The document discusses the challenges in designing increasingly large wind turbine blades. It outlines trends toward blades that are 75 meters long, compared to 5 meter blades from 30 years ago. Designing longer blades poses challenges like significant tip deflection. Solutions involve optimizing blade shape, using advanced materials like carbon fiber composites, and load reduction techniques. Future challenges include addressing issues like blade leading edge erosion and developing more cost efficient manufacturing and transportation methods. The long term outlook is continued reductions in the cost of wind energy through smarter, more competitive turbine and farm technologies.

1. siemens.com/answersUnrestricted © Siemens AG 2016 All rights reserved.
Large Wind turbine blade design
challenges and R&D Needs
Jacques Nader - Siemens Wind Power

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Outline
q Introduction
q Historic overview
q Trends in blade design
q Future challenges
q Long term outlook

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Wind Power and Renewables Division
Facts at a glance
One of the world’s leading suppliers of wind power solutions
Acquired Danish wind turbine manufacturer Bonus Energy A/S in 2004
Installed Base: > 17,400 turbines with ~ 34 GW capacity
Installed in FY 2015: > 1,970 turbines with > 5.6 GW capacity
~12,800 employees globally incl. Wind Service
Siemens Wind Power facts

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Onshore Wind – Siemens with considerable
experience and track record of installed projects
ON installed base as of June 2016: >26 GW
20161980
1979:2 x 22 kW (10.2m)
Vindeby,Denmark
1998:17 x 1.0-54
Wilsikow, Germany
2009:62 x 2.3-82
Wellington,New Zealand
2011:3 x 3.0-101
Lejbølle,Denmark
Installed base
201020001990
First project First 1MW turbines First CommercialDDFirst project w/o
subsidies
Cumulated Siemens onshore installations (GW)

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Offshore Wind – Leading player with >7,3 GW
installed base in strongest growing market
1991:5 MW
Vindeby,DK
2000:40 MW
Middelgrunden,DK
2011:630 MW
London Array,UK
First project MW turbines MasterAgreement
2012:1.8 GW DONG
Master Agreement
GW project
202020151990
450 kW
(ø35m)
(8 MW
(ø154m)
Cumulated Siemens offshore installations (GW)
OF installed base as of June 2016: >7,3 GW
Installed base

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Wind Turbine Blade R&D Competence Center in
Boulder, Colorado
• Established in 2008
• Currently 30 full-time engineers
• Will be 45 by end of this year
• Rotor research, design and technology
• 30% PhD & 70% Masters
• Investing inAmerican engineering
NIST
NOAA
UCAR
NCAR
SWP
CU
Boulder
Attractive Location for Top Talent:
• Forbes: “Boulder Tops List of America’s Smartest Cities”
• Money: “Louisville Best Places to Live”

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SWP 8.0-154 with 75 m blades
One of the world’s largest fiberglass component cast in one piece
• 75 m long blades and a
rotor diameter of 154 m.
• Blade weight of 25 tons
equal to 16 mid-sized
cars.
• The rotors swept area is
equivalent to 2½ soccer
fields.

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Fundamental changes in shape and design
30 years of blade development scaled to the same size
5 m blade from Bonus 27 kW
B75 m blade for SWT 8.0 MW
We have come a long way…

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Fundamental changes in shape and design
30 years of blade development scaled to the same size
5 m blade from Bonus 27 kW
B75 m blade for SWT 8.0-154
Two blades scaled to same size
• Profiles changed from 1930s aircraft
types to modern custom-made types
• Solidity changed from ~10% to much
less than 5%
• A75 m scaled version of the 27KW
blade would weight over 50 Tones

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PAST achievements: Aerodynamic shape design
G2 Planform: from B45 to B59
Designed 10 years apart
Dinoshell®
Dinotail®Flatback airfoils
Aeroelastic tailored blade
Pre-bend
Sweep
45 m blade
59 m blade
SWT-2.3-93
SWT-2.3-120
Stiff blade
Vortex Generators
High thickness airfoils

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Add-ons: simple designed kits providing AEP increase, support
the blade aerodynamics, reduce the blade soiling and noise
emission.
.
Dinoshells®
Lift enhancing
device applied at
the root section of
the blade
Vortex Generators
Vortex generators
(VGs) are used from
root to tip to
increase
aerodynamic
performance and
reduce impact of
blade soiling
Dinotail®
A device applied at
the trailing edge to
reduce trailing edge
sound emissions.
• Add-on are used to reduce noise, increase
AEP and robustness
• Very popular and widely used
• Add-on can be included in the design from
the beginning

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IPC technology is to blades what
is used to control a helicopter –
rotor imbalance is reduced!
ATB technology is to blades
what shock absorption is to a car
– turbulent loads are reduced!
Tends in Loads & Controls intelligence
Load reduction techniques
PitchFlapMoment
----- Baseline
----- IPC
“IPC primarily compensates for 1P load imbalances
(e.g. shear) resulting in lower fatigue loads”
Angle = 2.9 deg
200 400 600 800 1000 1200 1400 1600 1800 2000
0
200
400
600
800
1000
1200
“ATB passively compensates for gust loads
resulting in lower fatigue loads”
q Aero-elastic Tailored Blade (ATB)
q Individual Pitch Control (IPC)
q Real Time Condition Monitoring
q Active flaps

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Tip deflection challenge
Trade-Offs: Material vs Shape
Airfoil
thickness
Spar cap thickness Spar cap width Material stiffness
∆ ∝
𝑭𝑳 𝟑
𝑬𝑰
Design element Desiredtrends Possible limiting factor
Airfoil Thickness Aero performance
Spar cap thickness Mass penalty,manufacturability
Spar cap width Mass penalty,manufacturability
Material Stiffness Cost increase,manufacturability

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Tip deflection challenge
Material vs. Shape,
E vs. I, which one to invest in ?
glass
glass
carbon
carbon
Material Stiffness, E
Airfoil
Thickness, I
• How much risk are we willing to take?
• Is there a limit to airfoil thickness?
• Is carbon an enabler or does it also limit us?
• Depends on in-house design philosophy
• Depends on manufacturing concepts
• Structural topology
• A 75 m blade can have over 15m tip
deflection
40 50 60 70 80
Theoretical
cantilever tip
deflection
Actual SWP trend
Tipdeflection(m)
∆ ∝
𝐹𝐿3
𝐸𝐼
∆ ∝ 𝑳
Blade length (m)
Tip deflection challenge

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Summary - Size
“Advancements in blade shape and structural designs combined
with optimized material selection and load reduction techniques
allow us to overcome the limitation imposed by the square-cube law”
“This enables additional AEP to the customer”

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Future challenges
Leading edge erosion
Testing
Transportation
Manufacturing/automation
AEP
Tip deflection
Size

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Generic long term outlook
Competitive wind energy
LCOE
Cost efficient turbines
Smart wind turbines and
farms

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Thank you for your attention
Jacques Nader
Head of Blade Design
Siemens Wind Power
1050 Walnut St, suite 303
Boulder, CO, 80303
E-mail:
jacques.nader@siemens.com