Generation Of Electricity From Wind Power(project)

Generation of Electricity from Wind Power

GENERATION OF ELECTRICITY FROM WIND POWER 1. Introduction :Wind results from air in motion. Air in motion arises from a pressure gradient.

Wind can be proadly classified as “planetary” & “local”. Planetary

winds are caused by greater solar heating of the earth`s surface near the equator than near the northern or southern poles. This cause warm tropical air to rise and flow through the upper atmosphere towards the poles & cold air from the poles to flow back to the equator nearer to earth’s surface. The direction of motion of planetary winds with respect to the earth is affected by the rotation of the earth. The wam air moving toward the poles in the upper atmosphere assumes an easterly direction that results in prevailing westerlies.

The westerlies controls events

between the 300 & 600 latitudes. Because the earth`s axis is inclined to its orbital plane around the sun. Local winds are caused by two mechanisms.

The first is

differential heating of land & water. So far insulation during the day is readily converted to sensible energy of the land surface but is partly absorbed in layers below the water surface and partly consumed in evaporating some of that water. This is the mechanism of shore breezes. At night, the direction of the breezes is reversed because the land mass cods to the sky more rapidly than the water assuming the clear sky. The second mechanism of local wind is caused by bills & mountain sides. The air above the slop side heats up during the days & cools

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Generation of Electricity from Wind Power down at night, move rapidly than the air above the low lands. This causes heated air during the day to rise along the slopes & relatively cool heavy air to flow down at night. In India the interest in the wind mills was shown in the last fifties & sixties. An wind, in India are relatively low and very appreciably with the seasons. Data quoted by some scientists that for India wind speed value lies between 5 km/hr to 15-20 km/hr.

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Generation of Electricity from Wind Power

2. History of wind power Human beings have always dreamt of converting wind power to mechanical &, more recently, electric power.

Wind, more than any other

renewable energy source, has intrigued serious and amateur inventors over the ages, it is said that more patents for wind system have been applied for than almost any other device to date. In ancient times the kinetic energy of the wind was used to propel ships by sails. Windmills, however, are most recent, having been used for a little over a thousand years. The earliest reference to windmills appeared in Arab writings from the ninth century A.D. that described mills that operated on the borders of Persia & Afghanistan some two centuries earlier.

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Generation of Electricity from Wind Power

3. The power in the Wind The power in the wind can be computed by using the concepts of kinetics. The wind mill works on the principle of converting kinetic energy of the wind to mechanical energy. The kinetic energy of any particle is equal to one half its mass times the square of its velocity, or ½ mv 2. The amount of air passing in unit time through an area A, with velocity V, is A. V, & its mass M is equal to its Volume multiplied by its density ρ M = ρ AV

of air, or …………………..(1)

( m is the mass of air transversing the area A swept by the rotating blades of a wind mill type generator ) Substituting this value of the mass in expression of K.E. = ½ ρ AV.V2 watts = ½ ρ AV 3

watts

………………….. (2)

Second equation tell us that the power available is proportional to air density ( 1.225 kg/m3 ) & is proportional to the intercept area. Since the area is normally circular of diameter D in horizontal axis aero turbines, then, A= π

D2

( Sq. m )

4 put this quantity in equation second then

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Generation of Electricity from Wind Power Available wind power Pa = ½ ρ π D2 V3 4 = 1/8 ρ π D2 V3

watt

“ wind machines intended for generating substantial amounts of power should have large rotors and be located in areas of high wind Speed”.

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Generation of Electricity from Wind Power

4. Site Selection considerations The power available in the wind increases rapidly with the speed, hence wind energy conversion machines should be located preferable in areas where the winds are strong & persistant. The following point should be considered while selecting site for WECS. i) High annual average wind speed :The wind velocity is the critical parameter. The power in the wind Pw, through a given X – section area for a uniform wind Velocity is Pw = KV3

( K is const. )

it is evident, because of the cubic dependence on wind velocity that small increases in V markedly affect the power in the wind e.g. doubling V, increases Pw by a factor of 8. ii) Availability of wind V (t) curve at the proposed site :This important curve determines the maximum energy in the wind and hence is the principle initially controlling factor in predicting the electrical o/p and hence revenue return of the WECS machines, it is desirable to have average wind speed V such that V≥12-16 km/hr (3.5 – 4.5 m/sec). iii) wind structures at the proposed site :Wind specially near the ground is turbulent and gusty, & changes rapidly indirection and in velocity. This departure from homogeneous flow is collectively referred to as “ the structure of the wind”.

