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WIND ENERGY SYSTEMS

Dr.L.Ashok Kumar Dept. of EEE PSG College of Technology Coimbatore

www.ashokkumar.110mb.com

1

Overview of Presentation
• • • •
– –

Introduction History of Wind Machines Wind Resource Assessment Wind Energy Technology
Horizontal Axis turbine Vertical Axis turbine

• • • •

Wind Energy System Components Installation and Maintenance Environment Economics

Electricity!
More efficient light bulbs are great, but what is the BEST way to conserve electricity and reduce our consumption of fossil fuels???

• How much would it cost to run this 100 Watt bulb for a full day (24 hrs)? • 100 Watts x 24 hours = 2400 Watt Hours (2400 Watt Hours = 2.4 Kilowatt Hours) • 2.4 kWh x $0.08/kWh = $0.19

• What about this 25 Watt CFL light bulb, which produces the same amount of light? • 25 Watts x 24 hours = 600 Watt Hours (600 Watt Hours = 0.6 Kilowatt Hours)

TURN IT OFF!!! x $0.08/kWh = $0.05 • 0.6 kWh Be conscious of your energy choices!

Where do we get our electricity?

What is a Fossil Fuel???

What is “Renewable Energy?”

Advantages of Wind Power
• The wind blows day and night, which allows windmills to produce electricity throughout the day. (Faster during the day) • Energy output from a wind turbine will vary as the wind varies, although the most rapid variations will to some extent be compensated for by the inertia of the wind turbine rotor. • Wind energy is a domestic, renewable source of energy that generates no pollution and has little environmental impact. Up to 95 percent of land used for wind farms can also be used for other profitable activities including ranching, farming and forestry. • The decreasing cost of wind power and the growing interest in renewable energy sources should ensure that wind power will become a viable energy source in the United States and worldwide.

Major factors that have accelerated the wind-power technology development are as follows:

• high-strength fiber composites for constructing large low-cost blades. • falling prices of the power electronics. • variable-speed operation of electrical generators to capture maximum energy. • improved plant operation, pushing the availability up to 95 percent. • economy of scale, as the turbines and plants are getting larger in size. • accumulated field experience (the learning curve effect) improving the capacity factor.

What do wind energy systems provide?
• Electricity for
– Central-grids – Isolated-grids – Remote power supplies – Water pumping …but also… – Support for weak grids – Reduced exposure to energy price volatility – Reduced transmission and distribution losses
San Gorgino Windfarm, Palm Springs, California, USA

Utilisation of Wind Energy
• Off-Grid
– Small turbines (50 W to 10 kW) – Battery charging – Water pumping
Off-Grid, 10-kW Turbine, Mexico

• Isolated-Grid
– Turbines typically 10 to 200 kW – Reduce generation costs in remote areas: wind-diesel hybrid system – High or low penetration

• Central-Grid
– Turbines typically 200 kW to 2 MW – Windfarms of multiple turbines

INTRODUCTION
• Wind energy, the world's fastest growing energy source, is a clean and renewable source of energy that has been in use for centuries in Europe and more recently in the United States and other nations. • And todays world wind is one of the cheapest and cleanest energy source.

HISTORY OF WIND MACHINES
• Throughout history people have harnessed the wind. Over 5,000 years ago, the ancient Egyptians used wind power to sail their ships on the Nile River. Later people built windmills to grind their grain. The earliest known windmills were in Persia (the area now occupied by Iran). The early windmills looked like large paddle wheels. Centuries later, the people in Holland improved the windmill. They gave it propeller-type blades and made it so it could be turned to face the wind. Windmills helped Holland become one of the world's most industrialized countries by the 17th century. American colonists used windmills to grind wheat and corn, to pump water, and to cut wood at sawmills. Last century, people used windmills to generate electricity in rural areas that did not have electric service. When power lines began to transport electricity to rural areas in the 1930s, the electric windmills were used less and less.



• •

• Then in the early 1970s, oil shortages created an environment eager for alternative energy sources, paving the way for the re-entry of the electric windmill on the world landscape .

