Offshore Wind Farm Project

Wind energy Offshore wind farms Wind turbine Wind energy Offshore wind farms Wind turbine Wind energy Offshore wind farms Wind A Template for Offshore Wind Farm Projects Offshore wind turbine Wind energy Directed Research – MBA in Project Management farms Wind turbine Wind energy Offshore wind farms Wind turbine Wind energy Offshore wind farms Wind turbine Wind energy Offshore wind farms Wind turbine Wind energy Offshore wind farms Wind turbine Wind energy Offshore wind farms Wind turbine Wind energy Offshore wind farms Wind turbine Wind energy Offshore wind farms Wind turbine Wind energy Offshore wind farms Wind turbine 1

University of Northern Virginia - Cyprus Alireza Aleali

CHAPTER 1. INTRODUCTION ............................................................................................................................ 4 1.1 THE PROBLEMS A SSOCIATED WITH THE CONVENTIONAL SOURCES OF ELECTRICITY ................................................ 5 1.1.1 Fossil fuels ................................................................................................................................... 5 1.1.2 Nuclear ........................................................................................................................................ 7 1.1.3 Hydroelectric ............................................................................................................................... 8 1.2 THE WIND SOLUTION ............................................................................................................................ 8 1.3 WHY WIND ENERGY? ............................................................................................................................ 9 1.3.1 Relying on no fuel ........................................................................................................................ 9 1.3.2 Scattered supply of electricity....................................................................................................... 9 1.3.3 Efficiency /Feasibility.................................................................................................................. 10 1.3.4 Cost ........................................................................................................................................... 10 1.3.5 Predictable Cost of Electricity ..................................................................................................... 11 1.3.6 Security of supply ....................................................................................................................... 11 1.4 STATUS OF WIND INDUSTRY IN THE WORLD .............................................................................................. 11 1.5 FUTURE OF WIND I NDUSTRY.................................................................................................................. 13 1.6 OFFSHORE WIND INDUSTRY .................................................................................................................. 14 1.7 STATUS OF O FFSHORE WIND ENERGY ...................................................................................................... 14 1.8 FUTURE OF OFFSHORE WIND INDUSTRY ................................................................................................... 15 1.9 MOTIVATION FOR C ONDUCTING THE RESEARCH ......................................................................................... 16 CHAPTER 2. ENGINEERING PROSPECTIVE ....................................................................................................... 18 1.10 THE PARENT DISCIPLINE 1: ENGINEERING PROSPECTIVE ............................................................................... 18 1.11 CALCULATIONS ................................................................................................................................... 19 1.12 POWER OF THE WIND........................................................................................................................... 19 1.13 BETZ’ LAW (MAXIMUM POWER EXTRACTABLE) .......................................................................................... 20 1.13.1 Maximum Power Of The Site .................................................................................................. 21 1.15 CONVERSION EFFICIENCY ...................................................................................................................... 22 1.16 MEASURE – CORRELATE – PREDICT TECHNIQUE ......................................................................................... 23 1.17 WIND ROSE ...................................................................................................................................... 23 1.18 COMPONENTS OF THE SYSTEM ............................................................................................................... 24 2.9.1 Turbine ...................................................................................................................................... 24 2.9.2 Tower ........................................................................................................................................ 26 2.9.3 Rotor ......................................................................................................................................... 26 2.9.4 Nacelle ...................................................................................................................................... 27 2.9.5 Electronic Controller(s): .............................................................................................................. 28 2.9.6 There are Electronic controllers inside the turbine which control different parts of the turbine: ... 28 2.9.7 Sensors ...................................................................................................................................... 28 2.9.8 Tower ........................................................................................................................................ 29 2.9.9 The wind farm ground / sea station............................................................................................ 29 2.9.10 Scales of Wind Turbines ......................................................................................................... 30 CHAPTER 3. PROJECT MANAGEMENT PRESPECTIVE ....................................................................................... 31 3.2 DOCUMENTS OF A PROJECT ................................................................................................................... 31 3.2.1 Project charter ........................................................................................................................... 31 3.2.2 Scope of Work (S.O.W.) statement ............................................................................................. 32 3.2.3 Scope Of Work for an Offshore Wind Farm ................................................................................. 32 3.2.4 Project management plan .......................................................................................................... 33 3.3 CHAPTER 4. WORK PLANNING PROCESS ................................................................................................ 34 3.3.1 Definition: .................................................................................................................................. 34

3.3.2 Work Breakdown Structure ........................................................................................................ 34 3.3.3 Top-down approach ................................................................................................................... 35 3.3.4 Bottom-up approach .................................................................................................................. 35 3.4 TIME AND COST ESTIMATION ................................................................................................................. 36 3.4.1 Program Evaluation and Review Technique (PERT) ..................................................................... 36 3.4.2 Critical Path Method .................................................................................................................. 36 3.4.3 Gantt Chart ................................................................................................................................ 37 3.5.............................................................................................................................................................. 37

CHAPTER 1. INTRODUCTION Nowadays Electricity has become an indispensable part of our lives and is something often taken for granted. In industrial countries living even few hours without electricity is unthinkable for many. Economy is also very vulnerable to production of electricity. In fact there is strong and two way relation between growths of electricity production per capita and gross national product (GDP). Electricity is the fastest growing fuel in Energy sector. Global demand for electricity is growing by around 2.4% annually. This would mean doubling the production of electricity between 2004 and 2030 from 16,424 billion kWh to 30,364 billion kWh. That’s total of 85% escalation. According to the estimations and by 2025 electricity overtakes natural gas as the world’s largest source of energy for household use. This growth is present both in developing countries and industrialized countries. The member countries of The Organization for Economic Co-operation and Development (OECD) which are mainly developed countries with well established infrastructure are projected to have growing demand of 1.3%. Non-OECD countries which are mainly the developing countries are expected of have 3.5% growth in demand of electricity on average.

Growth of OECD and Non-OECD Residential Sector Delivered Energy Consumption by Fuel, 2004 – 2030 Source: International Energy Annual 2004

The prime sources of today’s electricity are fossil fuel power plants. 65.67% of the total electricity consumed world wide comes from fossil fuels. After that hydroelectric with 16.57%, then Nuclear with 15.71% and lastly renewable energies with mare 2.05% contribute to the electricity generation.

