PRESENTATION ON WIND ENERGY Application and Types & Design Principle of Wind Mills by

1. PRESENTATION ON WIND ENERGY Application and Types & Design Principle of Wind Mills by Dr. R.P. Saini Alternate Hydro Energy Centre Indian Institute of Technology Roorkee

2. Wind power is of course a form of Solar Power or ‘Solar Related Power’. The winds on earth surface are caused primarily by the unequal heating of the land and water by the sun. The differences in temperature gradients induces the circulation of air from on zone to another. The power in the blowing wind can be tapped and utilised. It has been estimated that roughly 10 millions Megawatts of energy are continuously available in the earth winds. In India the interest in the wind energy was shown in the last fifties and early sixties. An important reason for this lack of interest in wind energy must be that wind, in India are relatively low and very appreciable with the season.

3. In India wind speed values lies between 5km/hr to 15-20 km/hr. These low and seasonal winds imply a high cost of exploitation of wind energy. Calculation based on the performance of a typical wind mill have indicated that a unit of energy derived from a wind mill will be atleast several times more expensive then energy derived from electric distribution lines at the standard rates, provided such electrical energy is at available at the wind mill site.

4. Power from Wind : ‘Wind mill’ is the system which converts the wind energy into useful form of energy. The wind mill works on the principle of converting kinetic energy of the wind to mechanical energy. We know that the kinetic energy of a particle is ; K.E. = ½ mv2 - (1) Where, m is the mass of air.  The volume of air passing in unit time through an area of ‘A’ with velocity V and is the density of air.  m = ρAV  Substituting this in equation (1)  K.E. = ½ ρ AV3

5. This is the energy from air which we can tap. It is not possible to convert at the wind energy into another form of energy become the load would reduce the wind speed through the generator to zero. They stopping the machine. It is calculated theoretically consideration that the maximum conversion rate is 0.593 of the energy of the wind. Wind power is given by the following expression ; P = ½ ρ AV3 Cp Where, Cp = power coefficient   Energy available = (--------------------- ) Energy input The fraction of the available energy that is converted is called the power coefficient.

6. The factors which affects the nature of the wind close to the surface of the earth they are ; Latitude of the place. Altitude of the place. Topography of the place. Scale of the hour, month or year. The wind flow in the atmosphere is also improved by some other parameters. The best site at off shore and on the sea coast. The second best sites are in mountains. The lowest level of the wind energy is found in plains.

7. Advantages : • It is a renewable source of energy. • Like solar energy, wind power system are non-polluting. • On a small scale, upto a few kilowatts system is less costly. On a large scale costs can be competitive with conventional electricity and lower cost can be achieved by mass production. • Disadvantages : • Wind energy available in dilute and fluctuating in nature. • It requires storage capacity because of its irregularity. • These systems are noisy in operation a large unit can be heard many kilometers away. • Wind power systems have a very relatively high overall weight. • Large area are needed.

8. TYPES OF WIND MILLS A wind mill is a machine for wind energy conversion. A wind machine is a device that converts wind energy i.e. kinetic energy of wind motion to mechanical energy transmitted by the shaft. Wind machines are generally classified in terms of the orientation of the axis of rotation of their rotors as horizontal axis machines and vertical axis machines. In a horizontal axis machine, the rotor axis is horizontal can be adjusted so that it is parallel to the direction of the wind stream. On the other hand, in a vertical axis machine, the rotor axis is vertical and fixed, and is perpendicular to both the surface of the earth and the wind stream. Wind mills are generally classified as ; Horizontal axis type. Vertical axis type.

9. Horizontal Axis Type : For which the axis of rotation is parallel to the direction of the wind stream. Horizontal axis wind mill further classified as single blade, double blade and multi blades types. Vertical Axis Type : This is the simplest of the modern types of wind mill which works like a cup anemometer. This machine has become popular since it requires relatively low velocity winds for operation.