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Generation of Electricity from Wind Power iv) Altitude of the proposed site :If affects the air density and thus the power in the wind & hence the useful WECS electric power o/p. The wids tends to have higher velocities at higher altitudes. v) Local Ecology :If the surface is bare rock it may mean lower hub heights hence lower structure cost, if trees or grass or ventation are present. All of which tends to destructure the wind. vi) Distance to Roads or Railways :This is another factor the system engineer must consider for heavy, machinery, structures, materials, blades & other apparatus will have to move into any chosen WECS site. vii) Nearness of site to local center/users :This obvious criterion minimizes transmission line length & hence losses & costs. viii) Nature of ground :Ground condition should be such that the foundations for a WECs are secured, ground surface should be stable. ix) Favorable land cost :Land cost should be favorable as this along with other sitting costs, enters into the total WECS system cost.

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Generation of Electricity from Wind Power

5. BASIC COMPONENTS OF A WECS ( wind energy conversion system)

Basic components of WECS Aero turbine :- Aero turbine converts energy in moving air to rotary mechanical energy in general, they required pitch control & yow control for proper operation. A mechanical interface consisting of step up gear & a suitable coupling transmits the rotary mechanical energy to an electrical generator.

Yaw control :- for localities with the prevailing wind in one direction, the design of turbine can be greatly simplified. The rotor can be in a fixed orientation with the swept area perpendicular to the predominant wind direction. The purpose of the Controller is to sense wind speed, wind direction, shafts speeds & torque at one or more points, o/p power & generator temperature as necessary.

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Generation of Electricity from Wind Power

Rotors :- Rotors are mainly of two types. i)

Horizontal axis rotor.

ii)

Vertical axis rotor. One advantages of vertical axis machines is that they operate in all

wind direction & thus need no yaw adjustment. The rotor is only one of the important components for an effective utilization, all the components needs to be designed & matched with the rest of the component.

The windmill head :- they supports the rotor, housing the rotor bearing. It also houses any control mechanism incorporated like changing the pitch of the blades for safety devices & tail Vane to orient the rotor to face the wind.

Generator :- Among the constant speed generator candidates for use are synchronous induction & permanent magnet type. The generators of choice is the synchronous unit for large aero generator system because it is very versatile & has an extensive data base.

Controls :- Controls system performs the following function. 1. the orientation of the rotor into the wind ( azimuth of yaw ); 2. start up and cut-in of the equipment; 3. power control of the rotor by varying the pitch of the bladws; 4. shutdown and cut out owing to malfunction or every high winds; 5. protection for the generators, the utility accepting the power & PM 6. Maintenance mode.

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Generation of Electricity from Wind Power

Towers :- there are four type of towers. 1. The reinforced concrete tower 2. The pole tower 3. The built up shell – tube tower. 4. The truss tower. The type of the supporting structure and its height is related to cost and the transmission system incorporated it is designed to withstand the wind load during gusts.

Transmission :- transmission options are mechanical systems involving fixed ratio gears, belts, & chains, singly or in combinations or hydraulic system involving fluid pumps & motors.

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Generation of Electricity from Wind Power

6. Types of Wind mills There are generally two type of wind mills used in a practice are given below.

i)Vertical – Axis windmills :- These early machines, sometimes referred to as the person windmills, were vertical-axis machines. They involved from ships, sails of canvas and then of wood, were attached to a large horizontal wheel. The wind pressure against the sails caused to the wheel to ran. A vertical axle attached to the wheel usually turned a grindstone to grind grain into flour, hence the name windmill. Similar mills were know to have been used in the thirteenth century A.D. in China to evaporate sea-water for the production of salt, & later in the Crimea, Europe, and united states, through few of them remain today. One of the most successful early form of the vertical axis mill is the one named after savonious of Finland. The sevonius windmills hand single or multiple s – shaped sails and vertical axis. One advantages of its is that, they operate in all wind directions and thus need no yaw adjustments.

ii) Horizontal – axis windmills :- The vertical – axis was changed after the idea of a windmills reached Europe, into a vertical wheel horizontal – axis configuration. The first designed had sails built on a post that could be made to face into any wind direction, the vertical wheel drove a vertical axle through gear, such machine first appeared in France & England in the late twelfth century & were called post mills. Various modification of these mills involved in Europe and

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Generation of Electricity from Wind Power America throughout the middle ages & were uses for grinding grain, drainage, pumping, saw milling, & other purpose. Now a days, only few romantic mills remain & pumping relies mostly on electric drives.

Advantages :1. Simple blade controls 2. Lower blade weight & cost & lower gear box cost. 3. Counter weight costs less than a second blade. 4. pitch bearing do not carry centrifugal force.

