5/27/2009
TOPICS
Fundamentals of Wind Energy
(Wind--Diesel 101)
(Wind
E. Ian Baring-Gould,
National Wind
Technology Center &
Deployment &
Industrial Partnerships
Centers
May 31st 2009
Introduction
Energy and Power
Wind Characteristics
Wind Power Potential
Basic Wind Turbine Theory
Types of Wind Turbines
Review of Small and Large Turbines
Review of the Current Wind Market
Further Information
NREL is a national laboratory of the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy operated by the Alliance for Sustainable Energy, LLC
1400-1800 years go,
in the Middle East
What is Wind Power
800-900 years ago,
in Europe
140 years ago,
water-pumping
wind mills
ENERGY AND POWER
ENERGY: The Ability to do work
70 years ago,
electric power
Electrical energy is reported in kWh and may
be used to describe a potential, such as in
stored energy or the amount of energy used
over a time period, like 1000 kWh per day
POWER: Force at any instant
The amount of energy needed at any instant
in time. Represents current generation and
constraints such as Generator Size or an
instantaneous load which is measured in kW
The ability to
harness the power
available in the
wind and put it to
useful work.
Power in the Wind
Power from the Wind
P = 0.5 ρ v3
P = 0.5 ρ v3 Cp AS
P: power, Watt
Cp = Coefficient of
Performance (an
efficiency term)
ρ: density of air,
air kg/m3
V: wind speed, m/s
(W/m2)
We call this the Wind Power Density
which is a measure of the power available in
the wind at a specific point or as an average
over a longer period of time
AS = The swept area of the
wind turbine blades
Multiplied by time give you
Energy…
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Critical Aspects of Wind Energy
Velocity – The Impact on Increasing
Wind Speed
A small
increase in
wind speed
can increase
i
the power
greatly
V3: Doubling of the wind speed results in
an 8 fold increase in power
ρ: High density air results in more power
(altitude and temperature)
As: A slight increase in blade length,
increases the area greatly
Cp: Different types of wind turbines have
different maximum theoretical
efficiencies (Betz limit ≈0.593) but
usually between .4 and .5
3,000
2,000
1,000
30%
0.2
20%
0.1
10%
0%
4
5
6
7
Average Wind Speed, m/s
8
9
500 kW
2
1257 m
1000 kW
2400 m2
0
70
75
80
85
90
95
100
Density Change Compared to Sea Level, %
Changes with
Temperature
Tem p erature, F
Elevation, ft
Air Density Changes with
Elevation
4,000
0.3
Swept
Area
8,000
5,000
40%
Capacity Factor (%)
3
9,000
6,000
50%
Annual Energy Output
0.4
0.0
10,000
7,000
0.5
A nnual E ne rgy, M W h
P = 0.5 ρ Cp v3 AS
300 kW
110
100
90
80
70
60
50
40
30
20
10
0
-10
-20
-30
-40
415 m 2
2
25 kW 78 m
10 kW 38 m
90
95
100
105
110
115
120
125
1 kW 6 m
2
2
A = (π D )
4
2
Density Change Compared to 59 F, %
Wind Characteristics and
Resources
Understanding the wind resource at your
location is critical to understanding the
potential for using wind energy
• Wind Speed
– Wind Profile
– Wind classes
– Collection and reporting
• Wind Direction
• Wind speed change with height
Wind Speed
• Measured in m/s or mph
• Varies by the second,
hourly, daily, seasonally
and year to year
• Usually has patterns
– Di
Diurnall - it always
l
bl
blows iin
the morning
– Seasonal – The winter
winds are stronger
– Characteristics – Winds
from the sea are always
stronger and are storm
driven.
