SCHOOL OF SCIENCE AND ENGINEERING

INVESTIGATION OF INNOVATIVE STRUCTUERS AND MATERIALS OF THE TOWERS USED IN

Rawane Abdaoui

Suppurvised by : Abderrazzak El Boukili

May 3rd / 2018 Table of Contents

Table of Figures ...... 3 Abstract ...... 7 Introduction ...... 8 STEEPLE ANALYSIS ...... 11 Chapter 1: General Overview on Wind Turbines ...... 13 How is wind created?...... 13 Types of Turbines based on the site ...... 16 Offshore wind farms ...... 16 Onshore wind farms ...... 17 Types of Wind Turbines based on formalities ...... 18 Horizontal Axis Wind Turbines (HAWT) ...... 19 Vertical Axis Wind Turbines (VAWT) ...... 19 Chapter 2: Materials and Structures of Wind Towers ...... 21 Materials used in Tower ...... 21 Future Component Development Trends ...... 22 Different Types of the Towers of a Wind Turbine ...... 22 I. Tubular Steel Towers ...... 22 II. Lattice Towers ...... 23 III. Bolted Steel Towers ...... 23 IV. Steel Hybrid Towers ...... 23 Chapter 3: Fabrication, Installation and Industry Technologies: ...... 25 Manufacture of wind turbine towers ...... 25 Lamination of conical sections of towers...... 25 Designed by the Turbine Manufacturer ...... 26 Weight issues ...... 26 Blades with banana skin ...... 26 Wind Speed Measurement ...... 27 Wind Measurements ...... 27 Types of Tower ...... 28 Data Logging ...... 28 Innovations in wind technology ...... 28 Larger and articulated shovels ...... 28 Maximum efficiency with little wind ...... 29 Magnets to increase power ...... 29 Chapter 4: Design and Manufacturing of ...... 31 Environmental Impact and a research on No-Tower-needed wind turbines: ...... 31 Design parameters of the ...... 35 Design Using Computer Software: ...... 38 The project Prototype: ...... 39 2 Cost Characterizations ...... 45

Conclusion ...... 46

References ...... 47

Table of Figures

Figure 1: Wind Energy ...... 9 Figure 2: Importance of Wind Energy to produce power ...... 12 Figure 3: Creation of Wind ...... 14 Figure 4: Wind Turbine main Parts...... 15 Figure 5: Wind Turbine Towers View ...... 16 Figure 6: Off/Onshore Turbines ...... 18 Figure 7: Comparison Between Vertical and Horizontal axis ...... 18 Figure 8: Horizontal Axis Wind Turbine ...... 19 Figure 9: Vertical Axis Wind Turbine ...... 20 Figure 10: Table of materials used ...... 21 Figure 11: Types of Towers ...... 24 Figure 12: Fabrication of the Tower ...... 25 Figure 13: Banana Skin Method ...... 26 Figure 14: Wind Speed In Europe...... 33 Figure 15: an Example of the Design ...... 39 Figure 16: Wheel inspired from Johnson Wheel...... 41 Figure 17: Dynamo used with the wheel Figure 18: Dynamo Used ...... 41 Figure 19: Blades fabrication ...... 42 Figure 20 : The Final Result of the prototype ...... 44

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5 Acknowledgement

I would like to express my deepest appreciation to all those who provided me the possibility to complete this report Furthermore I would also like to acknowledge with much appreciation my capstone supervisor Dr. Abderazzak El Boukili who has invested his amazing effort in guiding me in achieving my goal. I have to appreciate the support given from my friends and family who have been always there for me.

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Abstract

Wind energy is considered one of the fast growing sources due to their minimal environmental impact. To meet the growing demand, wind turbines are being scaled up both in size and power rating. This study is important for any developing in the field. So the production, distribution and the use of the energy should be as technological efficient as possible and incentives to save energy. Taking a close look at the existing projects, narrowing down all the technologies and industry methods to come up with the best ideal wind turbine is a must in this project. In addition to a great focus on the towers of the turbines, the structure and materials used in different towers around the world. The challenge will be the relative relationship between the type of the tower and how efficient it is for its sight and use. A homemade prototype of a small wind turbine will be designed and fabricated in order to present the general concept wind turbines and the importance of their towers

7 Introduction

One of the mysterious secrets in life is Energy. Any strength or change of the actual state is a form of energy. To move a certain object, to have the right amount of nutrition in your body and to generate heat or power, energy is the key. We will have better food supply, clean water, sanitation, health, and education and communication facilities. Energy is an important factor in our daily life. The question is if the energy sources we have nowadays are relative to the continuous obligation. In addition of the lake of the natural sources, which is caused by the pollution of the lands and cities.

A lot of sources have been used to distract energy from such as wind energy, solar energy, hydrogen energy, geothermal energy, waves and tidal energy, and biomass energy. Nowadays, the most common is fossil that includes oil, coal, and natural gas. contains the remaining of very old living organisms that have been under high pressure and temperature for a long time. Besides the environmental impact of fossil fuel we can add the fluctuating price of fossil fuel especially oil and natural gas and the high dependency on the producing countries created a need for other sources of energy that are renewable and self- dependent. The transition towards 100% renewable energy is necessary but still there are a lot of obstacles to overcome such as the low efficiency, immature technologies and the high cost of investments in most of them. For these reasons, the shift to 100% renewables might take a century or even longer for some other countries since the conditions are variant from one country to another. One of the reasons for this shift is the fact that we reached the peak oil extraction already which means oil is getting rare or economically unfeasible. Meaning, we will need more developed technologies, higher strategic planning and the quality of the extracted oil will get lower and an added cost will be for extra refineries. Also, fossil fuel is getting more expensive to burn since many countries are taking action on limiting the amount of CO2 released to the atmosphere. In additions, a lot of standards, policies, and regulations have been made in order to regulate the environmental impact of energy production activities.