The growing demand for electricity is traditionally met largely by installing fossil fuele power plants. However there are important concerns regarding this trend which are going to be discussed in this chapter.

1.1

1.1.1

The Problems Associated With the Conventional Sources of Electricity

Fossil fuels

Traditionally fossil fuels have been very reasonable source of energy. They were chip, comparatively abundant and it is possible to store and move them in vast amounts relatively easily. However these some of these advantages are not very factual today and have turned into disadvantages. Fossil fuel contributes more to electricity generation than all other energy resources combined. Today the main concerns about fossil fuels are: 1. Scarcity 2. Growing demand 3. Dependency on other countries and Security of supply 4. Environmental issues

Scarcity Although there are arguments about the exact amount of fossil fuels, one thing is for sure and that is they are NOT unlimited; for the reason that it takes between 10 and 300 million years for petroleum material to be formed from organic material. One day sooner later they are going to end, according to most experts, as soon as 50 years for oil reserves and 400 years for gas reserves.

Dependency on other countries and Security of Supply On one hand most countries do not have enough oil and gas reserves to support their own needs and on the other hand the considerable number of countries that have excess of oil and gas reserves and export them are located in politically and economically unstable regions, like the middle east which is responsible for 66% of the worlds oil and gas production. [Wiki]

Clearly today’s dependency on oil, and therefore oil producing countries, involves huge risk of unsteady supply and unpredictable prices. As these countries go through internal and external crisis the prices of oil and gas fluctuate. Cost According to European Commission every $20 rise in oil price per barrel adds €15 Billion to EU’s energy bills. At the time of this writing the price of oil is all time high $150 a barrel and has had a continuous rise since 2003. Below is graph showing average price of oil in last 12 years.

Avarge price of oil 1996 – 2008 (Source: Bloomberg.com) Continuous growth of price of oil makes use of other sources of electricity production, such as wind, more economical and more feasible.

Growing Demand Another reason that can be associated to the raising oil price is the demand and supply factor. As mentioned before due to its very nature supply of fossil fuels are limited. But the demand has been growing rapidly in last 200 years, and it can be said that we are in all time high demand for oil. Developing countries, especially china and India, are the main cause of the high demand. Industrialization and Electrification process seen in these countries calls for vast amount of fossil fuel and electricity supply.

Environmental Issues

Using fossil fuels as the primary source for electricity generation has major harmful environmental affects, namely global warming and pollution. A recent study at Stanford university shows that for every 1 Celsius of global warming there’s is about 20,000 death world wide in a year [3]1 and it is believed that mass consumption of fossil fuels is one of the contributors to global warming. Energy sector is the largest source of green house gas emissions. Table 2 shows the amount carbon dioxide emitted by energy sector.

World Energy-related Carbon Dioxide emissions by Fuel Type 1990 – 2030 Source: International Energy Association

Excess Carbon Dioxide, as a toxic gas, is very harmful and causes variety of disease, especially for heart and lungs. Overwhelming use of fossil fuels caused emission of 26.9 Billion Metric Tons of Carbon Dioxide in 2004 which is a part of the cause to death and disease of thousands world wide. There are other pollutions associated to fossil fuel than air pollution. One of them is related to its transportation. Transportation of oil across the planet produces pollution and sometimes due natural accidents or damages large oil spills pour into waters and pollute large parts of oceans and kill of sea habitants.

1.1.2

Nuclear

Although nuclear energy has been providing significant amount of electricity in last 50 years and helped to decrease carbon emission, still is not a clean resource. There has been no convincing solution as to how to dispose the nuclear waste. Temporary solutions such as

burring them in non habitant areas, doesn’t reduce its long term danger, especially when more and more countries access to the nuclear technology. Besides nuclear power plants must run in an accurate and secure fashion, and mistakes can turn into catastrophic disasters, as in case of Chernobyl in Ukraine in 1984. 1.1.3

Hydroelectric

About 19% of the world’s electricity comes from Hydroelectric. Hydroelectric is one of cleaner resources, it has no emissions and it is abundant in many parts of the world. In Latin America it contributes to 75% of the electricity generation. Although Hydroelectric doesn’t emit carbon dioxide, it does effect the environment. A good example is the Three Gorges project in China. It will result in displacement of 2.3 Million people. []2 the water behind the dam will result in the flooding of large parts of land and eliminates the habitat for plants and animals. There has also been continues argument as to whether or not Hydroelectric is a form of renewable energy. Although hydroelectric renews, but the process is not instantaneous.

1.1.4

Conclusion

As one can see conventional sources of electricity cannot bare the demand for more and cleaner energy. Oil is scares, not really chip anymore, pollutant and causes global warming; Nuclear wastes can become hazardous as nuclear technology is used more and more. Hydroelectric can be considered a reasonable solution for some parts of the world, but the price for environmental changes caused by it is considerable. Therefore as the demand for electricity grows so do concerns about how to supply it with less harm and more availability. The solution to this problem is to diversify resources through a process called “diversification of the energy portfolio”. This is primararl achieved by utilizing renewable energies such as: solar, wind, geothermal, biomass, tidal, wave and so on.

1.2

The Wind Solution

Wind is one of the best resources of renewable energy being used. The infrastructure for utilizing the wind to generate electricity is the least expansive among renewable. In fact

capital requirement for commercial wind farms has dropped by 80% from 1986 to 2006. Wind, as a resource, is abundant in many countries is now being used for electricity generation in 70 countries. 1.3

Why Wind Energy?

The reasons why wind energy industry is fastest growing trade among all other renewable energies are not limited to being cost effective but also there are other strategically and economical derives behind it. Below the most important grounds for emergence of Wind Farms is discussed.

1.3.1

Relying on no fuel

Wind energy has no reliability to any kind of fossil fuel. Once a Wind Farm is established and is functional its costs are only for its maintenance. All a wind farm needs as source is continuous blow of wind, which is abundant, free and has zero air pollution.

