hub. This is following a documented study of EMI on large wind turbines (Krug, F., et al) This is predicted to be more effective at locations where ambient EMI is minimal and under limits that don’t affect communication signals.

3.3.5. Soil Conditions: This impact is one that is effected by and also affects the site selection. A strong foundation is prerequisite of a large turbine intended for generating power to be sufficient for an island the size of Cumbrae. Preliminary research has resulted in selected locations being situated in differently typed soils or ground conditions. The overall quality of soil on the Island is stable with mainly rocky costal platforms. Each location is marked according to its suitability to sustain a weighty turbine and hence extend to its life and performance throughout lifetime (See Annex 2)

3.4. Accessibility

For a project of this magnitude, cost saving becomes a decisive factor during feasibility study. The locations rate differently based on their accessibility at the very first inference such that locations 4 and 1 gain a preferentially favourable rate while location 5 gains the least rated value. The transport and availability of on-site space for a aesthetic and well structured site layout not only impacts the working conditions but also helps in environmental and ecological conservation such that the openness allows environmentally responsive changes that are highly limited by cramped site layouts. The former openness can be achieved at locations 1 and 2 but not at 3, 4 and 5.

A numerical rating for each of the above issues is done by assessment for each site location and used in the SMART based decision making. Although a logical conclusion may be arrived at, further detailed pre-assessments are required in the pre-planning phase including a public survey that establishes no objection to eventually selected final location.

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3.5. SMART Analysis

When using this tool, weighing of parameters actually is prioritising and is intended to be in-line with the aims of the project. It is evident from table 2b, that for the reporting team, environmental issue was most important and was weighed at 34% of overall importance. Then, the power providing capability through wind speeds was rated second most important at 31% and Accessibility at 19% was followed by Noise impacts at 16%. The weighing is in accordance with standards and reflects the team’s preferences of important issues for the project.

So, from the table above it can be seen that location NS 1657 is the best place for building a turbine. The document related to the above analysis can be found in Annex 3. Figure 2 give some primary information of the site selected.

Note: in both the above tables * includes impacts on wildlife, historical, archaeological and cultural heritage, soil; visual and aesthetic impacts; soil conditions and EMI.

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4. TURBINE STRUCTURE SELECTION

After the selection of site, a thorough investigation of wind speeds was performed and the variation of wind on a monthly cycle in year was tabulated. This revealed higher speed winds during the winter months and relatively lower speeds in summer months. Based on these wind speeds (UK-wind forecasts, 2010), a value of energy for every month was determined which helped in finding the power generation for that month. Table 3 gives average monthly values of wind speeds at N1657. For analysis in this report, these monthly values will be taken as absolute measure of wind speeds and is assumed to provide with approximately correct values. Power in kW and energy production in each month is also listed.

In Annex 4, detailed calculations are described for three individual heights at 60m, 80m and 100m. This choice of heights was based on majority of design types having diameters in this range. For each height, two diameters were considered and calculations yielded. In this document, the value of Cp is taken as 0.37 just for the sake of evaluating the maximum (even though unattainable) power and energy values. The efficiencies of generator and gearbox were 80% and 95% respectively. This yielded in overall efficiency of 28%. Each combination of height and diameter gave a different value of power and energy generation for a year. Please note that the recommendations of Annex 4 are without cost-benefit trade-offs. The next step was to consider a single design with a particular height at a particular rotor diameter. A number of issues affected the design choice and some of them were:

� Costs to be incurred against income gained � Conformation of design with stipulated standards � Power values that should produce energy values that should be optimised against demand

on the Island � Access to transmission lines of the National Grid

Each of these will give rise to trade-offs that will help in deciding the design that conforms to standards, provides acceptable energy values to cover demand and to save costs by optimising design.

4.1. Cost-Benefit Trade-offs

To build a successful wind turbine, the most essential factor is to consider whether the wind turbine is economic or not (Nelson, V., 2009). Because machine cost increasing quicker than energy production, the unit costs of energy production which calculated from energy production divide machine cost shows a slowly rising trend with size increasing (Harrison, R., et al, 2000).

4.2. Design Standards

Some of the important guidelines that the company will have to follow are the Grid Codes. The Grid Code covers all material and technical aspects relating to connections to, and the operation and use of, the GB electricity transmission system (Grid Code documents, 2010). Apart from these are the environmental protection standards to be followed during the construction, operation and decommissioning stages. A collection of various codes to be accepted will be enlisted as and when their need arises within different subsystem analysis later in the report. Some general requirements that the design needs to conform to are:

� Energy supply needs to lie within specified limits so as protect the grid from undue failures due to malfunction at the turbine’s end

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� The power needs to be supplied at a connection point at 400kV, 275kV or 132kV lines. � The equipment at the connection point needs to be supplied by the users (i.e. the company)

and needs to follow power quality, level and variation specifications from the National Grid.

4.3. Demand on the Island of Cumbrae

Since the aim of the present feasibility study was to provide on the electricity needs of the Island, the demand on it needs to be known. According to sub nationals electricity demand 2009 (Sub-national consumption statistics, 2009) the annual domestic energy consumption in the North Ayrshire area is 4MWh/year/person and this value is cannot be assumed to apply to the Isle of Cumbrae because of the fact that it forms a rather small part of North Ayrshire region. Hence, the demand is assumed to be 3.3MWh/year/person to counter the lack of information in published literature. Even then this gives a clear picture of demand in the region. In order to be able to calculate demand, the population on the Island has been estimated to grow from 1434 to 1830 as per the UK population growth rate of 0.276% as estimated by CIA (The world fact book). In this way, the value of demand will be 3.3x1830=6039MWh/year. Isles of Cumbrae do not have any industrial settings and enterprises and majority of its demand for electricity arises for domestic purposes. In order account for the electricity required for sub domestic purposes like electricity for streetlights and basic public amenities, the team proposes a thorough investigation. However, in lieu of absence of any data on this extra demand an assumption that this demand will equal 30 person’s demand is made. Such that number of people on the Island will become 1860 and the demand rise to 6138 MWh. Therefore, the capacity factor stands at 6138: (8760x1.7) =0.412=41.2%.

4.4. Access to transmission lines of the National Grid

Under norms of the National Grid code documents, the users (i.e. the company) will be required to make the power available to the grid by means of their own transmission lines if necessary. In the present case, the nearest point from the British Grid is 870m away and the path is almost manageable. The point of connection is shown in figure 7.

4.5. Decision Point

Based on the above trade-offs, a design that was cost effective, could lend to easy standardisation in compliance with current rules, could satisfy demand on the Island and also was easily connectable at reasonable costs was to be selected by the team. Since a number of factors were being considered, it was easy to lose sight of the aim and so each design was analysed and based on their performance on these parameters, the design with 80m height of tower with 80m diameter of rotor was zeroed in on. The decision analysis was subjective and was made keeping in mind the fact that the power generated was going to be sourced to the grid with a collateral agreement requiring the demand on the Island to be satisfied with reduced costs or ample benefits. This collateral agreement is

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then again subject to a number of variables but this is what the team has proposed to forge easiness of obtaining the permission to construct in case the turbine is built anyway.

Turbine design that has eventually been chosen is a horizontal axis, up wind and pitch controlled type of wind turbine. Figure 8 shows a very basic schematic of the chosen design. The team intends to review the performance of this design in pre-planning and measurement stages before actual construction when more values for calculation and more information will be available. However, it is predicted that many changes are unlikely to occur and the design will only be reviewed and minimally modified.

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5. TURBINE SYSTEM DESIGN

Until now in the project, the decisions on where to build the turbine and what design of turbine to build were investigated and presented. The subsequent sections to follow hereafter will contain preliminary information on the turbine’s subsystems each discussed by correspondingly relevant members of the team. Following is the list of the subsystems that will be further discussed:

� Aerodynamic subsystem � Mechanical subsystem � Electrical subsystem � Control subsystem � Foundation subsystem � Tower Layout

5.1. AERODYNAMIC SYSTEM

The following has been studied under the aerodynamic system of the turbine for deciding the location, design and also the design of rotor essentially used for conversion of wind energy into rotational energy of the rotor and thereafter mechanical energy of the shaft.

5.1.1. Wind Rose and Wind Distribution

To determine the exact design of the wind turbine and choose the location, the particular wind condition in Cumbrae Island should be considered firstly. From this point, the wind rose data from the nearest wind station and annual wind speed distribution could be helpful.

The wind rose data in Prestwick, which wind station, is quite near Cumbrae, between 1996 and 2005 shows that the majority wind in Western Scotland came from Southwest. And the wind speed between 11knots (5.66m/s) and 27knots (13.9m/s) could be seen as the most normal wind speed in this area. Meanwhile, depending on the average wind speed (7.8m/s) in Cumbrae at 45 meter (Energy statistics: wind speeds 2010), the wind speed at different height could been converted with the formula

Power=0.5xetaxPixradius2xaverage velocity3xrho

Then referring to average wind speed (8.2m/s) and wind distribution for every month in Western Scotland (Energy statistics: wind speeds, 2010), the wind speed for every month in Cumbrae at 80 meters high has been draw as follow and wind rose has been cited as well.

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From the figure above it could been seen that the lowest wind speed occurred in July and August which was accounted for 5.9 m/s, while the highest wind speed occurred in January which was accounted for 10.7 m/s.

Overall, from the data above it could be concluded that the annual wind speed in Western Scotland is between 5.66m/s to 13.9m/s and the direction is from southwest. However, more accurate data shows that the rated speed could only reach into 10.7m/s, so the turbine rate power generation should relate to wind speed at 10.7m/s.

5.1.2. Rotor Design

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Considering the wind turbine diameter (80m) and rated wind speed (10.7m/s), 5 types of wind turbine rotor was chosen from the top ten large wind turbine manufacture. Meanwhile, the location of the company was considered as well in order to reduce the transport cost. The detail information was constructed in the following table 3. Please refer the cost assessment in Annex 9. Taking into aspects like available data, suitability to wind speeds and costs, in conclusion, V82 wind turbine rotor which is manufactured by Vestas is chosen.

5.2. MECHANICAL SUBSYSTEM

Under this subsystem, an investigation of the yaw and pitch mechanisms are discussed. It gives a general overview of how these mechanisms work and how the team intends to approach them.

5.2.1. YAW SYSTEM

The yaw arrangement of wind turbines is the element responsible for the directing of the wind turbine rotor face into the wind as the wind direction changes.

5.2.1.1. Yaw bearing

One of the key mechanism of the yaw system is the yaw bearing. It is made up of either roller or gliding type and it acts moveable connection between the tower and the nacelle of the wind turbine. The yaw bearing is done to withstand high loads, excluding the weight of the nacelle and rotor, comprise the kinetic energy of the wind. It is mostly made up of hard stainless steel. The thickness is dependent on the weight of the nacelle and the forces of wind.

5.2.1.2. Yaw drives

The yaw drives is a means of rotating of the wind turbine nacelle. Each yaw drive comprises of powerful electric motor and a great gearbox, which enhances the torque. This is used to drive the nacelle.

