Offshore renewable energy : accelerating the deployment of offshore wind, tidal, and wave technologies

482 Pages·2012·23.14 MB·English

by  IEA-RETD (Organization)

RINA
INTERNATIONAL CONFERENCE
Marine and Offshore Renewable Energy

26 – 27 September 2012
© 2012: The Royal Institution of Naval Architects
The Institution is not, as a body, responsible for the opinions
expressed by the individual authors or speakers
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Marine & Offshore Renewable Energy, 26 – 27 September 2012, London, UK
CONTENTS

Economic Study of Floating Wind Farms
R Pérez, Universidad Politecnica de Madrid & M Lamas, Universidad de la Coruña, Spain

Risk Assessment for the Installation and Maintenance Activities of a Low-Speed Tidal Energy
Converter
I Lazakis and O Turan, Department of Naval Architecture & Marine Engineering (NA-ME),
University of Strathclyde, Glasgow, UK & T Rosendahl, Minesto UK Ltd, Belfast, UK

A Review of Modelling Techniques for Tidal Turbines
P G Davies, Lloyd's Register Group Services Ltd., UK
D Radosavljevic, Lloyd's Register EMEA, UK

The Turbine Foundation Liner Concept
J W Brouwer, Dutch Offshore Innovators BV, The Netherlands

Offshore Floating Vertical Axis Wind Turbines: Advantages, Disadvantages and Dynamics
Modeling State of the Art
M Borg, M Collu and F P Brennan, Cranfield University, UK

Design Considerations for a Floating OTEC Platform
J M Ross, OTEC International LLC, US

Biofouling Issue, Global Implications and Solutions Linked to Offshore Business
J A González, H J G Polman, L C Venhuis, M C M Bruijs and G van Aerssen, DNV KEMA
Energy & Sustainability, The Netherlands

The Use and Application of Carbon Fibre Composites in Turbine Blades
L N McEwen and M Meunier, Gurit (UK) Ltd, UK

Economic Profiling of Wind Energy
S Yasseri, Safe Sight Technology, UK

Feedforward Neural Networks for Very Short Term Wind Speed Forecasting
F Tagliaferri and I M Viola, Yacht and Superyacht Research Group, School of Marine Science
and Technology, Newcastle University, UK

The Opportunities and Limitations of Using CFD in the Development of Wave Energy
Converters
P Schmitt, T Whittaker & D Clabby, Queens University Belfast, Belfast, United Kingdom
K Doherty, Aquamarine Power Ltd, Edinburgh, United Kingdom

Connection of Marine Energy Converters: A Challenging Operation
J Beale, Wood Group Kenny, UK

The Wave Energy Cylinder
J L Drake, Ocean Wave Technology, Australia

Classification and Project Management of Hybrid WTI Jack Up Vessels
J Lee, DNV, UK

Authors’ Contact Details
© 2012: The Royal Institution of Naval Architects
Marine & Offshore Renewable Energy, 26 – 27 September 2012, London, UK
ECONOMIC STUDY OF FLOATING WIND FARMS

R Perez and M Lamas, Universidad Politécnica de Madrid and Universidad Politécnica de A Coruna, Spain

SUMMARY

Floating wind parks are wind farms that site several floating wind turbines closely together to take advantage of
common infrastructure such as power transmission facilities. Cost is an essential consideration for the successful
commercial deployment of the present floating wind turbine concepts into large scale offshore wind farms. The wind
turbine used in the present study is assumed to be a marinized version of an onshore system. The same would be the case
if a smaller or larger wind turbine system were to be used. The weight of larger wind turbines may be easily supported
by a floater of larger displacement. Thus, the major objective of this paper is to demonstrate, with a simple static cost
model, that platform cost can be brought into this economic range.