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Figure 1: Wind Energy

Electricity is very dependent on energy price as well and the demand is increasing due to the global increase in population. In fact, demand is increasing twice with respect to the overall energy use, and it’s expected to increase to two-third by 2035 comparing to 2011. Also, in 2012, more than 40% of the consumption was converted into electricity.

Renewable mean that these technologies have the minimum environmental impact and relying on infinite sources. So that, renewable energies are clean sources of energy with lower environmental impact and environmental cost comparing to conventional energy sources. In addition, they will not run out or deplete comparing to finite energy sources. A lot of advantages come with the exploitation of renewable energies such as self-supply source, creating jobs, and low operating cost. Also, it helps investing locally, create jobs in which support the local economy instead of going overseas. This money is spent to construct, operate, and maintain facilities instead of importing energy.

One of the challenges regarding renewable energy is how to satisfy the increasing energy demand with the most efficient price. Wind energy is one of the most economical renewable energy technologies especially the ones in good sites. At high wind sites, and high efficiency wind turbine, this technology can give good performance and compete with the conventional 9 energy production. However, the potential of this technology varies from one country to another but still, many countries are making considerable wind resources. The source of wind energy is the movement of air current in which harvest the of wind to convert it into power that could be a source of electricity. This electricity could be used for supplying homes, schools, farms, residential areas, etc. Local consumption of the produced power is preferred to avoid the losses in the transmission lines.

The driving force for wind turbine is temperature difference across earth’s surface. Meaning, sunlight heats part of the air and rises its temperature in which the heated air will rise up and the cool will sink down. The change in temperature will create a change in pressure in which what we call . Then, winds energy is a function of solar power. There are some challenges regarding the installation of wind turbines that sometimes become an obstacle in large-scale applications. For example, wind turbine is land dependent in which a high portion of land is needed that could be costly for some cases. Also, establishing a wind turbine in a residential area might not be very favorable by the residents of the region due to the high noise and the visual impact. Also, it has an impact on the birds living in the region beside the changes on the landscape. Also, electromagnetic interference might happen due to the installation of wind turbines. Additionally, the amount of power produced by a wind turbine varies from one day to another depending on the weather conditions. In case the wind turbine is connected to a grid, then the grid has to be maintained regarding voltage stability and frequency stability. Regardless these challenges, wind turbines are still attractive technologies in which a lot of countries are investing.

In Morocco, most of the wind turbines installed is in the north in Tangier-Tetouane region in which the conditions are suitable for such projects. These projects promote the shift towards more renewable sources and more self-dependence power supply.

10 STEEPLE ANALYSIS

Social Impact:

All societies around the world are in need of huge energy source to meet their needs the challenge is to find as much energy as needed with the least cost available. This study will help people to follow some steps to meet those needs.

Technological impact:

The industry sector has a lot of methods and strategies used to fabricate and make wind turbines and their towers. However, it is hard to know which one is the best to use at different sights. This project might narrow down steps of the study of any engineer who wants to install wind turbine towers.

Environmental Impact:

Wind turbine is considered as a green clean natural source of energy. There will be less pollution if we considered wind Turbines and gave importance to the research related to it. The energy transformed from wind is healthier than any other sources because it doesn’t go through any before energy is ready to be consumed.

Political Impact:

There is a great demand from governments to economically reduce the cost of energy resources consumed in a city.

Legal Impact:

In general, implementation and fabrication of wind turbine towers are not considered to be illegal in most countries, including Morocco.

Ethical Impact:

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Wind Turbines are ethically acceptable, since they do not produce air contamination and they use purely sunlight.

Figure 2: Importance of Wind Energy to produce power

12 Chapter 1: General Overview on Wind Turbines

In this chapter I will be discussing an overview over wind turbines. Wind is considered as a clean source of energy. It is much recommended to use this source more often to keep our planet free of pollution and carbon emission. As efficient as it can get wind has been making a lot of task for us since thousands of years ago. There are some of the live examples such as propelling sailboats, flying as well as grinding grains. Nowadays, the use of wind has retained its importance in a daily life of people around the world. Wind farms, houses and industrial building are all in need to a renewable source of energy such as wind to obey the huge need of energy sources, which happens to be expensive. An engineer always looks to create the most powerful wind Turbine that will relatively generate enough .

The power of wind is not constantly blowing in certain sites. The flow of wind does not blow in regular basis. Engineers try to tackle each obstacle at a time to make the right decisions for the most efficient wind turbine to be fabricated and installed eventually. It is cheap to install huge wind turbines in rural areas. However, the wind speed and power is not always available, which makes the calculation not very precise. The challenge then is to have the wind turbine be sensitive to those slow wind flows. The turbulent wind flow, trees and building close by makes it hard on the turbine to in a direct interaction with air.

All of the above are reasons to emphasize on being carful while choosing the right site for a wind turbine. There are several types of wind turbines that take into consideration different factors and variables. [1]

How is wind created?

Have we ever asked ourselves what is the source of wind? In our earth surface there happens to be some different level of heating sourcing form the sun. The warmer air comes to the top with a low pressure coming from the cooler air with a higher pressure. Wind is affected by the rotation of the planet, weather changing and also topographic effects.

