11/15/16 1 Wind Power: Now, Tomorrow C.P. (Case) van Dam EME-1 Mechanical Engineering November 14, 2016 How does it function? 11/15/16 2 Wind Turbine Power •  The amount of power generated by a turbine depends on the power in the wind and the efficiency of the turbine: •  Power in wind •  Efficiency or Power Coefficient, Cp: –  Rotor (Conversion of wind power to mechanical power) –  Gearbox (Change in rpm) –  Generator & Inverter (Conversion of mechanical power to electrical power) Power Turbine ! "# $ %& = Efficiency Factor ! "# $ %& × Power Wind ! "# $ %& P w = 1 2 ρA d V w 3 Basic Rotor Performance (Momentum Theory) Wind speed, Vw Air density, ρ Disk area, Ad Power in wind, Pw = 1/2 ρ Vw3 Ad Maximum rotor power, P = 16/27 Pw Rotor efficiency, Cp = P / Pw Betz limit, max Cp = 16/27 = 59.3% 11/15/16 3 Region 4 •  Region 1 Turbine is stopped or starting up •  Region 2 Efficiency maximized by maintaining optimum rotor RPM (for variable speed turbine) •  Region 3 Power limited through blade pitch •  Region 4 Turbine is stopped due to high winds (loads) HAWT Power Characteristics Johnson et al (2005) •  Peak Cp at TSR = 9 •  This Cp is maintained in Region II of power curve by controlling rotor RPM •  In Region III power is controlled by changing blade pitch. HAWT Cp-TSR Curve Jackson (2005) 11/15/16 4 •  Cp = Protor / (1/2 ρ Vw3 Ad) •  Solidity = Blade Area / Ad •  TSR = Tip Speed / Vw •  High power efficiency for rotors with low solidity and high TSR •  Darrieus (VAWT) is less efficient than HAWT Efficiency of Various Rotor Designs Butterfield (2008) Cp Tip Speed Ratio TSR = π D RPM / (60 Vw) kidwind.org C.P. van Dam Dutch Mill 16th century Water pumping, Grinding materials/grain W. Gretz, DOE/NREL Persian grain mill 9th century American Multi-blade 19th century Water pumping - irrigation Brush Mill 1888 First wind turbine 12 kW 17 m rotor diameter Charles F. Brush Special Collection, Case Western Reserve University telos.net/wind Gedser Mill 1956, Denmark Forerunner to modern wind turbines 11/15/16 5 Evolution of U.S. Utility-Scale Wind Turbine Technology NREL Wind Turbine Scale-Up and Impact on Cost U.S. DOE, Wind Vision, March 2015 •  Scale-up has been effective in reducing cost but uncertain if this trend can continue 11/15/16 6 Modern Wind Turbines •  1.0-3.0 MW •  Wind speeds: 3-25 m/s –  Rated power at 11-12 m/s •  Rotor –  Lift driven –  3 blades –  Upwind –  Full blade pitch –  70–120 m diameter –  5-20 RPM –  Fiberglass, some carbon fiber •  Active yaw •  Steel tubular tower •  Installed in plants/farms of 100-200 MW •  ~40% capacity factor –  1.5 MW wind turbine would generate about 5,250,000 kWh per year –  Average household in California uses about 6,000 kWh per year Vestas V90-3.0 MW 11/15/16 7 Technical Specificat ...

1. 11/15/16
1
Wind Power:
Now, Tomorrow
C.P. (Case) van Dam
EME-1
Mechanical Engineering
November 14, 2016
How does it function?
11/15/16
2
Wind Turbine Power
• The amount of power generated by a turbine depends on the
power in

2. the wind and the efficiency of the turbine:
• Power in wind
• Efficiency or Power Coefficient, Cp:
– Rotor (Conversion of wind power to mechanical power)
– Gearbox (Change in rpm)
– Generator & Inverter (Conversion of mechanical power to
electrical power)
Power
Turbine
!
"#
$
%&
=
Efficiency
Factor
!
"#
$
%&
×
Power
Wind