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Generation of Electricity from Wind Power HORIZONTAL AXIS WINDMILLS

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Generation of Electricity from Wind Power

VERTICAL AXIS WINDMILLS

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Generation of Electricity from Wind Power

7. Schemes for electric generation Several schemes for electric generation have been developed. These schemes can be broadly classified under three categories : 1. constant – Speed constant frequency systems ( CSCF ) 2. Variable – Speed constant frequency system (VSCF) 3. Variable – Speed variable frequency systems (VSVF)

i) Constant – speed constant frequency Systems (CSCF) Constant speed drive has been used for large generators connected directly to the grid where constant frequency operation is essential. A) Synchronous Generator :- for such machines the requirement of constant speed

is very rigid and only minor fluctuations about 1 % for short duration ( fraction of sec.) could be allowed.

Synchronization of wind driven generator with

power grid also will pose problems with gusty winds. B) Induction Generator :- if the stator of an induction machine is connected to

the power grid and if the rotor is driven above synchronous speed Ns (Ns = 120f/ρ), the machine become a generator and delivers constant line frequency power to the grid. The per unit slip is 0 and 0.05. The o/p power of wind driven induction generator is uniquely determined by the operating speed. Induction gen. Are basically simpler then synchronous gen. They are easily to operate, control & maintain.

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Generation of Electricity from Wind Power

ii) Variable speed constant frequency system (VSCF) Variable – speed drive is typical for most small wind generators used in autonomous applications, generally producing variable frequency and variable voltage output. To popular schemes to obtain constant frequency o/p are as follow. A) AC – DC – AC link :- With the advent of high powered thyristors and nine

voltage d.c. transmission system a.c. output of the 3 - φ alternate is rectified using a bridge rectifier and then converted back to A.C. using line commutated inverters. They utilize an a.c. Source which periodically reverse polarity and cause the commutation to occure naturally, since frequency is automatically fixed by the power lines, they are also known as synchronous inverters. B) Double output Induction Generator :- in this system a slip ring induction motor

is used. Rotor power output at slip frequency is converted to line frequency power by rectification & inversion output power is obtained both from stator and rotor & hence this device is called “double o/p induction generator”. Rotor o/p power has the electrical equivalence of an additional impedance in the rotor ckt. Therefore increasing rotor outputs lead to increasing slips & higher speeds. Such an operation increases the operating speed range from Ns to 2Ns i.e. slip varying from 0 to 1.0. C) A.C. commutation generator :- this system is also known as “Scherbias”

system employs two polyphase windings in the stator and a commutator

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Generation of Electricity from Wind Power windings on the rotor. Basic problem in employing this device for wind energy conversion are the cost and the additional maintenance and the care required by the commutator and the brush gear.

iii). Variable speed variable frequency (VSVF) Scheme Since resistive heating loads are essentially frequency in sensitive, the a.c. generator can be effected at a variable frequency corresponding to the changing drive speed. For this purpose capacitor excited (self – excited) squirrel caze induction machines can be conveniently used. This systems are gaining importance for stand alone wind power application. The magnitude and frequency of the emf depends on the value of the load impedance, prime-mover speed and excitation capacitance. Methods of analyzing these variable – voltage variable frequency generator have been developed to predit the no load and load performance characteristics. The variable o/p voltage can be converted to constant d.c. using choppers or controlled rectifiers on constant a.c. using force – commutated inverters. Ac converters and transducers can be introduced to monitor and control the desired performance quantities.

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Generation of Electricity from Wind Power

DESIGN OF WINDMILL TOWER

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( all dimensions in cm)

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Generation of Electricity from Wind Power

BLOCK DIAGRAM OF WIND POWER GENERATION

WIND

WIND WIND TURBINE

GEARING AND COUPLING

ELECTRICAL GENERATOR CONTROLLER ENERGY STORAGE

ENERGY STEP-UPING DEVICE

LOAD UTILIZATION

8. Designing of WINDMILLS Govt. Poly. Washim.

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Generation of Electricity from Wind Power

MECHANICAL COMPONENT :A wind mill is machine for wind energy conversion. A wind turbine converts the kinetic energy of the wind’s motion to mechanical energy transmitted by the shaft. A generator further converts it to electrical energy. So it is necessary to keep in mind, while designing the windmill’s structural part.

1. Design of tower :Generally there are four types of tower i.e. 1) The rainforced concrete tower. 2) the pole tower . 3) The built up shell – tube tower 4) the truss tower. In the project there is a pole tower. Which is made up of mild steel can be with stand, in large force of wind. The tower & its height is related to cost and transmission system incorporated. So the hight of our power is 45.5 cm. & width at bottom is 24 cm & at top is 13.5 cm.

