The document provides an overview of offshore wind cables, including key industry players, cost breakdown, drivers, challenges, and innovations. It discusses how medium voltage array cables connect turbines to substations, and high voltage export cables connect offshore substations to onshore. Cable installation most commonly uses simultaneous lay and bury with a plough. The industry faces challenges from poor understanding of environmental conditions and planning for installation. Innovation focuses on cable installation robots, HVDC technologies, and new cable types to help reduce costs as the offshore wind market rapidly expands.

1. OFFSHORE WIND CABLES
June 2012
Key industry players, cable cost breakdown, economical and technical drivers,
challenges and key innovations

2. Table of Contents
01 Introduction to offshore wind cables
02 Key industry players
03 Cost breakdown
04 Economical and technical drivers
05 Cable challenges
06 Demand for cost reductions
07 Key innovations
08 Remarks
09 Perspectives
4
6
7
8
9
10
11
12
13

3. Foreword
This insight provides an introduction to offshore wind cables and the key
industry players.
The cost structure of cables, the demand for cost reductions, as well as
the economical and technical drivers are examined.
Furthermore, the major challenges within the cable industry and key
innovations in recent projects and those under development are studied.
Page 3
The insight has been
developed in close
collaboration with Catalyst
Strategy Consulting, an
international consultancy,
which operates in the nexus
of technology and business,
and holds ample experience
and specialization in
especially the Maritime,
Energy & Offshore, and
Cleantech industries

4. Medium voltage array cables interconnect the turbines and the substation, high voltage
export cables connect the offshore substation to onshore and subsea cable burial is the
current best practice to ensure cable protection
Page 4
INTRODUCTION TO OFFSHORE WIND CABLES
Source: MEC Intelligence analysis
Array/infield/collection grid cables – interconnecting turbines to substation
• Transformers at each wind turbine, usually in the base of the tower, are used to step up from the generation voltage, typically 690 volts (V), to a
medium voltage of typically 25–40 kilovolts (kV)
• This voltage range seems to be preferred because standardized equipment is available at competitive prices and because higher voltage transformers
would be too big to fit readily into the tower cross sections
• A grid of medium-voltage submarine cables, typically buried 1–2 meters (m) deep in the seabed, is used to connect the wind turbines to an offshore
substation
Transmission/export cables – connecting offshore substation to onshore substation
• The transmission system begins at the offshore substation, which steps up the voltage to a transmission voltage of 130–150 kV, the highest voltages in
use today for AC submarine cables. This higher voltage allows a much smaller diameter and lower cost submarine cables to be used for the long run to
shore
• There are two technology options available for the transmission system associated with offshore wind power:
• HVAC (high voltage alternating current)
• HVDC (high voltage direct current)
• HVAC is generally thought to be the most economical for distances shorter than 50 km
• Between 50 km and 80 km HVAC and HVDC are expected to be similar in costs
• Above 80 km HVDC will likely be the economically most attractive solution
• This is mainly due to the effective capacity of a given HVAC drops with distance due to capacitive and inductive characteristics of the cable and
their associated line losses (~10% loss)
• HVDC avoids these line losses completely and is therefore the preferred technology for long distance.
Cable installation
• Subsea cable burial ensures cable protection in distribution systems worldwide and is widespread best practice in the telecoms industry. Left
unprotected, power cable, fiber optic telephone cable and oil and gas pipe is vulnerable to damage from ship anchors, fishing activity and other threats.
INDICATIVE

5. A number of different methods for cable installation exist but the most common is to
simultaneously lay and bury the cable using a plough
Page 5
CABLE INSTALLATION
Source: MEC Intelligence analysis
Simultaneous lay and bury using plough
• A plough is pulled by a cable laying vessel/barge and the cable is laid by a turntable on the vessel
• The plough buries the cable in a trench of approx. 2 m deep using a high pressure water jet
• The water jet fluidizes the sand/mud and the cable sinks into the trench
• Most common method for cable installation especially for export cables
• Cables are stretched to ensure a
high tension when put in the
trench using a control system on a
barge
• Important to minimize tension at
turning points to ensure cable stays
in the trench
• Diver is used to confirm the
touchdown of the cable in the
trench and to carry out post-lay
inspection of the array cables
• Inflated airbags are used to pull-in
the export cable onto the shore
• Inter-array cables are pulled-in
from the substation to the
foundations fed up through J-tubes
inside the foundations
INDICATIVE
1
2
3
4
5
Simultaneous lay and bury using ROV
• Similar to abovementioned method but utilizes a ROV instead of a plough
• The ROV carries the cable in a spool which limits is use to inner-array cables
• The preferred installation method when using the turbine installation vessel for cable installation
Pre-excavate
• A backhoe dredge is used to pre-excavate a trench
• A cable laying vessel lays the cable in the trench and the trench is filled using the dredge
• The method may also utilize floating cables over the trench via airbags
• Used for both array and export cable installation
Lay and trench
• A cable laying vessel lays the cables on the seabed and a trench is made using a ROV
• This method has been used for both array and export cables
Pull and trench
• Cables are pulled among turbines using a winch and later on they are buried with a ROV or plough
• Only useful for inner-array connections
Installation methods General

