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2nd Annual New England Marine Renewable Energy
Technical Conference - 11/2/2010
Brian D. Kuhn, Director
Offshore Wind Power Systems (OWPS),
a division of OWES, LLC
Source: DOE NWX National Renewable Energy Webinar, September 2010
Source: DOE NWX National Renewable Energy Webinar, September 2010
The quest for ever
increasing rotor sizes has
begun reversing the
economy of scale curve –
especially offshore.
"Sadly, it would seem we have
not derived benefits from
learning, scale and technological
improvement over the last five
years," says Rob Hastings,
director of the marine estate at
the UK's Crown Estate. "We
have, indeed, gone backwards.”
July 12, 2010 in Recharge News
Today’s designs are basically terrestrial turbines (3
bladed, HAWT, monopole designs ‘stuck in mud’) placed
in shallow waters (<30m) – not specifically designed for
where most of the energy is.
Whether coastal machines , or ‘floaters’ to get us to where
the winds are far greater and the opposition is less:
A different design is needed;
none has achieved ‘market lock’.
•9 of 11 projects currently being
tracked in US along the eastern
seaboard are within 21 km of
shore.
97,975 vs 809,725 mW
•The wind resource potential at 5
to 50 nautical miles off the US
coast is estimated to be more
than the total currently installed
electrical generating capacity of
the United States (more than
900 GW)
Source: Energy From Offshore Wind, NREL – Butterfield, Musial 2006
Although the architecture might seem new,
it’s really from an old name in wind energy…
AWEA Lifetime Achievement Award - 1999
Naval Architect, Captain USN
Professor, UMass Renewable Energy Lab
World-Class Authority on Offshore Systems
Patent Holder of many offshore designs
Major Advantages:
Smaller, Lighter
Components result in
Volume Manufacturing
‘Down tower’ Weighting
(low CG & met centric
height) perfect for
‘floaters’
Self-Yawing Tethered, or
Traditional Platforms
,
The concept of the multi-rotor array and its
corresponding weight and cost reductions have
dramatic implications on the entire offshore project.
Huge blades (up to 200’+ long)
built as ‘one up’ construction
Generators the size of houses –
300’ in the air
All the weight is up-tower, increases tower and foundation
costs and loads, hard to float
Work done at sea costs ‘8-10 times’ that as on land
Results in higher than terrestrial costs: $6,000+/kW vs
<$2,000/kW
Multiple smaller rotors favor volume manufacturing
of more lightly loaded blades
High use of ‘off-the-shelf’ components
Scalability via # of rotors, not size of blades
Tower superstructure weight and cost reduced via:
Alternating rotors counter-rotate, nulling out gyroscopic
moments and reducing loading
Space frame (lattice) designs used, monopoles not required
Weight of generation moved from nacelles down to floating
hull or platform and aggregated. ‘Down-tower’ power.
Higher Specific Yield (kW/m2) without
violating Betz Limit
Ability to optimize pitch angles to take
advantage of wind speed at respective tier levels
Shorter blades easier to fabricate and install/kW
Smaller rotors more responsive to changes in wind speed
turbulence
Smaller blades can be made with thinner cross-sections,
gaining aerodynamic efficiencies
Ability to run rotors at higher tip speeds ratios at different
tier wind speeds
Asymmetric placement of lighter rotors along vertical axis
increases effective overall ‘hub height’.
With weight down-tower and ‘out of the crow’s nest’,
Center of Gravity (G) is lowered and Metacentric
Height (GM) is decreased – vastly improving stability
for traditional and ‘floating’ designs. Down-tower
power makes ‘wind ship’ naval architecture more cost
effective. WEH coined term ‘Wind Ships’, and
envisioned an armada of them along coasts.
Large rotors require huge
specialized cranes mounted
on vessels
Single machine downtime is
costly, encouraging repairs in
foul weather
Lack of Portside staging and fabrication sites
Use of On-Board Jib Crane/Hoist simplifies
installation and repair/replacement of rotors
or components
Loss of single rotors has minimal impact on
overall output, allowing service to be
scheduled in better (less costly) weather
 If Wind Ship: towed to location and moored
via umbilical.
 If Wind Ship: self-yawing, moving freely
within watch circle
Size of specialized vessels
required to transport and lift
rotors and towers are huge
Jones Act requiring US flagged
vessels – there are none
Lack of Fleet is a real barrier to
entry, time and money sunk costs
before anything is operational
Small rotors allow use of on-
board jib boom/hoist
Jones act not an obstacle –
vessels available or can be
reconfigured
Wind ships: Towing to site like a
flip-ship
Sprite graphic
showing rotor
going up and
down
Near shore projects will
face the largest
opposition
Near shore projects
involve the most State
and Federal jurisdiction
What’s not to like???
Floating designs can be
located farther offshore –
‘over the horizon’
Greater wind energy
resource helps economics
Out of Sight means more
politically supportable
Several US & Int’l Patents Filed –
IP includes designs on both MultiRotor Arrays and hull designs for
floating ‘Wind ships’
•Scale Testing of Multi-Rotor Array
design at Langley Wind Tunnel.
•Computational Fluid Dynamics
(CFD) analysis confirms little
interference between rotors
Garrad Hassan & Partners Ltd., wind energy
consultants (now part of Germanischer
Lloyd) confirm primary scaling benefits of
the technology, issue report: “Multi-Rotor
Wind Energy Systems”
Finite element modeling for a 5 MW system
conducted by Aerotrope Consulting
Engineering, issue report: “OWES 5.0 MW
Multi-Rotor Support Structure and Yaw
System Study”
Present – continuing
work on
terrestrial version of
MRA by OWES, LLC
Need graphic, wordsmith
Need graphic, wordsmith
Now forming
development
consortium for
prototypes and pilot
plants
•
Offshore wind environment (coastal or deep) demands
new architecture, especially for floating ‘wind ships’
•
Wind ships allow us to go into deep water - after the
lion’s share of ocean winds - cost effectively
•
It may look like a ‘sea change’, but OWPS approach is
based on sound naval architecture and application of
well known rotor technologies
•
A new consortium is being launched –
Shipmates Wanted
Contact:
Brian D. Kuhn
Director
Offshore Wind Power Systems
Brian.Kuhn@OffshoreWindPowerSystems