WORLD WIND POWER SCENARIO (all data in MW) as on January 2011

Source: c-wet website

INDIAN WIND POWER SCENARIO
STATE WISE INSTALLED CAPACITY OF WIND POWER IN INDIA Sr.No 1 2 3 4 5 6 7 8 9 State Andhra Pradesh Gujarat Karnataka Kerala Madhya Pradesh Maharashtra Rajasthan Tamil Nadu Others Total Installed Capacity As on 31.03.2010 136.10 1863.70 1472.80 27.80 229.40 2077.70 1088.50 4906.80 4.30 11807.1 Source : MNRE Installed Capacity As on 31.03.2011 192.00 2176.00 1727.00 35.00 276.00 2317.00 1525.00 5904.00 4.00 14156

Where Does Wind Come From?
• The differential heating of earth’s atmosphere causes wind.

The Jet Stream
• The jet stream is responsible for the transport of heat and momentum in the mid latitudes

Wind energy
• Wind energy is actually a converted form of solar energy. • The sun’s radiation heats different part of the earth at different rates during the day and night, but also when different surfaces (e.g., water and land) absorb or reflect at different rates. • This in turn causes portions of the atmosphere to warm differently. • Hot airs rises, reducing the atmospheric pressure at the earth’s surface, and cooler air is drawn in to replace it. • Air has a mass, and when it is in motion, it contains the kinetic from mass in motion. • Some portion of that energy can be converted into other forms mechanical force or electricity that we can use to perform work.

What is Wind?
• Wind is simply air in motion. It is caused by the uneven heating of the earth's surface by the sun. Since the earth's surface is made up of land, desert, water, and forest areas, the surface absorbs the sun's radiation differently. All renewable energy (except tidal and geothermal power), ultimately comes from the sun The earth receives 1.74 x 1017 watts of power (per hour) from the sun About 1% or 2% of this energy is converted to wind energy (which is about 50-100 times more than the energy converted to biomass by all plants on earth) Differential heating of the earth’s surface and atmosphere induces vertical and horizontal air currents that are affected by the earth’s rotation and contours of the land  WIND. e.g.: Land Sea Breeze Cycle

• • •





Winds are influenced by the ground surface at altitudes up to 100 m. Wind is slowed by the surface roughness and obstacles. When dealing with wind energy, we are concerned with surface winds. A wind turbine obtains its power input by converting the force of the wind into a torque (turning force) acting on the rotor blades. The amount of energy which the wind transfers to the rotor depends on the density of the air, the rotor area, and the wind speed. The kinetic energy of a moving body is proportional to its mass (or weight). The kinetic energy in the wind thus depends on the density of the air, i.e. its mass per unit of volume. In other words, the "heavier" the air, the more energy is received by the turbine. At 15° Celsius air weighs about 1.225 kg per cubic meter, but the density decreases slightly with increasing humidity.

• • • •





A typical 600 kW wind turbine has a rotor diameter of 43-44 meters, i.e. a rotor area of some 1,500 square meters.



The rotor area determines how much energy a wind turbine is able to harvest from the wind. Since the rotor area increases with the square of the rotor diameter, a turbine which is twice as large will receive 22 = 2 x 2 = four times as much energy.





To be considered a good location for wind energy, an area needs to have average annual wind speeds of at least 12 miles per hour.

Global Winds
• The global wind patterns are created by uneven heating and the spinning of the earth. The warm air rises near the equator, and the surface air moves in to replace the rising air - two major belts of the global wind patterns are created. The wind between the equator and about 30° north and south latitudes move east to west. These are called the trade winds because of their use in sailing ships for trades. Two features of the wind, its speed, and the direction, are used in describing and forecasting weather





Local Winds
Land Breezes and Sea Breezes
• Land masses are heated by the sun more quickly than the sea in the daytime. The air rises, flows out to the sea, and creates a low pressure at ground level which attracts the cool air from the sea. This is called a sea breeze. At nightfall there is often a period of calm when land and sea temperatures are equal. • At night the wind blows in the opposite direction. The land breeze at night generally has lower wind speeds, because the temperature difference between land and sea is smaller at night.

Mountain Breezes and Valley Breezes
• Mountain breezes and valley breezes are due to a combination of differential heating and geometry. When the sun rises, it is the tops of the mountain peaks which receive first light, and as the day progresses, the mountain slopes take on a greater heat load than the valleys. • This results in a temperature inequity between the two, and as warm air rises off the slopes, cool air moves up out of the valleys to replace it. This upslope wind is called a valley breeze. • The opposite effect takes place in the afternoon, as the valley radiates heat. The peaks, long since cooled, transport air into the valley in a process that is partly gravitational and partly convective and is called a mountain breeze .