3. !
"#
$
%&
P
w
= 1
2
ρA
d
V
w
3
Basic Rotor Performance
(Momentum Theory)
Wind speed, Vw
Air density, ρ
Disk area, Ad
Power in wind, Pw = 1/2 ρ Vw3 Ad
Maximum rotor power, P = 16/27 Pw
Rotor efficiency, Cp = P / Pw

4. Betz limit, max Cp = 16/27 = 59.3%
11/15/16
3
Region 4
• Region 1
Turbine is stopped or
starting up
• Region 2
Efficiency maximized
by maintaining
optimum rotor RPM
(for variable speed
turbine)
• Region 3
Power limited through
blade pitch
• Region 4
Turbine is stopped
due to high winds
(loads)
HAWT Power Characteristics
Johnson et al (2005)
• Peak Cp at TSR = 9
• This Cp is maintained in Region II of power curve by

5. controlling rotor RPM
• In Region III power is controlled by changing blade pitch.
HAWT Cp-TSR Curve
Jackson (2005)
11/15/16
4
• Cp = Protor / (1/2 ρ Vw3 Ad)
• Solidity = Blade Area / Ad
• TSR = Tip Speed / Vw
• High power efficiency for
rotors with low solidity and
high TSR
• Darrieus (VAWT) is less
efficient than HAWT
Efficiency of Various Rotor
Designs
Butterfield (2008)
Cp
Tip Speed Ratio TSR = π D RPM / (60 Vw)
kidwind.org

6. C.P. van Dam
Dutch Mill
16th century
Water pumping, Grinding materials/grain
W. Gretz, DOE/NREL
Persian grain mill
9th century
American Multi-blade
19th century
Water pumping - irrigation
Brush Mill
1888
First wind turbine
12 kW
17 m rotor diameter
Charles F. Brush Special Collection,
Case Western Reserve University
telos.net/wind
Gedser Mill
1956, Denmark
Forerunner to modern wind
turbines
11/15/16

7. 5
Evolution of U.S. Utility-Scale
Wind Turbine Technology
NREL
Wind Turbine Scale-Up and Impact on Cost
U.S. DOE, Wind Vision, March 2015
• Scale-up has been effective in reducing cost but uncertain if
this trend can continue
11/15/16
6
Modern Wind
Turbines
• 1.0-3.0 MW
• Wind speeds: 3-25 m/s
– Rated power at 11-12 m/s
• Rotor
– Lift driven
– 3 blades
– Upwind
– Full blade pitch
– 70–120 m diameter
– 5-20 RPM
– Fiberglass, some carbon fiber

8. • Active yaw
• Steel tubular tower
• Installed in plants/farms of 100-200 MW
• ~40% capacity factor
– 1.5 MW wind turbine would generate
about 5,250,000 kWh per year
– Average household in California uses
about 6,000 kWh per year
Vestas
V90-3.0
MW
11/15/16
7
Technical Specifications -
Vestas V90
• Rotor
– Diameter 90 m
– Swept area 6,362 m2
– Nominal rpm 16.1→Tip speed= π⋅ D⋅ rpm/60 = 75.9 m/s
– Operational range 8.6 - 18.4 rpm
– Number of blades 3
– Power regulation Pitch/OptiSpeed
(Note, OptiSpeed not available in USA and Canada)
– Brake Independent blade pitch

9. (Three separate hydraulic pitch systems)
• Tower
– Hub height 80 m, 105 m
Technical Specifications -
Vestas V90
• Operational data
– Cut-in wind speed 4 m/s
– Nominal wind speed 15 m/s
– Cut-out wind speed 25 m/s
• Generator
– Type Asynchronous with OptiSpeed
– Rated output 3,000 kW
– Operational data 50 Hz, 1000 V
• Gearbox
– Type Two planetary and one helical stage
• Weight
– Nacelle 70 t
– Rotor 41 t
– Tower
• 80 m, IEC IA 160 t
• 105 m, IEC IIA 285 t
11/15/16
8
Wind Turbine Blade Diagram

10. de Vries, Windpower Monthly, 1 July 2012
Why wind energy?
11/15/16
9
Why Wind Energy?
• Renewable
– Guaranteed “fuel” availability
– Many regions in world are wind energy rich
– No cost volatility
• Clean
– Emission free operation
– No waste generation
• Installation
– Rapidly deployed
• Security
– Non-centralized installation and operation
– No imported fuel requirement
• Economics
– Cost effective energy
– Local economic benefits
• Does not rely on water
E. Mayda