10. Rotors : Various types of rotors used in wind machines are (i) multi-blade type, (ii) propeller type, (iii) Savonius type, and (iv) Darrieus type. The first two are used in horizontal axis machines, and the last two in vertical axis machines. The multi-blades rotor consists of a number of curved sheet metal blades which increase in width going outwards from the centre. The number of blades usually ranges from 12 to 20. They are fixed at their inner end to a circular rim. They are also fixed near their outer edge to a second rim, which provides support. The diameter of the rotor usually ranges from 2 to 5 m. In contrast to a multi-blade rotor, the propeller rotor consists of only two or three blades made from glassfibre reinforced plastic. The blades have aerofoil sections with a high thickness-to-chord ratio and yield a high lift relative to the drag. The diameter of the rotor usually ranges from 2 to 25 m. The Savonius rotor consists essentially of a hollow cylinder (approximately elliptical in shape) sliced in half, the two halves being fixed to a vertical axis with a gap in between to make an S-shape. Torque is produced by the pressure difference between the two sides of the half facing the wind.

11. Various Types of Wind Machine Rotors

12. Multi-blade Type Wind Machine : A simplified sketch of a multi-blade type wind machine is shown in Fig. the main elements are the rotor, the wind mill head (casing), the tail vane, the transmission system and the the supporting structure (tower). The machine is normally used for pumping water. For this reason, an additional component at the base of the tower is a water pump. The rotor overhangs at one end of the shaft emerging from the wind mill head. The centre of the rotor is referred to as the hub. Just behind it is the front bearing of the machine. The transmission system consists of a power shaft, a speed reducing gear drive, a crank shaft-connecting rod mechanism and a pump rod. The gear drive reduces the rotational speed by a factor of 3 or 4. The rotational motion is then converted to a reciprocating motion by the crank shaft-connecting rod mechanism which in turn is connected by means of the pump rod to the water pump. The pump rod passes through the base of the wind mill head which sits on a ball-bearing turn table. The tail vane, a simple shape cut from sheet metal, is attached to the back side of the wind mill head. It serves the purpose of aligning the rotor withe the direction of the wind. The tower is usually a steel truss construction. It serves the purpose of keeping the rotor and the wind mill head at an appropriate height from the ground where the wind speed is adequate.

13. Multi-blade Type Wind Machine

14. Propeller Type Wind Machine : A sketch of a propeller type wind machine is shown in Fig. The machine is normally used for generating electricity, capacities ranging from a fraction of a kilowatt to a few hundred kilowatts being available. The main elements of the machine as seen from the outside are the rotor, the nacelle and the tower. The power extracted from the wind by the blades is transmitted through the hub to a gear train and then onto a generator and housed inside the nacelle. The nacelle also houses various control systems. These include the braking mechanism and the roller assembly permits rotation of the nacelle about a vertical axis and helps to align the rotor with the direction of the wind. This design is usually adopted for large capacity machines. In some cases, the diameter is large enough to permit ascent through an internal staircase. For small capacity machines, a steel truss design is used.

15. Propeller Type Wind Machine

16. Performances of Wind Mill It is important to note that the convertible power of energy is proportional to the cube of the wind speed. i.e. Power = ½ x e x Cp x A x ρ x v3 Where, e = efficiency of the blade. Cp = conversion factor. A = area swept out by the blades. V = wind velocity. ρ = density of air. The efficiency of a wind generator depends upon the design of a wind rotor and the rotation speed expressed as the ratio of blades tip speed to wind speed.   Blade tip speed Tip Speed Ratio (TSR) = -------------------------- Wind speed The term tip-speed-ratio will be used instead of rotor rpm to help for compare different rotor.

17. For any given wind speed, higher rpm means higher TSR. If the tip is travelling at 100 mpH in a 20 mpH, the TSR = 5. Typical values of TSR range from 1 to 15. By using the TSR we can ignore the rotor rpm and diameter, and consider rotor performance in a more generalised discussion. If we know the wind speed, the rotor diameter and its operating RPM you can calculate the TSR, or speed ratio (SR) at any fixed radius between the centre of rotation and the tip. 2 π r N Speed ration = ---------------- 60 V

18. Power Coefficient : Energy available Cp = -------------------------- Energy input Fraction of the available energy that is converted is called the power coefficient. The power coefficient of an ideal wind machine rotor varies with TSR and approaches maximum value of 0.59 where TSR reaches, a value of 5 or 6 two blades 0.47 Other design have approx about 0.35.