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So, which is better…
Wind Maps and Class
1. A location where the wind that blows only
50% of the time at 10 m/s but is calm the
rest of the time
2. A location where the wind that blows all of
the time at 5 m/s
Careful:
Wind class is defined
at a specific height
P = 0.5 ρ Cp v3 AS
Both have exactly the same annual average
wind speed…
Wind Direction
Wind Speed Data Collection and
Reporting
1600
1400
1000
800
600
400
200
0
0
1
2
3
4
5
6
7
8 9
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
Wind Speed (m/s)
Wind Rose
Wind Speed Rose
CONTINENTAL
TRADE WINDS
Can also have a wind
direction change intensity
– similar to turbulence
Impacts on Wind Speed
Many things impact the
speed and direction of the
wind at any specific
location, making local
measurements important
Wind Speed Increases with Height
• Because of friction
with the earth, air
closer to the surface
moves more slowly
• The farther we get
away from the earth
(increase in altitude)
the higher the wind
speed gets until it is
no longer effected by
the earths surface
140
12:10
12:20
12:30
12:40
12:50
Pow er Law
Log Law
120
100
Height, m
Time (Hours)
1200
Collection
• Measured every 1
or 2 seconds
• Averaged every 10
or 15 minutes
• Reported as hour
averages
Turbulence Intensity
Wind Speed
Frequency of
Occurrence
Histogram based
on hour average
data for a year
80
60
40
20
0
0
2
4
6
Wind Speed, m/s
8
10
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⎡h ⎤
VN = VO ⎢ N ⎥
⎣ hO ⎦
Wind Shear
Height
Wind Speed, m/s
m
50
12.6
• The type of
surface
(grass,
trees)
impacts the
wind shear
• Real vs.
apparent
height
12.2
40
11.7
30
11
20
10
8.8
10
5
0
N
Factoring in Measurement Height
The Power Law
⎡h ⎤
VN = VO ⎢ N ⎥
⎣ hO ⎦
VN: Wind speed at new height,
VO: Wind speed at original height,
hN: New height,
hO: Original height,
N: Power law exponent
exponent.
N
Terrain
Water or ice
Low grass or steppe
Rural with obstacles
Suburb and woodlands
Power Law Exponent
0.1
0.14
0.2
0.25
---------------------------------------------------------------------------------------------------------------------Source: Paul Gipe, Wind Energy Comes of Age, John Wiley and Sons Inc, 1995, pp 536.
------------------------------------------------------------------------------------------------------------------------
SURFACE
Micro-Siting Example:
Obstruction of the Wind by a Small Building
Height Impacts on Power
Increase Comparred to 30 ft
3.50
Wind Speed Increase
Wind Power Increase
3.00
2 50
2.50
Prevailing wind
2.00
1.50
H
Region
of highly
disturbed
flow
2H
1.00
0
50
100
150
200
250
Tower Height, ft
2H
20H
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Aerodynamic Drag
Basic Wind Turbine Theory
Lift and Drag – The different types of
wind turbines
Aerodynamics – How turbines work
Power Curves – The performance of
wind turbines
Power Availability - Power your can
get from the wind
Different types of lift turbines
PANEMONE TURBINE
CUP
FLAP PLATE
shield
rotation
WIND
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Classic Drag Devices
Some Modified Drag Devices
Aerodynamic Lift
Lift Wind Turbines
Wind Turrbine Power (kW)
WTG Power Curve
18
16
14
Important Terms
Rated
wind speed
12
10
8
6
4
2
0
Cut out
wind speed
Cut in
wind speed
0
5
10
15
Wind Speed (m/s)
20
25
30
• Cut in wind speed: The wind speed that the turbine
starts producing power (may be different than the
speed at which the turbine starts spinning)
• Rated Wind Speed: The wind speed at which the
turbine is producing “rated power” – though “rated
power” is defined by
p
y the manufacture
• Cut out wind speed: The wind speed at which the
turbine stops producing power
• Shut down wind speed: The wind speed at which the
turbine stops to prevent damage
• Survival wind speed: Wind speed that the turbine is
designed to withstand without falling over
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Wind Speed Frequency of Occurrence
Wind Turbine Power Curve
Average Wind Speed: 5 m/s (11 mph)
Bergey 1500 (manufacturer’s data)
1600
1.8
1.6
1400
1.4
1200
Time (Hou
urs)
Power (kW
W)
1.2
1
0.8
1000
800
600
0.6
400
0.4
200
0.2
0
0
0
1
2
3
4
5
6
7
8 9
10 11 12 13 14 15 16 17 18 19 20 21 23 23 24 25
0
1
2
3
4
5
6
7
8 9
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
Wind Speed (m/s)
Wind Speed (m/s)
Annual Energy Production: 2643 kWh/year
Bergey 1500 @ 5 m/s (11 mph) average wind speed
Types of Lift Turbines
HAWT
VAWT
450
400
Energy
y (kWh)
350
300
250
200
150
100
50
0
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
Wind Speed (m/s)
All available energy may not be captured
Basic Properties of HAWT
•
•
•
•
Basics of a horizontal axis wind turbine
Types of turbines
Small distributed turbines
Large grid connected turbines
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5/27/2009
Parts of a Wind Turbine
Basic Motion of a Wind Turbine
Pitch
Rotation
Rotor
Yaw
Different Types of Wind Turbines
• Utility-Scale Wind Power
Small (≤10 kW)
600 - 5,000 kW wind turbines
1,500 kW
– Installed on wind farms, 10 – 300 MW
– Professional maintenance crews
– Classes 5 and 6 (> 6 m/s average)
• Distributed Wind Power
Sizes and Applications
300 W - 600 kW wind turbines
10 kW
Homes
Farms
Remote Applications
(e.g. water
pumping, telecom
sites icemaking)
sites,
Intermediate
(10-250 kW)
Village Power
Hybrid
Systems
Distributed
Power
– Installed at individual homes, farms,
businesses, schools, etc.