NOMENCLATURE 2. TECHNICAL FLEXIBILITY: FLOATING
WIND TURBINE CONCEPTS
The nomenclature, in this technical paper, uses SI units.
It is ordered alphabetically. Numerous floating support platform configurations are
AHV Anchor Handling Vehicles possible for offshore wind turbines when one considers
CCGT Combined Cycle Gas-Fired Turbine the variety of mooring systems, tanks, and ballast options
DOE United States Department of Energy that are used in the offshore Oil and Gas (O&G)
EU European Union industries.
NREL National Renewable Energy Laboratory
O&G Oil & Gas 2.1 OIL & GAS INDUSTRY: DIFFERENCES
SDB Shallow Drafted Barge AND LESSONS LEARNED
TLP Tension Leg Platform
VLA Vertical Load Anchor Although the characteristics of proven offshore floating
platforms used by the O&G industries are similar to the
concepts being considered for floating wind turbine
1. INTRODUCTION platforms, it is their differences that will allow the
necessary cost reductions:
Wind is the fastest growing renewable energy source,  Oil platforms must provide additional safety
increasing at an annual rate of 25% with a worldwide margin to provide permanent residences for
installed capacity of 74·109 (W) in 2007. The vast personnel. Wind platforms do not.
majority of wind power is generated from onshore wind  Oil platforms must provide additional safety
farms. Their growth is however limited by the lack of margin and stability for spill prevention. This is
inexpensive land near major population centers and the not a concern with wind platforms.
visual pollution caused by large wind turbines.  Wind platforms will be deployed in water
depths up to 182.4 (m). Oil platforms are
Wind energy generated from offshore wind farms is the deployed in depths from 456 (m) to 2432 (m).
next frontier. Large sea areas with stronger and steadier  Submerging wind platforms minimizes the
winds are available for wind farm development and 5·106 structure exposed to wave loading. Oil
(W) wind turbine towers located twenty miles from the platforms maximize above-water deck/payload
coastline are invisible. Current offshore wind turbines are area.
supported by monopoles driven into the seafloor at
coastal sites a few miles from shore and in water depths Wind platforms will be mass-produced and will benefit
of 10-15 (m). The primary impediment to their growth is from a steep learning curve.
visual pollution and the prohibitive cost of seafloor
mounted monopoles in larger water depths (Lamas & In any case, if we see the evolution of the O&G rigs in
Perez, 2011). depth, we can expect that same evolution will occur to
floating wind farms, but at a higher speed, as a lot of
An economic feasibility analysis has been performed. knowledge is already available. See figure 1.
Key cost components includes the material and
construction costs of the buoy; material and installation Therefore, the technical challenges affects more to the
costs of the tethers, mooring lines, and anchor
turbine than to the platform itself.
technologies; costs of transporting and installing the
Technical solution:
system at the chosen site; and the cost of mounting the
• Wind Energy conversion stabilized and well
wind turbine to the platform.
known.
© 2012: The Royal Institution of Naval Architects
Marine & Offshore Renewable Energy, 26 – 27 September 2012, London, UK
Technological challenges:
• Wind turbine and maritime environment.
• Adapt wind turbine to platform motion.
• Adapt an O&G structure to energy production at
a reasonable cost.

Figure 2. Floating support platform concepts for offshore wind
turbines. SOURCE: NREL

Previous concepts with concepts that already are being
used today in the North Sea are shown in the following
figure 3:

Figure 1. Synergies between offshore petroleum industry and
wind structures. SOURCE: NREL

Deploying wind turbines offshore creates the potential
for innovative designs. For instance, wind turbines may
have faster rotor speeds due to less stringent noise
restrictions. In addition, some groups are investigating
the use of downwind and vertical axis turbines due to
their potential for reduced maintenance and higher
fatigue resistance.

The financial risk involved with building these large
scale projects is deterring such innovations. Companies

like StatoilHydro, the developer of the HyWind project,
Figure 3. Bottom mounted and floating wind turbines.

and Principle Power, which is working on the WindFloat SOURCE: PRINCIPLE POWER

concept, are partnered with existing commercial offshore
wind turbine manufacturers and are designing their Below we briefly summarize the characteristics of the
floating foundations to be compatible with many kinds of solutions used today and the floating:
turbines. This reduces the technical and financial risks  Monopiles:
significantly, since the hulls are designed according to o Basic extension of turbine tower w/
offshore O&G rules, leveraging the knowledge base of transition piece.
an industry with decades of experience in building o Economically feasible in shallow water
floating structures. depths, 10-30 (m).