History of Wind Mills

Early History
• • • • • • • • • • • 5000 BCE (before common era): Sailing ships on the Nile River were likely the first use of wind power Hammurabi, ruler of Babylonia, used wind power for irrigation Hero (Heron) created a wind-pumped organ Persians created a Vertical Axis WT (VAWT) in the mid 7th Century 1191 AD: The English used wind turbines 1270: Post-mill used in Holland 1439: Corn-grinding in Holland 1600: Tower mill with rotating top or cap 1750: Dutch mill imported to America 1850: American multiblade wind pump development; 6.5 million until 1930; was produced in Heller-Allen Co., Napoleon, Ohio 1890: Danish 23-meter diameter turbine produced electricity

Later History
• • • • • • • 1920: Early Twentieth Century saw wind-driven water-pumps commonly used in rural America, but the spread of electricity lines in 1930s (Rural Electrification Act) caused their decline 1925: Windcharger and Jacobs turbines popular for battery charging at 32V; 32V dc appliances common for gas generators 1940: 1250kW Rutland Vermont (Putnam) 53m system (center) 1957-1960: 200kW Danish Gedser mill (right) 1972: NASA/NSF wind turbine research 1979: 2MW NASA/DOE 61m diameter turbine in NC Now, many windfarms are in use worldwide

WIND ENERGY TECHNOLOGY

• Horizontal Axis Turbine • Vertical Axis Turbine • Old-fashioned windmills

DIFFERENT TYPES OF WIND TURBINES
• Drag-type turbines
– Persian windmill – Chinese wind wheel – Saviounus

• Lift-type turbines
– VAWT, Vertical Axis Wind Turbine
• Darrieus

– HAWT, Horizontal Axis Wind Turbine
• The Danish concept • American multiblade • Grumman windstream

DRAG-TYPE TURBINES

Savonious

The Persian windmill

The Chinese wind wheel

DRAG-TYPE TURBINES

Ref: www.ifb.uni-stuttgart.de/~doerner/edesignphil.html

Horizontal Axis Wind Turbine
• HAWT (Horizontal Axis Wind Turbines) have the rotor spinning around a
horizontal axis – The rotor vertical axis must turn to track the wind – Gyroscopic precession forces occur as the turbine turns to track the wind

• The purpose of the rotor, of course, is to convert the linear motion of the wind into rotational energy that can be used to drive a generator. The same basic principle is used in a modern water turbine, where the flow of water is parallel to the rotational axis of the turbine blades.

Horizontal Axis Wind Turbines (HAWT)
Sailwing, 1300 A.D.
Experimental American Farm, 1854 Wind farm

Dutch post mill

Dutch with fantail

1.8 m

Modern Turbines

75 m

LIFT-TYPE TURBINES HAWT, AMERICAN MULTIBLADE

LIFT-TYPE TURBINES HAWT, THE DANISH CONCEPT
• The blades upwind the rotor • Constant speed on the rotor • Power output limitation
– Stall control

• Brakes
– Mechanical – Aerodynamic

LIFT-TYPE TURBINES HAWT, GRUMMAN WINDSTREAM

DEVELOPMENT OF HAWT

SPEED

HEIGHT [M]

n

20

17

13

5 – 15

3 – 10 rpm

HAWT
Horisontal-Axis Wind Turbines

SMØLA

HAWT
Main Components
• • • • • Foundation Tower Nacelle Hub Turbine blades

Ref. Wind Power Plants, R.Gasch, J.Twele

Horizontal axis Turbine

HAWT Examples
• • • Charles Brush (arc light) home turbine of 1888 (center) – 17 m, 1:50 step-up to drive 500 rpm generator NASA Mod 0, 1, 2 turbines The Mod-0A at Clayton NM produced 200kW (below left)

VAWT
• The only vertical axis turbine which has ever been manufactured commercially at any volume is the Darrieus machine, named after the French engineer Georges Darrieus who patented the design in 1931. (It was manufactured by the U.S. company FloWind which went bankrupt in 1997). The Darrieus machine is characterized by its C-shaped rotor blades which make it look a bit like an eggbeater. It is normally built with two or three blades.