1.3.2

Scattered supply of electricity

Nuclear, fossil fuel and hydroelectric power plants, require heavy investments, and in return provide enormous amount of electricity which is then distributed among large number of cities and users. However this centralized setup of electricity generation has 2 main disadvantages. First of all case of an emergency or a maintenance service shut downs, can result wide spread electricity cut. The case of 2003 blackout throughout Northeastern, Midwestern US and Ontario Canada, which left around 50 Million people without electricity and resulted around $6 Billion loss, is a good example of such case. [1] And secondly demand for electricity in developed countries increases by a low rate (e.g. 1.7% average for US). So once a new Fossil fuel, Nuclear or Hydroelectric power system is built it take sometimes up to 20 years, sometimes even more, for the plants to be used to its full potential, which means lower Return on Investment. Wind energy addresses both of these issues. There are several wind turbines each Wind Farm, each providing usually 1.8~3.6 MW of energy. Therefore, in case of an emergency or

maintenance shut down, a wind turbine can be shut off without seriously effecting capability of the power plant. The same concept, distribution of electricity generation units, also means shorter time for ROI. Because when more power is needed, simply adding a wind turbine or upgrading to newer turbines on already existing wind farms can meet the demand. Or a new wind farm can be constructed just large enough to address the need.

1.3.3

Efficiency /Feasibility

According to a research done by Department of Energy in US, prime locales of the world have the potential of supplying more than ten times global energy needs. Practically almost all countries have possibility of generating sizeable amount of electricity through their potential wind farm sites. Large Wind Technology is central point of Research and Development of major Industrial countries. In the US, the DOW has established partnerships with public and private bodies to expand research to improve Large Wind Technology and Distributed Wind Technology. Therefore every year more and more efficient and less expensive turbines are introduced to the global market. The latest development in commercially available turbine is Enercon’s E112 capable of generating 4.5 to 6.0 MW of electricity, enough to power 4000 average homes. It has cut-in wind speed of 2.5 m/s and cut out wind speed of 28-34 m/s.

1.3.4

Cost

As the wind farms use free and abundant wind as their source , the main expenses are of the initial construction, launching and maintenance of the turbines. By advancement of technology the installation costs are dropping and less maintenance is required. In capital and energy costs, wind now competes on its merits with conventional power technologies and it has become least expensive source of electrical power-traditional or new-in many parts of the world. Since 1980s, wind technology capital costs have reduced by 80% world wide. Operation and maintenance costs have declined by 80% and availability factor of gridconnected wind plants has increased to 95%. In 2004, the capital cost of wind generation plants was $600 per kW and electricity generation cost has reduced to 6 cents per kWh.

At the time of this writing wind turbines are capable of producing electricity at 4 – 9 cents/kWh in the Class 4 wind (5.8 m/s at a height of 10 m) regimes that are broadly available across the United States, depending on many factors, including project financial structure.

1.3.5

Predictable Cost of Electricity

One of the challenges facing industries and families in last few years has been fluctuations in cost of energy. Cost of electricity produced by Wind Energy is very predictable, once the initial investment is made and associated natural risks are taken to account and contingencies are made.

1.3.6

Security of supply

In some way the electricity produced from wind farms is more reliable than fossil fuel and nuclear stations. The reason being that the source (fuel) of wind farms is not controllable by any supplier and is free for any country to use. There is little uncertainty about the supply of electricity once long term wind data are available and careful predictions have been made.

1.4

Status of Wind Industry in the World

Wind farms have been constructed for commercial use in over 60 countries and all most all major countries have long term plans to establish Onshore and Offshore wind farms, including oil rich countries like Iran, UAE and Qatar which their oil resources are estimated to be large enough to support local demand and export (global) for the next 80 years. Wind industry has been experiencing record breaking growth rates in last decade and is the fastest growing source of energy among both renewable and non-renewable. Since 2005 US wind energy industry experienced a growth rate of around 40%. Meaning it has doubled the installed capacity of wind turbines. In Europe wind energy contribution to total new installed capacity was 40% of total in 2007. In US Wind generation increased to 26 billion kWh in 2006, up from 18 billion kWh in 2005, representing 45% growth. This moved wind’s share of the renewable generation market from just 5 percent to 7 percent in one year.

Global growth rate of wind power capacity has been between 21% to 40% in last 10 years. By year 2007 the total wind capacity installed reached 94 GW and the total market value for new generating equipments of wind energy was € 25bn. Table 2 demonstrates the growth of wind industry in term of cumulative installed capacity in the last 10 years. Relative to total consumption Denmark is the leading nation in harnessing the power of the wind with 20% of its electricity demand met by wind power, 7.432 TWh in 2006.

Global Commulative Installed Capacity 100,000 90,000 80,000

in MW

70,000 60,000 50,000 40,000 30,000 20,000 10,000 2007

2006

2005

2004

2003

2002

2001

2000

1999

1998

1997

0

Year Source: Global Wind Energt Council

Germany is the first country in terms of total wind power installed capacity 22,247 MW in 2007. USA with 16,818 MW, Spain with 15,145 MW, India with 8,000 and China with 6,050 MW in cumulative installed capacity come after Germany. Table 2 is the list of top 10 countries in terms of installed capacity. MW

%

Germany

22,247

23.6

US

16,818

17.9

Spain

15,145

16.1

India

8,000

8.5

China

6,050

6.4

Denmark

3,125

3.3

Italy

2,726

2.9

France

2,454

2.6

UK

2,389

2.5

Portegual

2,150

2.3

Rest of world

13,019

13.8

Total

94,123

100

Total installed capacity by 2007 1.5

Future of Wind Industry

Wind industry is expected to grow even more rapidly due to raising oil prices and environmental concerns. Many countries have commited to reduce their carbon emissions by signing Kyoto protocol. Wind energy is one of the most feasible ways of achieving set targets. It has a mature technology and proven results in terms of stablitiy and reliability. It is also the least expensive source of renewable energy. Global Wind Energy Council has made predictions according to market trends and major issues that are expected to effect growth of wind industry in mid-term. The results of this forecast can be seen in table 2.