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Figure 3: Creation of Wind

This project is going to be a study about each of the fabrication, structure and the material used in ideal wind turbine in Morocco. A sight on the different structures, materials and

Wind turbines are classified into two general types: horizontal axis and vertical axis. Regardless of the design of the wind turbine, they share some components such as:

1. Anemometer: a tool that is used for measuring the speed of wind

2. Blades: the main parts of the wind turbine that will be in contact with air in which they rotate once wind passes. Due to this interaction, electricity will be produced eventually.

3. Brake: the function of the break is to stop the wind turbine for maintenance or for emergency cases. Also, the break has different types in which could be electrical, mechanical, or hybrid break.

4. Controller: the part of the wind turbine that is functionally linked to wind speed in which turbines start and stop. Usually, when the wind hits 8 mph or 3.6 m/s, it starts the machine and stops it when wind speed reaches 55 mph or 24.6 m/s. It is an important component since it prevents the blades from damage during high wind conditions.

5. Generator: the part of wind turbine that is responsible for producing electricity at 60 cycles usually.

6. Shaft: the part of the wind turbine that signals the generator for conducting electricity.

7. Tower: the place where the turbines are hold for a certain height to get more wind.

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Figure 4: Wind Turbine main Parts

The tower of a wind turbine is made from tubular steel, concrete, or steel lattice. Supports the structure of the turbine. Wind turbines generate more energy when the height of the towers increases since the wind speed increase, as the tower gets taller. That’s why our focus in this project will be on towers. We will cover, the design, the fabrication of different kind and structures of the towers used in the wind turbine.[2]

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Figure 5: Wind Turbine Towers View

Types of Turbines based on the site

There are two types of wind turbines based on the topographic position. Onshore wind turbines and off shores ones. The decision made to choose one of them is based on a lot factors, politically, financially and even geographical. However, some of their advantages and disadvantages will follow.

Offshore wind farms

Advantages:

 There is a higher chance of higher sizes of the turbines, since its far away from any obstacle.

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 Since very far away from any coastal land amount of wind will be more efficient. There are no topographic effects that could block the flow of the wind.   Wind Speed is higher.

Disadvantages:

 Most expensive wind farms, a lot of cables and equipment’s should be supported inside the coast to their batteries.   Even though further cables mean better wind force, the long way results in voltage drop off.

Onshore wind farms

Advantages:

 A huge mass of onshore farms still cost cheaper than others.   There will be no voltage drop off.   They are very quick to be built, few months at most.

Disadvantages:

 A lot of citizens consider onshore wind turbines to be a visual pollution that ruins nature’s beauty.   The blockage of buildings and hills all over around make the onshore farm capture less wind.   Noise can be one of the main factors that ruins the spread of the onshore wind turbines since the communities nearby always complain hearing a sound of a 200 feet far, car driving by at 25 miles per hour.

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Figure 6: Off/Onshore Turbines

Types of Wind Turbines based on formalities

Based on functionality versus form, there would be two types of wind turbine. Vertical Axis Wind turbine and Horizontal Axis Wind Turbine. What are their differences and how can we make the right choice between them to use in your system?

Figure 7: Comparison Between Vertical and Horizontal axis

18 Horizontal Axis Wind Turbines (HAWT)

The technical principle for a horizontal wind turbine is based on Yaw mechanism in which three blades –usually- placed on up-wind. The blades or the rotors are rotating to an axes parallel to the ground, and electric generator runs at higher speed comparing to the rotors. Gearbox and pitch control are necessary in order to optimize the output power of the wind turbine. The advantages of a HAWT is the high efficiency comparing to vertical axes wind turbine since the blades are able to be in contact with wind through the whole rotation of the blades. Moreover, the output power is optimized in different wind conditions through variable pitch. However, HWAT has some disadvantages such as the high visual impact due to the high towers of the turbine. Also, HWAT is one of the large equipment technology in which makes it difficult and expensive to manufacture, transport, and install them.

Figure 8: Horizontal Axis Wind Turbine

Vertical Axis Wind Turbines (VAWT)

The technical principle of the vertical axis wind turbine is a gearbox and generator placed near to the ground. For VAWT technology the blades rotate on an axis perpendicular to the ground. VAWT has advantages in which it doesn’t have to be pointed out towards wind. Also, it

19 can be placed in locations such as buildings where HAWT cannot be used. Mostly this form is used in residential applications, due to their small size they can fit in houses and industrial buildings. Vertical axis wind turbines can capture wind form all 360 degrees and top to bottom. Which is going to be very efficient in case of tumultuous wind conditions. Its recommended when wind is not consistent in the area. In addition, generator and gearbox are placed at ground level. Moreover, VAWT has lower cut-in speed comparing to HAWT, which means it’s easier for VAWT to overcome friction and rotate. However, still VAWT has some disadvantages such as the low efficiency comparing to HAWT and also the difficulty in maintenance. Commercially, fewer designs of VAWT are available in the market comparing to the variety of HAWT designs.