The yaw drive diagram above is made up of three parts

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• The mechanical pump (Bonfiglioli, 2009) which is located at the top. It is used to generate Figure 12: Pump system for yaw gears the rotation which is required to cause the movement of the gear teeth. We can use the calculation below to calculate the torque and mechanical power.

Torque is defined as

T= r x F Τ is the torque vector r is the displacement vector =0.2m (assumed) F is the force = mass x acceleration

Mass = 125 000 kg (estimated mass of the nacelle)

Acceleration= 9.81m/s

T= 0.2 x (125000 x 9.81)

T= 245250 Nm

Power (KW) = torque x 2П x rotational speed

Rotational speed = 8m/s (assure due to the fact the it will have to be monitored so that the nacelle will be position properly)

Power (KW) = 245250 x 2 x 3.142 x 8

Power = 12329.208 KW

Power =16527HP

This is use to calculate the power required to turn the nacelle round and it is the mechanical power of the motor. The motor is four in number so the power calculated is divided into four and the reason is that is to reduce the stress load on the motor. It is also designed in such a way that three of the four motor will be able to turn the nacelle and the one left is use for safety reason in case of damage to any of the drive or increase in speed of the wind.

• Gearbox system is also part of the yaw drive. The gear system is used to reduce the amount of mechanical power to be applied.

Power on one of the motor = 16527/4 = 4132HP

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So to reduce the mechanical pump capacity we can say that we need a pump of about 40-45 HP

The mechanical power varies but the lager the power the smaller the gear box.

• Gear teeth: the gear teeth are attached to the yaw bearing teeth which has to fit with the teeth. It is most made up of hard steel to make it hard enough to carry the weight.

Figure 13: Yaw system mechanism

5.2.2. PITCH SYSTEM

The pitch system is similar to the yaw system only with a smaller radius n taking in considerations the weight and diameter of the blades.

5.2.2.1. Pitch Control

• Working way electromotor pitch adjust, independently blades adjust

• Pitch –controlled 4-points double row angular contact ball slewing ring with inner ring gear bearing

• Pitch adjusted rate 7.5 /s-12.5 /s • Pitch adjusted angle range -94 • Battery lead acid, 250-300VDC • Slip ring 29 rows

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5.2.3. OPERATING CONDITIONS AND BEARING DIMENSIONS 5.2.3.1. Bearing Loading

The yaw bearing is mounted in a tubular tower is required to endure for 20 years considering 50% operating time so considering a bearing of this capacity. Also take into consideration that the wind turbine might be turned once or twice a month.

The tables above shows the bearing size and an experiment carried out. If the same bearing is to be used we will consider condition 1-5 when determining the bearing limited load.

5.2.3.2. Brake system

The mechanical brakes are applied as a support system for the aerodynamic braking system, and as a stopping brake, once the turbine is stopped in the case of a halt controlling the turbine. The disk brake involves a flat spherical brake disk and

plurality of brake callipers with hydraulic pistons and brake pads (Gasch, R., Twele, J., 1993). The hydraulic brakes (pump, valves, and pistons) are able to fix the shaft and nacelle in a fixed position .The highest speed of the rotating shaft is used to calculate the force that the blade needs to apply.

The drum brake will have the same diameter as the low speed shaft while the disc brake will have the same diameter of the high speed shaft. Parts of a brake system are Conveyors, flywheel brakes, mining vehicle brakes, railroad maintenance equipment, tension brakes.

Since we have a generator with a maximum revolution of 1500rpm from the graph above we will apply a mechanical pressure of 5HP to hold the shaft in to position at the high speed region. Using the graph we can also calculate the pressure to be applied on the brakes on the low speed shaft, yaw bearing and pitch bearing. This can be done be using the revolution at which the gears are rotation and applying the force required.

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5.2.4. GEARBOX FOR WIND TURBINES

A wind turbine is a machine that translates the kinetic energy in wind into mechanical energy. Wind turbines utilize a gearbox (Gears and Gearbox, 2010), jointly with a generator to convert mechanical power into electricity.

A range of gears and gearboxes are employed in wind turbines for connecting low-speed shaft to the high-speed shaft and increasing the rotational speeds. These gearboxes increase the RPM in the wind turbines to a level that is required to produce electricity (Eaton Corporation, 1997). Figure 17: Mechanical Pressure vs. RPM standards

5.2.4.1. TYPES OF GEARBOX USED

• Planetary Gearbox • Helical Gearbox • Worm Gearbox

Planetary gearboxes are mostly used in modern turbines because of the following reasons.

5.2.4.2. ADVANTAGES OF USING A PLANETARY GEARBOX

This gearbox offers many advantages as compared to other types of gearbox. Some of them are:

• The gearbox drive increases the efficiency and provides extremely low speeds. • These gearboxes deliver high reduction ratios and transmit a higher torque. • These gearboxes are compact and lightweight, requiring little installation space • High reliability due to proper distribution of stress among different load-bearing components. • Higher torque to weight ratio • Low backlash • Compact size • Less weight • High cyclic and radial load carrying capacity • Improved efficiency • Modular construction allowing assembly in several stages • Greater resistance to shock • Improved lubrication

Planetary gear

Planetary gear is an outer gear that revolves around a central sun gear. Planetary gears can produce different gear ratios depending on which gear is used as the input, which one is used as the output

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5.2.4.3. MATERIALS USED

Materials used for constructing them including:

• Stainless steel • Hardened steel • Cast iron • Aluminium

5.2.4.4. GEARBOX SPECIFICATIONS

There are a number of performance specifications which must be considered while choosing a gearbox for different industrial applications. Some of the important specifications (Leech, 2009) are:

1. Gear ratio: The ratio may be specified as x : 1, where x is an integer. The circular speed v {m/s} = 2π r n Where r is the radius {m} n is the revolution per second {RPS) n = v / 2π r To convert RPS in to RPM, multiply RPS by 60.

Therefore, Gear ratio: 52:1

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5.2.5. SHAFT

Wind turbine shaft is connected to the rotor. As the rotor rotates, the shaft revolves also. In this way, the rotor transfers its mechanical, rotational energy to the shaft (low speed end), which enters the gearbox then the shaft (high speed end) transmits it from the other end of the gearbox to an electrical generator on the other end. Typical diameter of shaft wind turbines from 600 to 1500mm which weighs 2000 kg - 4,500 kg which is made up of high grade steel

5.3. ELECTRICAL SUBSYSTEM

Until now all the calculations in estimating the energy have been performed in order to estimate the energy producible economically from an appropriately designed turbine that effectively uses the available wind energy trends that have been outlined previously. It has been convincingly proved that a turbine at 80m height agl and 80m diameter is most economical as it not only satisfies the demand but also utilises resources optimally.

Realistic calculations that take into account the scheduling and maintenance breaks, that a turbine normally has to undergo, will now be produced. In order to do this certain assumptions have been taken into account before the calculation is performed:

• The turbine will be scheduled for bi-monthly, half-yearly and yearly maintenance during a period of one year as depicted in the table below:

• In one year, the turbine is scheduled for working all but 40 days that will be reconciled in maintenance described above. BWEA (www.bwea.com) states that electricity is produced 70-85% of the time (Further reduction in working time can bring by an equal estimate of irregular shutdowns contributing to total shutdown. Even though such a scenario is unlikely

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to be proved ideal, it helps arrive at the extent of power that will be extractable by the turbine. Hence, ignoring the realistic downtime due to insufficient winds (which won’t be many), the annual working time of the turbine is 8760-80=8680 days.

• This gives an average working value of 23.78 hours per day. The energy calculations will take this figure into account for yearly supply.

The energy produced will be transmitted over a company owned transmission line between the national grid at 132kW near the Millport city centre. This distance has been approximately estimated to be 870m (Google earth).In order to establish the electricity specifications over this transmission line, whose rating is to be established in tune with the grid code rule of the national grid.

The following points have been collected from the grid code regulations document that the company will need to fulfil in order to make use of the national grid (www.nationalgrid.com) for generation and thereafter transmission purposes:

• The grid is not responsible for transporting power from the site of the user to the connection point. Hence, the company will have to finance the transmission line between the site located in the OS location NS1657 and the connection point estimated to be 870 m away (Figure 7).

• The connection will have to satisfy some specifications of electrical energy being transported into the grid: � System frequency could rise to 52Hz or fall to 47Hz in exceptional circumstances with

nominal value 50Hz � System voltages coupled to 132kV line (in present case), will have to remain within the

limits +/- 10% of the nominal value unless abnormal conditions prevail. � Voltage waveform quality given by Harmonic content to be predicated by the

Engineering Recommendations and Phase Unbalance to be within 2% for this site lying in Scotland.

� Voltage fluctuations in Scotland for 132kV and above voltage lines, requires bilateral agreement that cannot be overridden. Severity of Flicker can be 1.0 Unit for short term and 0.8 Unit for long term.

� Earth Fault factor in Scotland for 132kV an above is below 1.5 � In addition, the compliance of grid code requires transmission busbar zone equipment,

including circuit breakers, switch disconnectors, Earthing devices, power transformers, voltage transformers, reactors, current transformers, surge arresters, bushings, neutral equipment, capacitors, line traps, coupling devices, external insulation and insulation co-ordination devices.

• The maintenance of the equipment listed will be exercised on the bi-monthly basis with nominal automated diagnostics being run to evaluate cumulative wear and tear. A more detailed maintenance and repair schedule and document will be produced after sanction of the project.

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5.3.1. Realistic Calculations:

The Table 10 accounts for the amount of power generated monthly by the turbine of selected dimensions i.e. 80m Height and 80m Diameter, according to the formula:

Power=0.5xetaxPixradius2xaverage velocity3xrho

Where eta=efficiency of turbine taking into generator, gearbox and Cp value into account=0.37; radius=80m; average velocity taken in mps considered here for every month; rho=estimated value of density at the height 80m. It can be inferred that the maximum average power that can be produced at

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this height, for speeds ranging between a maximum of 10.7mps to minimum of 5.9mps is around 0.9 MW. This value is within the safe limits of grid connectivity that has a 4MW capacity.

This value of power needs to provide for the demand of the Island of Cumbrae which will now be calculated keeping in mind that demand is not constant during a day and falls during the night. The assumptions that this calculation entails are listed below:

• The value of demand is taken as 6039 MWh on the Island for a year and an additional demand equivalent to 30 person’s requirement as an assumption for the miscellaneous and general purpose demand, gives a total value of yearly requirement as 6138 MWh as previously mentioned.

• The premise of this feasibility study being the provision of cheap power to residents of Cumbrae, the supply has to be more than this value of average demand, that is not uniform over a period of single day and night in any year but is rather an estimate of total value of power demanded over a year.

We have seen that the power generated by the turbine of selected dimensions gives 0.9MW rated output. However, the energy produced by it is given by the following table:

The value in bold and underline is the value of 6176MWh in a period of one year. This

value is about same as the value demanded on the Island. This value although an estimate draws a clear indication of appropriateness of the dimensions of the turbine, which have been decided not just based on energy production but also based on the cost trade-offs arising from selling energy preferentially to satisfy demand of the Island rather than the nation. The values in the last column are a result of the following formula:

MWh produced in a month = kW based on average rated speed of that month x no. of hours in that month

Totalling energy produced in each month gives a value of power produced per annum and helps in deciding whether this is capable of covering the demand in a year. Accounting for transmission and connection point losses will obviously result in power losses and hence this value of generated power is suitable to have a safe upper bound of generation.