Preditcted Global Total Installed Capacity 2008 - 2012 300,000 250,000

150,000 100,000 50,000

Year Table 2. Forecasted growth rate for years 2008 to 2012 Source: Global Wind 2007 report, Global Wind Energy Council

2012

2011

2010

2009

0 2008

in MW

200,000

1.6

Offshore Wind Industry

There are two categories of commercial wind farms, onshore and offshore. Onshore wind farms have been in use in for decades and they represent 98% of total wind farms by capacity. Onshore wind industry enjoyed 33.4% growth annually between 1992 to 2006. Offshore wind farm, on the other hand, are rather a new concept. It offers more advantages than onshore wind farms. First of all wind resources are stronger in the see, because there is no turbulence. Second, unlike onshore wind farm which are installed on hill tops or flat country sides, they have little or no visual impacts. Third they have the potential to be used close to large population centers close to shore, where onshore wind farms are not feasible due to lack of space.

1.7

Status of Offshore Wind Energy

Offshore wind farms are essential part of energy portfolio diversification in Europe. The first commercial offshore wind farm was established in 1991 in Denmark. At the time when this research was conducted there were 21 offshore wind farms operating and 100% of them were located in EU countries namely, Denmark, the United Kingdom, the Netherlands, Sweden and Ireland. There are 18 offshore wind farms operating. In 2007 the capacity of Europe’s offshore wind farms was 1,100 MW which represents 1.8% of the total wind energy capacity installed and produced 3.3% of the total electricity produced by wind. Table 3 shows installed capacity of offshore industry in the world.

Table 3 Total global installed capacity

Source: Delivering Offshore Wind Power in Europe, 2007, European Wind Energy Association

There are several reasons why Europe is pioneering the offshore wind industry. First, traditionally Europe has strong position in wind industry in general. 8 out of 10 commercial wind turbines produced in the world are made in Europe. Second, in terms of offshore wind resource Europe is situated in one the best, if no the best, geographical positions on earth. As a matter of fact developing 5% of North Sea surface wind energy for electricity production can generate 25% of EU’s needs. Third, major consumption centers are located close to the shore; in fact 50% of EU citizens live less than 50 km away from the coastline, which makes it more economical to transfer and distribute electricity generated offshore. Fourth, Europe has strong maritime infrastructure. Last but not least, because centers of population are located close to coast line, there is little or no room for gigantic wind turbines to be installed onshore.

1.8

Future of Offshore Wind Industry

Offshore wind industry has just begun to develop and be massively utilized. There are various numbers from 20 GW to 80 GW predict as the total installed offshore wind energy capacity by 2020 in Europe. In 2007 European Wind Energy Association expected two different most likely scenarios in which 20 GW to 40 GW are estimated to be the total installed capacity. Political and regulatory barriers have made the growth of offshore wind industry slower. Nevertheless most major market players and government agencies predict a faster growth in coming years, as this industry matures, proves its efficiency and regulatory complications are eased. There are many offshore wind farm projects under construction and many more are in planning stage. The fist Giga Watt capacity off shore wind farm is licensed to be built in UK close to London. Figure 1 is the map of operating and future offshore win farms in EU.

Operating Wind Farms

Planned to be built in 2008 - 2009

Map of Offshore Wind Farm in European Union Source: Delivering Offshore Wind Power in Europe, 2007, Erupean Wind Energy Association

1.9

Motivation for Conducting the Research

The expected massive growth of off-shore wind farms projects both in terms of quantity and installed capacity motivated the author to conduct a research regarding the requirements for installing off-shore win farms, costs, durations, various activities and work packages involved. This research intends to present a template that can be used initially for the planning of offshore wind projects. It provides an introduction to Engineering concepts that are necessary to understand while planning or managing such projects. It also includes list of various work packages that are involved in the project life cycle of such projects. They contain resource estimation, feasibility studies, planning, design, construction, monitoring and commissioning. The conducted research is largely based on literature made available from companies that have implemented such projects and have publicized the lessons learnt from their performed projects. The durations and costs mentioned are estimated for an average project and are guide lines that must be modified according to conditions of different projects.

As there has not been large number of off-shore wind farm projects executed, not sufficient literature is available. Some companies such as Vestas publish reports indicating the lessons learnt. This research will also demonstrate how Project management principles, tools and techniques can help businesses and government to plan, design, construct and manage wind power plants projects within budget and deadlines. The demonstrated templates are for a 60 MW generic off shore wind farm consisting of 30 turbines with 2 MW capacities.

CHAPTER 2. ENGINEERING PROSPECTIVE

1.10 The Parent Discipline 1: Engineering Prospective

Wind is a form of solar energy. Winds are caused by the uneven heating of the atmosphere by the sun, the irregularities of the earth's surface, and rotation of the earth. Wind flow patterns are modified by the earth's terrain, bodies of water, and vegetation. Humans use this wind flow, or motion energy, for many purposes: sailing, flying a kite, and even generating electricity. The terms wind energy or wind power describes the process by which the wind is used to generate mechanical power or electricity. Wind turbines generate electricity by harnessing the natural force of the wind in order to power an electrical generator. They convert the kinetic energy in the wind into mechanical power. This mechanical power can be used for specific tasks (such as grinding grain or pumping water) or a generator can convert this mechanical power into electricity. The first windmill to generate electricity was installed in 1887 in Scotland3. An experimental grid-connected turbine with as large as 2 MW was installed in 1979 and a 3 MW was tested in 1998. Today large turbines are routinely installed, commercially competing with electric utilities in supplying economical, clean power in many parts of the world. The average turbine size was 300 kW until early 1990s. New mechanics being installed are in the 1-to-3-MWcapacity range. The latest commercially available development, at the time of this writing, is Erenco’s E-126 which is the world’s largest wind turbine. This turbine has a rotor blade length of 126 meters (413 feet) and is expected to produce 7+ MW of electricity, enough to power 5000 average European homes. (More information on is given in latter chapter). 4 Figure 3.1 is a conceptual layout of a modern multi-megawatt wind tower suitable for utility scale applications. Improved turbine designs and plant utilization have contributed to a decline in large-scale wind energy generation costs from 35 cents/kWh in 1980 to 3 to 4 cents/kWh in 2004 in favorable locations. At this price wind energy is the least expensive new source of energy in the world, less expensive than coal, oil, nuclear, and most natural-gas-fired plants. Hence it has become economically attractive to utilities and electric cooperatives. In 2006, the greatest growth in the renewable sector was in wind generation, which contributed 95 percent of the

growth in renewable energy. Wind generators produced 26.6 million MWh, 49.3 percent higher than in 2005. In this chapter the technical issues of wind farms are reviewed and discussed, technical specifications are explained.