 Jackets:

2.2 CURRENT CONCEPTS o Economically feasible in transitional water
depths, 30-50 (m).
Figure 2, below, illustrates several of the concepts, o Derivatives from O&G technology.
which are classified in terms of how the designs achieve
 Floating:
static stability.
o Economically feasible in deep water, 50­
 The Spar-buoy concept achieves stability by 900 (m).
using ballast to lower the center of gravity o Two prototypes have been deployed
below the center of buoyancy and can be (HyWind and Blue H).
moored by catenary or taut lines.
 The Tension Leg Platform (TLP) achieves The following figure 4 shows the potential of floating
stability through the use of mooring line tension wind turbines on the solutions anchored to the bottom of
brought about by excess buoyancy in the tank. very schematically: as depth increases, increases
 The Barge concept achieves stability through its exponentially the cost of the latter, while the cost of the
waterplane area and is generally moored by float rises as linear but very gently.
catenary lines.
 Hybrid concepts, which use features from all
three classes, are also an option.

© 2012: The Royal Institution of Naval Architects
Marine & Offshore Renewable Energy, 26 – 27 September 2012, London, UK
 Low construction and installation costs.

The 5·106 (W) wind turbine used in the present study is
assumed to be a marinized version of an onshore system.
The same would be the case if a smaller or larger wind
turbine system were to be used. The weight of larger
wind turbines may be easily supported by a floater of
larger displacement. Otherwise, buoyancy is free.

Guidance on the economic attributes of offshore wind
farms is offered by the recent economic analysis carried
out by Pace Global Energy Services LLC carried out for
a proposed 144 ·106 (W) offshore wind farm off the Long
Figure 4. Cost of different concepts from wind turbines.

SOURCE: EDP-INOVAÇAO
Island coastline consisting of forty 3.6 ·106 (W) General
Electric wind turbines supported by bottom mounted
truss towers. As part of this analysis Pace Global
3. E CONOMIC FLEXIBILITY OF evaluated the economics of the proposed wind farm
FLOATING WIND FARMS against the twenty year costs of an standard Combined
Cycle Gas-Fired Turbine (CCGT) consistent with the
Floating wind parks are wind farms that site several Long Island Power Authority’s resource planning in the
floating wind turbines closely together to take advantage non-renewable domain. The conclusion of the Pace
of common infrastructure such as power transmission Global analysis is that the breakeven cost for an offshore
facilities. wind farm to be competitive with the CCGT is
approximately $3000 per installed kilowatt including
The following figure 5 shows a provision of a floating interconnection costs. The estimated cost of the proposed
wind farm: 144 ·106 (W) offshore wind farm alone was estimated at
$5231 per kilowatt of nameplate capacity. The
underwater cable and substation upgrade costs were
estimated at $400 per kilowatt. The offshore wind farm
was assumed to be operating at an annual average
capacity factor of 36% and the projected cost of natural
gas would range from $9.21-$15.68/MMBtu over the
2010-2027 period. Further details of the economic
analysis are provided in the Pace Global report.

An analogous economic analysis applies to an offshore
wind farm with turbines supported by floaters. The
breakeven cost would be $3 millions per installed MW or
$15 millions per floater supporting a 5·106 (W) wind
turbine, including interconnection costs. For a
Figure 5. Bottom mounted Wind Farm. SOURCE: NREL hypothetical 10·106 (W) wind turbine the breakeven costs

range from $30 millions per floating unit. Floaters may
Cost is an essential consideration for the successful
be deployed in shallow and deeper waters and their
commercial deployment of the present floating wind
economic advantages versus bottom mounted support
turbine concepts into large scale offshore wind farms
structures become evident as the water depth increases.
(Lamas & Perez, 2011).
Moreover, the rate of increase of the costs of the floater
Main cost drivers:
as the wind turbine size increases and the cost of the
1. The full assembly of the wind turbine floater
mooring system with increasing water depth is likely to
system at a coastal facility offers essential cost benefits
be moderate.
relative to offshore assembly.