5.3.2. Grid Connectivity

From electrical point of view, the generation and consequently the size of the turbine is limited

not just by cost (that has helped in arriving at the size of 80m height and 80m diameter), but also grid connectivity that in addition to connection point rules of protective equipment and limits of variation of different parameters (that can potentially be harmful for the power system dynamics). In this section, a brief description of how the grid connectivity dictates power generation and transmission will be made.

In order that the power generated by the company’s turbine is used and an income generated

thereof, the grid connection is essential and is one that requires a detailed study. The aim of this section is to substantiate the level of complexity related with making a connection and its effects on the turbine and the power system.

Connecting a wind turbine to the grid is tricky proposition but not one that can be avoided. The

variability of the output from the wind turbine can have adverse effects on the overall dynamics of the power system, a clear reason enough for stringent grid code rules. A robust and effective power control

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strategy needs to be devised, more so in the case of a variable speed generation scheme, that allows conversion of larger ranges of wind speeds to be converted into electrical power that while penetrating the grid produces little or no effect on the power dynamics of the system. Transmission operators are expected to provide consumers with an invisible product that can neither be stored nor be allowed to go waste. Moreover, it needs to be made available when it’s desired or ordered for making it perfect for just-in-time management (Garrad Hassan, 2009). Hence, heavy reliance on forecasting is required and special mention to forecasting errors also can be made.

In this particular area of Scotland, the grid code rules as mentioned previously apply and are as

stringent as they are elsewhere. Since the feasibility study aims at power provision on the Island that will make power cheap for its residents, more focus could have been given to embedded generation. But, since this is not yet legalised in UK, the scheme of grid connection that will be followed is through transmission network. A detailed description of the power electronics in conjunction with the power being transferred will be made at a later stage. These power electronic devices will be responsible for provision of stability to power while being aided by the protection equipment. The use of an assortment of FACTS devices would be in order to ensure compliance of grid code limitations and also improving power quality in the selected part of the grid while improving the efficiency of the turbine. This would consequently improve the life of the turbine to 20-25 years as an assumed estimate.

The variability of power output from the turbine during a year deserves a special mention. A

recommendation for bilateral agreement with the national grid is being made with an intention that the high power levels during the winter months can be considered as power generated to offset the low levels during summer and hence making it clear that any unprecedented rise in vacationing population may not be inconvenienced by low power levels of the proposed wind turbine. This is however unlikely because the power calculations performed previously have taken into account the vacationing population as well and hence this agreement will be explicitly made for the interest of any unprecedented rise in people visiting the Island during summer.

Keeping in mind the amount of wastages resulting from absence of any kind of electrical

storage mechanism, the proposed report is offering power levels high enough for the Island to sustain itself without the grid and low enough to avoid any losses attributed to power generation levels lying higher than demand on the Island. The level of power being offered brings costs, losses and environmental impacts down by a considerable level while covering up the Island’s demand and ensuring optimum use of available resources.

5.3.3. Connection Scheme:

The variable speed power generation scheme is proposed for basically the following reasons

(Muljadi, E., Butterfield, C.P., 1999): • Variable speed is more efficient system of generation as the rotor maintains best flow

geometry for maximum efficiency. • Even low speed winds, in variable speed system can be utilised because rotor and wind

speeds could be matched and hence rotor could be connected to the grid even at low speeds. • At and above rated speeds however, the pitch control was activated to maintain the blade

angle such that power regulation above rated power could be achieved.

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• Variable speed power generation scheme offers better output power quality offered to the grid, higher efficiency of power generation and greater operational flexibility.

• Faces fewer problems with grid connectivity compared to fixed speed. The down side to this however are the cost issues and that variable speed scheme costs higher

than fixed speed generation scheme. This could be offset in improving power balance of the turbine and reducing material costs and overheads. The proposition of cheap power is reason enough to offer better quality of power which would not just offer better regulation and quality improvement in the grid area to which it is connected but also offer reduced losses and hence save valuable energy from a renewable resource. The variable scheme is brought about by using an AC-DC-AC link as shown in the schematic below, with auxiliary power being provided through a rectifier with its input from the generator output during steady state operation.

The control of aerodynamic power at the turbine blades will be through pitch regulated system that will help in:

• Control of upper limit of rpm at which blades will be pitched out to regulate output power at rated limit.

• Utilization of aerodynamic power from low and medium speed winds by suitable pitching angle that maximises torque and hence power.

• Smoother variation of rotor speeds offered by high inertia of rotor blades translates into similar smooth variation of electrical power.

• At low and medium wind speeds, pitch is regulated to gain maximum torque and thereby maximum mechanical power that is capable of producing highly efficient electrical power.

• At high wind speeds, the pitching of blades is done such that the increasing power output due to higher wind speeds is curtailed at the point where rated power is being produced. At this point, the pitch is regulated to shed excess aerodynamic power and the turbine begins to operate at low efficiency. The pitching is expected to occur when the wind speeds are higher than 14m/s.

5.3.4. Technical Specifications of Electrical Parts:

Hereunder is a brief description of each of the above major equipments that are housed in the

Hub except the transformer:

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1. Generator: The generator selected is a China make and is manufactured by FUJIAN SAINT MEILAN

MOTOR WIRING CO. ltd. The product specifications from the manufacturer are listed below Key Specifications/Special Features:

� TFW2 series three-phase AC synchronous generator

� With CE and ISO9001:2000 certificate � Output: from 6.5 to 1,200kW � Steady state voltage adjusting rate: under 2.0% � Transient state voltage adjusting rate: under -15

+20% � Voltage setting range: under +10%UN � Line voltage waveform distortion rate: under 5% � Voltage deviation rate under 3-phase

asymmetric load under 5% � The average efficiency reaches advanced levels � Conforms to IEC and GB/T 15548-95 standards

2. Grid Rectifier: This is used to rectify the AC output of the turbine into

DC. This forms the first part of the AC-DC-AC link that plays a very important part in power quality control from the turbine. The rectifier chosen is a 3ph bridge type and is from IXYS Corporation. It is free from Lead and is hence more preferred.

3. Grid Inverter:

This is the output stage of the AC-DC-AC link that

provides power factor correction along with fast reverse recovery. The inverter chosen is a 3ph IGBT based six-pack inverter module capable of connectivity to the chosen grid rectifier. It is from the same manufacturer and is also Lead free. The following is the manufacturer’s description of the product:

4. Auxiliary power rectifier:

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This is used to rectify power from the generator output to provide for the current in the field winding of the synchronous generator. This is necessary in the present connection scheme because the generator output is decouples from the network and hence its output frequency isn’t network dictated and hence DC to its field is required throughout its operation. Even when this may not be the case, this particular rectifier is identified as Auxiliary power rectifier. The manufacturer is IXYS Corporation. The following is the specification list from the manufacturer:

The entities under 2, 3 and 4 are power electronic devices

(FACTS) that are required by this scheme of generation. The Grid Rectifier rectifies the ac power to dc power and transmits it to the inverter which converts this dc power back to ac power for transmission over the 877m long transmission line. This rectification and inversion provides not only offers to control the output frequency within prescribed limits by the grid code but also reduces losses and helps detect faults in conjunction with protective equipment. These devices are robust and efficient in operation and can be remotely controlled by dispatching through SCADA protocols.

5.3.5. Protective Equipment:

In order to offer better security and reliance of power generated by the turbine, protective equipments like relays and circuit breakers are essential in any generation system. This not only protects the plant from the system surges but also protects the grid from unprecedented failures at the generation end that may disturb the overall grid dynamics. In case of wind power, protective equipments play an important role because of poor reliability on wind patterns and forecasting errors. Since wind power patterns directly influence the generated power levels, the protection of generation equipment is mandatory in view of any gusts arising from storm fronts. Annex….gives a detailed list of equipment that will be employed.

5.4. CONTROL SUBSYSTEM

The need for a control system is not just to control power within certain limits in compliance of rules of power generation and transmission but also to have a level of predictability of generated power and to have flexibility of operating times in order to facilitate maintenance. In modern wind turbines, almost all control is exercised remotely via SCADA. This section summarises all the details of the

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turbine’s control mechanism.

5.4.1. Control Subsystem Objectives:

The most important objectives (Munteanu, I., et al, 2006) for the wind turbine control subsystem are:

• To Control the wind capturing for speeds larger than the rated

• Maximising the output power efficiency that captured by the wind

• Alleviating the variable loads, in order to guarantee a certain level of resilience of the mechanical parts

• Transferring the electrical power to the grid at appropriate frequency.

5.4.2. Cut-in and Cut-out wind speed (Bianchi, F., et al, 2007):

The ideal power curve for a typical wind turbine is sketched in Figure 21. It is shows that the range of operational wind speeds is between the cut-in (Vmin) and cut-out (Vmax) wind speeds, otherwise the turbine remains stopped. That is because below cut-in wind speed, the wind energy is not enough for the operation costs and losses. Over the cut-out wind speed, the turbine is shut down to protect the turbine system because the high wind speeds because of a high stress on the mechanical systems.

5.4.3. Summary

Rated Output 1.7MW at 14m/s

Cut-in 4m/s

Cut-out 13m/s 5.4.4.1. SUPERVISORY CONTROL AND DATA ACQUISITION (SCADA) Communications medium

To monitor and control using the SCADA system for wind turbine, it is required to use a communications media network between the wind turbine and control room. This media could be one of the following (Gardner, P., et al, 20004):

1- Copper twisted pair (RS485) 2- Fiber Optic 3- Radio telemetry

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Because the high cost of the cables, it is better to use the same cable routes for SCADA

communications as for the power distribution. It is concluded that optical fibers within the power cables could be the best option.

5.4.4. FOUNDATION SUBSYSTEM

5.5.1. CONSTRUCTION OF FOUNDATION

The foundation of the turbine offers an anchoring platform that holds the wind turbine in a firm, stabilized and upright position. The wind turbine should be able resist forces imposed by the rotating blades and wind by using and applying the right reinforcement and volume of concrete in the foundation. Large excavation of work is normally needed for the foundation. Most of the excavated materials will still be used to backfill in and around the foundation.

For the this particular project, it is assumed that the ground condition of the top soil and subsoil is good (Silt-sand) with propels the use of spread footing foundation which on the other hand is economically viable that is to say, it is cheap (AWEA, 2008). The specifications of this foundation require a wide and shallow excavation for the structure construction. Foundations are designed using the information base on the geotechnical investigation.

On top of the foundation is located the turbine base. The base comprises of metal ring with series of anchor bolt connections to pin down the turbine tower on top of the foundation. The turbine is connected to the foundation using large bolts that are entrenched into the foundation structure at a specific depth and an electrical earthing mat is cast in place when the foundation is casted. The backfill of the foundation is done to provide more support to the foundation. The backfill is then compacted for firm support. The steps for foundation assembly are listed below:

• Site Survey • Clearing/Grub site • Site Grading • Rock Removal and Blasting • Excavation • Installation of Below Grade Raceway for Power Cable Equipment (conduit, Trench, Duct

Bank, etc.) • Installation of below Grade Grid Mat • Installation of sub-layer crushed rock surfacing

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• Backfill with required aggregate • Installation of Foundation.

a. Place Rebar b. Place Turbine c. Place Forms d. Pour Concrete.