1.11 Calculations

Although the detailed calculation and design of wind farms is not of responsibility of a Project Manager, the conceptual knowledge of basic parameters and equations is essential to efficient management of a wind farm project.. In this section common calculations and laws of the wind are reviewed and some simple rules are presented where applicable (rule of thumb).

1.12 Power of the wind

The Electricity produced in a wind turbine is a function of several parameters: key among them are: Air density (ρ,

/

)

Rotor-blade-sweep area (A,

),

Wind velocity (V, m/sec)

Time (t, sec) and a conversion efficiency factor The instant energy (dE, kWs) produced is the power rate (P, kW) multiplied by the instant time period (sec), as given by: dE= P dt

(2.1)

The kinetic energy generated in the wind turbine is given by KE= Power = (mass low per second)V

(2.2)

And the mass flow rate of air, m (kg/s), is given by M=ρAV

(2.3)

Where: = air density (kg/m3), which is 1225

⁄

at sea level and 20 °C

A

= area swept by the rotor blades (A = Π r2, m2),

V

= velocity of the air (m/s)

By applying the volumetric flow rate (AV) and the mass flow rate of the air (ρAV), the mechanical power coming in the upstream wind is given by the following equation: = (

)

=

(2.4)

1.13 Betz’ Law (Maximum Power Extractable)

Betz’ law shows the maximum energy that can be extracted from a fluid at certain speed and that it is not possible to capture all the power. In case of wind turbines it means that not all the power in upstream wind can be captured as the downwind continues to move with a lower speed. The power extracted from the wind is the difference between the power of upstream and downstream wind. So it can be driven, from Equation 2.2, that: ){

= (

Where,

−

}

(2.5)

= mechanical power extracted by the rotor, i.e., the turbine output power, = upstream wind velocity at the entrance of the rotor blades, and = downstream wind velocity at the exit of the rotor blades.

Mass flow per second of air that passes through the plane of rotor blades can be calculated by averaging the downstream and upstream wind speeds, therefore from Equation 2.4 and 2.5: ){

= (

−

}

(2.6)

It is algebraically possible to rearrange Equation 2.6 to the following form: =

(2.7)

It is common to show Power extracted from the wind as the following:

Where:

=

The factor

=

C

(2.8)

(2.9)

is called the power coefficient of the rotor or the rotor efficiency and is the

fraction of the upstream wind power that is extracted by the rotor blades and fed to the electrical generator.

Betz’s mathematically proved that the maximum value of when

to be

or 0.59 and that occurs

⁄ is 1/3. In figure 2.1 the relationship between upstream and downstream ratio and

the power coefficient is demonstrated.

Figure 1. Adopted from http://en.wikipedia.org/wiki/Betz'_law The practical maximum for two-blade turbines is from 0.4 to 0.5 and 0.2 to 0.4 for multiblade modern turbines.

1.13.1 Maximum Power Of The Site

As a rule of thumb it is possible to state that maximum power that can be extracted from a site is calculated by the below simple formula, assuming the maximum =

is 0.5: (2.10)

Important observation from the above equation is the affect of wind velocity, which is by 3rd power, in output power of the turbine, and thus the overall performance of the wind farm. 5

1.14 Wind power density (Wind Class) As mentioned before the power density of the wind determines how much energy can ideally be extracted by a wind turbine and is influenced by two factors: wind speed and air density. To simplify the comparison of the wind resource at different sites, wind power density has been standardized in Wind Power Classes. These classes are based on wind speeds taken at certain heights, generally using sea level air densities. Since the wind speed at any site will vary with height due to the effects of the terrain on the wind flow, the wind class is often defined at more than one height. A site with a measured average wind speed of 5.8 m/s at a height of 10m and 7.2 m/s at a

height of 50 m has a Class 4 wind resource.6 Table 2.1 displays the wind speeds associated with Wind Power Classes at 50m, assuming sea level air density. 10 m height

50 m height

Wind Class

1 2 3 4 5 6 7

Wind speed m/s

Wind power

Wind speed m/s

Wind power

0-5.1 5.1-5.9 5.9-6.5 6.5-7.0 7.0-7.4 7.4-8.2 8.2-11.0

0-160 160-240 240-320 320-400 400-480 480-640 640-1600

0-5.6 5.6-6.4 6.4-7.0 7.0-7.5 7.5-8.0 8.0-8.8 8.8-11.9

0-200 200-300 300-400 400-500 500-600 600-800 800-2000

As a rule of thumb it can be said that wind farms can be practical where class 2 or higher wind conditions exist most of the time.

1.15 Conversion efficiency

The second major limitation for the power rate is the large and continuous variation in the wind speed. This variation is especially important since the rate is proportional to the third power of the wind velocity (Eq. 2.4). A twofold change in velocity results in an eightfold change in power output. Thus a major problem in estimating the annual output of a wind turbine in (kWh) is the time variation means wind velocity over an annual period. Long term wind statistics for a proposed wind-farm site generally compiled as a Weibull probability function to estimate the mean number of hours per year at each velocity interval. The data are plotted in the form of a Raleigh wind speed frequency distribution. 3 The following is a report with graph of Missouri Anemometer Loan Project; Data are collected at 20 meters above ground level and covers first year of data collection. Site1003 Skidmore Missouri in Eastern Atchison County Data collection ongoing as of November 30, 2005 Prepared by the Missouri Department of Natural Resources' Energy Center.7

1.16 Measure – Correlate – Predict Technique

A common method used to predict the wind condition is Measure-Correlate-Predict Technique. Wind speed data are collected over a short period of time, e.g. 1 year, and then are correlated to long term data from a nearby site to predict long term annual wind speeds.

Figure 2.2 Frequency Distribution Graph of Missouri Anemometer Loan Project

1.17 Wind Rose

Another tool which is commonly used when assessing a potential site is called Wind Rose. Wind Rose is basically graphical representation of the frequency of the wind from different direction at a particular point. The length of each "spoke" around the circle is related to the frequency that the wind blows from a particular direction per unit time. Each concentric circle represents a different frequency, emanating from zero at the center to increasing frequencies at the outer circles. A wind rose plot may contain additional information, in that each spoke is broken down into color-coded bands that show wind speed ranges. Wind roses typically use 16 cardinal directions, such as north (N), NNE, NE, etc., although they may be subdivided into as many as 32 directions.8 Figure 2.1 represents a sample wind rose. Wind roses are used to determine the best location and direction for the turbines to capture the wind.