VAWT (Vertical Axis Wind Turbines) have the rotor spinning around a vertical axis – This Savonius rotor will instantly extract energy regardless of the wind direction – The wind forces on the blades reverse each half-turn causing fatigue of the mountings – The two-phase design with the two sections at right angles to each other starts more easily

Vertical Axis Wind Turbines (VAWT)
This sample shows the diversity of VAWT over the years Darrieus with Savonius

Panemone, 1000 B.C.

Savonius

Giromill

Experimental Savonius

LIFT-TYPE TURBINES VAWT, DARRIEUS

LIFT-TYPE TURBINES VAWT, DARRIEUS

Ref: www.ifb.uni-stuttgart.de/~doerner/edesignphil.html

Vertical axis wind turbine.

Advantages of VAWT’s
1) You may place the generator, gearbox etc. on the ground, and you may not need a tower for the machine. 2) You do not need a yaw mechanism to turn the rotor against the wind.

Disadvantages of VAWT’s
• • • Wind speeds are very low close to ground level, so although you may save a tower, your wind speeds will be very low on the lower part of your rotor. The overall efficiency of the vertical axis machines is not impressive. The machine is not self-starting (e.g. a Darrieus machine will need a "push" before it starts. This is only a minor inconvenience for a grid

.

Small Wind Turbines: American
• In 1854, patented wind pumpers were popular across the US, later spreading to other nations By 1870, improvements made with sheet steel blades stamped to an aerodynamic contour These turbines use 2 turns of the rotor to 1 stroke of the pump lift rod gear ratio to allow starting at a low wind speed AEI states that there are some 30,000 farm wind pumps in the Southern Great Plains at 0.25 kW each, or some 5 MW total







Small Wind Turbines
• Bergey produces small wind turbines up to 50 kW

Small Wind Turbines: “Homemade”
• Amateur or hobbyist wind turbines are often somewhat crude, but many sources of construction information are available • Books by Paul Gipe and Hugh Piggott are essential references • Blades are usually made of fir, pine, fiberglass, or metal • Turbine at right uses a bicycle front axle for strength, PVC blades, and a permanent magnet servomotor as a generator

Large Systems: Size and Numbers
• Rotor hub is high above turbulent ground wind layer • Production line assembly • 660kW to 7 MW power models • Groups of 10 to 1000s of turbines • Attractive, modern appearance

Large Systems
• • FPL Stateline and Vansycle Ridge Wind Farms in southeast WA and northeast Oregon Wasco OR shown; plowed fields for wheat underneath

Offshore Wind Farms
• • • Wind farms are often placed offshore a few miles because the winds are unimpeded (have a good “fetch”, or upwind distance, of the wind) Depths of less than 60 feet are preferable Undersea cables carry power to shore terminals

Types of Electricity Generating Windmills
Small (10 kW)
• Homes • Farms • Remote Applications
(e.g. water pumping, telecom sites, icemaking)

Intermediate (10-250 kW)
• Village Power • Hybrid Systems • Distributed Power

Large (250 kW - 2+MW)
• Central Station Wind Farms • Distributed Power

Vertical Wind Speed Variation
• • • • • At a given location, wind speed increases as we go above the earth surface. At the earth surface, the wind speed is zero due to the friction of air with the surface. As we go up, wind speed increases more rapidly at lower heights but less rapidly at greater heights. At about 2000 m from the ground the change in the wind speed becomes zero. The vertical variation in the wind speed depends on
– Roughness of the terrain – Wind speed near the ground – Represented by  (0.01 to 0.3)



If wind speed for a given location and at a given height is known, the V at any other height at the same location can be estimated.
– V(at unknown ht) = V (at known ht) x (New ht/Ref ht) 

Kinetic Energy
• Kinetic energy (KE) is the energy of motion

• Air molecules have mass, and wind is moving air. Thus, wind has kinetic energy. • Wind turbines convert the wind’s kinetic energy into mechanical kinetic energy (spinning the rotor). • Mass = density * volume: m  rV • What is the kinetic energy of a 1m cube of air moving at 5 m/s in Colorado (r = 1 kg/m3)?