2. Design of blade :Wind turbine blades have on airfoil – type cross section and a variable pitch. While designing the size of blade it is must to know the weight and cost of blades in the project four blade with vertical axle are used, it has a height in width is 12 cm & 20 cm long it is very light in weight so wind required for producing torque should be less. The angle between two blades is 900. So if one Blade moves some what other blacks comes in the position of first blade, so the speed is increases some what.

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Generation of Electricity from Wind Power

3. Axle designing :While designing the axle of blades if should be properly fitted to the blade. The axle having should be as possible as less in thickness & light in weight for the four blade, the axle used is very thin in size are all properly fitted. So no problem of slipping & fraction is created, it is made up of Aluminium which having very light weight.

4) Designing of Gearing ( Pulley) The gearing mechanism of windmills is one of the considerable thing because if there will be proper gearing system provided, the driving force required for the driving the shaft of generator requires very less no. of rotation. While deciding the size of gear ( pulley), it should have more dimension as compared with pulley of generator. The ratio of gearing mechanism should be as more as possible because speed of

blade is very less; so if the pulley completed one

revolution at the same time, the pulley of generator should complete more revolution. For example if the ration of gearing mechanism is 1:10 then if means, in one revolution of pulley A, the pulley of generator complete 10 revolution so the speed can increase considerably. Also the pulley should have height in weight, so no consumption of power will take place in revolving. For the project the dimension of pulley A is 9 cm. and for pulley required for generator is 1 cm. So in one revolution of pulley A, the second pulley completes 9 revolution. It is made up of wooden piece. So it has very small weight. It should be properly attached to the

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Generation of Electricity from Wind Power axle of blades. So no friction will take place. The thickness of pulley is 0.7 cm. for the driving purpose, belt is used, which tide in these two pulleys but with the belt drive system, slipping problem will take place.

5) Design of Bearing :For the smooth operation of Axle, bearing mechanism is used. If have very less friction loss the two ends of axles are pivoted in the two same dimension pulley. The Bearing has diameter of 3 and 2.5 cm. bearing are generally provided for supporting to the axle and smooth operation of shaft. Greece is used for bearing maintenance

 ELECTRICAL COMPONENTS Generator :- For the conversion of kinetic energy into electric energy, of generator are used in windmills. The shaft of generator connected by means of belt to the pulley. As the rotation of pulley increase. The emf. will induces in the generator. The generator can be used induction type or permanent magnet type. The generator of choice is the synchronous unit for large aerogenerator system. The generator should have to operate in both the direction. So as to limit short ckt due to change in rotation direction. The motor as generator used for project is 12 volt generator. The generator used is variable speed constant frequency type. The o/p of generator is given to the energy storage system. The maximum o/p voltage of generator is upto 12 V.

Energy storage / battery :Govt. Poly. Washim.

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Generation of Electricity from Wind Power The o/p of generators is given to the battery for electric energy storage purpose. The capacity of the battery is upto 12 V. Generally this battery is lead acid type battery and also restorable . The supply of generator is given to the battery through a diode; for the purpose or if the battery will pulley charged, the generator will acts as a motor and takes current from battery, so as to avoid if diode is used in series with supply. A siren is used for the battery for purpose. When battery will pulley charge it gives alarm or horn. The o/p of battery is given to the step-up transformer.

Step-up transformer A step-up transformer receives energy from storage battery. The working principle of step-up transformer is same as that general transformer but in step-up transformer, primary winding having more no. of turn and secondary winding have less turn as complete to primary winding. The design of transformer is in such a way that it gives positive cycle in both positive and negative direction by using half wave rectification. This transformer step-up the voltage up to some extend. The T/F having in project are 6-0-6 voltage rating.

Controller :-

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Generation of Electricity from Wind Power When the battery will fully charged it will give supply to the generator at the stopping condition. So energy can be consume in this process. So by using diode in series with supply it can be avoided.

Hartley oscillators The purpose to use Hartley oscillator in the project is that when, the step-up transformer step-up the electric energy or voltage, the oscillator will increase the frequency of voltage o/p giving from the transformer and by using oscilloscope we can observe the increased frequency.

where L = L1 + L2 L=

1 ( 2πf )2C

&

F =

1 2π √ LC

Siren :Govt. Poly. Washim.

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Generation of Electricity from Wind Power Siren is used for alarming purpose when battery will fully charged if the battery will fully charged then, the energy will wasted. Alarm ckt is necessary to avoid it and it helpful to connect another set of battery for charging purpose.