Figure 9: Vertical Axis Wind Turbine

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Chapter 2: Materials and Structures of Wind Turbine Towers

Materials used in Wind Turbine Tower

There are a variety of materials applied while building wind turbine. As mentioned before, there are a lot of factors that should be taken into consideration. For example, turbulent wind flows, dependency on external sources and geographical effects. The selection of the materials changes as well with the size of the machine. It affects the technology used for material, structure, fabrication and installation. Steel is one of most materials used in a wind turbine. Especially in towers, Steel is strong and heavy which explains It is the best material to be used in this strong mission. The table that follows has an overall idea about the use of materials in the wind turbines. [3]

Figure 10: Table of materials used

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Future Component Development Trends

A wind turbine tower holds 65% of the total weight. The focus on using the right material for the tower is an important process. It can affect the efficiency of the turbine and also can play a big role on the cost. For example, concrete is cheaper than steel. Concrete in towers has the potential to lower cost, but may also be enforced by some parts of steel. Which leads to the same conclusion, steel is a main basis and its heavy and expensive. However, experiment has found a lighter composite with a close range of strength and fatigue, Aluminum. The new material trend is recommended in small wind turbines.

Different Types of the Towers of a Wind Turbine

Wind energy is considered one of the cleanest energy technologies since it doesn’t pollute air and doesn’t release the harmful greenhouse gases. It has lower environmental impact comparing to fossil fuel based power since it emits no CO2. Wind turbine towers recover the energy used in building, constructing, operating and dismantling within just few months of operation. In order to fully exploit the potential of a wind turbine, its main components should be made out of steel. Steel is a very strong material that is able to carry the turbine with the rotating blades besides providing a strong frame. The nacelle frame is quite heavy that weights about 300 tons in which safe steel is required for successful operations. Thus, high value steel is used in the nacelle such as electrical steels in which used to conserve energy. For the strength and durability of steel, wind turbine tower industry has implemented steel in most of their components.

I. Tubular Steel Towers

Large tubular steel industry relies on steel in manufacturing their large components in section of 20-30 meters in which each section ends with flanges. Usually, these sections are bolt together on site. Tubular steel towers have a conic shape with increasing diameter towards the base that gives more support to the tower. Also, this type of tower designs helps to save some materials since the tower is thinner at the top. The advantage of using steel in this design is to give enough strength and support to carry the heavy weight turbine. Moreover, steel is suitable for conical shaped tower since it’s very flexible to form such design without breaking.

22 II. Lattice Towers

Lattice towers has different profile since it is made of welded steel instead of steel sheets. Lattice tower has an advantage of lower cost investment comparing to other types of towers since it uses less material. For example, lattice towers uses half of the materials used in manufacturing tubular towers yet the lattice tower still provides high strength and reliability to support the turbine. Steel enables producing similar strength towers with less material due to the metallic characteristics and the excellent strength. Lattice towers allow wind to pass through the tower section and the base and reduces the resistance and pressure on the structure. There is one disadvantage of lattice towers, which are the aesthetics complaints of people since they don’t have good appearance. Due to these complaints, the market has witnessed a remarkable decrease in the use of these towers in modern wind turbines.

III. Bolted Steel Towers

This type of wind turbine towers consists of some sections in which each placed on top of one another. The sections are made of steel shells and usually are assembled on site. The tower is formed by bolting the steel shells (bended steel plates) together with tension-controlled bolts. The formation of the tower through bolting the steel allows building high towers since there is no maximum hub height besides easier transportation comparing to the requirement of other towers. Throughout the lifetime, these towers are easily maintained and fast to erect.

IV. Steel Hybrid Towers

For taller turbines, steel and concrete hybrid towers are considered ideal for this purpose since they bring good characteristics of both materials. For this type of tall towers, they don’t actually need to increase the diameter and many experts in the wind turbine towers industry belive that the hybrid towers are the future of the industry. The combination of the steel upper section with the concrete bottom section we can provide tall towers with high stability.

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Figure 11: Types of Towers

24 Chapter 3: Fabrication, Installation and

Industry Technologies:

Manufacture of wind turbine towers

Lamination of conical sections of towers

Nowadays, most of the towers in modern wind turbines are tubular truncated-conical steel towers.

Figure 12: Fabrication of the Tower

This image of a tower manufacturing workshop shows how a steel plate is rolled into a conical subsection for a wind turbine tower. It is a little complicated to get the conical shape, because the tension (pressure) of the steel cylinders has to be different at both ends, in order that the plate is properly curved. The towers are assembled from these smaller conical subsections, which are cut and laminated with the correct shape, and subsequently joined by welding. The towers are

25 usually manufactured in sections of 20 to 30 m, being the transport by train or road the limiting factor. The typical weights of modern towers are 40 Tm for a 50 m turbine tower with a rotor diameter of 44 m (600 kW), and 80 TM for a 60 m tower for a rotor diameter of 72 m (2000 kW).

Designed by the Turbine Manufacturer

The wind turbine towers are generally designed by each turbine manufacturer, since the entire wind turbine as a whole has to be approved as a unit. Therefore, even if some towers are manufactured by independent producers, they are always specific to each manufacturer. Often independent tower manufacturers also produce oil tanks and pressure vessels, since the machinery and inspection procedures are very similar.

Weight issues

The weights of the towers (per kW of installed power) have decreased by around 50% in the last five years thanks to more advanced design methods. Although the tower is still a part of the wind turbine quite heavy, so transport costs are important. In larger markets, it is generally best not to transport the road towers more than 1000 km. In the event that the distance is greater (and that it is a large project) the towers are usually manufactured locally.[4]

Blades with banana skin

Figure 13: Banana Skin Method 26

To achieve a cone-shaped section, the sheet that is used to wind must have the longer sides curved, and the short sides do not have to be parallel. Most tower manufacturers use laser cutting machine tools to obtain the desired shape in the steel sheet.