Figure 2.3 A sample Wind Rose

1.18 Components of the system

Almost all the wind turbines that produce electricity consist of a rotor with blades that turns on a horizontal shaft; the latter is connected to a mechanical transmission assembly or gearbox and, finally, to an electrical generator, both of which are located in the nacelle mounted at the top of the mast.

2.9.1

Turbine

Turbine is the most important component of a wind farm. It converts energy of the wind to electricity. Therefore choosing the right type of turbine is of vital importance to success of a

Wind Farm Project. Principles by which wind turbines operate are the same in all modern wind turbines. The wind turbine captures the wind’s kinesthetic energy using a rotor which has two or three blades. The rotor is installed on a tall tower, to enhance the energy capture the power of the wind. Numerous wind turbines are installed at one site to build a wind farm of the desired power generation capacity. As seen on formula 2.4 swept area of a rotor blade plays a key role in power generation of a wind turbine, therefore one of the most important factors while choosing a wind turbine is the size of the blades. The larger the blades, the larger the swepts area and thus larger output power of the turbine. Larger and lighter turbines enter the market almost every year, providing more power per turbine. In 2008 German company Enercon introduced E112 which is capable of producing 4.5 MW to 6 MW of electricity. Operation with constant or variable rotor speeds are both common in the market. Automatic power control systems ensure that the turbine is kept in operation mood most of the time; depending on wind speed, with cut out at very high speeds (mechanical safety): by means of the angle of the blade (pitch) or its own aerodynamics (stall). Availabily of 98% per year is the common standard. Figure 2.3 provides a schematic view of a wind turbine’s major components

Figure 2.3 Schematic view of a wind turbine

2.9.2

Tower

Tower is the base of the turbine on which the necle and the rotor are installed. It is constructed both by steel and concrete. The aerodynamics of the tower is the major engineering challenge.

2.9.3

Rotor

Rotors are up to 90 meters in diameter and usually consist of 1 to 3 blades. The most commonly used are 3 bladed rotors which provide best balance of high rotation speed, load balancing and simplicity. 2 and 1 bladed are more complex in design. They have to rotate much faster than 3 bladed rotors to provide the same amount of power The blades are usually made of glass-reinforced polyester or epoxy fiber up to 50~60 meters length. The lighter and stronger carbon fibers are preferred and are used in larger blades. The rotor typically with three blades provides the best balance of high rotation speed, load balancing, and simplicity. The rotor itself is composed of following subcomponents: Rotor Blades: Blades utilize the principles of lift to convert the energy of the wind into mechanical energy. Stall-regulated blades limit lift, or momentum, when wind speeds are too great to avoid damaging the machine. Variable-pitch blades rotate to minimize their surface area and thereby regulate rotational speed. Pitch Drive: This system controls the pitch of the blades to achieve the optimum angle for the wind speed and desired rotation speed. At lower wind speeds a perpendicular pitch increases the energy harnessed by the blades, and at high wind speeds, a parallel pitch minimizes blade surface area and slows the rotor. Typically one motor is used to control each blade. Power is either electric or provided by hydraulics in the nacelle, and supplemented by a hydraulic accumulator in the event of system failure. Extenders: These steel components serve as a means to support the rotor blades and secure them to the hub. Hub:

The hub serves as a base for the rotor blades and extenders, as well as a means of housing the control systems for the pitch drive. It rotates freely and attaches to the nacelle using a shaft and bearing assembly.

2.9.4

Nacelle

The nacelle includes: Outer frame protecting machinery from the external environment Internal frame supporting and distributing weight of machinery Yaw Mechanism and Four-Point Bearing to rotate the turbine directly into the wind in order to generate maximum power. Typically, four yaw sensors monitor the wind direction and activate the yaw motors to face the prevailing wind. A four-point bearing connects the nacelle to the tower. The yaw mechanism turns the blades 90 degrees from prevailing winds under high winds to reduce stress on internal components and avoid over-speed conditions. Low Speed Shaft and High Speed Shaft which transmit rotational work from the rotor hub to the gearbox and from the gearbox to the generator. Gearbox Converts low-speed rotation from the input shaft of the rotor to high-speed rotation; from about 30 to 60 rotations per minute (rpm) to about 1000 to 1800 rpm, the rotational speed required by most generators to produce electricity, which then drives the high-speed shaft of the generator assembly. Wind turbine gearboxes typically use a planetary gear system. The gear box is a costly (and heavy) part of the wind turbine and engineers are exploring "direct-drive" generators that operate at lower rotational speeds and don't need gear boxes. Coupling attaches the gearbox to the generator. Flexible couplings may be used to reduce oscillating loads that could otherwise cause component damage. Bearings: A number of bearings are required for the shafts, gearbox, yaw mechanism, generator, and other rotating parts. Mechanical Brakes: A mechanical friction brake and its hydraulic system halt the turbine blades during maintenance and overhaul. A hydraulic disc brake on the yaw mechanism maintains nacelle position when nacelle is stationary. Electrical Generator converts high-speed shaft work into electrical energy

Power Electronics: Couples the generator output to the step-up transformer input, typically with an IGBT bridge, allowing the generator to run at variable speed while still outputting 50 or 60 Hz AC to the grid. Also makes reactive power possible. Cooling Unit: A large fan drives air to convectively cool the generator and gearbox and exhausts waste heat from the nacelle assembly. Ducting directs cool air to the generator

2.9.5

Electronic Controller(s):

The controller starts up the machine at wind speeds of about 8 to 16 miles per hour (mph) and shuts off the machine at about 55 mph. Turbines do not operate at wind speeds above about 55 mph because they might be damaged by the high winds.