11. • 1980s: U.S. was the leader in
installed wind power capacity
• 1990s: other countries quickly
outpaced the U.S.
• 2000s: US installations rapidly
increased, driven by competitive
pricing and favorable policies
• 2012: Record new capacity
• 2013-present: Significant
concern and uncertainty over
Production Tax Credit (PTC)
status, record low natural gas
prices, competition from PV
Historical Trend
in Installed Wind
Power Capacity
11/15/16
10
Global Installed Wind Power
Capacity
Percentage Energy Consumption from Wind
U.S. DOE, Wiser & Bolinger (2015)

12. 11/15/16
11
U.S. Wind Power Potential
Source: DOE/NREL
USA Installed Wind Power
Capacity
11/15/16
12
Why Wind Energy?
• Renewable
– Guaranteed “fuel” availability
– Large available resource in USA
– No cost volatility
• Clean
– Emission free operation
– No waste generation
• Installation
– Rapidly deployed
• Security
– Non-centralized installation and
operation
– No imported fuel requirement

13. • Economics
– Cost effective energy
– Local economic benefits
• Does not rely on water
C.P. van Dam
WA: 15% x 2020*
OR: 50%x 2040*
(large utilities)
CA: 50%
x 2030
MT: 15% x 2015
NV: 25% x
2025* UT: 20% x
2025*†
AZ: 15% x
2025*
ND: 10% x 2015
NM: 20%x 2020
(IOUs)
HI: 100% x 2045
CO: 30% x 2020
(IOUs) *†

14. OK: 15% x
2015
MN:26.5%
x 2025 (IOUs)
31.5% x 2020 (Xcel)
MI: 10% x
2015*†WI: 10%
2015
MO:15% x
2021
IA: 105 MW IN:
10% x
2025†
IL: 25%
x 2026
OH: 12.5%
x 2026
NC: 12.5% x 2021 (IOUs)
VA: 15%
x 2025†KS: 20% x 2020
ME: 40% x 2017
29 States +
Washington DC + 3
territories have a Renewable
Portfolio Standard

15. (8 states and 1 territories have
renewable portfolio goals)Renewable portfolio standard
Renewable portfolio goal Includes non-renewable alternative
resources* Extra credit for solar or customer-sited renewables†
U.S. Territories
DC
TX: 5,880 MW x 2015*
SD: 10% x 2015
SC: 2% 2021
NMI: 20% x 2016
PR: 20% x 2035
Guam: 25% x 2035
USVI: 30% x 2025
NH: 24.8%x 2025
VT: 75% x 2032
MA: 15% x 2020(new resources)
6.03% x 2016 (existing resources)
RI: 38.5% x 2035
CT: 27% x 2020
NY:50% x 2030
PA: 18% x 2021†

16. NJ: 20.38% RE x 2020
+ 4.1% solar by 2027
DE: 25% x 2026*
MD: 20% x 2022
DC: 20% x 2020
Renewable Portfolio Standard Policies
www.dsireusa.org / August 2016
11/15/16
13
California Wind Resource
• California wind maps. Developed by AWS Truepower for
CEC
• Mean annual wind speed at 30, 50, 70, 100 m heights at 200
m spatial resolution
• Maps indicate limited onshore resource except for several
areas: San Gorgonio, Tehachapi, Altamont, Solano
CA Energy Future
• California has an aggressive Renewables Portfolio Standard
(RPS). This standard requires all utilities to adopt the following
RPS targets:
- An average of 20% of retail sales from renewables in 2011-
2013.
- 25% by the end of 2016.
- 33% by the end of 2020.