Wind Speed Measurement

Wind Speed is measured by Anemometer. This device is formed of vertical axis and three cups to capture the wind and register the number of revolutions per minute. It also detects wind direction that is why it is normally fitted within a wind vane. There are two types of anemometers:

Mechanical such as cup anemometer described above and non-mechanical such as ultrasonic, laser and hot wire. This type of anemometers detect the sound’s phase shifting or the reflected coherent light of air molecules. Furthermore, the Hot Wire detects the wind speed through temperature differences of wires placed in wind shade and wires placed in the wind.

It is advised to use non-mechanical anemometers for their poor sensitivity to ice. However, in practice the mechanical ones are the most used.

Wind Energy Measurements

Anemometers measure wind energy. In fact, their price may differ in the market. Cheap Anemometers can be Ok for meteorology however they are very inaccurate with measurement error ranging from 5 to 10 %. This can lead to an economic disaster as the user can risk counting an energy 1.13 - 1 = 33% higher than it is in reality. This percentage increase to 75% if we take into account the differences of wind turbine hub height.

Therefore, it is advised to use professional anemometer with an error around 1% for a price ranging between 700 and 900USD.

The best way to place the anemometer for an accurate wind speed measurement is at the top of a mast with the same hub height of the used wind turbine. It will minimize the airflows related disturbances and avoid the uncertainty of different wind speeds in different heights

27 Types of Tower

Wind Turbine Towers may vary. They can be guyed thin cylindrical or lattice. It is preferred to have thin cylindrical poles in order to limit the wind shade from the tower.

Poles are considered easy assembled kits than can be installed to measure wind at the turbine hub height without canes. Therefore, the anemometer, data logger and pole will cost about 5000 USD.

Data Logging

Wind speed and directions data are collected on electronic chips from an anemometer. Once a month the chips must be collected and replaced with blank chips to collect the data of following month.[5]

Innovations in wind technology

In recent years, advances in wind technology have focused on the sophistication of wind turbines to make them more adaptable to different weather conditions and increase their productivity. Design aspects have also been taken into account to facilitate assembly and make them more accessible for maintenance. The advantages and numbers of the wind continue to draw attention to the innovation and technology sector and new projects are emerging, some already in operation, which are bringing significant improvements in power generation.

Larger and articulated shovels

One of the aspects that is being worked on to increase the power of wind turbines is the magnitude of the blades. One of the most recent proposals is the one presented by researchers from the University of Virginia and the Sandia National Laboratory, in the United States, who are working on a 200-meter-long blade that could make possible the creation of 50 MW turbines. that would suppose a substantial increase in comparison with the current power that situates approximately in 8 MW in shovels of until 84 meters in length. The expansion of the size of the

28 blades has a clearly economic reason, since the more diameter the rotor has, the more energy a wind turbine can generate, that is, the longer the blades the more the cost of electricity will be reduced. The placement of these large blades is a great challenge at the logistics level: how to transport the blades to the facilities and how to build the wind towers with cranes of insufficient size? In spite of everything, there are already companies that dedicate their efforts to innovate in this area in order to build towers of up to 400 meters, such as "climbing cranes". In addition to larger blades, another concept is being developed, that of Eric Loth, mechanical and aeronautical engineer, who is committed to articulating the blades, which would allow them to fold according to the force of the wind: under optimum conditions they would remain open and close in cases of extreme wind.

Maximum efficiency with little wind

Another aspect that is intended to improve is the use of medium and low wind in areas where conditions are not optimal for the development of wind energy. One of the pioneering companies in this field is Siemens, which in the last year has developed a wind turbine with a rotor of 120 meters and a blade of 59 meters long. Both the blades, of reduced weight in comparison with the conventional models, like the train of power, are optimized to generate the maximum energy in conditions of not favorable winds. These machines get good results in terms of profitability and also in terms of reducing the level price of energy. In addition, the new designs seek better accessibility to key components, such as access to the weather station from inside the gondola.

Magnets to increase power

The advances in the field of wind technology are focused, above all, on improving the capacity to produce energy and, in this sense, one option is magnets. The Haliade wind turbine, developed by Alstom Wind (now General Electric), is the first to be developed by the company, which has permanent magnets, 6 MW and 73.5 meters long blades. The system available is direct drive and have fewer components, which increases the reliability of the equipment and also its energy efficiency, since it can produce up to 15% more electricity than other turbines of its generation, reaching 5,000 households . These machines, designed to be installed in offshore wind farms,

29 will be installed in three future French offshore wind farms (Saint-Nazaire, Courseulles-sur- Mer and Fécamp) and will soon be installed in the first offshore in the United States, in Block Island.[6}

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Chapter 4: Design and Manufacturing of small wind turbine

Environmental Impact and a research on No-Tower-needed wind turbines:

Since fossil fuel energies are usually accompanied with the release C02 emissions which are harmful to the environment, and since fossil are decreasing and their price is increasing, it is important to find alternatives which come from clean sources, such as, wind, sun, and sea.

In the east of Morocco, especially, in the regions next the high atlas, middle atlas, and Anti-Atlas do not benefit from electricity. Then, usually villages in these regions suffer from extreme weather conditions which affect their health and prevent them from going to schools. Moreover, they do not benefit from technologies such as computers. Also, though current wind turbines are considered to be green they have a negative impact on the environment including CO2 emissions in the manufacturing process and the alteration of the structure of ecosystems.

This research emphases on the potential benefits of Airborne Wind Energy in rural areas in the east of Morocco next to the Atlas mountains ,their positive impact on the environment, as well as on the aerodynamics and performance of the Airborne Wind Turbine. This research does neither include a structural analysis of the Airborne Wind Turbine nor an analysis of the control systems of the latter. These analyses will be left for future research.