20. WIND POWER IN INDIA 1.Ranks 4th in the world. 2.Wind power potential of 46,500 MW. 3.Installed capacity of 7082 MW 4.Major work carried out by “Centre For Wind Energy Technology”. (Established in 1998) 5. In India the cost of wind energy varies from Rs 4.10/kWh to Rs 3.60/kWh

21. Wind Power In India… • There are approximately 10500 WEG installed all over the country which are owned by private players. Whereas the total numbers of WEG owned by the government is approximately 400.

22. WIND POWER DENSITY MAP

23. STATEWISE INSTALLED CAPACITY (SOURCE IWEA)

24. WIND POWER IN WORLD • Worldwide installed capacity of wind power is 78,728 MW • The first five countries are (i) Germany (20,952 MW) (ii) Spain (12,500 MW) (iii) USA (12,376 MW) (iv) India (10500 MW) and (v) Denmark (3136 MW)

25. World Wind Energy Resource (Map prepared by US –DOE in 1985)

26. WIND ENERGY FARM 1.It is a collection of wind turbines in the same location. 2.Individual turbines are connected to a medium voltage collection system. 3.Production varies with the wind. 4.Power produced by wind turbines is stepped up with a transformer to a high voltage transmission system.

27. TYPES OF WIND ENERGY FARM 1.Onshore wind farm. 2.Nearshore wind farm 3.Offshore wind farm.

28. ONSHORE WIND FARMS 1.Turbine installations on hilly and mountainous region or plain areas. 2.Attention must be paid to the exact position of the turbines. 3.Local winds are monitored for a year or more before wind generators are installed. 4.Easy operation and maintenance.

29. ONSHORE WINDFARMS Wind energy farm in Mupandal ,Tamil Nadu.

30. NEAR SHORE WINDFARM 1. This type of wind farm may share land and water . 2. Sea shores tend to be windy and good for turbine installations because primary source of wind is due to differential heating and cooling of land and sea over the course of day and night. 3. Winds at the sea level carry more energy than winds of the same speed in mountainous areas because the air at sea level is denser.

31. NEAR SHORE WINDFARM Mandvi, Gujarat

32. OFFSHORE WINDFARM 1.These are generally more than10 km away from the land. 2.It is most expensive as compared to onshore and near shore windfarm. 3.Power is transmitted by the turbines through undersea cables. 4.Difficult to operate and maintain.

33. OFFSHORE WINDFARM(Horns Rev ,Denmark)

34. COMPONENTS OF WINDFARM 1. The wind turbine. • Electrical network. 1. COMPONENTS OF WIND TURBINE. (i) The transmission system. (ii) The generator. (iii) Control and safety systems. (iv) Wind turbine tower.

35. COMPONENTS OF WIND TURBINE

36. The Generator • Two basic types of generators are used for the WTGS. These are synchronous and asynchronous Wind turbines may be designed with either synchronous or asynchronous generators, and with various forms of direct or indirect grid connection of the generator. • Direct grid connection mean that the generator is connected directly to the (usually 3-phase) alternating current grid. • Indirect grid connection means that the current from the turbine passes through a series of electric devices which adjust the current to match that of the grid. With an asynchronous generator this occurs automatically.

37. WIND TURBINE TOWERS ● The tower of the wind turbine carries the nacelle and the rotor. ●The price of a tower for a wind turbine is generally around 20 per cent of the total price of the turbine. Types of wind turbine towers (i)Tubular steel towers (ii) Lattice towers (iii) Guyed pole towers (iv) Hybrid towers

38. Tubular steel towers Most large wind turbines are delivered with tubular steel towers, which are manufactured in sections of 20-30 meters with flanges at either end, and bolted together on the site. The towers are conical (i.e. with their diameter increasing towards the base) in order to increase their strength and to save materials at the same time. Wind Turbine Tower…

39. Lattice towers Lattice towers are manufactured using welded steel profiles. The basic advantage of lattice towers is cost, since a lattice tower requires only half as much material as a freely standing tubular tower with a similar stiffness Wind Turbine Towers…

40. Guyed pole towers Many small wind turbines are built with narrow pole towers supported by guy wires. The advantage is weight savings, and thus cost. The disadvantages are difficult access around the towers which make them less suitable in farm areas. Wind Turbine Towers…

41. Hybrid towers Some towers are made in different combinations of the various towers tower which you see in the figure which may be said to be a hybrid between a lattice tower and a guyed tower. Wind Turbine Tower..