5.5.2. FOUNDATION DESIGN

The design process of wind turbine foundation is mainly dependent on two things: the dead load caused by the turbine tower, the nacelle and blades of the structure and; the moment force caused by the wind pressure on the structure.

Reinforced concrete spread footing is most commonly used because it is simple, cheap and economic solution for turbine towers (Singh, A., 2007). It is also useful for sites with good soil bearing capacity. The spread footing foundation aims at attaining the strength and stability requirement against shear and flexural loads46.The design requires details on the strength of concrete, safety factor to be used or assumed and soil bearing capacity. When designing a spread footing foundation, the load from the entire turbine pushes down on the central portion of the wind turbine foundation. This is the case with wind turbine foundation. The downward force causes a compressive force along the top of the footing and on the other hand, the tensile force at the bottom of the footing. Concrete by nature endures high compressive loads. The tensile force on the other hand exceeds the tensile strength of the concrete and therefore requiring tensile reinforcement at the portion enduring the tensile forces. The reinforcements that prevent the concrete footing from failing under the heavy loading conditions consists of a rebar assembled in a mesh style mat and cast in place at the bottom of the spread footing to withstand the tensile force.

In the design of spread footing foundation, foundation loads are gotten from the manufacturers, these loads are given as

• Vertical load (V) • Horizontal Shear force (H) • Moments (M)

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These loads are specified at extreme conditions (worst case loading) with reference to the centre of the tower on top of the foundation. Figure below show some structural forces acting on turbine foundation.

The foundation Stiffness is designed to withstand these loads. The maximum foundation stiffness is not to exceed the foundation stiffness provided by the manufacturer. The wind turbine has holes on the inside and outside edge from the base is fitted on the foundation

The loads imposed on the spread footing are first assessed in order to determine the amount of rebar that will be used to reinforce the footing. The wind turbine assembly has a dead load of 2,157KN (220tonnes), a figure gotten through research on Vestas V82- 1.65MW turbine. Also, additional pressure by the wind imposes a lateral force on the windward side of the wind turbine causing an overturning moment force at the base of the tower and top of the foundation. The maximum wind speed of the turbine location, 15m/s is used as a design parameter of the foundation. The 15m/s wind speed causes a drag force acting on the entire components of the turbine (tower and rotor blade).

Please refer to Annex 5 for detailed calculations of the foundation.

5.5. TOWER LAYOUT

The tower of the wind turbine supports the nacelle and the rotor. Wind turbines are constructed with circular steel sheets, with sections of 20-50 meters with flanges at either end, and bolted together on the site. The towers are conical which means their diameter increasing towards the base in order to increase their strength, balance the weight of the turbine and to save materials at the same time.

The wind turbine tower is made up in to section to ease transportation and put together on the site by the flange with a bolt. It is also consists a man hole which is used to access the nacelle through a ladder that is installed inside the tower. The tower is also used to reduce to amount of noise produced, electrical panels fitted inside it, electrical wiring to the transformer is passed through it. The tower is fitted with platforms every few meters to enable the worker take a rest from time to time, hold falling object from falling down when working in the tower.

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6. ENVIRONMENTAL IMPLICATIONS

As it has been previously discussed, environmental safety plays a very important part in this feasibility and affects every decision made therein. Since, a power station that serves the purpose of reducing the carbon footprint should not leave a large one itself destroying the actual purpose. This section is all about how each environmental was closely studied. Included herein is the proposal that we intend to place forth to the honourable members of the board, the life cycle assessment of the turbine and also the amount of CO2 saved in the process which in turn gives the payback period.

6.1. SUPPORT STATEMENT – PLANNING APPLICATION FOR A WIND TURBINE

PROPOSAL TO INSTALL A LARGE SCALE WIND TURBINE ON T HE

ISLE OF CUMBRAE

It is proposed to install a large scale wind turbine on land at Isle of Cumbrae

� The wind turbine is designed for generating electricity and will be mounted of an 80m tower, with rotor diameter of 80m (40m radius), hub-height of 80m, overall turbine height from ground to the tip of 120m and its annual output is 1.7MW.

� The turbine is expected to generate an average of 0.9MWh of electricity each year, which will save approximately 1903.5 tonnes of carbon dioxide (see following next section).

� The turbine has been particularly designed for low noise operation and minimal visual impact with an excellent performance. The wind turbine has a survival wind speed of 15 m/s.

� The turbine blades are made with composite materials. The tower on the other hand is made of steel.

� The projected location of the wind turbine can be seen in Figure 3 and it is considered to position the turbine as indicated. The projected location is roughly 500m from the closest property not possessed by the resident.

� The national wind speed database (www.metoffice.org) gives an annual mean minimum wind speed of 8.2m/s for Grid Ref NS 1657 and the projected site is within recommended guidelines.

� In addition to the wind turbine, related infrastructures will include: - An operations control building; - Underground power cables; - Access road; and - A temporary construction compound.

6.2. ENVIRONMENTAL IMPACT ASSESSMENT

1. NOISE AND VIBRATION

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Noise can have adverse effect on the environment and the quality of life in a community especially when it is a new development in that vicinity.

It is projected that the duration of the construction period of this project would last for 6 to 7 months. The restraint of the working hours is planned to address noise during construction, which may be audible at the closest properties, though the chances are still very low based on the fact that the location of the expected site is about 0.5km away from the closet properties, except for road users who may perceive it. However, by using recent silencing equipment (Klug, H., 2002 and Illgen, A., et al, 2007) and plants, in combination with the distances between the proposed site and properties, it is unlikely that construction noise would violate the specified guideline limits and this shows an acceptable construction noise. Anticipated Traffic levels during construction period are virtually low, and the connected change in traffic noise along the route to the wind turbine site is equally considered insignificant.

It is assumed that during the decommissioning of the wind turbine, noise will be in general less or similar to that experienced during the construction stage. Therefore, it is presumed that noise as a result of decommissioning of the wind turbine may be audible, but will once more be limited by controlling work hours and transport routes.

2. LANDSCAPE AND VISUAL IMPACT

The landscape and visual assessment has indicated that the proposed wind turbine will change the landscape and visual baseline conditions during its constructional and operational stages.

The construction phase of the projected wind turbine is relatively short, and will have minor effect on the landscape and visual impact within the local area.

Residential amenity can be defined as a term used to mean the views and amenity of a residential property, relating to main drive and garden areas, views to and from the property. Visual effects may not be necessarily unpleasant, this is a subjective issue. The turbine has been specifically designed to have low visual impact, with slender blades and a balanced nacelle as compared with the tower. The turbine is to be mounted at 7.3m above sea level compared to the nearest proper 411.62m away at an elevation of 77 m above sea level. There would be moderate visual effects on view experienced by road users of B896 road to the West and North of the site. However, with the increasing distance from the wind turbine, a visual effect on the receptors reduces.

3. ECOLOGY

The scope of the ecological assessment established by a combination of consultation and desk study to show existing biological data according to the site and its surrounding area. Field surveys were conducted around the site with reference to the Scottish Natural Heritage Guidelines (Scottish Natural Heritage, 2001).

The site is composed of open uncultivated grassland with more extensive area of semi-natural grassland which clearly, is not a farmland maybe as result of its proximity from the road and geology. It is not positioned near any wildlife park or site. It is 300m away from horse grazing grassland which is on a well elevated part of the landscape.

Densities of breeding birds around the site are immensely low and the semi-grassland within the site supports little or bird species typical of semi-upland agricultural landscape.

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The future conditions are not likely to change significantly even if development were not to proceed.

4. ARCHAEOLOGY AND CULTURAL HERITAGE

The evaluation of cultural heritage results has required a desk-based assessment of the projected wind turbine site, a site walkover survey and a re-examination of all the possible effects on the setting of the designated features.

The desk-based assessment necessitated a review of all important and available information on the nature and degree of cultural heritage interest on and within the proposed site. These incorporated existing records of known features, historic maps and aerial photographs. Beside, a thorough walkover of the proposed site in order to take cognition of the ground conditions and to ascertain any subsequent unrecorded features of cultural interest.

In conclusion, there are detected cultural heritage sited 150m away from the proposed site location but there are no chances of obstructing visitors or disturbing the existing cultural heritage area.

5. SHADOW FLICKER

Shadow Flicker is an event which occurs when shadows are casted on nearby properties close to turbines as the blades rotate and normally would affect properties to the west or east of a turbine at dusk and dawn. In accordance with the guidance set out in Planning Policy Statements 22, Companion Guide, shadow flickers effects have been assessed at properties within the 10 rotor diameters (800m) of the projected wind turbine. The closest property is about 0.5km away from the turbine and it positioning means that this would not be a problem.

6. SAFETY, HEALTH AND ENVIRONMENT

Safety is of paramount importance and all operational and construction works would be organized under a Safety, Health and Environmental Policy. This would map out how construction is to be carried out to ensure the health and safety the public, workforce and the minimal environmental impact within and around the site.

Access by the public would be restricted during the construction period, but once the wind turbine is in full operation, normal access rights would be re-instated.

The drawn up Environmental Management Plan outlines ways proposed to ensure that environmental compliance is adhered to and best practices are used on site during construction, operation and decommissioning of the wind turbine after its useful years.

7. ELECTROMAGNETIC INTERFERENCE (EMI)

Wind turbine can present an obstacle for incident electromagnetic waves, which may be reflected, scattered, or diffracted by a wind turbine (Manwell, J.F., et al, 2009). The turbine location is not close to any telecommunication, radio or radar transmitter, none is within sight of the proposed location of the wind turbine. The closest and only property around the proposed location is 0.5Km away. The possibility of interfering with their radio, television or telecommunication signals has been checked and found to be very low. Today, EMI from wind turbines are less likely because most blades are now made from composite materials typically, glass reinforced plastics (GRP) which is essentially

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transparent to electromagnetic waves (AUSWEA, 2004). There are no metallic components on the blades therefore, the possibility of interfering with television signals. Also, the tower and blades are relatively slim and curved. They tend to disperse rather than obstruct or reflect waves (Manwell, J.F., et al, 2009). If interference becomes apparent after the wind turbine is constructed, the area will be re-tested as part of the initial site survey and some possible mitigation can be carried out.

Such mitigation may include (www.wind.appstate.edu):-

� The installation of better quality antenna or more directional antenna.

� Directing the antenna towards an alternative broadcast transmitter.

� Installation of an amplifier.

� Relocation of the antenna to achieve better signal to noise ratio.

� Installation of a terrestrial digital set top box for digital TV.

� Installation of satellite or cable TV.

6.3. LIFE CYCLE ASSESSMENT

Life cycle assessment helps evaluate and give meaning to the investment made in building a wind turbine. It helps determine the duration of its service and also helps plan for its decommissioning at the end of its life. A turbine’s life is intimately related with its CO2 emissions value per kWh and also the time within which it pays off its capital costs. Typically the former value lies between 3 months to 5 months depending on size of the energy value and the latter lies between 20-25 years (www.bwea.com).