2. Other important cost drivers include the floater
It is possible to provide a rough cost comparison
weight (consisting of steel and concrete) and the tension
performed for two different platform architectures using
of the tethers and mooring lines at their anchors.
a generic 5·106 (W) wind turbine. One platform is a
3. The latter drive the cost of the foundation
Dutch study of a tri-floater platform using a catenaries
structure. In the case of the TLP this may be a gravity
mooring system, and the other is a mono-column tension­
caisson while for the catenaries it will consist of anchors
leg platform developed at the National Renewable
widely used by the offshore industry.
Energy Laboratory (NREL). Cost estimates showed that

single unit production cost is $7.1 millions for the Dutch
Therefore an important objective of the present study is
tri-floater, and $6.5 millions for the NREL TLP concept.
the selection of floater and mooring system designs with:

 Acceptable dynamic response properties.
© 2012: The Royal Institution of Naval Architects
Marine & Offshore Renewable Energy, 26 – 27 September 2012, London, UK
However, value engineering, multiple unit series 4. CURRENT PROTOTIPES IN TEST PHASE
production, and platform/turbine system optimization can
lower the unit platform costs to $4.26 millions and $2.88 As of 2011, there have been only two operational
millions, respectively, with significant potential to reduce floating wind turbines used to farm wind energy over
cost further with system optimization. These foundation deep-water, and one more expected to be tested in
costs are within the range necessary to bring the cost of summer 2011.
energy down to the United States Department of Energy
(DOE) target range of $0.05/kWh for large-scale 4.1 BLUE H TECHNOLOGIES
deployment of offshore floating wind turbines.
Blue H Technologies of the Netherlands operated the first
Although the vision for large-scale offshore floating floating wind turbine, a prototype deep-water platform
wind turbines was introduced by Professor William E. with an 80 (Kw) turbine off of Puglia, southeast Italy in
Heronemus at the University of Massachusetts in 1972, it 2008. Installed 21 (km) off the coast in waters 113 (m)
was not until the mid 1990’s, after the commercial wind deep in order to gather test data on wind and sea
industry was well established, that the topic was taken up conditions, the small prototype unit was decommissioned
again by the mainstream research community. A recent at the end of 2008. Blue H has successfully
Dutch report presents a complete bibliography and a decommissioned the unit as it embarks on plans to build
summary of the research to date, and is the basis for a 38-unit deepwater wind farm at the same location.
some of the later cost studies. Current fixed-bottom
technology has seen limited deployment to water depths The Blue H technology utilizes a tension-leg platform
of 30 (m) thus far. Although this technology may be design and a two-bladed turbine, see figure 6. The two­
extended to deeper water, eventually floating wind bladed design can have a much larger chord, which
turbine platforms may be the most economical means for allows a higher tip speed than those of three-bladers. The
deploying wind turbines in the coastal waters beyond the resulting increased background noise of the two-blade
view shed of densely populated urban load centres. rotor is not a limiting factor for offshore sites.
Worldwide, the deep-water wind resource has been
shown to be extremely abundant, with the United States
potential ranked second only to China.