2.9.6

There are Electronic controllers inside the turbine which control different parts of the turbine:

Base controller, located at the base of the tower, utilizes PC’s and fiber optics to monitor and record performance data, as well as to facilitate communication between both sub-controllers and external parties. Nacelle controller monitors activity within the nacelle assembly. Hub controller, being used in more recent models, communicates directly with the nacelle controller to more precisely monitor rotor activity

2.9.7

Sensors

There are two types of sensors in a wind turbine: An anemometer, located on the tower, measures wind velocity and relays data to the yaw mechanism. A wind vane measures wind direction and relays data to the yaw mechanism. A cable twist counter monitors cables within the tower to determine if the turbine has been yawing in one direction for an extended period of time. A thermocouple senses temperature within the nacelle assembly.

2.9.8

Tower

The tower is the supporting structure for the turbine. It is typically made of rolled, tubular steel, and built and shipped in sections because of its size and weight. Common tubular towers incorporate a ladder within the hollow structure to provide maintenance access. Utility-scale towers range in height from 60-100m and weigh between 200-400 tons. Tubular towers made of steel and generally painted in light grey, with heights of up to 100 meters Typical components of a wind turbine tower are described below: Rolled steel tubes connected in series. Flanges and bolts joining each section. A concrete base serving as a stable foundation for the turbine assembly. Concrete segmented towers and hybrid steel/concrete towers may also be used for large turbines in cases where steel tower section transportation is difficult. Base supports the tower and transfers the loads to the foundation soil or bedrock. The foundation size and type depends on the foundation conditions but is typically constructed with steel-reinforced concrete. Flinger and Bullets join tower segments.

2.9.9

The wind farm ground / sea station

Apart from the turbines wind farms have ground facilities to transfer electricity and provide two way communications with outside the wind farm. In case of offshore wind farms electricity and data cables are collected at a Base Station. The following provides a list of items of a wind farm on the ground or sea surface. Electrical collection system: Transformers step up voltage transmission in the collector line to convert energy generated by the turbine into usable electricity for utility grids. Underground cables are used to connect the power lines until a standard 25kV overhead collector line may be used. Reclosers and risers act as circuit breakers and isolate a section of the line should there be a power fault. Power substations raise the voltage for standard long-distance transmission. Communication and control System: The communications subsystem allows the wind turbines to monitor themselves and report performance to a control station. Data collection equipment and fiber optic cables allow the turbine to monitor and report performance. A

control station consolidates data and routes information to the local utility it includes the following: control cable, data collection, and wind farm control station

2.9.10 Scales of Wind Turbines

Utility-scale turbines range in size from 100 kilowatts to as large as several megawatts. Larger turbines are grouped together into wind farms, which provide bulk power to the electrical grid. Single small turbines, below 100 kilowatts, are used for homes, telecommunications dishes, or water pumping. Small turbines are sometimes used in connection with diesel generators, batteries, and photovoltaic systems. These systems are called hybrid wind systems and are typically used in remote, off-grid locations, where a connection to the utility grid is not available.

CHAPTER 3. PROJECT MANAGEMENT PRESPECTIVE 3.1

Introduction

Project management, as a subject, has been studied since 1950s.

3.2

Documents of a Project

There are three major documents for large projects, namely: Project charter, Scope of Work (S.O.W.) statement and Project management plan.

3.2.1

Project charter

Project charter is the documents issued by the client that officially authorizes beginning of a project. It provides the project manager with the authority to apply organizational resource to project activities. It consists of a mission statement, including background, purpose, and benefits, a goal, objectives, scope, assumptions and constraints and it clearly documents project definition in order to bring a project team into necessary agreement. In another work project charter is a formal document that summarizes the business, management and financial aspects of a project. It includes scope, objectives, benefits, costs, risks and plans. It is the basis of project change control and serves as a 'contract' between the Project Manager and Project Sponsor. The objective of this activity is to secure management approval and to provide the Project Manager with the authority to apply organizational resources to project activities. The charter becomes a source of reference for the project team. Project manager should be assigned before developing a project plan while project charter is being created.

3.2.2

Scope of Work (S.O.W.) statement

It is the definition of what the project is supposed to accomplish and the budget (of time and money) that has been created to achieve these objectives. Any change in project scope has a change at least in cost, time or other resources. It can also be said that Scope of Work document or Scope Statement is a document that describes the totality of the work to be performed. The Scope Statement must include all the items and jobs to be performed and only the necessary ones. Defining scope of work is one the most important tasks to be performed by the client of any project. Scope of work shows the totality of the work to be done in the project and includes all the project deliverables. It is required to ensure that project includes all the work required, and only the work required, to complete the project successfully. Project scope management is primarily concerned with defining and controlling what is and is not included in the project.

3.2.3

Scope Of Work for an Offshore Wind Farm

During Project Planning of an Offshore Wind farm, the Project Manager, through regular communication with the Customer representatives, refines the Project Scope to clearly define the content of the deliverables to be produced during Project Execution. This definition includes a clear description of what will and will not be included in each deliverable. In case of off-shore wind farm the following issues must be included in scope statement: •

Project description

•

Capacity of the project

•

Type of the turbines

•

Number of wind turbines and their capacities

•

Type of foundation

•

Grid connection cables

•

Subsea export cables

•

Inter-array cables

•

Off-shore substations and their electrical equipments

•

Onshore-substations and their electrical equipments

•

Meteorological masts

•

SCADA building and equipments

•

Onshore operating and maintenance base

•

Total estimated cost of the project

•

Annual electricity output

•

Site Area

•

Site features: distance from the shore, wind speed, water depth, soil conditions

•

Available nearby ports

•

Wind farm layout

•

Other wind farm features

•

Location of the site or potential sites if not selected yet

•

Summary of environmental impact report

3.2.4

Project management plan

The project management plan is a document that describes the project management system used by a project team. The objective of a project management plan is to define the approach to be used by the Project team to deliver the intended project management scope of the project. The project manager creates the project management plan following input from the project team and key stakeholders. The plan should be agreed and approved by at least the project team and its key stakeholders. The project management plan typically covers topics used in the project execution system and includes the following main aspects: •

Scope Management

•

Schedule Management

•

Financial Management

•

Quality Management

•

Resource Management

•

Communications management

•

Project Change Management

•

Risk Management

•

Procurement Management

It is good practice and mostly required by large consulting and professional project management firms, to have a formally agreed and version controlled project management plan approved in the early stages of the project, and applied throughout the project.