Large (250 kW – 2+
MW)
– On the “customer side” of the meter
– High reliability, low maintenance
– Classes 2 and 3 (5 m/s average)
Turbine Blade
Alternator
(Permanent Magnet)
Central Station Wind
Farms
Distributed Power
Small wind
turbines
Nacelle
Tail Boom
Tail Vane
Nose Cone
Tower Adapter
(contains slip rings)
Tower
• Typically use a
permanent magnet
alternator
• Generates wild AC
(variable voltage and
f
frequency)
) power th
thatt
must be treated.
• Can provide AC or DC
power
• Passively controlled
Overspeed Protection of Small WTG
During High Winds
Furling: The rotor
turns out of the
wind during high
winds to reduce
power
• Used to control
rotor speed and
power output
• Dynamic activity
• Can cause noise
issues (flutter)
• Not all small wind
turbines do this
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5/27/2009
Small Wind Turbine Towers
Tilt-Up Towers
• Guyed lattice and tube
towers are the least
expensive and
most commonly used towers
for small wind turbines
• Adequate space is needed
for the guy wires and their
anchors
• Free-standing towers are
used where space is limited
Turbine installation in
remote areas can be a
problem.
To solve this problem:
• Tilt-up versions of guyed
towers are available for
easier installation and
maintenance.
• Self erecting technology
also used wisely
Small Wind Turbine
Maintenance and Lifetime
The Wind Turbine Controller
• Battery-Charging
• “Low maintenance” not “no
maintenance”
– Converts AC power to DC for battery-charging
– Regulates the battery voltage to prevent overcharging
– When the battery is fully charged:
• Inspection and maintenance every
year: tightening bolts and electrical
connections, inspecting slip ring
brushes, checking for corrosion, etc.
• Between 2 and 4 years: blade leading
edge tape may need replacement
• Beyond 5-10 years: blade or bearing
replacement may be needed
• Power is diverted to another load, or …
• The rotor is unloaded
nloaded and allowed
allo ed to
“freewheel”
• Grid Interconnection
– “Inverter,” converts the power to
constant frequency 60 Hz AC
• Lifetimes of 10 to 20 years are
possible
• Water Pumping
– Direct connection to the pump
• Some Jacobs wind turbines have
been operating for
more than 60 years with periodic
maintenance!
Small turbines – the Wild West of Wind
“Hot Tips” on Small Wind Energy
• “Buy Reliability”
“Based on experience, I side with the ‘school of heavy
metal,’ those who believe that beefiness of
components is directly related to the longevity of the
equipment.” M. Sagrillo, small wind turbine expert
• “Taller is Better”
Taller towers give better performance due to smoother
wind and higher wind speeds
• “Micro-Siting”
For best performance, locate wind turbines above and
away from obstructions to the wind
• Small Wind Turbine industry is unorganized & lacks
working standards
– Currently, Third party certification is typically limited to the
inverter (UL 1740)
– Limited 3rd party testing & certification
• Current IEC small turbine testing standard generally
not used due to the expense
• Small wind turbine testing & certification schemes for
North America are under development (Small Wind
Certification Council [SWCC, AWEA Small Wind Test
Standard (in draft stage)]
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5/27/2009
Large Wind Turbines
Questions to Ask about SWT
• What level of certification does
the turbine have?