42. COSTS ASSOCIATED WITH THE WIND FARM The costs associated for installing a windfarm can be grouped into the following categories (i) Turbine (ii) Electrical (iii) Fixed • Auxiliary (i) Turbine costs Turbine costs include the following: (i) Purchase price of the turbine (ii) Shipping (iii) Import duty (for imported turbines) (iv) Concrete and other foundation costs (v) Labor (vi) Circuit Breaker CB

43. (ii) Electrical cost • Electrical costs includes the following (i) Transformers (ii) Conductors (iii) Trench • Trench is for the conductors to be placed underground which connects the generator to the transformer. (iii) Fixed costs Fixed costs are those costs which are not strongly sensitive to the size of the windfarm, such as buildings and legal documents. We include the following in this category

44. Fixed costs (i) Permits: These are required and granted by local government agencies. (ii)Zoning: Agricultural land will probably need to be rezoned to industrial use (or other category) before a permit can be granted. (iii)Wind Study: Wind speeds need to be measured at the proposed site for an appropriate amount of time (uptoto a year) before a decision is made to build a windfarm. (iv Power Purchase Agreement: This would include the engineering and legal fees incurred in writing an agreement with the utility buying the electricity produced by the windfarm.

45. Fixed Costs… (v)Engineering Design: A Professional Engineer must perform a detailed design for the windfarm and prepare a set of plans which can be used for construction. This would include the electrical design plus the soil tests, earthwork, and footings necessary for long operation of the windfarm. (vi)Control Building: Each windfarm will have a building or portion of a building to house the computers, meters, controls, and maintenance personnel. The computers (if not the maintenance personnel) will require this space to be clean and climate controlled.

46. Fixed costs… (vii) Maintenance Building: This would be a building or portion of a building where maintenance and repair operations are conducted. It should be large enough to house the largest item which might be repaired. It may need an overhead crane to lift and move parts. This may be a final assembly building during construction, where tower pieces are connected together, the blades are bolted to the hub, etc. (viii) Visitors Center: This might be a part of the Control Building or it might be a totally separate facility. Careful attention should be given to this requirement for the first few windfarms in a given part of the country so that visitors can be properly cared for. (ix)Meteorological Tower:This would be a tower located near the Control Building with anemometers at several heights. Wind speed data would be used for monitoring wind turbine performance and such tasks as starting turbines after low wind conditions and stopping them in high wind conditions.

47. (iv) Auxiliary costs • Auxiliary costs are those costs which are related to construction, which vary with the size of the windfarm or the type of the turbines They include: (i) Land: It is probably not feasible to use the land in a windfarm for any purpose other than grazing, and that would probably not be worth the nuisance of keeping gates closed, so it will probably be necessary to purchase the land for the windfarm. (ii) Access Roads: Gravel roads are needed within the site so the turbines can be repaired in good weather. A road is also needed from the site to the nearest all weather road. This could be substantial expense in remote or mountainous regions. (iii) Grading: There may be earthwork necessary besides building roads and parking lots. Sharp peaks or gullies may affect the wind flow enough to justify some earth leveling activity.

48. Auxiliary costs… (iv) Vehicles: A windfarm will probably require one or two pickup trucks and a larger truck for moving large components around the site. (v) Crane: Windfarms with turbines that tilt over on a hinged base will not require a crane, but a crane would be very desirable for turbines that do not tilt over . A crane can always be rented, but the extensive use of such a machine on a windfarm could easily justify its purchase. (vi) Fence: A windfarm in grazing land would require a barbed wire fence to keep cattle out. Depending on population densities and insurance requirements, it may be necessary to build a fence to keep people out of the windfarm area. Such a fence would need to be minimum six feet

49. Feasibility Analysis Of Wind Farm • For economic viability of the project following factors are considered. • Sites with annual mean wind speed of 5.5 m/s with a hub height of 30 m and power density of 150 watts /sq.m is considered to be economically viable. • Nearest load centre and nearest distance from the grid. • Availability of basic infrastructure such as roads and other aspects such as (iv) Cost of land, safety considerations and Meteorological hazards.

50. Economic Viability Of Wind Power Project The important deciding parameters to judge whether the plant is economically viable or not are as follows. (i) Payback period should be less than loan repayment period. (ii) Net present value (NPV) >1. (iii ) Internal rate of return (IRR) >1. (iv) Benefit cost ratio (BCR) >1.