3.3

CHAPTER 4. Work Planning Process

3.3.1

Definition:

Work Planning Process is a systematic approach used by project managers to develop work plans. A work plan is a document created by the project management team, which provides a listing of all tasks to be performed, the date on which they are scheduled for their execution. The Project Management Institute divides the Work Planning Process into three phases: 1. Work Breakdown Structure (WBS) Development, 2. Time and Cost estimation, 3. Schedule development.

3.3.2

Work Breakdown Structure

Work Breakdown Structure (WBS) is a hierarchical list of all the tasks necessary to be performed in order to achieve objectives of the project stated in the SOW document. These tasks include but are not limited to activities required to plan, perform feasibility study, design, construct and commission the project. The WBS acts as a check list for the work to be accomplished. It breaks down the large parts or “phases” of the project into smaller achievable tasks that can easily be monitored. It also facilitates the better planning for budget and schedule. Related pieces of work in the WBS are grouped together and called a Work Package. Specific resources must be allocated to each of these work packages so that that the subset tasks can be achieved. As a rule each work package must of following criteria: •

Specific, clearly defined

•

Measurable

•

Achievable, deliverable

•

Resource, time and cost assignable

•

Acceptable duration

•

Independent task

The Work Breakdown Structure for offshore wind farm projects are rather extensive and require careful considerations and must be developed by getting helped from experienced staff.

3.3.3

Top-down approach

There are basically two approaches used to identify project activities top-down and bottom-up approaches. Top-down approach is initiated from the goals specified in the project charter. It breaks down the goal into deliverables it then identifies activities that must be performed from the beginning to the completion of the project. The work is then successively decomposed into smaller, more manageable components until the project planning team is satisfied that the work is defined at a sufficient level of detail that allows estimating time, cost and resource requirements.

3.3.4

Bottom-up approach

In this approach the planning group makes a list the activities that need to be completed in order to accomplish the first-level breakdown with using brain-storming and pervious project documents. Then the team groups the activities that seem to be related to one another into different work packages. This helps to include missing activities or take out unnecessary ones. Once the team is satisfied it has completed the activity list for the first-level breakdown, the members are finished. Each group then reports to the entire planning team the results of its work. Final critiques are given, missing activities added, redundant activities removed. At the stage is to make sure the activities listed cover all of the deliverables mentioned in the scope of work.

The next stage is to confirm that the lower-level items are both necessary and sufficient for accomplishment of the decomposed items. At the final stage to each item is validated for clarity and completeness of definition.

3.4

Time and Cost estimation

After all task to be performed are listed it is necessary to allocate time duration and cost. Time durations are according to expected amount of time that the tasks require. It is not possible to predict all the durations accurately, but a best estimate must be assigned.

3.4.1

Program Evaluation and Review Technique (PERT)

PERT is way to make better decisions for time durations of different tasks. It provides a formula by which the optimistic, pessimistic and most probable estimated durations can be taken into account. t = (a + m + b)/6

(1.1)

Where: • a : optimistic time • m : most likely time • b : pessimistic time

3.4.2

Critical Path Method

Critical Path is a method by which critical tasks and their relationship to other tasks are identified. Critical tasks are the activities that any delay in their completion date will have negative effect on overall project duration. This then helps in planning and executing the project. As is sometime possible to remove certain activities from the critical path, by some kind of change i.e. modifying procedures. This change often makes other activities “critical”. It is also possible to have two or more critical paths.

3.4.3

Gantt Chart

Gantt Chart is one of the most popular tools of Project Management discipline that was developed to manage complex projects. It is a form of bar chart that shows during certain period of time what activities are to be performed, how long they should take and their dependency on other task.

CHAPTER 4. APPLICATION OF PROJECT MANAGEMENT IN OFFSHORE WINDFARM PROJECTS 4.1

INTRODUCTION

Offshore wind farm projects are a very complex engineering and management endeavor. In this chapter applied project management tools and principles are demonstrated and some sample templates are given.

4.2

Explanation of Main WBS Items

A sample of WBS of an offshore wind farm up to level 3 is given in the appendices. In this section explanation on main items are given for illustration purpose.

4.2.1

Project initiation

This work package includes the preliminary tasks to be under taken in order to initiate the project. It is smaller work package of: •

Planning and Control

•

Scope of the work definition

•

Site Selection

•

Project Definition

In this stage opportunities are identified, potential sites are investigates, overall scope of work is defined, and plan for management of the whole project is created. During this work package the project is given a Yes or No according to overall assessment. It also includes milestone of initial plan complete.

4.2.2

Feasibility studies

If project is found of reasonable potential is given an initial green light on the last work package then Feasibility work package starts. The main objective of the Feasibility study is to ensure that enough wind power exists on the site, is it environmentally, legally, socially and technically viable to build offshore wind farm at the selected location or not?

Offshore wind farm have extensive feasibility study plan that takes more than a year to perform. The reason being is that wind profile and speed must be studied at least for a period of one year before it can be accepted as a reliable source. And because accurate historical wind data are almost never available for offshore wind farms projects, a mast must be erected at the potential site and wind data to be collected for a period of at least one year. Other site conditions must also be carefully surveyed, such as: Geotechnical, Geophysical, Metocean. Rigid environmental regulations are often applied to offshore projects. The Client must provide a detailed environmental impact assessment report to legal authorizes and supervising bodies. The study includes impact of the project on fishes, sea mamels, sea plant, fishery, tourism and so on. Visual impacts and noise study are also among very important subjects of environmental impact studies. Feasibility study also includes technical issues such as proximity to nearby grid connections, assessment of grid cables and turbine transport feasibility.

3

James Blyth - Britain's first modern wind power pioneer, by Trevor Price, 2003, Wind Engineering, vol 29 no. 3, pp 191-200 4

http://www.metaefficient.com/news/new-record-worlds-largest-wind-turbine-7-megawatts.html

5

Kurger Paul, Alternative Energy Resources: the quest for sustainable energy, 2006

6

www.nwseed.org/publications/Guidebook/

7 Prepared by the Missouri Department of Natural Resources' Energy Center, Missouri Anemometer Loan Project, Data collected at 20 meters above ground level, 2005 8

http://en.wikipedia.org/wiki/Wind_rose