A wind turbines life is dependent on the life of its constituent components. In the present case, the LCA model developed by L. Schleisner (Schleisner, L, 1999) is being used. The energy assessment that forms a part of this model takes into account the energy use related to production, transportation and manufacture of 1kg of material. This approach of life cycle assessment is suitable in our case as it is typically used to compare the environmental impacts for different products performing the same functions (Scottish Natural Heritage, 2001). It however needs to be made clear that this model is based on study that was performed in Danish conditions and it is for the sole purpose of study that the protocols of production, transport, manufacture and disposal in the case are being considered as being same as the Danish ones.

6.4. ENERGY BALANCE

Compared the amount of Co2 emitted by fossil fuel such as coal, wind turbine has very low Co2 emission. One of the factors considered on knowing the sustainability of a wind project is through calculation of Co2 payback time or period Co2 saving and finally coming up with the payback. Every unit of electricity produced by the wind displaces a unit of electricity which would otherwise be produced by a power station burning fossil fuel.

To calculate Co2 savings for this wind turbine, a formula obtain from BWEA website is used:

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Co2 (in tonnes) =

Where A= the rated capacity of the wind turbine in MW;

0.3 is a constant, the capacity factor, which takes into account the intermittent nature of the wind, the availability of the wind turbines and array losses.

8680 is the number of hours in a year.

For a 1.70MW wind turbine:

Co2 (in tonnes) = = 1903.5tonnes of Co2/year

V82-1.65MW Vestas has a CO2 emission of 6.6 grams/kWh (6.6x10-6 tonnes/kWh) obtained from a Life Cycle Assessment (LCA) conducted on V82-1.65MW onshore wind turbine (Product Brochure).

For One year, 6175991.268kwh of electricity is generated by this turbine. Therefore for its Design life of 20 years, it generates

6175991.268x20x6.6x10-6 = 815.23 tonnes of CO2

CO2 Payback Time (Rankine, R. K et al, 2006) = Total life-cycle CO2 production CO2 saved each year

CO2 Payback Time =

This implies that payback period is 5 months.

6.5. SUSTAINABILITY

A much written and discussed about topic, Sustainability looks at the ability of the wind turbine to provide the service it is intended for a definite amount of time during which it endures the wear and tear with minimal effect on its surrounding ecology and environment. Consideration of sustainability forms an important issue in a feasibility study to make a decision that will either make or break the chances of the wind turbine to be of good use even after a number of years it has remained in service. Sustainability is highly demanded in case of renewable energies and requires a considerable effort to afford a sustainable power station capable of serving in such a way that it is dependable, reliable for years to come without environmental or ecological damage.

Considering this case and applying the same concept to the proposed wind turbine, the result can be viewed to be rather satisfying and complementary to the aim of the report of minimal environmental and ecological damage. With just 5 months of CO2 Payback period, the wind turbine in its typical life span of 20 years (N.E.P.) is able to give more than 15 years of clean energy that sustains an Island’s population. This is further translated to effective use of the resources at hand and also minimal wastage during the production, transport and construction stages. In view of this, a natural recommendation that follows is that the use and acquisition of materials is performed with care such

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that the vendors realise the company’s need to build an efficient, safe, sustainable wind turbine which is intended for a targeted purpose.

6.6. WIND TURBINE DISPOSAL AND COST

Most new generation wind turbines in use are still new and therefore, there are no evidence and experience whatsoever on what their impacts on the environment will be after their useful life.

The Life-Cycle Assessment of Vestas V82-1.65MW has been conducted by Vestas and the research came up with a CO2 emission of 6.6gram/kWh. In the process of the assessment, the disposal of a wind turbine was considered and this calls for the use of such information for this project. In the assessment, it was assumed that the production of raw materials, the manufacturing process and its disposal were the major part of environmental impact in the whole life of the wind turbine. The information used for this evaluation is from Vestas website.

Three disposal means are assumed to be, namely

� Recycling � Landfill � Incineration

The turbine system is divided into the following components systems; � Tower � Nacelle � Blade (consisting of three blades, hub and spinner) � Foundation � Internal Cables (which connects the turbine to transformer station) � Transformer Station � External Cables – connecting the wind turbine to the existing grid.

Table 13 shows the different system components of Vestas V82-1.65MW wind turbine and their weights as shown in Vestas website.

It has been assumed that plastic and composite are land filled

The foundation will be buried to avoid further environmental disruption or harm. Most materials used for the turbine

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set up are going to be recycled as shown in the table above. The likes of glass fibre and plastics are better put in the landfills or can sold to be used for fabrication especially now the tax on landfills are rising. The costing details of the decommissioning process will be shortly presented. However, it is appropriate to mention here the decommissioning costs of the whole unit following a similar study (N.E.P). The costs would be roughly around £ 10,000. Please note that this value is at present rate of inflation. Inflation is being assumed constant in the report.

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7. HEALTH AND SAFETY

Health & Safety management can be regarded as a process of improving risk assessment on some level. Risk assessment now is becoming increasingly vital and efficient to evaluate a task. The purpose of risk management is not to eliminate the risks because most risks are impossible to eliminate but rather to be prepared for, in a rational manner of project implementation to reduce the risk.

Health and safety management for the wind turbine encompasses risk measurement regarding onsite safety measures, occupational hazards and related safety policy. Noise related concerns and public health impact of noise from turbine has already been extensively discussed as a part of site assessment and was one of issues factored into decision making. In addition to that it has been found that rural environment background noise can be less than 30 dB but the standard (ETSU-R-97 ) allows the noise level from the turbines to be 43dB (A) at night and 35-40dB (A) during the day(Van den Berg, G.P., 2005). A study of respondents affected by wind turbines at a distance of 300m to 400m from their houses revealed the adverse effects of wind turbine noise (Harry, A., 2007) and keeping this in mind the noise reduction is an inevitable priority and its measurements and consequent implications form a major pre-planning consideration.

In regards to the occupational health and safety on-site, its performance should be evaluated against internationally published exposure guidelines, of which samples used here, include:

� “Indicative Occupational Exposure Limit Values published by European Union member states” (http://europe.osha.eu.int/good_practice/risks/ds/oel/ ),

� “Guidelines for Health & Safety in the Wind Energy Industry” (http://www.bwea.com/safety/index.html )

� “National Institute for Occupational Health and Safety (NIOSH)”

� (http://www.cdc.gov/niosh/npg/ )

� OHSAS 18001: Occupational Health and Safety Assessment Series (OHSAS) Developed by the British Standards Institute, available at British Standards Institution (BSI) website.

7.1. ACCIDENTS AND FATALITY RATES

It is imperative for modern and large projects like this to consent to a high level of safety precautions for the benefit of its employees and workers. Facility rates may be benchmarked against the performance of facilities in this sector in developed countries through consultation with published sources like US Bureau of Labour Statistics and UK Health and Safety Executive.

While the operation of the wind turbine does not require staff or personnel, routine maintenance does which as mentioned earlier is 40 hours a year and may increase with deteriorating life of the turbine parts. Following of the published health and safety guidelines should is to be made a mandatory rule within the company’s safety and fatality avoiding policy.

7.2. COMMUNITY SAFETY ASSESSMENT

7.2.1. Wind turbine system protection

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Community health and safety hazards during the construction, operation, and decommissioning of onshore wind energy projects are similar to those of most large industrial facilities and infrastructure projects.

a) Blade and ice throw

There are several mechanisms of ice accretion on structures. The most important of these, for wind turbines, is rime icing which occurs when the structure is at a sub-zero temperature and is subject to incident flow with significant velocity and liquid water content. The precise deposition mechanism is the subject of ongoing experimental and theoretical research. However, the authors have a substantial body of field observations which has played an important role in the work reported here. (E.A. Bossanyi and C.A. Morgan, 1996)

The risk of a person being hit by a fragment of ice thrown from an operational wind turbine depends on the following factors:

� The probability of the turbine having ice build-up on the blades

� The likelihood of ice fragments becoming detached from the blade, which is undoubtedly a function of radial position on the blade and on blade azimuth. It may also depend on the speed of rotation of the blades, as well as on blade pitch, blade profile and flexibility.

� The point where the detached ice fragment lands, which also depends on the radial position and azimuth at the time of becoming detached, and on the rotor speed and wind speed. The speed of the fragment at the end of its trajectory is also of interest, and this depends on the same factors.

� The probability of the person being in an area of risk and any safety precautions taken.

Occurrence of icing conditions

An estimate should be made of the time (number of days per year) during which icing conditions occur at the turbine site:

“ Heavy icing” - more than 5 days, less than 25 days icing per year

“Moderate icing” - more than 1 day, less than 5 days icing per year

“Light icing” - less than 1 day icing per year

“No icing” - no appropriate icing conditions occur

The data presented in Figure 33 may be useful in determining the safety distance for the chosen level of allowable risk (Morgan, C., et al, 1998)

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Mitigation of Risk

In this specific situation where a significant risk to the public or operational staff is believed to exist, the Ice throw management strategies include: (Laakso et al. (2003))

� Curtail wind turbine operations during periods of ice accretion

� Implementing special turbine features which prevent ice accretion or operation during periods of ice accretion.

� Post signs at least 150 meters from the wind turbine in all directions;

� Use synthetic lubricants rated for cold temperature;

� Operational staff should be aware of the conditions likely to lead to ice accretion on the turbine, of the risk of ice falling from the rotor and of the areas of risk.

� Provide full-surface blade heating, if available, or otherwise use leading-edge heaters at least 0.3 m wide.

b) Lightning protection

Here, this aspect should have been considered when wind turbine manufacturing companies are producing components of wind turbine.

(IEC TR 61400-24, Wind turbine generator systems-Part 24: Lightning protection, 2002)

c) Aircraft and marine navigation safety

Wind turbine blade tips at maximum may reach up to 120 meters in height. If located near airports or known flight paths, a wind farm may impact aircraft safety directly through potential collision or alteration of flight paths.

The solution is to use anti-collision lighting and marking systems on towers and blades.

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d) Public Access

Measures to prevent potential hazards to public:

• Use gates on access roads; • Fence the wind farm site, or individual turbines, to prohibit public access close to the

turbine; • Prevent access to turbine tower ladders; • Post information boards about public safety hazards and emergency contact information � Establish Self-servicing Single Portable Toilet for staff and tourists (it is easy to repair and

move);

Please note that additional details on vortex shedding can be found in Annex 8.

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8. QUALITY ASSURANCE PLAN

The Quality Assurance Plan is very important to ensure that all steps of the project are monitored, all component of the system are tested and determine signoff procedures. Process provide quality assurance through testing, correction, re-testing, and review sessions.

The Quality Plan is to specify the responsibilities and procedures to ensure that the data and information produced as part of Wind turbine project are reliable, achieve the purpose, objectives and deliverables of the project. It is shows the internal management that ensure the project quality.

