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WIND ENERGYNON CONVENTIONAL ENERGY SOURCE

NON CONVENTIONAL ENERGY SOURCES

Abstract

The ever increasing rapid use of the fossile fuels day by day has

threatened exhausting of conventional energy sources very soon. Also the use

of conventional energy sources has increased the global pollution level which is

resulting in climate change. Therefore time has come for searching altogether

other sources of energy which are inexhaustible and gradually replace the

conventional sources. The non conventional energy sources such as solar,

wind, tidal, ocean etc are basically renewable energy resources. The energy

available from each of theses sources can be used to produce mechanical

and electrical power. These are produced continuously in nature and are

essentially inexhaustible atleast in the frame work of human societies.Wind

energy is one of non conventional energy source. Wind power is one of the most

ecofriendly means to generate electricity . The time taken to set up wind power

project is very short compare to set up a conventional thermal power plant using

coal or nuclear energy.


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Contents

o Introduction.

o Wind energy.

o Constructional materials.

o Power generation.

o Wind sensor.

o Energy utilisation.

o Advantages.

o Disadvantages.

o Conclusion.


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Introduction

Energy , a word derived from Greek word Energia, meaning

capacity for doing work. All forms of energy are interconvertable by appropriate

processes. Energy can also be classified as conventional and non conventional

eneegy sources. Presently most of our energy sources comes mainly from

fossile fuels such as coal, petrolium, and natural gas.The ever increasing rapid

use of fossile fuels day by day has threatened exhausting of these sources very

soon. . Without energy, the world's entire industrialized infrastructure would

collapse; agriculture, transportation, waste collection, information

technology, communications and much of the prerequisites that a developed

nation takes for granted.Therefore time has come for searching altogether other

sourceses of energy which are inexhaustible called non conventional energy

sources such as wind energy, tidal energy, solar energy, bio energy and so on.

These energy resources replenish themselves naturally in a relatively short time

and therefore will always be available.Except the biomass energy sources all

other renewable energy sources offer pollution free environment and also help in

maintaining the ecological balance.

Introduction to Wind Energy

Wind energy is the energy contained in the force of the winds

blowing across the earths surface.When harnessed, wind energy can be

converted into mechanical energy for performing work such as pumping water,

grinding grain by wind mills and producing electrical energy, by wind turbines.The

circulation of air in the atmosphere is caused by the non uniform heating of the

earths surface by the sun. The air immediately above a warm area expands and

becomes less dense. It is then forced upwards by a cool denser air which flows inthe surrounding areas causing a wind.
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Wind machines were used for grinding grain in Persia as early as

200 B.C. This type of machine was introduced into the Roman Empire by 250

A.D. By the 14th century Dutch windmills were in use to drain areas of the Rhine

River delta. In Denmark by 1900 there were about 2500 windmills for mechanical

loads such as pumps and mills, producing an estimated combined peak power of

about 30 MW. The first windmill for electricity production was built in Cleveland,

Ohio by Charles F. Brush in 1888[1], and in 1908 there were 72 wind-driven

electric generators from 5 kW to 25 kW fig(1). The largest machines were on 24

m (79 ft) towers with four-bladed 23 m (75 ft) diameter rotors. In Denmark wind

power was an important part of a decentralized electrification in the first quarter of

the 20th century, partly because of the Danish wind power scientist Poul la Cour.

Fig (1) A Two Bladed Wind Turbine

By the 1930s windmills were mainly used to generate electricity on

farms, mostly in the United States where distribution systems had not yet been

installed. In this period, high tensile steel was cheap, and windmills were placed

atop prefabricated open steel lattice towers. A forerunner of modern horizontal-

axis wind generators was in service at Yalta, USSR in 1931. This was a 100 kW

generator on a 30 m (100 ft) tower, connected to the local 6.3 kV distribution

system. It was reported to have an annual load factor of 32 per cent, not much

different from current wind machines.

Construction Materials


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Wood and canvas sails were originally used on early windmills due to

being cheap and easily manufactured. Unfortunately they require much

maintenance over their service life. Also, they have a relatively high drag

(low aerodynamic efficiency) for the force they capture. For these reasons

they were superseded with solid airfoils.

One of the strongest and stiffest construction materials available for wind

turbine blades is carbon-fibre in an epoxy resin matrix, however is very

expensive and only used by some blade manufactures for highly loaded

parts of the rotor blades and when stiffness is critical. Modern rotor blades

(up to 126 m (413 ft) diameter) are made of lightweight glass-reinforced

plastic (GRP) with an epoxy orpolyester resin matrix. Smaller blades can

sometimes be made from aluminium, however GRP is the most common

material for modern wind turbine blades. Fig(2)Wind turbine blades can

however be made from a wide variety of materials.

Fig(2) A person standing beside medium size modern turbine blades.

For a given survivable wind speed, the mass of a turbine is

approximately proportional to the cube of its blade-length. Wind power

intercepted by the turbine is proportional to the square of its blade-length. The

maximum blade-length of a turbine is limited by both the strength and stiffness of

its material.Labor and maintenance costs increase only gradually with increasing

turbine size, so to minimize costs, wind farm turbines are basically limited by the

strength of materials, and siting requirements.Typical modern wind turbines havediameters of 40 to 90 meters (130-300 ft) and are rated between 500 KW and 2

MW. Currently (2005) the most powerful turbine is rated at 6 MW.