1 2 KE  mv 2

Energy Conservation and Energy Conversion
• When the turbine extracts kinetic energy from the wind, the speed of the wind is reduced.

• Some of the wind’s kinetic energy is converted into mechanical kinetic energy, i.e., the rotation of the turbine rotor. • Some of the wind’s kinetic energy remains in the wind (conservation of energy).

1 2 KE  mv 2

KEwind

in

 KEturbine  KEwind

out

Speed and Power Relations
• The kinetic energy in air of mass “m” moving with speed V is given by the following in SI units:

• The power in moving air is the flow rate of kinetic energy per second. Therefore:

• The volumetric flow rate is A·V, the mass flow rate of the air in kilograms per second is ρ·A·V, and the power is given by the following:

Power Extracted from the Wind • The actual power extracted by the rotor blades is the difference between the upstream and the downstream wind powers



The mechanical power extracted by the rotor, which is driving the electrical generator, is therefore:

• Cp is the fraction of the upstream wind power, which is captured by the rotor blades. The remaining power is discharged or wasted in the downstream wind. • The factor Cp is called the power coefficient of the rotor or the rotor efficiency.

Betz Limit

• All wind power cannot be captured by rotor or air would be completely still behind rotor and not allow more wind to pass through. • Theoretical limit of rotor efficiency is 59% • Most modern wind turbines are in the 35 – 45% range

Rotor Swept Area The output power of the wind turbine varies linearly with the rotor swept area. For the horizontal axis turbine, the rotor swept area is given by:

For the Darrieus vertical axis machine, determination of the swept area is complex, as it involves elliptical integrals.

Power Coefficient
• Power coefficient Cp is a measure of the aerodynamic efficiency of the wind turbine
Protor Q C p aero   1 Pwind 2 rAv 3

– Q = turbine’s aerodynamic torque – W = rotor rotational speed – Betz limit - theoretical maximum
16 C p  Betz    0.5926 27

Cp for Various Configurations

Air Density
• The wind power varies linearly with the air density sweeping the blades. The air density varies with pressure and Temperature in accordance with the gas law:

Wind Speed Distribution
• • • • • • • • Having the cubic relation with the power, the wind speed is the most critical data needed to appraise the power potential of a candidate site. The wind is never steady at any site. It is influenced by the weather system, the local land terrain, and the height above the ground surface. The wind speed variesby the minute, hour, day, season, and year. Therefore, the annual mean speed needs to be averaged over 10 or more years. Such a long term average raises the confidence in assessing the energycapture potential of a site. However, long-term measurements are expensive, and most projects cannot wait that long. In such situations, the short term, say one year, data is compared with a nearby site having a long term data to predict the long term annual wind speed at the site under consideration. This is known as the “measure, correlate and predict (mcp)” technique. The wind-speed variations over the period can be described by a probability distribution function.

Why do windmills need to be high in the sky??

Importance of Wind Speed
• No other factor is more important to the amount of power available in the wind than the speed of the wind • Power is a cubic function of wind speed – VXVXV • 20% increase in wind speed means 73% more power • Doubling wind speed means 8 times more power

Wind Speed Distribution
Weibull Distributions
0.250

0.200
Proportion of Time

0.150

0.100

0.050

0.000 0 2 4 6 8 10 12 14 16 18 20 Wind Speed Bin (m/s) AWS = 5.0 m/s k = 2.0 PD = 146 watts/m^2 AWS = 5.0 m/s k = 3.0 PD 108 watts/m^2 AWS = 6.0 m/s k = 2.0 PD = 253 watts/m^2

• Weibull Probability Distribution

The variation in wind speed are best described by the Weibull probability distribution function ‘h’ with two parameters, the shape parameter ‘k’, and the scale parameter ‘c’. Effect of Height The wind shear at ground surface causes the wind speed increase with height in accordance with the expression

• Energy Distribution

• It is advantageous to design the wind power to operate at variable speeds in order to capture the maximum energy available during high wind periods.

Lift & Drag
• The Lift Force is perpendicular to the direction of motion. We want to make this force BIG. α = low

α = medium <10 degrees

• The Drag Force is parallel to the direction of motion. We want to make this force small.

α = High Stall!!