There are several methods that can be used to ensure that this wind turbine project is meet a high standards quality:

• Internal Project Reviews what are the team work sessions in which the team reviews all deliverables for a phase before scheduling a methodology review

• Testing all equipments need to be tested before delivery it to the place and parallel during the integration and for the system after the integration

• Inspections these are reviews of a deliverable by the Executive Committee, or sometimes by an implementation team, for the purpose of inspecting and approving the deliverable

Quality Assurance Sessions

The Quality Assurance process will continue in the following sessions: Project Plan The project team and the steering committee need to review the project plan to ensure milestone dates are on target and to make any needed changes.

Review of Quality Plan The Quality Plan needs to be reviewed monthly in meetings to update it and to sure that applied for the project.

Communication Plan The communication plan, is the way that project team members are communicated to each other and to other people to ensure that key dates are on target, to ensure that communications are effective. Functional and Technical Requirement Documents Functional and technical staff review the functional technical requirement documents. Users and technical manager sign off.

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Systems Tests System Integration testing management reviews system tests. Functional staff signs off. Parallel Tests System need to be tested in Parallel of integration Functional staff signs off. Post-Implementation Review This document is to record what was done right and what was done wrong, and what is need to be improve. This needs to be referred to in later phases of the project.

Data Management Plan Data Management System It is needed that there is a data manager and data management system. All the project data needs to be saved on a common project computer and on a CDs or DVDs. Referencing System It is important that the project has a referencing system, for the documents and all deliverables. Data policy Provide information on data policy and access procedures (e.g. licensing arrangements) for within and between-project data interchange, and release to external bodies.

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9. CONSTRUCTION PLAN From the Gantt chart in Annex 6, it can be seen that government planning and building

permission should be got before any planning and constructing for legal consideration, and the time duration is estimated in 2 weeks. Data measurement will follow when the planning permission ready. In the section, anemometer will be placed on Isle of Cumbrae for a month, ground condition, like soil ingredients, will be considered in order to justify if the ground has been chosen is strong enough for building a turbine.

In practice, designers will modify the system design basing on the estimation have been given. The design for all the components, road, foundation and logistic should be done before construction plan. Meanwhile, as it has been mentioned before, building permission should be applied 2 weeks before design process was finished to ensure that construction stage will not be delayed.

After that, roads are needed to be built before equipments and components arrived. It is estimated to be built in 4 weeks. Moreover, because ordering period for turbine is normally 3 weeks, components should be ordered week after work on access roads has begun. On the other hand, foundation should be built before any assembling but after roads are built (because the equipments should be transported to the location), and the duration is 2 weeks. So the assembling stage will follow the foundation stage in week 22 and last for 1 week.

Finally, considering the environmental factor, all the waste should be removed from the island and surrounding will be recovered as its original sight see. However, it is worth to mention that, after the turbine is decommissioned, company has the responsibility to deal with decommission issues like removing the turbine parts from the island, cover the foundation with soil and grass et al. which last for 1 month.

Please note that all the times mentioned are an estimate and are linked to supplier-company relationships and other variable factors like weather, permission delay, transport delays etc. The Gantt chart in Annex 6 forms part of the recommendation regarding the planning process of building the turbine.

The construction of the wind turbine will last for 5-6 months and usually working hours are 7:00 -19:00 hours.( Technical Appendix 8d: construction traffic summary (environmental traffic volume 2-Technical appendices, Throapland loos wind farm EIA, October 2009). The construction plan would follow the flow chart in figure 35.

9.1. SITE CLEARENCE

First of all we have to clear the site which is filled with small trees and grass all over the place. The distance from the sea to the site where we construct the wind turbine is 204 metres. So, we have to clear this area first.

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9.2. ACCESS ROADS

Now the access road has to be built so that the turbine parts can be transported through this access road to the site location. Access track is excavated to 600mm and then it is constructed. Usually the access tracks are made such that there will be smooth transportation of heavy and very huge turbine. The bottom layer 300mm is made up of compacted granular material and the above layer of 300mm is made up of fine crushed stone.

Road is cambered and any water from the surface is removed and also drainage is provided to the side of the track. The access road is maintained without any damage during the transportation of

the turbine.

9.3. CONSTRUCTION SCHEME

The site office and warehouse are built on the site. Substations are built and interconnected roads are build so that there will be easy access to the places required. The underground cables are connected from turbine to the substation.

The turbine site is excavated first and the base typically requires a concrete foundation and size of 17.5 m x 17.5 m x 1.75 in depth. The required area is excavated to a suitable formation as suggested by the engineer. The foundation will receive concrete, shuttering and steel reinforcement will then put in place and imported, ready mixed concrete poured into the shuttering to form the base. The base will be left like that for 4 weeks to settle.

After that earthing cables are installed and also the perforated drain. Hard standing area is constructed beside the turbine for the cranes and other vehicles required erecting the turbine.

After this wind turbine is transported through ship from Denmark directly to the site

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Now we will transport the wind turbine and its components using the required equipment from the sea shore to the site. The turbine components are transported and placed near the foundation and assembled. After that the wind turbine is lifted using the crane and placed in position. After this the working of the wind turbine is supervised for couple of days so that there will be no problems. The transportation will cost around 37400 pounds (Fingersh, et al., 2006). The generated electricity is transported to the nearest grid i.e. 1253 meters from the sea shore. The cost for the electrical connection costs around 23036 pounds (Fingersh et al., 2006).

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10. FINANCIAL VIABILITY OF THE PROPOSAL

10.1. Cost Estimation

The wind turbine system cost mainly includes two groups, one is initial capital cost and the other is operation cost (Harrison et al, 2000).

Initial Capital Cost

The initial capital cost includes the sum of the turbine system cost and the balance of station cost (Fingersh et al, 2006). It should be notes that construction financing and financing fees are not calculated in initial capital cost, because these costs are contained in the fixed charge rate (Fingersh, et al, 2006).

Due to most of turbine components cost can be got from marketing research, wind turbine system cost has been estimated in subsystems. The turbine system cost would be collected in table below.

*Please refer to Annex 9 for details on calculations in table 15

Balance of Station Cost

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The majority of balance of station cost is hard to found in specifically. It would be estimated in the following section. It should be note that the construction cost, such as labour cost and temporary equipment cost, has included in the sub-cost. For example, the foundation cost have already includes the foundation constructing labour cost and potential temporary equipment cost.

1. Foundations As previous foundation section shows, the materials for building a foundation are 218 cubic

meter concrete and 10 tones steel. Because the cost of concrete is £ 74 per cubic meter (Kellysearch, 2010) and steel is £ 640.68 per ton, the material cost of foundation is £ 22,538.8 (218 *£ 74 + 10 * £ 640.68).

It is assumes that there are 10 site workers, working time is 8 hour per days and every week works 5 days. According to the construction plan, the construction time is 8 weeks. Hence, the overall working hours is 3200 hours (8 weeks *5 days *8 hours * 10 workers). The general civil engineering workers salary is £ 6.77 per hours. Consequently, the labor cost of foundation is £ 21,664.

According a similar wind turbine construction cost, the equipment hiring cost is $ 2,960 per days. After the currency exchange ($ 2,960 * 0.66 = £1,953) (Rates FX, 2010), the equipment cost would be £78,120 (8 weeks * 5 days * £1,953).

Overall, the foundation cost is £122,322.8 (£22,538.8 + £ 21,664 + £78,120)

2. Transportation Because the transportation cost of 15,000 kwh turbine is $ 50,000, it assume that 17,000 kwh

turbine is $ 56,666 (50,000/15,000*2,000) (Fingersh et al., 2006).

After the currency exchange ($56,666 * 0.66 = £40,400) (Rates FX, 2010), the transportation cost would be £40,400.

3. Roads, Civil Work Because the roads and civil work cost of 15,000 kWh turbine is $ 79,000, it assume that 17,000

kWh turbine is $ 89,533 (79,000/15,000*2,000) (Fingersh et al., 2006). After the currency exchange ($89,533 * 0.66 = £59,091) (Rates FX, 2010), the transportation cost would be £59,091.

4. Assembly & Installation Assembly and installation = $ 1.965 * (hub height * rotor diameter) 1.1736 (Fingersh et al., 2006)

After the currency exchange ($ 1.965 * 0.66 = £1.2969) (Rates FX, 2010),

Hence, assembly and installation cost is estimated as £ 38,004 (1.2969 * (80*80) 1.1736

5. Electrical Interface/ Connection Because the roads and civil work cost of 15,000 kWh turbine is $ 122,000, it assume that

17,000 kWh turbine is $ 138,266 (122,000/15,000*2,000) (Fingersh et al., 2006). After the currency exchange ($138,266 * 0.66 = £91,256) (Rates FX, 2010), the transportation cost would be £91,256.

6. Engineering & Permits Because the roads and civil work cost of 15,000 kWh turbine is $ 32,000, it assume that 17,000

kWh turbine is $ 36,266 (32,000/15,000*2,000) (Fingersh et al., 2006). After the currency exchange ($36,266 * 0.66 = £23,936) (Rates FX, 2010), the transportation cost would be £23,936.

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7. Designing labor cost Because our managers tend

to young and lack working experiment, the lowest salary will be assumed in the job marking. Moreover, because the salary was calculated by per year, it would be transformed by per hour to meet our calculation of labor cost. Formulate: Days (per year) – weekend (per year) = working days 365 – 104 = 261 Assumption: every day work 8 hours. Therefore, working hours: 261*8= 2088 hours Salary per hours Formulate: year salary / hours = salary per hours Labor cost Formulate: ∑ (working hour × salary per hours)

Overall, the balance of station cost can be shows below.

Operation cost

The operation costs contain all of the annual costs associated with operating the wind turbine (Harrison et al, 2000). The major cost factors are regular operation and maintenance, repair and insurance cost (Harrison et al, 2000). The typical 15 years operation cost is 3.5 c€/kWh (European Wind Energy Association, 2009). According to the currency exchange (3.5*0.9), it assumes the operation and maintenance cost is 3.15p/kWh. Therefore, in this case, the operation costs are assumed as £194,544 (6,176,000* 0.0315)

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10.2 Net annual income

There are several methods to get the income from wind turbines. Lease to local people or selling electricity to national grid are two major methods to receive the income (AWEA, 2000). It assumes that selling electricity to national grid is chosen by this case.

The electricity price in Isle of Cumbrae is about 8 p / kWh (UKPower, 2010). Based on this information, it’s assumed that the electricity selling price to national grid is 5p/kWh. Moreover, because government encourages the production of green power, the renewable producer can receive enhanced price which is about £ 34.5 /MWh by the Renewables Obligation Certificates (ROCs) (BEWA, 2010 [2]) (http://www.bwea.com/business/roc.html). Therefore, it can be an approximate estimate that the premium price is 3.45p / kWh. Overall, it can assume that our selling price is 8.45 p / kWh in the first year. The electricity tends to increase in the future (EIA, 2009). It was estimated will increase from 8 cents/kWh to 12 cents/kWh in America (EIA, 2009). It assumes the trend is the same as UK, therefore electricity prices are assumed to increase 0.2 p/kWh/year. The annual supply is 6176 MWh (6176000kwh). Because of the time value of money, future cost must be discounted (Nelson, 2009). It is assumed that the discount rate is 0.05. In this case, the net annual income can be got table 19.