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Power Generation

In 1941 the world's first megawatt-size wind turbine was connected to the

local electrical distribution system on Grandpa's Knob in Castleton, Vermont,USA. This 1.25 MW Smith-Putnam turbine operated for 1100 hours before a

blade failed at a known weak point, which had not been reinforced due to war-

time material shortages. In the 1940s, the U.S. had a rural electrification project

that killed the natural market for wind-generated power, since network power

distribution provided a farm with more dependable usable energy for a given

amount of capital investment

For large, commercial size horizontal-axis wind turbines, the generator is

mounted in a nacelle at the top of a tower, behind the hub of the turbine rotor. A

speed increasing gearbox may be inserted between the rotor hub and the

generator, so that the generator cost and weight can be reduced.

Commercial size generators have a rotor carrying a field winding so that a

rotating magnetic field is produced inside a set of windings called the stator.

While the rotating field winding consumes a fraction of a percent of the generatoroutput, adjustment of the field current allows good control over the generator

output voltage (one of the such turbine is illustrated in fig3). Very small wind

generators (a few watts to perhaps a kilowatt in output) may use permanent

magnets but these are too costly to use in large machines and do not allow

convenient regulation of the generator voltage .

Fig(3) Wind Turbines


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Electrical generators inherently produce AC power. Older style wind

generators rotate at a constant speed, to match power line frequency, which

allowed the use of less costly induction generators. Newer wind turbines often

turn at whatever speed generates electricity most efficiently.

This can be solved using multiple technologies such as doubly fed

induction generators or full-effect converters where the variable frequency current

produced is converted to DC and then back to AC, matching the line frequency

and voltage. Although such alternatives require costly equipment and cause

power loss, the turbine can capture a significantly larger fraction of the wind

energy. In some cases, especially when turbines are sited offshore, the DC

energy will be transmitted from the turbine to a central (onshore) inverter for

connection to the grid.

Wind sensor

Wind sensors are used to know the speed of the wind, direction of windflow. One of the example for wind sensor is ultrasonic wind sensor which has

following advantages Fig(4),


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Fig(4) Wind Sensor

Measures wind speed and direction from the smallest breeze to hurricane

force gales (0...65 m/s), including gusts

Superior data availability and accuracy in all wind directions due to the

patented three transducer layout

Averaging of wind speed and direction

Analog, RS-232, RS-422, RS-485 and SDI-12 outputs

Low power consumption

No moving parts: virtually maintenance free

Stainless steel construction

Heated model available

US National Weather Service relies on Vaisala ultrasonic technology

Wind Energy Utilization

Five nations Germany, USA, Denmark, Spain and India accountfor 80% of the worlds installed wind energy capacity. Wind energy continues to

be the fastest growing renewable energy source with worldwide wind power


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installed capacity reaching 14,000 MW .The prediction for the years 1997-2010 is

shown in Fig(5).

Fig(5) Worldwide installed capacity and prediction 1997-2010,

India ranks 5th in the world with a total wind power capacity of

1080MW out of which 1025MW have been established in commercial projects. In

India the states of Tamilnadu and Gujarat lead in the field of wind energy. At the

end of March 2000 India had 1080-MWs capacity wind farms, of which Tamilnadu

contributed 770-MW capacity. Gujarat has 167MW followed by Andhra Pradesh,

which has 88 MW installed wind farms.There are about a dozen wind pumps ofvarious designs providing water for agriculture, afforestation, and domestic

purposes, all scattered over the country.

Early in the millennium, Suzlon commissioned its Vankusawade

wind park in the Satara District of Indias Maharashtra state which at 201 MW of

capacity, ranked as Asia's largest on completion. Suzlon has since taken great

strides and is today building what will be among the worlds largest wind parks.

Suzlons Dhule wind park site, located approximately 30 km from the town of

Nandurbar in Maharashtra, is spread across a vast, undulating expanse.

Advantages of non conventional energy sources

These energy sources are non exhaustible.

Minimisation of transmission cost.

Except biomass energy all other renewable energy resources are

pollution free.


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The power generation cost is low compared to conventional energy

sources.

Minimisation of power transmission losses.

Locally available energy sources are effectively utilised.

Disadvantages of non conventional energy sources

The intermittent nature of the availability of energy setback in the

continuous supply of energy.

Some of renewable energy sources such as wind, tidal etc are

concentrated only in certain regions.

The application of renewable energy resources to transport sector is not

viable as on today

The state of the art in harnessing renewable energy sources is not yet fully

developed to meet present day requirements.

ConclusionThe Conventional sources of energy are going to exhaust in

near future. Now time has come to utilize the locally available energy sources to

the maximum extent as they are ecofriendly and does not cause pollution.

Eventhough these sources cannot satisfy our complete need, utilization of Non

conventional energy sources reduces the burden of depending on Conventional

sources which are hazardous and pollution oriented. Presently our 90% need

comes from conventional energy sources because production cost of energy from

non conventional energy resources is very high as it is produced in small scale

but if we produce energy in large scale the cost will come down.Therefore precise

measure and strategy are planned and implemented to ground floor level and

making maximum use of these sources.

References

http://www.wwindea.org/

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

www.Suzlon.com


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http://www.energy.ca.gov/

http://www.eia.doe.gov/

www.fe.doe.gov/education

www.ase.org/greenschools

www.conserinfo.org

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