17. - 50% by the end of 2030.
• In 2012, California served about 22% of retail electricity
sales
from facilities using renewable energy sources such as wind,
solar, geothermal, biomass, and small hydroelectric.
• The CEC estimates that this electricity was generated from
about
12,300 MW of wholesale generation and 1,600 MW of self-
generation.
• CA operating renewable energy capacity grew from 14,100
MW
in 2012 to 17,400 MW in 2013.
• On track to meet or exceed 33% RPS by 2020
- + rooftop PV - 5%
- + large hydro - 10% Source: CEC
11/15/16
14
CA Generation Mix 2013
Source: CEC
California High Renewable Day
Saturday, 12 April 2014
Renewables at 42.2% of load
Renewables at 31.9% of 24 hr load

18. Source: CAISO
Hour of Day
11/15/16
15
Source: CAISO
Hour of Day
Wind 19.9% of load
California High Renewable Day
Saturday, 12 April 2014
1. Downward ramping capability
Thermal plants to serve load at night
ramped down to deal with influx of
solar after sunrise
2. Minimum generation flexibility
Thermal resources must have lower
minimum generation levels to
minimize overgeneration
3. Upward ramping capability
Thermal resources must have quick
start up and ramp up capabilities to
deal with sundown loss in solar and
peak load

19. 4. Peaking capability
System must be capable to meet
reliably peak loads
5. Sub-hourly flexibility
System flexibility needed to meet
sub-hourly ramping
Source: E3 - Energy+Environmental Economics
50% RPS Provides New
Challenges
11/15/16
16
50% RPS Study Conclusions &
Recommendations
• 50% RPS does not face major technical hurdles
• May lead to overgeneration conditions during
daylight hours
• Will lead to higher electricity rates than 33% RPS
•
Solution
s to mitigate operational challenges and

20. reduce cost:
- Increase regional coordination - sharing of flexible
resources across WECC territory
- Develop diverse portfolio of renewable resources
- Implement long-term, sustainable solutions to address
overgeneration
- Implement distributed generation solutions
Source: E3 - Energy+Environmental Economics
Why Wind Energy?
• Renewable
– Guaranteed “fuel” availability
– Large available resource in USA
– No cost volatility
• Clean
– Emission free operation
– No waste generation
• Installation
– Rapidly deployed

21. • Security
– Non-centralized installation and
operation
– No imported fuel requirement
• Economics
– Cost effective energy
– Local economic benefits
• Does not rely on water
C.P. van Dam
11/15/16
17
Rapid Deployment of Wind
Turbines
• Windplant requires

22. installation of:
– Access roads
– Underground power
collection system
– Underground
communication system
– Turbine foundations
– Towers
– Nacelles
– Rotors
• 100 turbine, 150 MW
plant can be completed
and on-line in 6 months
C.P. van Dam
Why Wind Energy?
• Renewable
– Guaranteed “fuel” availability
– Large available resource in USA
– No cost volatility

23. • Clean
– Emission free operation
– No waste generation
• Installation
– Rapidly deployed
• Security
– Non-centralized installation and
operation
– No imported fuel requirement
• Economics
– Cost effective energy
– Local economic benefits
• Does not rely on water
C.P. van Dam
11/15/16

24. 18
Why Wind Energy?
• Renewable
– Guaranteed “fuel” availability
– Large available resource in USA
– No cost volatility
• Clean
– Emission free operation
– No waste generation
• Installation
– Rapidly deployed
• Security
– Non-centralized installation and
operation
– No imported fuel requirement
• Economics
– Cost effective energy

25. – Local economic benefits
• Does not rely on water
C.P. van Dam
Wind and Wholesale Energy Prices
U.S. DOE, Wiser & Bolinger (2015)
0
10
20
30
40
50
60
70

26. 80
90
100
2003
9
570
2004
13
547
2005
17
1,643
2006
30
2,311

27. 2007
26
1,781
2008
39
3,465
2009
49
4,048
2010
48
4,642
2011
42
4,572

28. 2012
14
985
2013
26
3,674
2014
13
1,768
2
0
1
4
$
/M
W
h
NationwideWholesalePowerPriceRange(bycalendaryear)

29. Generation-
WeightedAverageLevelizedWindPPAPrice(byyearofPPAexecuti
on)
Windprojectsampleincludesprojects
withPPAssignedfrom2003-2014
PPAyear:
Contracts:
MW:
11/15/16
19
Why Wind Energy?
• Renewable
– Guaranteed “fuel” availability
– Large available resource in USA
– No cost volatility