Wind Turbine Design

Airfoil
Just like the wings of an airplane, wind turbine blades use the airfoil shape to create lift and maximize efficiency.

Twist & Taper
• • Twist from blade root to the tip is used to optimize the angle of attack all along blade and result in a constant inflow along the blade span Taper is used to reduce induced drag and increase the L/D ratio

Tip-Speed Ratio
ΩR

Tip-speed ratio is the ratio of the speed of the rotating blade tip to the speed of the free stream wind. There is an optimum angle of attack which creates the highest lift to drag ratio. Because angle of attack is dependant on wind speed, there is an optimum tip speed ratio

R

Where, Ω = rotational speed in radians /sec

ΩR TSR = V

R = Rotor Radius V = Wind “Free Stream” Velocity

Wind Turbine Design

Power Coefficient vs Tip Speed Ratio
• Power Coefficient Varies with Tip Speed Ratio • Characterized by Cp vs Tip Speed Ratio Curve
0.4 Cp 0.3 0.2 0.1 0.0 0 2 4 6 8 Tip Speed Ratio 10 12

Rotor Solidity
Solidity is the ratio of total rotor planform area to total swept area a Solidity = 3a/A
Low solidity (0.10) = high speed, low torque High solidity (>0.80) = low speed, high torque

R

A

Wind Turbine Design

Tip-Speed Ratio
• Ratio of the linear speed of the tip of the blade to the wind speed • Linear speed of a rotating object is angular speed times distance from center of rotation

wR l v
– – – –

l = tip-speed ratio R = rotor radius w = angular speed v = wind speed

• What is the tip-speed ratio of a 20 m diameter rotor rotating at 6 rad/s in 10 m/s wind?

How big will wind turbines be? 2005
1980 1985
150 m2

1990 1995

250 m2

2000

800 m2 1,800 m2 3,700 m2

A= 12,000 m2

2010

Slide courtesy NREL

Elements of Wind Energy Projects
• Wind resource assessment • Environmental assessment • Regulatory approval • Design • Construction
– Roads – Transmission line – Substations

Wind Turbine Components

Wind Turbine Components

Wind Turbine Description
• Components
– Rotor – Gearbox – Tower – Foundation – Controls – Generator
Schematic of a Horizontal Axis Wind Turbine



Types
– Horizontal axis • Most common • Controls or design turn rotor into wind – Vertical axis • Less common

Large Turbine Components
Note railing

SECTIONAL VIEW

Wind Turbine Components

Parts of a Wind Turbine

IMAGE OF A TYPICAL WIND TURBINE

Wind Turbine Perspective
Workers
Blade
112’ long

Nacelle
56 tons

Tower
3 sections

Small Turbine Components



A small turbine has a free-spinning assembly that the wind turns in azimuth by pushing on the tail

LARGE TURBINES: • Able to deliver electricity at lower cost than smaller turbines, because foundation costs, planning costs, etc. are independent of size. • Well-suited for offshore wind plants. • In areas where it is difficult to find sites, one large turbine on a tall tower uses the wind extremely efficiently.

SMALL TURBINES:  Local electrical grids may not be able to handle the large electrical output from a large turbine, so smaller turbines may be more suitable.  High costs for foundations for large turbines may not be economical in some areas.  Landscape considerations

Wind Turbines: Number of Blades

 Most common design is the three-bladed turbine. The most important reason is the stability of the turbine. A rotor with an odd number of rotor blades (and at least three blades) can be considered to be similar to a disc when calculating the dynamic properties of the machine.  A rotor with an even number of blades will give stability problems for a machine with a stiff structure. The reason is that at the very moment when the uppermost blade bends backwards, because it gets the maximum power from the wind, the lowermost blade passes into the wind shade in front of the tower.