Technically, the feasibility of deepwater wind turbines is
not questioned as long-term survivability of floating
structures has already been successfully demonstrated by
the marine and offshore oil industries over many
decades. However, the economics that allowed the
deployment of thousands of offshore oilrigs have yet to
be demonstrated for floating wind turbine platforms. For
deepwater wind turbines, a floating structure will replace
pile-driven monopoles or conventional concrete bases

that are commonly used as foundations for shallow water
Figure 6. Scheme and picture of this prototype. SOURCE:
and land based turbines. The floating structure must
BLUEGROUP.COM
provide enough buoyancy to support the weight of the
turbine and to restrain pitch, roll and heave motions As of 2009, Blue H is building the first full-scale
within acceptable limits. The capital costs for the wind commercial 2.4 (MWe) unit in Brindisi, Italy which it
turbine itself will not be significantly higher than current expects to deploy at the same site of the prototype in the
marinized turbine costs in shallow water. Therefore, the southern Adriatic Sea in 2010. This is the first unit in the
economics of deepwater wind turbines will be planned 90 (MW) Tricase offshore wind farm, located
determined primarily by the additional costs of the more than 20 (km) off the Puglia coast line.
floating structure and power distribution system, which
are offset by higher offshore winds and close proximity 4.2 HYWIND BY STATOIL
to large load centres (e.g. shorter transmission runs).
Integrated cost of energy models indicate that if platform The world's first operational deep-water floating large­
costs can be held near 25% of the total system capital capacity wind turbine is the HyWind, in the North Sea off
cost that DOE cost goals of $0.05/kWh are attainable. of Norway. The HyWind was towed out to sea in early
June 2009. The 2.3 (MW) turbine was constructed by
Thus, the major objective of this paper is to demonstrate, Siemens Wind Power and mounted on a floating tower
with a simple static cost model, that platform cost can be with a 100 metre deep draft. The float tower was
brought into this economic range. constructed by Technip, and Nowitech contributed to the
design. Norwegian Research Centre for Offshore Wind
Technology (Nowitech) is a consortium of thirty
members, including SINTEF and the Norwegian
© 2012: The Royal Institution of Naval Architects
Marine & Offshore Renewable Energy, 26 – 27 September 2012, London, UK
University of Science and Technology at Trondheim. Year 2008:
Statoil says that floating wind turbines are still immature  Blue H half-scale prototype installation.
and commercialization is distant.  EDP and Principle partner to deploy WindFloat
technology.
The installation is owned by Statoil and will be tested for Year 2009:
two years. After assembly in the calmer waters of Åmøy  HyWind full-scale prototype installation 2.3
Fjord near Stavanger, Norway, the 120 (m) tall tower (MW) turbine.
with a 2.3 (MW) turbine was towed 10 (km) offshore into Year 2011:
220 (m) deep water, 10 (km) southwest of Karmøy, on 6  EDP and Principle Power will start in summer
June 2009 for a two year test deployment. the test of the WindFloat.

Alexandra Beck Gjorv of Statoil said, “The experiment]
should help move offshore wind farms out of sight ... The
5. POTENTIAL MARKET IN THE
global market for such turbines is potentially enormous,
EUROPEAN SCENARIO
depending on how low we can press costs”. The unit
became operational in the summer of 2009. HyWind was The cost model start defining the wind energy
inaugurated on 8 September 2009. market in the EU:

As of October 2010, after a full year of operation, the In the Year 2010:
HyWind turbine is still operating and generating  Total installed capacity of 3·109 (W).
electricity for the Norwegian grid, see figure 7. The
 Meeting 0.3% of total EU electricity demand.
turbine cost US$62 million to build and deploy.
 Avoiding almost seven millions tons of CO
2
annually.
In the Year 2030:
 Total installed capacity of 150·109 (W).
 Meeting between 13% and 17% of total
European Union electricity demand.
 Avoiding almost 300 millions of tons of CO
2
annually.
Time to market:
 Five to ten years.
Players in the market:
 Market Leaders are involved: Statoil / Siemens.
 Two floating platforms already installed.
The EU15 Potentia Market:
Figure 7. Scheme and picture of this prototype.
 Good offshore wind resource (load factor >

3000h).