30. • Clean
– Emission free operation
– No waste generation
• Installation
– Rapidly deployed
• Security
– Non-centralized installation and
operation
– No imported fuel requirement
• Economics
– Cost effective energy
– Local economic benefits
• Does not rely on water
C.P. van Dam
Water and Energy
Jane Woodward
“The Evolving Energy Revolution”

31. BioForum: Energy Prospects in a Changing World
California Academy of Sciences
13 September 2008
“Water will emerge as a major factor in
energy supply, prices and choices”
11/15/16
20
But it is not easy!
• Key factors for a successful wind energy
project
– Appropriate Site
• Wind regime
• Site size, shape, topography
• Transmission
• Land owners, host community

32. • Accessibility
• Constructability
• Airports and radar installations
• Habitat
• Power demand
• Energy pricing
– Appropriate Technology
• Turbine
• Manufacturer support
– Appropriate Participants
• Expertise and financial strength
• Documentation
• Tax appetite
• Skilled transport & construction
• Skilled O&M provider Source: GEC (2007)
UC Davis
Why Offshore Wind?
• Terrestrial wind power sites saturated
• Excellent wind resource
– High wind speeds

33. – Low turbulence
– Near load centers
• Remotely located
• No road transportation constraints
– Larger turbines
• Local economic benefits
– Jobs
– Infrastructure
– Taxes
11/15/16
21
2 - 41
California Offshore Wind
Potential & Operating
Environment

34. Source: Schwartz et al, 2010
GW by Depth (m)
Region 0-30 30-60 >60 Total
California 4.4 10.5 573.0 587.8
Pacific Northwest 15.1 21.3 305.3 341.7
Source: Elliott et al, 2011
Source: NREL
Statoil Hywind
Turbine rated
capacity 2.3 MW
Turbine weight 138 tons
Draft hull 100 m
Nacelle height 65 m

35. Rotor diameter 82.4 m
Water depth 200 - 220 m
Displacement 5300 m3
Mooring 3 lines
Diameter at water
line 6 m
Diameter of
submerged body 8.3 m
November 2013: The Crown
Estate approved lease for
30MW Hywind project 20-30
kilometers off Scotland
Source: Statoil
11/15/16

36. 22
Principle Power
Source: Banister, Principle Power, July 2014
• Principle Power WindFloat-1
(2 MW) installed off northern
Portugal in October 2011;
still producing today
• Generated and delivered
over 10 GWh of energy to
Portuguese grid
• Technical availability 93%
• Performed through extreme
weather events, including
waves over 15 m
• Energy output consistent
with onshore turbine under
same wind conditions
• WindFloat-2 (6 MW)

37. projected for installation off
Oregon Coast. Total
installation 5 WF-2
WF-1 WF-2
Principle Power Project Site
Source: Banister, Principle Power, July 2014
• Lease application
filed with BOEM
on 14 May 2013
• Lease issuance
target Q2 2015
• Commissioning
target before end
2017
• Approx. 18 miles
offshore
• Project will be in
about 350+ meters

38. (1,200 ft) of water
• Generally sandy/
silly bottom
11/15/16
23
Marine Development Parties in CA
Selected agencies
• Bureau of Ocean Energy
Management
• California Governor’s Office
• California Energy Commission
• California Public Utilities
Commission
• California Fish and Wildlife
• U.S. Fish and Wildlife
• National Oceanic and

39. Atmospheric Administration
– National Marine Fisheries
Services
– National Marine Sanctuaries
– Office of Ocean and Coastal
Resource Management
• California State Lands
Commission
• California State Parks
• National Park Service
• U.S. Defense Department
– Army
– Navy
– Air Force
– Coast Guard
• Ocean Protection Council
• California Coastal Commission
• Federal Energy Regulatory

40. Commission
• County agencies
Final Observations -
Offshore Wind Power
• Great Opportunity
– Bountiful energy
resource
– Near load centers
– Benefits from
extensive onshore
technical and
regulatory
experience
– Leverage experience
from other industries
• Oil and gas
industry

41. • Great Challenge
– Young industry
– Costs are currently
high
– Lack of established
infrastructure
• Coastal facilities
• Ships
– Cost challenges
• Larger turbines
• Deep water /
floating platforms
• Maintenance
– New environmental
considerations
– Complex regulatory
process with limited
experience

42. C.P. van Dam