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11. ECONOMIC ANALYSIS

Since the overall earning has larger than lifecycle cost, a wind turbine is an economically feasible (Nelson, 2009). Firstly, the payback time, when the earning equal cost, would be calculated. Then the life cycle cost need be considered. Cash flow, would be showed in the finally.

11.1 Simple Payback

As a preliminary judgment of economic feasibility, the value of money, borrowed or lost interest and operation costs should be considered (Nelson, 2009). However, it should notes that the simple payback is not considered the value of money. Therefore, the Fixed Charge Rate should be considered. The FCR consists of construction financing, financing fees, return on debt and equity, depreciation, income tax and property tax (Fingersh, et al, 2006). A fixed charge rate of 15% has been assumed in this case. This represents the assumption of 5% general inflation rate, 10% return on debt and equity and no tax implication.

Simple payback formula: (Initial cost of installation) / (net annual income – initial cost of installation * fixed charge rate – annual operation and maintenance cost) (Nelson, 2009)

Simple payback = £934,378 / (£521,872.00- £934,378 * 15% -£194,544.00) = 5 year

It seems, the payback time is much shorter than the life cycle time. Therefore, it seems the wind turbine is economic feasibility.

11.2 The Life Cycle Cost

In order to calculate the total cost of the system, a life cycle time need be analyzed (Nelson, 2009). Life cycle cost: initial cost of installation + operation cost – net salvage value (Nelson, 2009). It should note that the net salvage value is typically equip 20% for mechanical equipment (wind turbine system cost)

Life cycle cost = £934,378 + £2,424,448.25 – 0.2 * £639,399 = £3,358,698

As we mentioned, the net income of wind turbine is £5,229,014.33. It is much bigger than the life cycle cost. Hence, it seems the wind turbine is economic because the overall earning has larger than lifecycle cost.

11.3 Cash Flow

The firstly year cash flow = Net Present Value of Net annual income – initial investment – fixed charged cost.

The Second- final year cash flow = Net Present Value of Net annual income – accumulative cash flow – fixed charged cost. The first year cost for the first year is including £ 934,378

According to the cash flow, it seems the break even period is about 6 years. Cash flow tends to positive in the following 14 year. Therefore, the wind turbine seems economic feasibility.

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11.4 Conclusion

Based on the economic analysis, such as payback, life cycle cost and cash flow, the project of wind turbine is economically feasible. It should be noted that this situation is based on the assumption of getting premium price. If we cannot get the Renewables Obligation Certificates, the payback time is bound to increase. In most large scale projects, payback time of more than 5 years is not considered cost effective. Therefore, in case when the certificate is not issued, the wind turbine is not all that economic.

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12. SUMMARY AND RECOMMENDATIONS

In conclusion to the extensive research within available published literature, it wouldn’t be incorrect to say that a more in-depth and non-hypothesized research would yield a better picture of the extent of feasibility. However, the results from this report suggest that a wind turbine on the Isle of Cumbrae which is indeed famous for its natural beauty, will be a good proposal for the company under certain inflexible rules which are as follows

• The payback is kept within 5 years • The environmental guidelines mentioned in the report are adhered to • Health and safety guidelines mentioned in the report are adhered to • A public survey necessitated by project aims is mandatory • Company should be capable of following the various technical codes and guidelines

listed in the report

The present value of green power in the Isle of Cumbrae costs 11.69p/kWh (UKpower, 2010) and that of general power is 9.26p/kWh (UKpower, 2010). Considering the fact that the price of electricity production at 8.45p/kWh which is obviously less in comparison to other renewable energy sources and marginally less than general power, the proposal can be stated to be good.

A public survey on the Isle of Cumbrae would be recommended because there are issues like public concern over noise from turbines and environmental and ecological issues that need a highly subjective evaluation and the dearth of literature has curtailed the investigation to the extent where we can assume that owing to growing interest in wind power the related concerns become manageable and controllable. The team suggests:

• A survey of public opinions • Detailed wind speed measurements • Extensive investigation of nearby aviaries or wildlife • Variability limits of wind speeds within limits that allow power extraction • Assessment of suitable working times of the turbine owing to seasonal changes in

weather • Assessment of working conditions of the site in regards to its ability to be conducive to

working conditions • Assessment of ground conditions for suitable and robust foundation • Quality survey of materials to be employed

It is the view of the team to base the judgment on public opinions to have greater support throughout the life cycle of the turbine and not just during its planning, construction, operation and decommissioning stages.

The final decision: A wind turbine on the Isle of Cumbrae on the suggested site is a good proposal but one that is not devoid of subjective extensive evaluation.

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ANNEXURES

The documents that follow here are those that were produced during the course of the project.

Annex 1

Location specific energy calculations

Hereunder are the calculations for power available at selected locations on the Isle of Cumbrae. The result has been concluded in selection of location 1 bearing the OS grid value at NS 1656 as the best location for building the wind turbine. Please carry out further investigation on this site. The second best site would be NS 1657, in case the first location isn’t good enough or has some problem. Please be guided rightly and keep all informed.

Energy available from the wind at Isle of Cumbrae

Locations selected by Aerospace Engineers Yadan Rao and Sajal Thakur

Wind statistics: 45agl 25agl 10agl (all values in m/s) 1. NS 1656 7.9 7.4 6.7 2. NS 1657 7.5 6.9 6.1 3. NS 1555 7.4 6.9 6.0 4. NS 1756 7.3 6.7 5.9 Power Calculations:

Equation used: Pmax=CP[0.5x rho x A x U3] KW CP=Coefficient of Performance (Betz Coefficient)=0.37 (Assumed value) rho= Density of Air. Following is the manual calculation result for different heights in the grid location NS @45agl=1.251 kg/m3 ; @25agl=1.254 kg/m3 ; @10agl=1.257 kg/m3

A= Area swept by the turbine blades of diameter‘d’ Following calculation selects 3 blade diameter lengths: 12.5ft (3.81m); 50ft (15.24m); 200ft (60.96m) d�3.81m 15.24m 60.96m A�11.97m2 47.9m2 191.5m2 U= Values of wind flow (unobstructed) at the selected location

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Power available at selected locations for different diameter lengths at different heights

1. NS 1656 Also a suitable location but may cause objections from golf lovers. The wind speed statistics also are conveniently high and suitable for power generation. The location needs to be further evaluated in terms of ease of transport. Specific location suggestion: Wee Minnemoer (an old dried up loch).

KW 3.81m 15.24m 60.96m 45m 1.366 5.46 21.85 25m 1.125 4.5 18 10m 0.837 3.35 13.4

2. NS 1655����Not an ideal location as it falls in the town centre 3. NS 1657

The area seems to be most appropriate in terms of locales that are devoid of heavy human habitation. The wind statistics are a little lower in comparison to location 1.

KW 3.81m 15.24m 60.96m 45m 1.17 4.3 18.7 25m 0.912 3.7 14.6 10m 0.632 2.53 10.11

4. NS 1555 This location has a cemetery and a war memorial, hence not a good site. Although a shore location at Sheriff’s port has easy access. KW 3.81m 15.24m 60.96m 45m 1.12 4.5 18 25m 0.912 3.7 14.6 10m 0.6 2.4 9.62

5. NS 1756 This location is in-land and has a town in the direction of wind so resulting wind figures are unimpressive in comparison to all others especially at standard level of 10m. This is also a famous tourist spot. KW 3.81m 15.24m 60.96m 45m 1.07 4.31 17.2 25m 0.835 3.34 13.4 10m 0.572 2.3 9.2

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Important Note: Please note that the values are all an approximate figure and are supposed to help in arriving at a possible location. Extensive and more accurate calculations need to follow the location selection. Several variables have been included in the above calculations but they been normalized to particular value for ease of calculation

Annex 2

Source: Built Heritage and Archaeology documents www.scapetrust.org/pdf/Clyde1/clyde1_map5.pdf

Annex 3 : SMART Analysis

SMART analysis was employed with using three main criteria and giving different weight.

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In the SMART analysis, the five locations chosen by aerospace engineers were compared with certain main criteria like power generation, environment and access to the location. Depending on the Google satellite map, geography condition and electric calculation, the team members located mark to each location with three criteria. For example, although the wind speed at location NS 1655 and NS 1657 is exactly the same, NS 1655 locates in the town centre, which means the project will influence the daily life of local people such as noise, traffic and so on. So in environment NS 1655 was marked a lower number 2 but in access to the road it was marked 10. Then, considering the influence degree of the factors is

variable, the weight of the criteria in site selection has been regarded. Since the project feasibility depends on the local resident and government permission in a large extent, for instance, the project could not influence the nature landscape and local daily life, environment-friendly was considered as the most importance factor which is 0.37. Meanwhile, commercial feasibility is also an importance issue for invest company so that power generation was marked as an important factor but less than environment which is 0.31. And then access to the road was marked as the least important factor which is 0.19. In addition, the noise predictions were marked with 0.16 so that they too explicitly help in the decision for the location. So, from the table above it can be seen that location NS 1657 is the best place for building a turbine.

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Annex 4: TOWER SPECIFICATIONS BASED ON POWER REQUIREMENT

The proposed wind turbine site lies in the ordnance grid NS 1657. Although the exact location co-ordinates still need to be decided by the team, the energy calculations hereunder have been completed with an informed assumption that wind speed in same grid of 1 km2

region has same values at different heights. The following steps lead us the calculation following it:-

• Estimation of wind speed variations over a monthly period1 in NS1657 grid location

• Obtaining wind speed data at 12magl for different heights i.e., 60m, 80m, 100m • Calculating Energy (KW) and Energy consumption values (MWh) for different heights at

different diameters. • Subsequent plots of wind speeds and energy values

AIM : Assuming 4MWh/year/person2, the Annual demand on the Isle of Cumbrae without the general purpose lighting and miscellaneous purposes is 4MWhX1500 = 6000MWh Adding the extraneous and general purpose energy consumption of 1500MWh, we get a total annual consumption of about 7500MWh. At Height= 60m

Fig1 Fig 2

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At Height=80m

Fig 3 Fig 4

At Height = 100m

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Fig 5 Fig 6

The following are the inferences drawn based on the above calculations:

• At a height of 60m, neither a 60m diameter nor 100m diameter is capable of producing the energy value required by the Isle.

• At 80m height, 60m diameter produces just about annual demand and 80m diameter produces a value that is almost exact.

• At 100m height, both 80m and 100m diameters produce more than the demand and can be considered for further analysis including cost benefit trade-offs.

• Note is to be taken that at 80m diameter, the turbine can be shown to generate around 7% more than the estimated demand and at 100m diameter, it is capable of giving about 70% more than the demand.

•

Voltage and Current calculations:

The average annual power figure for a turbine at 100m height and 80m diameter is 932 KW According to Grid Code requirements, the power factor needs to be maintained between 0.85 to 0.953. Hence, the maximum apparent power is 981KVA and consequently the value of reactive power which plays a major part in conductor size decision is 306 KVA. The average annual power figure for a turbine at 100m height and 100m diameter is 1456 KW Similar calculations give a maximum apparent power of 1533 KVA and consequently the value of reactive power is 479 KVA. Based on the above calculations and the inferences drawn thereof, the final recommendations of this document are: HEIGHT: A 100m height is suitable for satisfying the demand and being able to afford future expansion if planned. Higher power figures from a 100m high turbine can offer more profit via return on investment of extra power supplied to the grid.