If fossil fuels are to be compared with wind energy generation, wind energy generation will be found more sustainable, since does not contribute harmful emissions to the atmosphere, nor waste products and materials required to manufacture the systems.Then, because wind energy is generated at high altitudes in a vast space and in conditions in which high power densities are available when compared to ground-based wind generation, there is a high potential that land footprint will be very small.

Furthermore, according to the American Wind Energy association, in 2008 manufacturers in the United States had installed more than 5,000 utility scale wind turbines, which

31 had required more than 1,1 million metric tons of iron and steel, 920,000 cubic meters of concrete, 2,4 million steel bolts, and 43,000 kilometers of reinforced steel rebar.[7]

Also, a tower, including the concrete base, is considered to represent 30 to 65% of the overall weight of the wind turbine.

Moreover, in order to reach higher altitudes for more power densities, longer and stronger supports need to be built, hence, more material will be needed. Furthermore, in order to manufacture 1 ton of steel in a ballast route 2 tons of CO2 emission are released. [3]

And knowing that in 2016 1,470 thousands of metric tons were used in the US in order to build wind turbines one can notice how large the amount of CO2 that was emitted. And this is without accounting for CO2 emission coming from transportation and the building of factories. It is also important to account for the effect of the CO2 emission from the production of concrete.

It was reported that the manufacturing of concrete contributes greenhouse gases by generating carbon dioxide while the thermal decomposition of calcium carbonate and carbon dioxide, and by using the energy coming from the combustion of fossil fuels. On average, 900 kg of CO2 are emitted for the production of 1 ton of cement.

Thus, we can clearly notice that the amount of CO2 that is released in the manufacturing conventional wind turbines is huge. It is also reported that huge wind turbines have an energy payback of less than 6 months and a carbon dioxide payback of around 6 months. Nevertheless, this does not account for the instant and immediate consequences of CO2 emissions such as the alteration of ecosystem structures the destruction of wildlife habitat, and the killing of birds.

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Figure 14: Wind Speed In Europe

From this Figure we can clearly notice that in Europe wind speeds increases as we go higher ,and this is explained by the no-slip condition, that is, when the winds gets in contact with the ground their velocities approaches to 0 m/s .And the further the wind is from the ground the higher the velocities are. It is also important to mention that this phenomenon does not happen only in Europe but also in all over the world. And the relationship between the power and velocity is

(1)

Where ρ is the air density A is the cross-sectional area of the wind being considered, and U is the wind speed. Moreover, the equation clarifies that the wind speeds are critical to the amount of power that is generated, since wind velocity is cubed.

According to this chart the wind velocities at 10 m above the ground in the eastern region of Morocco is 2.5 m/s. And the following equation can help in the approximation of wind velocities at different altitudes:

Where

33    V: the speed to the height H.    v0: the speed to the height H0 (10-metre height).   α: the friction coefficient or Hellman exponent (0.2).

Solving for V, the he velocity wind speed at 700 m is .

And to determine the density at 700 m, 273.15 K (room temperature), and P=98.53KPa (pressure at 700 m):

Where

   ρ: Density )    M air: Molar mass (kg/mol)    P: pressure in (Pa)    R u: Universal constant (J/mol-K)   T: temperature (K)

The calculation gives is .

Then the speed of sound Vs at 700m where the density is and the temperature is

Moreover the dynamic viscosity is

Where    μ: Dynamic Viscosity.    μ0: Reference Air Viscosity kg/ (m-s).   T: Temperature (K).

After calculation, this is the following result μ =

After defining the characteristics of the system location and the atmosphere, the amount of energy in the wind can be estimated. 34

Design parameters of the Airborne Wind turbine.

This system is to provide 35 kW of electricity, and based on this a wind turbine will be designed. Also, it is important to mention that the wind turbine will be inside a helium balloon, and its inside will be in the form of a Venturi tube in order to accelerate the wind inside.

First, let’s determine the wind velocity in the middle of Venturi tube, using Bernoulli’s equation:

Where    P: Pressure (Pa).    ρ: Density .    V in: Velocity at the entrance of the Venturi tube (5.847 m/s).    R in: radius of the entrance of the Venturi tube (5.55 m).   R out: Radius in the middle of the Venturi tube (3.25 m).

Where   Vout: Velocity in the middle of the venture tube.

In addition, the Mach number and the Reynolds’s number should be determined.

35

Where

Ma: Mach number.

V out: Velocity inside the venture tube (17.05).

Vs: Speed of sound at 700 m altitude.

Solving for Ma yields = 0.053.

And the Reynolds’s number is found by using the following equation:

Where    Re: Reynolds’s number.    l:Chord length (m).    V out: Velocity in the middle of the venture tube (m/s).   μ: .

And the result is 179876.99.

Now that we have the velocity that the wind turbine will be subjected to we need to determine the wind turbine characteristics. We determine the radius that we need based on the power and the wind velocity that was calculated.

Where    Power: Power generated by the wind turbine (W).    Cp: the coefficient of performance (0.42).    V out: The velocity that hits the turbine (m/q).   A: area swept by the blade ( ) ( ). 36 When solving for the radius r the equation yields r = 2.7538 m.

In order to design a wind turbine that captures most of the kinetic energy, the best angle of attack, the highest lift to drag ratio and the corresponding, drag coefficient, lift coefficient and the twist angle should be determined.

Continuing by uploading an airfoil model with its specific coordinates in Q-blade Software, then, simulating in it to find out the best angle of attack of attack and the highest lift to drag ratio (Cl/Cd).