9. APPLICATIONS OF WIND ENERGY Govt. Poly. Washim.

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Generation of Electricity from Wind Power Wind-turbine generators have been built a wide range of power outputs from kilowatt or so to a few thousand kilowatts, machine of low power can generate sufficient electricity for space heating & cooling of names & for operating domestic appliances. Low power WEC generators have been used for many years for the corrosion protection of buried metal pipe lines. Application of somewhat more powerful turbines upto about 50kw, are for operating irrigation pumps. Navigational signal. Aero generators in the intermediate power range, roughly 100 to 25 kw. Can supply electricity to isolated populations. Pumping Application :- A typical wind powered pumping application is onethat might use a horizontal –axis wind used to pump irrigation water. Large number water pumping wind mills have been used in Indian forms other applications that are being developed include the pumping of water for aqueducts or for pumpedhydro storage of energy. Direct Heat Application :- Mechanical motion derived from wind power can be used to drive heat pumps or to produce heat from the friction of solid materials, or by the charining of water or other fluids or in other cases, by the use of centrifugal or other types of pumps in combination with restrictive orifices that produces heat from friction and turbulence when material having a high heat capacity such as water, stones, electric etc. or the heat may be used directly for such application as heating and cooling of water.

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Generation of Electricity from Wind Power Electric Generation Applications :-

Wind power can be used in centralized

applications to drive synchronous a.c. electrical generator. In such applications, the energy is fed directly into power networks through voltage step-up transformers. In dispersed applications , wind power can be used to generate D.C electric power that, in turn, can be used for d.c. applications or space heaters, such as resistance heaters or can be stored in batteries and then inverted for use by a.c. load.

10. Safety System Govt. Poly. Washim.

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Generation of Electricity from Wind Power Safety systems of wind turbines comprise The following features. 1) The Computer :- The wind turbine is controlled by a computer with monitors

the most important gauging instruments and compare the result if error are found the wind turbine is stopped. 2) Emergency stop: - If a situation arise which calls for the wind turbine to be

stopped immediately, the emergency stop is used. The wind turbine will stop in few seconds by featuring the blades directly into the wind. It can not be started again before what course the emergency stops has been rectified. 3) Revolution counters :- To prevent the rotor from racing, two revolation

counters have been mounted on the shaft. These operates quiet independently ans activate the emergency stop if the revolution of the turbine exceed 24 rpm. which is max. 4) Wind Velocity :-

This is measured and controlled by the computer in two

ways. First gusts of wind are registered and if they are too storage the turbine is stopped. Then average wind speed are measured over periods of 10 min, and the wind turbine is also stopped if these are too high. 5) The Parachutes :- Each blade tip has a parachutes, which is activated if the

rpm. exceeds 28. An iron plumb bob, otherwise held in place by a magnet, is released from the blade trip, the centrifugal force of the magnet pulling out the parachute. This decreases the speed of the wind turbine considerable enough to

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Generation of Electricity from Wind Power stop it from racing. The parachute is an extra safety device should other fail. Till now they never been used. 6) Lightning rods :- The three blades and the mill or wind turbine cap are

protected from lightning by these rods going from the tip of each blade to the ground.

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Generation of Electricity from Wind Power

11. Advantages and Disadvantages of WECS Advantages :1) It is a renewable source of energy. 2) Like all forms of solar energy, wind power system are non-polluting so it has no adverse influence on the environment. 3) Wind energy system avoid fuel provision and transport. 4) On a small scale upto a few kilowatt system is less costly. On a large scale costs can be competitive conventional electricity and lower costs could be achieved by mass production. Disadvantages :1) Wind energy available in dilute and fluctuating in nature. 2) Unlike water energy wind energy needs storage capacity because of its irregularity. 3) Wind energy system are noisy in operation; a large unit can be heard many kilometers away. 4) Wind power systems have a relatively high overall weight, because they involves the construction of a high tower and include also a earbox a hub and pitch changer, a generator coupling shaft etc. for large system a weight of 110 kg/kw ( rated) has been estimated. 5) Large areas are needed, typically, propellers, 1 to 3 m in diameter deliver power in the 30 to 300 w range.

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Generation of Electricity from Wind Power 6) Present systems are neither maintenance free non-practically reliable. However, the fact that highly reliable propellers engines are built for aircraft suggest that the present trouble could be overcome by industrial development work.

Environmental Aspects :Wind turbines are not without environmental impact and their operation is not entirely risk free. Following are the main effects due to a wind turbine. 1) Electro-magnetic interference :- eg. T.V. Radio etc. 2) Noise 3) Visual Effects 4) Bird life 5) Risk

REFERENCE 1) G.D. Rai  Non conventional energy source.0 2) M.M. EI

Wakil

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