• Is a power curve available? If
so, how was it developed?
• Has the turbine been previously
installed? (In the U.S., near the
proposed site)
• How many units have been
deployed?
• Is there any sort of dealer
infrastructure?
• How long has the manufacturer
been in business? (What is the
experience of the company key
personnel?)
• Is the inverter UL listed? (Grid
tied systems)
Parts of a Wind
Turbine Power Plant
• Typically
induction or
variable speed
permanent
magnet
generators
• Create AC
power supplied
to the grid
• Actively
controlled
Loopwing Tromc
Hush Turbine 3000
Vertikalrotor 500
Skystream 2400
Windkraft 500
Windport 5000
http://www.allsmallwindturbines.com/
Nacelle
Characteristics of Large WTG
Blades
Boeing 747-200
Tower
Control of Large WTG
Fixed Pitch (Stall regulated): The shape of the blade
varies over its length so that as wind speed increase
parts of the blade stop producing lift and limit power.
Variable Pitch: The rotation (pitch) of each blade is
individually controlled to control lift
Yaw: Motors control yaw behavior based on a wind
direction vain, used to shut down wind turbine in high
winds but can also be a source of problems.
Brake: All wind turbines are required to have two of
them but there are several types:
Power Types
• Induction (Constant speed)
• Permanent Magnet (Variable
speed) using power electronics
Power System
y
Efficiencies
• Aerodynamic
• Rotor
• Drive train / gear box
• Generator
• Power Conversion (if applicable)
Other Large (and Small) Turbines
Considerations
•
•
•
•
•
Policy
Siting
Transmission
External Conditions
Intermittency
Aerodynamic: Flaps on the blades that cause drag.
Mechanical: Disks or calipers, like your car.
Electrical: using the generator to cause electrical resistance.
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5/27/2009
Avian (Bird) Research
Policy
• Encourage economic
development and use
of local resources
• facilitate “green”
markets
• Federal, state and
local incentives such
as the Production Tax
Credit (PTC) and
Renewable Portfolio
Standards (RPS)
Siting
• Avian and other
wildlife
• Noise
• Visual Impact
• Land Ownership
•
Over 200 projects, two problem sites.
•
Biggest problem was in the Altamont Pass.
•
Managed by careful site selection.
Nysted Windfarm - Denmark
External Conditions
Transmission
Are Wind Turbines Noisy?
•
•
•
•
• Grid Access
• System studies
• Allocation of available
capacity
• Scheduling and costs
for usage (firm and
non-firm)
fi )
What is the sound
level of a utilityscale turbine?
Remote Systems
• Amount of energy
from wind
• Control of system
voltage and frequency
• Use of excess wind
energy
Intermittency
• Operational Impacts
(ancillary services)
45 decibels at 350
meters
Lightening
Extreme Winds
Corrosion
Extreme temperatures
– voltage/VAR control,
load following, etc.
• 10-20% of system
capacity is reasonable
Current Status of the Wind Industry
Total Global Installed Wind Capacity
Other General Wind Terms
120000
110000
Capacity (MW)
70000
60000
50000
40000
United States: 25,408 MW
Germany: 23,600 MW
Spain: 16,000 MW
India: 9,522 MW
China: 9,500
,
MW
World total 2008: 115,254 MW
30000
20000
10000
06
08
07
20
20
04
03
05
20
20
20
20
00
02
01
20
20
98
97
99
20
19
96
19
Europe
19
19
95
93
United States
19
92
91
94
19
19
90
19
19
19
87
89
19
88
19
86
Source: WindPower Monthly
19
19
83
85
19
19
84
0
19
The stronger the resource the higher the Capacity Factor
Usually reported monthly or yearly
25-40% is typical, up to 60% has been reported
Reason for the “only works 1/3 of the time” quote.
80000
82
–
–
–
–
90000
19
turbine is available to produce power (Maintenance
parameter)
• Capacity Factor: The annual energy production of
a wind
i d tturbine
bi di
divided
id d b
by th
the th
theoretical
ti l production
d ti if
it ran at full rated power all of the time (Resource
parameter)
1.