Number of Blades: One
• Rotor must move more rapidly to capture same amount of wind – Gearbox ratio reduced – Added weight of counterbalance negates some benefits of lighter design – Higher speed means more noise, visual, and wildlife impacts • • • Blades easier to install because entire rotor can be assembled on ground Captures 10% less energy than two blade design Ultimately provide no cost savings

Number of Blades: Two
• • Advantages & disadvantages similar to one blade Need teetering hub and or shock absorbers because of gyroscopic imbalances Capture 5% less energy than three blade designs



Number of Blades: Three
• • Balance of gyroscopic forces Slower rotation – increases gearbox & transmission costs – More aesthetic, less noise, fewer bird strikes

Blade Material: Wood
Wood – Strong, light weight, cheap, abundant, flexible – Popular on do-it yourself turbines • • • • Solid plank Laminates Veneers Composites

Blade Material: Metal
• Steel – Heavy & expensive • Aluminum – Lighter-weight and easy to work with – Expensive – Subject to metal fatigue

Blade Material: Fiberglass
• Lightweight, strong, inexpensive, good fatigue characteristics Variety of manufacturing processes – Cloth over frame – Pultrusion – Filament winding to produce spars Most modern large turbines use fiberglass





Wind Turbine
• A wind system transforms the kinetic energy of wind to mechanical or electrical energy. • Wind turbines are mounted on a tower to capture the most energy. • Turbines catch the wind’s energy with their propeller-like blades. • Usually two or three blades are mounted on a shaft to form a rotor. • A blade acts much like an airplane wing.

Wind Turbine Generators
• Wind power generators convert wind energy (mechanical energy) to electrical energy. • The generator is attached at one end to the wind turbine, which provides the mechanical energy. • At the other end, the generator is connected to the electrical grid. • The generator needs to have a cooling system to make sure there is no overheating.

SMALL GENERATORS:  Require less force to turn than a larger ones, but give much lower power output.  Less efficient i.e.. If you fit a large wind turbine rotor with a small generator it will be producing electricity during many hours of the year, but it will capture only a small part of the energy content of the wind at high wind speeds. LARGE GENERATORS:  Very efficient at high wind speeds, but unable to turn at low wind speeds. i.e.. If the generator has larger coils, and/or a stronger internal magnet, it will require more force (mechanical) to start in motion.

Large Wind Turbines
• • • • • • • 450’ base to blade Each blade 112’ Span greater than 747 163+ tons total Foundation 20+ feet deep Rated at 1.5 – 5 megawatt Supply at least 350 homes

Wind Amplified Rotor Platform
• Wind Amplified Rotor Platform (WARP) is a different kind of wind system that is designed to be more efficient and sue less land than wind machines in use today. • The WARP does not use large blades; instead it looks like a stack of wheel rims. • Each module is a pair of small, high-capacity turbines mounted to both of its concave wind amplifier module channel surfaces.

Wind Turbine Capacity
Diameter 60 ft 164 ft 216 ft 279 ft 328 ft 394 ft Capacity 0.10 MW 0.75 MW 1.5 MW 2.5 MW 3.5 MW 5.0 MW

Average Turbine Size
1980 1995 0998-1999 2000-2001 2002-2003 2004-2005 2006 2007 0.25 MW 0.50 MW 0.71 MW 0.88 MW 1.19 MW 1.44 MW 1.60 MW 1.65 MW

Wind Turbine Capacity
• The output of a wind turbine depends on the turbine’s size and the wind’s speed. • Wind speed is a crucial element in projecting turbine performance. • A site’s wind speed is measured through wind resource assessment prior to a wind system’s construction. • Generally, an annual average wind speed greater than 10 mph is required for small wind turbines while larger utility scale wind plants need a slightly higher minimum average wind speed of 13 mph.

Wind Turbine Capacity
• • The power available in the wind is proportional to the cube of its speed. Doubling the wind speed increases the available power by a factor of eight. For example, a turbine operating at a site with an average wind speed of 11 mph could in theory generate 33% more electricity than the one at 10 mph. Therefore, a small difference in wind speed can make a big difference in the capacity.





• Garden State Offshore Energy (GSOE) will employ a propietary deep water foundation • technology which enables wind turbines to be located in deep waters far from shore. • Thanks to these deep water foundations, the GSOE project will be located more than 16 miles offshore, making it virtually invisible from New Jersey's beaches. • From the Music Pier in Ocean City, NJ - the location closest to GSOE project – the wind turbines will be virtually invisible from shore.