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DIAMETER:

It is profitable to have either diameter of 80m or 100m. Since a 25%increase in diameter from 80m to 100m causes 70% increase in power generation, it seems to be more preferred choice. Please give your inputs about this point. These are the required tower and rotor specifications for which cost-benefit analysis needs to be done.(Accounting Manager can contact any one of us for clarification and help) PS: Electrical specifications will be issued after faculty consultation.

REFERENCES:

1. http://www.metoffice.gov.uk/climate/uk/ws/

2. E-mail from Professor Ross Wilson 3. Grid Code document from Scottish Power:

http://www.scottishpower.com/ConnectionsUseMetering.htm

Important note: Please note that the recommendations of this document when subject to cost analysis through rate of investment and income study yielded a different choice of height and diameter namely 80m height and 80m diameter.

Annex 5

FOUNDATION CALCULATIONS Loads Vertical Load = Weight of all the turbine components on top the footing = 220 tons (www. vestas.com) Shear force, F (lbs) = A (ft2) ×P (mph) × Cd (www. arraysolutions.com/products/windloads.html) Where, P = wind pressure in psf, Cd = coefficient of drag, A = Area of the blade sweeping surface. Area of the blade sweeping surface = 3blades ×length ×width = 3 ×40 ×3.5 = 420m2 =4520.842ft2 Wind Pressure, P = 0.00256 × V2 (V = wind speed in mph) Maximum wind speed (cut out speed), V = 15m/s =33.56mile per hour (mph) but, 1psf = 0.04788 KN/m2 1.28psf = 0.04788 × 1.55 = 0.07KN/m2 Coefficient of drag of blade = 1.5 (www.fortiswindenergy.us/FA_Load_calculation_2008.06.29.pdf) Shear force, F = 4520.842 × 0.00256 × 33.562 = 19552.147lbs = 8.87tons Overturning moment, M = Shear force × Hub height = 8.87 × 80 = 709t.m

Design

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The soil type map below shows the soil types distribution in UK with Isle of Cumbrae island circled in red. The as indicated is organic which was assumed to have a similar property with loamy soil. It is assumed that it comprises of silt-sand (assumed based on personal observation from site visit). The soil bearing capacity of silty- sand soil, qa = 2t/ft2 = 21tons/m2 (Nawy, 2009);

(http://www.british-towns.net/naturalmaps/UK generalisedsoiltype.asp)

Design Factor of Safety For the safety of the turbine as against failure considering the cost of designing and erecting one, factor of safety is used as a safety measure. The assume factor of safety = 1.5 Design Load = Loads × factor of safety (1.5) Vertical load = 220 × 1.5 = 330tons Moment = 709 × 1.5 = 1063.5tons Shear force = 8.87 × 1.5 = 13.31tons Pmax = 2P/3*S(L/2 - e) where P = vertical axial load, e = eccentricity of the load on the spread footing,

Pmax = maximum soil stress; e = M/P where M =moment (Singh, 2007) Area of footing, A =L × S Assuming a square for its ease in design and construction, L=S; A =L2

P = 220tonnes (weight of turbine components); material reduction factor, α = 0.85 Area = 220/21 + 6(3690)/√0.85 ×220 × 21 = 364m2 Assuming a square footing, Area = L × S = L2 For serviceability with wind load, the soil bearing capacity should be more than the maximum soil bearing stress. The minimum length of the footing is obtained using the above equation. Vertical load, P = 330ton; e = 1063.5/330 = 3.22 Substituting values and solving quadrilateral, Length of footing, L = 10.5 ≈ 11m L= √364 = 19m Checking for shear force Assuming Depth, D = 1.8m Vu < Ф × 2√ fcˈ × L × D (Singh, 2007) Where Vu = ultimate shear force = 13.31ton, Ф = material reduction factor = 0.85 (ACI Committee 318, American Concrete Institute, International Organization for Standardization, Building code requirements for structural concrete (ACI 318-08), fcˈ= Concrete compressive strength = 2500t/m2, D = Depth of footing Substituting into the above equation

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13.31tonnes < 0.85 ×2 ×√ 2500 × 11 ×1.8 = 1683 tons (o.k) Required Reinforcement ratio, Ps Ps = Фfc/fy(1-√1-2Mu/Фfc×S×D) (Singh, 2007) Assuming fy = 250MPa = 25000ton/m2, Mu = ultimate moment, D = 1.8m, L = 11m, Ф = 0.85 Substituting these figures, Ps =0.51% which satisfies the minimum as well as maximum reinforcement required (Eurocode2) (www.eurocode2.info/PDF/How_Foundations_FINAL.pdf) Pedestal To avoid punching effects of the tower on the footing, pedestal is to be added on top of the footing. Assuming a pedestal height of 1.2m and a diameter, 5.5m (STAAD Solution Center, Nov. 2007, STAAD.pro2007 Design of Wind Turbine Foundations) Pedestal Area = π × D2/4 = π × 5.52/4 = 23.75m2 Footing Volume = L × L × D = 11 × 11× 1.8 = 217.8m3 Pedestal = A × D = 23.75 × 1.2 = 28.5m3 But the density of steel, ̍ = 7.85t/m3 (http://hypertextbook.com/facts/2004/karensutherland.shtml) Weight of steel (Tons) = Ps × ̍ ×Vol. of concrete, where ̍= density of steel Steel in Footing = 0.51% × 7.85 × 218 = 8.720 Steel in Pedestal = 0.51% × 7.85 × 28.5 = 1.141 Total steel weight required = 8.720 + 1.141 = 9.861≈ 10T

Footing Design Load Vertical (tons) Shear (tons) Moment (t.m)

330 13.31 1063.5

Foundation Dimensions Footing (m) Pedestal (m)

11 ×11×1.8 Dia. = 5.5; H =1.2

Material Requirement Concrete (m3) Steel Bars(tons)

218 10

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Annex 2

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Annex 7: QUALITY ASSURANCE PLAN CHECKLIST

The following checklist is provided as part of the evaluation process for the Quality Assurance Plan. It is very important to sure that every step of the project meet the specifications and requirements of the project.

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Quality Assurance Checklists tables (Source: U.S. Department of Housing and Urban Development, 2009.)

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Annex 8: Vortex Shedding

A vortex is a spiral motion of any fluid around a centre. When fluid passes through any object results in the formation of vortex shedding. Low pressure vortices are created on the other side (opposite to flow facing side) of object, forcing the object to move towards the low pressure zone. If the vortex shedding frequency of wind turbine tower equals to resonance frequency of itself, the tower begin to oscillate and its movement can become self-sustaining. This vortex shedding can result into violent oscillation which can destroy or damage the structure of tower.

Fig 1 Vortex shedding behind circular object

(http://en.wikipedia.org/wiki/Vortex_shedding)

Calculation of vortex shedding Let assume that the shape of our tower is cylindrical and the frequency of vortex shedding can be calculated from following formula:- f = St×

St – Strouhal number (0.18 for a cylinder); D- diameter of tower; V-maximum wind velocity; f = vortex shedding frequency f = 9.3 Hertz Calculation of natural frequency of tower Let assume the wind turbine as a cantilever with a mass at the end and other end is fixed rigidly. The formula for frequency for frequency is following:-

f = ×

E - modulus of elasticity; I - second moment of Inertia; M – total mass at the end; L – length of tower f = 91.88 Hertz Result & Conclusion The natural frequency of tower is much higher than the frequency of vortex shedding. Therefore we can conclude that our tower is safe from any damage from vortex shedding created by the wind. Annex 9: Commentary on table 15 referenced from Fingersh, L., et al, 2006.

� Rotor cost includes the cost of blades, hub and spinner and nose cone o The following formulae were used to calculate the above costs: o Baseline Material Cost: 2002$ = 0.4019R^3 - 955.24 o Hub cost = hub mass * 4.25 [6] o Nose cone cost = nose cone mass * 5.57

� The cost of variable spd electronics estimate formula: machine rating * $ 12

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o According to the currency exchange rate (0.66) (Rates FX, 2010), the formula would change that machine rating times £ 7.2. Therefore, variable speed electronics cost is £122,400 (17000 * £ 7.2)

� The Main frame cost formula: 17.92 * rotor diameter1.672 � Main frame cost: 17.92 * 801.672 = $ 27,246

o According to the currency exchange rate (0.66) (Rates FX, 2010), the Main frame cost is £ 17,928 ($ 27,246 * 0.66)

� Hydraulic, Cooling system cost: machine rating * $1.2 o According to the currency exchange rate (0.66) (Rates FX, 2010), the formula would

change that machine rating times £ 0.792. Therefore, variable speed electronics cost is £ 14,462 (17000 * £ 0.792)

o Hydraulic and Cooling Systems mass: 0.8 Kg * machine rating. Therefore, in this case, the mass would be 13,600 Kg (17000*0.8Kg)

� Nacelle cover cost: machine rating * $11.537 + $3849.7 o According to the currency exchange rate (0.66) (Rates FX, 2010), the formula would

change that machine rating times £ 7.61 and plus £ 2540.8. Therefore, variable speed electronics cost is £161,910.8 (17000 * £7.61 + £ 2540.8)

o Nacelle cover mass: Nacelle cover cost/10. Therefore, in this case, the mass would be 13,191 Kg (161,910.8/10)

� From 1999 to 2002, control, safety and condition monitoring systems are increasing from $10,000 to $35,000 regardless of machine size or rating. In this case, it assume that every year will increase $ 8333 (($35000-$10000)/ (2002-1999)). Therefore, the Control, Safety System, Condition Monitoring is $ 101,1664 (8 * $ 8333). According to the currency exchange rate (0.66) (Rates FX, 2010), $101,1664 will equal to £ 67,098.

� Tower mass: 0.2694 * swept area * hub height + 1779 � Swept area of blade: (Rotor diameter/2)^2*3.14 = 5024 � Tower mass: 0.2694*5024*80+1779= 110,056 kg =110 tons � The hot rolled coil steel in UK estimates £ 640.68 per tons (MEPS, 2010) � The cost of the tower: 110 * £ 640.68 = £75,474.8

Annex 9 NAME TASK SECTIONS EJIOFOR IKENNA 1.7, 1.9, 1.11,2.10 3, 5, 9, 12

PENG QING 1.8, 1.12, 2.2, 2.3, 2.4,2.10 4, 5, 10, 11, 12

RAO YADAN 1.2,1.11, 2.1, 2.2 3, 5, 9, 10, 12 ALI MOHAMMED ADIL 1.3, 1.4, 1.5,1.11, 1.13 1, 4, 5, 6, 12

QINGYN GAO GALT 1.6, 2.5,1.13 3, 5, 6, 7, 12

SIBEUDU ARINZE 1.4, 1.6, 2.7, 2.8, 2.9 3, 6, 7, 12

SAEED ALAMRI 1.1, 2.5, 2.6, 2, 5, 8, 12

SAJAL THAKUR 1.1, 1.2, 1.10,1.12,2.3 3, 4, 5, 12

SUNDEEP KUMAR 1.7, 1.9, 2.10 5, 9, 12

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