 Offshore wind potential is mostly in transitional
The 13 (km) long submarine power transmission cable
and deep waters: ~65%.
was installed in July, 2009 and system test including
 Energy Potential: ~220·109 (W).
rotor blades and initial power transmission was
 Ports and docks available along European coast.
conducted shortly thereafter.
Portuguese & Spanish Potential:

The installation is expected to generate about 9 (GW·h)  Continental shelf ends near the coast.
of electricity annually.  Grid connection available near the coast.
 Limited Potential for water depths < 40 (m).
The Small Waterplane Area Twin Hull, a new class of  Energy Potential in PT: ~12·109 (W).
offshore wind turbine service boat, will be tested at  Energy Potential in SP: ~98·109 (W).
HyWind.
In the table 1 it is possible to compare the Offshore
4.3 RESUME AND COMPARISON potential market in 109 (W):

As of 2011, there have been only two operational DEPTH EU15 PORTUGAL SPAIN
floating wind turbines used to farm wind energy over 0-30 77 2 18
deep-water, and one more expected to be tested in 40 - >200 >140 >10 >80
Table 1. Potential market comparison between
summer 2011.

Year 2007:
In the next table 2 it is showed the potential market in
 Statoil Hydro and Siemens sign agreement for
Spain:
HyWind project.

 Sway raises €16.5 million in private placement.
© 2012: The Royal Institution of Naval Architects
Marine & Offshore Renewable Energy, 26 – 27 September 2012, London, UK
Potential Market in Spain windows and requires a large crew to be stationed at sea
during the entire installation process. For the option of
Total capacity expected > 80.000 (MW)
mounting the wind turbine at the shipyard, it is assumed
Costs in commercial phases 3 (€m / MW)
that a crane would be on site that would charge a lifting
Total market 240.000 (€m)
fee per wind turbine. Once the platforms are
Windgenerators manufactured, mounting the wind turbine at the shipyard
Assumed Windgenerator capacity 5 (MW) would then be an assembly line process utilizing the
Potential Windgenerator units 16.000 crane on site. Due to the assembly line style of this
Windfarm process, mounting wind turbines to platforms in a
Windfarm total capacity 150 (MW) shipyard is estimated to be even less expensive than
mounting a wind turbine onto a foundation on land.
Windgenerator units of 5 MW 30

Potential Windfarms in Spain 533
Anchor and mooring line costs were taken from quotes
Cost of a Windfarm 150 MW 450 (€m)
from the offshore industry and from product manuals.
Yard costs 30%
NREL considered two alternative anchoring technologies,
Yard costs 135 (€m)
the drag embedment Vertical Load Anchor (VLA) and
Table 2. Potential market in Spain the suction pile. The VLA is a patented, proprietary

technology, and is installed either by one or two Anchor

Handling Vehicles (AHV) that drag the anchor into the
6. COST ANALYSIS
sea bed. Once the AHV loads the anchor to its installation

load, the anchor snaps into its vertical load-bearing
Several cost analysis have been developed by different
orientation, and installation is complete. This installation
Universities and Laboratories. In this paper we have
technique avoids the need for subsea equipment, but can
performed a recompilation of several TLP cost analysis
result in anchor placement that is difficult to control or
to estimate the total cost of the floating structure,
predict, and necessitates thorough geotechnical data of a
mooring systems, and installation processes associated
large footprint of the sea floor. Suction pile anchors are
with each design. Generally, the costs estimated in this
cylindrical caissons that become embedded into the sea
kind of studies do not include the wind turbine, power
floor through suction. The caissons are lowered to the sea
electronics, or transmission system.
floor, and suction is applied to a valve at the top of the

caisson. A combination of suction and the exterior
It is necessary to mention that several assumptions were
hydrostatic pressure drive the pile into the sea floor. This
made about the construction and installation process, and
installation process requires the use of subsea pumps, and
the costs of labour, materials, and equipment. These
sometimes divers. The caissons, however, are easily
assumptions were based on quotes from manufacturers,
manufactured, and avoid the retail fees associated with
consultants, and contractors in the marine industry.
the VLA. A cost of $25 and $15 per (KN) of vertical load,

or a minimum anchor cost of $50000 and $25000 were
Floating wind turbine systems are intended for
estimated for the VLA and the suction pile, respectively.
deployment in a wind farm setting, consisting of many