2.
3.
4.
5.
100000
• Availability: The amount of time that the wind
Rest of World
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5/27/2009
Major Source of New Generation Capacity Additions
80
80%
70%
60%
60
50%
40%
40
30%
20
20%
•
•
•
•
•
2008: 42%
2007: 35%
2006: 18%
2005: 12%
2000-04: <5%
80
Wind project sample includes
projects built from 1998-2008
70
2008 $/MWh
90%
Total Annual Capacity
dditions (GW)
Ad
Percent of Annual Capacity
Additions
90
100
100%
Wind Has Been Competitive with
Wholesale Power Prices in Recent Years
10%
60
50
40
30
20
Nationwide Wholesale Power Price Range (for a flat block of power)
10
Cumulative Capacity-Weighted Average Wind Power Price
0
0%
0
2000 2001 2002 2003 2004 2005 2006 2007 2008
Wind
Gas (CCGT)
Coal
Total Capacity Additions (right axis)
Other Renewable
Gas (non-CCGT)
Other non-Renewable
Source: EIA, Ventyx, AWEA, IREC, Berkeley Lab
2003
2004
2005
2006
2007
2008
53 projects
66 projects
87 projects
107 projects
127 projects
159 projects
2,467 MW
3,268 MW
4,397 MW
5,810 MW
8,341 MW
11,091 MW
Source: FERC 2006 and 2004 "State of the Market" reports, Berkeley Lab database, Ventyx, ICE
Note: Wholesale price range reflects flat block of power across 23 pricing locations; wind costs represent
capacity-weighted average price for wind power for entire sample of projects built from 1998-2008
The Near-Term Wind has Become Somewhat Less
Attractive
Wind Prices Have Been Rising Since 2002-03…
2008 Po
ower Price (2008 $/MWh)
90
Note: Prices include the value of the PTC
80
70
60
50
40
30
20
Capacity-Weighted Average 2008 Wind Power Price (by project vintage)
10
Individual Project 2008 Wind Power Price (by project vintage)
0
2000-01
2002-03
2004-05
2006
2007
2008
902 MW 1,801 MW 1,717 MW 766 MW 3,425 MW 1,856 MW
• Wind power prices bottomed out with projects built in 2002-03
• Projects built in 2008 are ~$15-20/MWh higher on average
Drivers for Wind Power
•
•
•
•
•
•
•
•
Declining Wind Costs
Fuel Price Uncertainty
Federal and State Policies
Economic Development
Public Support
Green Power
Energy Security
Carbon Risk
2008
2009
Wholesale Price
Range
• Wind prices are likely to increase further in 2009 as installed costs will remain high as
developers work through turbines ordered at peak prices, and given higher equity yields.
• Wholesale price’s are also likely to increase as the economic depression reverses course
Further Information / References
Web Based:
• American Wind Energy Association http://www.awea.org/
• Wind Powering America
http://www.eere.energy.gov/windpoweringamerica/
• Danish Wind Industry Association guided tour and information.
http://www.windpower.org/en/tour/
Publications:
• Ackermann, T. (Ed’s), Wind Power in Power Systems, John Wiley and
Sons west Sussex
Sons,
Sussex, England
England, (2005).
(2005)
• Hunter, R., Elliot, G. (Ed’s), Wind-Diesel Systems. Cambridge, UK:
Cambridge University Press, 1994.
• Wind Energy Explained, J. F. Manwell, J. G. McGowan, A. L. Rogers
John Wiley & Sons Ltd. 2002.
• Paul Gipe, Wind Energy Basics: A Guide to Small and Micro Wind
Systems, Real Goods Solar Living Book.
• AWS Scientific Inc. “Wind Resource Assessment Handbook” produced
by for the National Renewable Energy Laboratory, Subcontract number
TAT-5-15283-01, 1997
Thanks to:
• Ken Starcher, Alternative Energy Institute, West Texas A&M University
11
5/27/2009
Carpe Ventem
E. Ian Baring-Gould
National Wind Technology Center &
Deployment & Industrial Partnerships
Centers
303-384-7021
[email protected]
NREL is a national laboratory of the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy operated by the Alliance for Sustainable Energy, LLC
12