Design of wind turbines and wind facilities

Wind turbine technical features
• Wind turbines consist of four main components—the rotor, transmission (gearbox), generator, yaw system, and control systems. Turbines can be direct drive (no gearbox) as well. The nacelle rotates (or yaws) according to the wind direction. Turbines can vary rotational speed, blade pitch, or both. Turbines deployed in multiple groups, called arrays, are arranged to avoid shadowing the wind from turbine to turbine. Turbines can be turned on and off remotely by an operator at a central control station. Turbines don’t spin unless the winds are sufficient to generate electricity, or in extreme winds associated with severe storms.

• • •





Other important wind power terminology
• Turbine power rating --the maximum instantaneous power output of the wind turbine, quoted in Watts. Typical value is 1.5 Megawatts (1.5 million Watts). Turbine energy production --a cumulative amount of energy produced by the wind turbine for a given period, usually a year. Quoted in kilowatt-hours (kWh) or megawatthours (MWh). Capacity factor --the average power output of the wind turbine, as a fraction of its power rating. A typical value is 28 percent. This reflects both the variability of the wind at a site and the efficiency of the turbine. Average wind speed --the long-term average speed of the wind, usually quoted in meters per second. (1 m/s = 2.24 mph). Typical value is 6 m/s. Tower height --the height of the turbine to the hub of the rotor, usually quoted in meters (1 meter = 3.28 feet). Typical values are 80 meters. Wind shear --the speed-up of wind with height, given as the exponent of a power-law equation. Typical low value--.15; high value--.30. Turbulence intensity --the roughness of the wind at a site. This is a dominant criteria for specifying a wind turbine. Typical low value--.15; high value--.30. •











Nacelle

Nacelle and Yaw system

Ref. www.windpower.org

Nacelle

Nacelle Design

Ref. Wind Power Plants, R.Gasch, J.Twele

Nacelle Drive Trains

Ref. Wind Power Plants, R.Gasch, J.Twele

Yaw system

Ref. www.windpower.org

Yawing – Facing the Wind
• Active Yaw (all medium &
large turbines produced today, & some small turbines from Europe)
– Anemometer on nacelle tells controller which way to point rotor into the wind – Yaw drive turns gears to point rotor into wind

• Passive Yaw (Most small
turbines)
– Wind forces alone direct rotor

• Tail vanes • Downwind turbines

Towers
Lattice tower Tubular steel towers, Guyed Pole Tower

Concrete tower

Tower designs

Ref. Wind Power Plants, R.Gasch, J.Twele

The 7.5 MW Jersey-Atlantic Wind Farm

Wind Energy Cost Trend
1979: 40 cents/kWh

2000: 4 - 6 cents/kWh (no subsidy)

• Increased Turbine Size • R&D Advances • Manufacturing Improvements • Operating Experience

NSP 107 MW Lake Benton wind farm 4 cents/kWh (unsubsidized)

2004: 3 - 5 cents/kWh (no subsidy)

 A typical 600 kW turbine costs about $450,000.  Installation costs are typically $125,000.  Therefore, the total costs will be about $575,000.

 The average price for large, modern wind farms is around $1,000 per kilowatt electrical power installed.

 Modern wind turbines are designed to work for some 120,000 hours of operation throughout their design lifetime of 20 years. ( 13.7 years non-stop)

Maintenance costs are about 1.5-2.0 percent of the original cost, per year.

ENVIRONMENT
• Wind energy is considered a green power technology because it has only minor impacts on the environment. Wind energy plants produce no air pollutants or greenhouse gases. However, any means of energy production impacts the environment in some way, wind energy is no different .



Aesthetics and Visual Impacts Elements that influence visual impacts include the spacing, design, and uniformity of the turbines. Birds and Other living Resources Preconstruction surveys can indicate whether birds or other living resources are likely to be affected by wind turbines. Noise Like all mechanical systems, wind turbines produce some noise when they operate. In recent years, engineers have made design changes to reduce the noise from wind turbines. TV/Radio Interference In the past, older turbines with metal blades caused television interference in areas near the turbine. Interference from modern turbines is unlikely because many components formerly made of metal are now made from composites. Global Warming Wind energy can help fight global warming. Wind turbines produce no air emissions or greenhouse gases .









Impacts of Wind Power: Noise
oModern Turbines are relatively quiet oRule of Thumb: Stay about 3 times a hub’s height away from houses

Bird Kill?

Carnage!

Jobs in the Wind Industry

Construction

Operations/ Maintenance

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