individual units. Because the TLP may be deployed with
Two methods of anchor installation were outlined as
the wind turbine already mounted, each unit is assumed
well. Installation Option 1 employs a barge and a tug,
to be produced by an assembly line style process in a
and Installation Option 2 requires an AHV. While
shipyard and towed to its installation site for
Installation Option 1 has a lower cost on a daily rate,
commissioning. The platforms will first be fabricated in
Installation Option 2 promises a lower cost per anchor. It
the shipyard. The turbines will be installed to the
is assumed that floating wind turbine systems will be
platform using a crane at the shipyard. The mooring
installed in a wind farm array, and will require enough
system will then be installed and the floating wind
anchor installations to make Installation Option 2 more
turbine units will then be towed to their installation sites
economical.
and attached to their mooring lines. It is also assumed
Installation Option 1
that these structures are intended for deployment in
Barge $10000/day
United States coastal waters, and are therefore
manufactured and commissioned in the United States. Tug $30000/day
The cost of steel and concrete were estimated by Labour $7000/day
considering quotes from manufacturers, and were taken Anchors Installed 3 anchors/day
to reflect unfinished steel and batch concrete produced in Inst. Cost per Anchor $15666.67/day
the United States. The cost of mounting the wind turbine
Installation Option 2
to the floating platform was estimated for mounting the
AHV $65000/day
wind turbine at the shipyard and at sea. For the option of
Labour $7000/day
mounting the wind turbine at sea, a costly crane would be
Anchors Installed 7 anchors/day
required, and with a full crew manning the process 24
hours a day, two installations could be accomplished in Inst. Cost per Anchor $10285.71/day
24 hours. This option is subject to unpredictable weather Table 3. Drag Embedment Anchors. SOURCE: NREL
© 2012: The Royal Institution of Naval Architects
Marine & Offshore Renewable Energy, 26 – 27 September 2012, London, UK
system that will fill a large footprint, thus using
The cost of transporting the assembled system to its significantly more line.
installation site, and installing it to its mooring lines was
estimated assuming an installation site of 100 miles from
the shipyard. 7. CONCLUSIONS

The table 4, table 5 and table 6 to follow detail these A cost analysis estimates the total costs for these kinds of
estimates and show the total cost breakdown for each structures are from $1.4 to $1.8 million. These values
system. include the construction, labour, mooring system, and
installation costs of the platform, as well as the cost of
Steel Material Cost $700/ton mounting the wind turbine to the platform. These
Concrete $100/ton numbers do not include the cost of the wind turbine,
Construction Labour $40/hour
power electronics, or the transmission system. These
Table 4. Platform Construction and Materials. SOURCE:

estimates offer promising values and encourage further
NREL

consideration of floating wind turbine systems.

Hours per Installation 6 hours/turbine
Workers per Installation 5 workers/turbine Floating platforms for wind turbines have been proposed
Labour Rate $40/hours for many years but only recently has the technology
Crane Fee per Tower $6250/turbine matured enough to seriously consider overcoming the
Inst. Cost per Turbine $7450/turbine
technical challenges required to design successful
Table 5. Wind Turbine Installation in Shipyard. SOURCE:
machines. The offshore O&G industry has proven that
NREL
the technical challenges can be overcome but the

economics of implementing this industry’s solution
Installation per Day 2/day
would prohibit any deployment of machines in a
Labour $16800/day
Crane $500000/day competitive wind energy market. The challenge is a
Barge $10000/day primarily economic one. These economic challenges
Tug $30000/day
present technical challenges.
Inst. Cost per Turbine $278400 t

Table 6. Wind Turbine Installation at Sea. SOURCE: NREL

8. ACKNOWLEDGEMENTS
The total costs for the TLP based on these assumptions

are estimated to be $1.81 and $1.41 million, respectively.
We are heartily thankful to our families whose
The general cost breakdown for each structure is shown
encouragement, guidance and support from the initial to
in figure 8.
the final level of the technical paper.