The results were tabulated and the highest lift to drag ratio was determined and the corresponding values are:    Angle of attack (Ω): 5.5°    Cl: 1.2344.    Cd: 0.0138.   Cl /Cd: 93.797.

The next step was to divide the blade on 20 parts where the first part is the hub and the root of the blade, and they are 0.45 m, and the remaining is divided on 19 (2.7538/19 = 0.122m).

And for each section of the blade we calculate the wind speed ratio, cord length, angle of attack, and the twist angle. And to do this, equations from blade optimum rotor theory are used:

37 Design Using Computer Software:

For the importance of the wind energy and the efficiency of wind turbines to create electricity with less time and less means. The study helped me illustrate all the steps needed. I came up with a conclusion of how to make your own wind turbine and get some energy out of it. At first you collect all the data needed, such as wind speed, destinations of restrictions and a lot of other factors that will be tackled in this chapter. In the section of the software design I used SolidWorks program for its beneficial characteristics to show the geometric facial of the tower. The process started with making some calculations of the trusses and loads that could be on held on the tower, and resulted in the right three dimensions that represent the different parts of our tower (the top, the bottom and the middle). [8]

First step was to check for all the requirement and parapets that are needed for the designing the tower on SOLIDWORKs.

Tower Analysis:

The three pervious thicknesses are implemented above in the analysis.

Inputs

Top Diameter (m)

Bottom Diameter (m)

Max Velocity (m/s)

The number of blades(Thrust)

Height (m2)

Turbine Mass (Kg)

Output:

Horizontal Force

Maximum Stress

Top Deflection

38

Figure 15: an Example of the Design

The project Prototype:

Energy production has always been essential to ensure a good quality of life within a society. Saying that, renewable energy technologies offer the possibility of clean and abundant energy, wherefrom wind turbine technology arises as a quite remarkable one.

On many sites around the world, the presence of wind turbine farms is increasing dramatically. However, the wind turbines implemented are usually of conventional design which comes with a lot of disadvantages. For instance, the horizontal axis wind turbines are relying on wind direction to which the blades should be facing for energy generation. Second, these conventional wind turbines are not suitable for turbulent and gusty winds. Last but not least, these traditional wind turbines have a high installation price and maintenance cost due to gearbox failures. Consequently, the best way to tackle all of these issues and enhance the efficiency is to simply change the design of the wind turbine. Saying that, wind turbines in general are suspected to pose threat to human health and wildlife. [1] Therefore, it is wise to put them offshore for maximum precaution.

39

State of the Art

Naturally, wind turbine projects cost a lot of money. Therefore, it is always wiser to start by making a smaller prototype with the same characteristics, due to the scalability of fluids. Consequently, there will be a possibility to conduct efficiency tests repeatedly and at a very low cost. On the other hand, the production of small scale wind turbine would be difficult if conventional methods were to be used. A set of constraints will make the process unpleasant. For example, the production will be difficult-to-machine especially if the material used is metallic. Furthermore, conventional methods will make the designer’s choices less flexible which would be a serious restriction in the case of fabricating a small wind turbine. Moreover, the traditional methods will be relatively slow since they produce one piece at a time. [9]

In other words, steps of production such as machining, joining and assembly would be essential. Consequently, it will require more time to gather the different pieces. In addition to that, repairing any damages which occurred during the production of the prototype would not be possible.

Methodology

Design aspects

The prototype of the small wind turbine has three main parts. On the top, small well shaped Three blades. Extracted from a hollow structure to minimum materials. This is estimated to improve both efficiency and cost effectiveness. Second is the generator of energy It is fixed in a third part to achieve easy movement and thus higher efficiency. The body consists of a Jhonson Wheel, a Dynamo attached to a smaller wheel and a bicycle chain. Concerning the lower part, we tried to make it as simple and supportive as possible. Metal stand with a one-meter high. This prototype is in fact a miniature simulation of real life application and therefore its functioning properties must be tested as well. Therefore, the design should consider the material cost, the possibility of rotation of the wheels. And the efficiency of blades movement. [10]

Materials for prototype

40 for this project, the main focus is to create a small homemade wind turbine prototype to confirm the properties of a full sized wind turbine. These properties must necessarily include both the movements of the blades due to air and the generator rotation of the whole product. Consequently, choose steel and plastic to monitor our material series As They are more appropriate for the generation of such prototypes which will not be exposed to thermal and/or excessive mechanical stress. Besides being a first choice for prototyping, steel and plastic used is an eco-friendly thermoplastic as well. This material also ensures great stability and a fairly acceptable surface quality compared to other polymers.

Figure 16: Wheel inspired from Johnson Wheel

Figure 17: Dynamo used with the wheel Figure 18: Dynamo Used

Process selection

41

The process selected for this project is material gathering. Consequently, the shape and size of the final product is determined after the relative calculations of the height, weight and mechanism.

Figure 19: Blades fabrication

Discussion

The objective of this project was to produce a prototype for a small homemade wind turbine. We tried to come up with a fairly efficient design, optimal support structure and manufacturing conditions. On that account, a close attention was given to the orientation of the forging which affects the removability of the support structure. As a matter of fact, the team struggled with joining the final product of the upper part, as it failed during the first couple of times due to difficulties when forging a big structure vertically.

Concerning the first Trial , it was not successful as the main issue was finding the right wheels and the other metal materials, as a result it was a time consuming till we figured out the right sizes and fixed them fit just as will. Moreover, the second trial was indeed better but there were

42 still some misalignments on the blades which could not be tolerated. By the end, we decided to change the orientation of the printing which gave it a better result. Furthermore, we tried to smooth the surface of the blades to make the movement easier when it will be in contact with the lower part. This surface texture improvement was actually necessary for both aesthetic and functional purposes.