Lastly, we offer our regards and blessings to all of those
who supported us in any respect during the completion of
the technical paper.

9. REFERENCES

1. AUBAULT, A. and YEUNG, R.W., ‘Multi-Hull
Interference Wave-Resistance in Finite-Depth
Waters’. 24th Intl. Workshop on Water Waves &
Floating Bodies. Zelenogorsk. Russia, 2009.
2. AUBAULT, A.; CERMELLI, C.A. and RODDIER,
Figure 8. Total Estimated Cost Breakdown for TLP and SDB D.G., ‘Structural Design of a Semi-Submersible

Platform with Water-Entrapment Plates Based on a
The TLP and Shallow Drafted Barge (SDB) are
Time-Domain Hydrodynamic Algorithm Coupled
somewhat comparable in cost. However, the TLP is
with Finite-Elements’. ISOPE 2006. San Francisco,
estimated to cost less. One reason is that although the
USA.
structures are comparable in mass, the TLP’s
3. CERMELLI, C.A.; AUBAULT, A.; RODDIER,
parallelepiped surface will probably be constructed more
D.G. and MCCOY, T., ‘Qualification of a Semi-
easily than the very wide and flat shape of the SDB. Also,
Submersible Floating Foundation for Multi-
the TLP requires suction pile anchors that can be
Megawatt Wind Turbines’. Offshore Technology
fabricated in the process of the floater construction.
Conference. Houston, Texas, USA, 3–6 May 2010.
These devices are estimated to be less expensive than
4. CERMELLI, C.A.; AUBAULT, A. and RODDIER,
proprietary drag anchors that are available through
D.G., ‘WindFloat: A Floating Foundation for
anchor manufacturers. The TLP also will require less line
Offshore Wind Turbine. - Part II: Hydrodynamics
than the SDB, which will be moored through a catenary
© 2012: The Royal Institution of Naval Architects
Marine & Offshore Renewable Energy, 26 – 27 September 2012, London, UK
Analysis’. OMAE 2009. Honolulu, HI, USA. MACCREADY, T. and CERMELLI, C., ‘Design
5. DANMEIER, D.; SEAH, R.; FINNIGAN, T.; and Installation of a Tension Moored Wind
RODDIER, D.G.; AUBAULT, A.; VACHE, M. and Turbine’. OMAE 2007. San Diego, USA.
IMAMURA, J., ‘Validation of Wave Run-Up 11. YEUNG, R.W.; PEIFFER, A.; TOM, N. and
Calculation Methods for a Gravity Based Structure’. MATLAK, T., ‘Design, Analysis and Evaluation of
OMAE 2008. Estoril, Portugal. the UC-Berkeley Wave-Energy Extractor’. OMAE
6. LAMAS, M. and PÉREZ, R., ‘Floating Offshore 2010. Shanghai, China.
Wind Farms: The Seed of Artificial’. Journal of
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7. PISTANI, F.; THIAGARAJAN, K.; SEAH, R. and 10. AUTHORS’ BIOGRAPHY
RODDIER, D.G., ‘Set-up of a sloshing laboratory at
the University of Western Australia’. ISOPE 2010. Rodrigo Pérez Fernández PhD in Naval Engineering at
Beijing, China. the Universidad Politécnica de Madrid (Spain). He holds
8. RODDIER, D.G.; AUBAULT, A. and, CERMELLI, the current position of Naval Consultant at SENER.
C.A., ‘Electrical Power Generation by Tidal Flow
Acceleration’. OMAE 2007. San Diego, USA. Miguel Lamas Pardo PhD in Naval Engineering at the
9. RODDIER, D.G. and WEINSTEIN, J., ‘Floating Universidade da Coruña (Spain). From 2001 it has
Wind Turbines, Mechanical Engineering’. ASME. worked in the most important shipyards of Ría of Vigo,
April 2010. first in Barreras Shipyard and later in Vulcano Factories.
10. RODDIER, D.G.; ZAMBRANO, T.;

© 2012: The Royal Institution of Naval Architects