On the other hand, the lower part was relatively easy to deal with. First, it was designed to not need a support structure. This allowed us to save time in the post processing. Nevertheless, there was a problem concerning a big screw that will gather whole parts together. It was very hard to find. the final component.

Finally, parts were assembled all together and checked for functioning and blades movement. Due to the surface roughness of the pole and the dimensions of it, it was not possible to achieve free rotation for the final upper part product.

Additive manufacturing became a fast growing sector during the past few years. One application of additive manufacturing is the production of prototypes as one piece and with little effort integrate functional parts and create more complex products. Consequently, less material is used with less effort and less cost. The resulting additive manufactured wind turbine was a partial success. In parallel to the purposes of the project, the wind turbine prototype seemed to succeed perfectly in one task which was the rotation of the wheels of the prototype.

The upper part blades moved with difficulty due to the diameter of the pole and the blades deformations. In conclusion, such designs can ultimately allow conducting tests and simulate conditions that might face real life scale wind turbines and therefore might save time, effort and money.

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Figure 20 : The Final Result of the prototype

44

Cost Characterizations

Wind tower is an essential component for the wind turbine system. Improvements in wind turbine system have led to acceleration in reaching the acceptable capacity of a single wind turbine. However, it will decrease the total number of towers installed in the near future due to the increased total annual capacity during this period. Naturally, the growth of the installed capacity of the wind turbines is highly dependent on the growth of the wind turbine industry. Sometimes it’s impacted by the total power demand, supply uncertainties, governmental policies and the fluctuations of energy price that are dependent on oil or natural gas.

The major wind energy market includes China, USA, UK, and Germany, Canada that is about 90% of the global wind turbine market. Same statistics applies for the towers market in which these countries have the highest demands of tower installations. However, Denmark and Netherlands are playing a major role in manufacturing wind turbines to be exported to EU market and North America market.

45 Conclusion

In my project I have done a research of wind turbines and their . I have worked on the understanding, analyzing and comparing different types and materials the towers that are used in the wind turbine. Steel was one of the most important materials used in the whole turbine. After understanding the mechanism and the design, I have tried to make my own design in Solidworks program. Where I linked with my old MALAB program where I can plug the data I needed for the three parts of the tower, the top, the bottom and the middle part. I took the height and the diameter of the three parts and tried to design them is Solidworks. The design of the tower was very simple and it had three assembled parts. After the design, I worked on the prototype of a wind turbine with my teammate Rayhane. The prototype took a lot of time in terms of assembling the part and choosing the right material. Finally, we spent a week trying to connect the electrical circuit and make it work along with the mechanism of the turbine. I have understood more while actually making the prototype, it was more efficient than the research I made about wind turbines and their towers. In my Innovative section, I came up with an idea for the rural areas in the Atlas Mountains in Morocco. Since I have studied all the results of the towers and how a big of a procedure they are. I found that Airborne Wind Turbines which has no towers are going to be the best solution to maintain in the areas of my study. It will customize the costs of the installation the manufacturing and the design of the huge towers.

46 References

[1] Troy L. Cahoon1 and Frederick G. Harmon2, "Airborne Wind Energy: Implementation and Design for the U.S. Air Force," in enu.kz/. [Online]. Available: http://enu.kz/repository/2011/AIAA-2011-6154.pdf. Accessed: Nov. 28, 2016.

[2] "Wind Energy in the United States and Materials required for the Land-Based Wind Turbine Industry from 2010 Through 2030," in pubs.usgs. [Online]. Available:https://pubs.usgs.gov/sir/2011/5036/sir2011-5036.pdf. Accessed: Nov. 27, 2016.

[3] ULCOS, "CCS for iron and steel production," in globalccsinstitute,2013.[Online].Available:https://www.globalccsinstitute.com/insights/authors/d ennisvanpuyvelde/2013/08/23/ccs-iron-and-steel-production. Accessed: Nov. 28, 2016.

[4] Michael A. Nisbet Medgar L. Marceau, and Martha G. VanGeem, "Environmental Life Cycle Inventory of Portland Cement Concrete," in nrmca,

2002.[Online].Available:http://www.nrmca.org/taskforce/item_2_talkingpoints/sustainability/sus tainability/sn2137a.pdf. Accessed: Nov. 27, 2016.

[5] J. Glennie, "Carbon and energy payback of a wind turbine," SaskWind, 2016. [Online]. Available: https://www.saskwind.ca/blogbackend/2016/1/14/carbon-and-energy-payback-of-a- wind-turbine. Accessed: Nov. 7, 2016.

[6] "Environmental Impacts of Wind-Energy Projects," in nap,2007.[Online].Available:https://www.nap.edu/read/11935/chapter/5#90.Accessed:Nov.27, 2016.

[7]Christin Gear , "Estimating the carbon footprint of a fabric," in oecotextiles,oecotextiles, 2011. [Online].Available:https://oecotextiles.wordpress.com/

[8] IEC 61400-1, International Standard, Wind Turbines – Part 1: Design Requirements, Third Edition, 2005.

[9] ASCE 7-05, Minimum Design Loads for Buildings and Other Structures, Chapter 6: Wind Loads, 2005.

[10] Ishihara, T. and Sarwar, M.W., Numerical and Theoretical Study on Seismic Response of Wind Turbines, 2008.

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