6. The offshore wind cable industry is relatively fragmented in cables, consolidated in
equipment, populated by 4-5 key players in cable installation
Page 6
KEY INDUSTRY PLAYERS
Source: MEC Intelligence analysis
• Nexans (FR)
• ABB Submarine Cables (SE)
• LS Cable and System (KR)
• JDR Cable Systems (UK)
• NKT Cables Group (DE)
• NSW/Corning (DE)
• Prysmian Cables and Systems (Draka
Offshore) (IT)
• Siemens (DE)
• ZTT Group (CN)
• Borealis Group (AT)
INDICATIVE
• Pharos Offshore Group (UK)
• SMD (UK)
• CTC Marine (UK)
• JD-Contractor (DK)
• Global Marine Systems (UK)
• VSMC (DE)
• S.B. Submarine Systems Co.
Ltd. (CN)
• Beluga Shipping (DE)
• Modus Seabed Intervention
(UK)
Cable manufacturers Equipment manufacturers Cable installers

7. The general trend shows a decreasing cost pr. installed MW offshore – however, the value mix is
changing, as logistics and installations costs are taking a larger share of the value compared to
traditional cost components - e.g. the turbine – Cable cost is expected to grow along with distance
to shore and effective load increase
Page 7Source: MEC Intelligence analysis
Logistics
and
Installation
21%
Other
5%
Project
Mgmt and
Permits
6%
Electrical
infrastructure
& cables
14%
Foundation
19%
Turbine
35%
Total
installation
100%
Total
100%
Logistics
28%
Installation
72%
Tower
17%
Blade
25%
Foundation
35%
Total
100%
Cables
2%
Substation
4%
Hub
8%
Nacelle
9%
Capital Cost Breakdown (% per MW) Installation & Logistics
(% per MW)
Installation* (% per MW)
Logistics (% per MW)
Foundation
33%
Total
100%
Cables
33%
Substation
8%
Hub
7%
Nacelle
7%
Tower
7%
Blade
7%
Turbine
Unit cost trend compared relatively to peers
COST BREAKDOWN
*Note on installation split of turbine – split will vary
• Nacelle and hubs are joined at the port along with 2 blades = one unit
• Tower is one unit
• The third blade is one unit
INDICATIVE

8. The primary economical and technological drivers are related to the installation and
burial of subsea cables and ~70% of insurance claims from offshore wind farm
operations relate to cable damage
Page 8
ECONOMICAL AND TECHNICAL DRIVERS
Source: MEC Intelligence analysis
• Installation of subsea cables has been characterized
by cost overruns and cable damage in a number of
cases
• Subsea cables have been the largest source of
insurance claims in offshore wind to date
• It has been estimated that subsea cable laying
accounts for between 5-10% of the capital cost of
the wind farm development but ~70% of insurance
claims from wind farm operations relate to cable
damage
INDICATIVE
• Technology development has a key role to play in
impacting costs
• As offshore wind farms are located further from
shore, point-to-point HVDC systems will prove more
cost effective than HVAC
Economical Drivers Technical Drivers

9. Poor understanding of environmental conditions, poor planning regarding cable
installation and risk of shortage of high-voltage cables and trained workers pose the
primary cable challenges
Page 9
CABLE CHALLENGES
Source: MEC Intelligence analysis
• Poor understanding of weather and
marine environment
• Access difficulties due to unexpectedly
severe weather conditions
• Harder or softer ground being
encountered impeding burial machinery
• Unexpected topography e.g. slopes and
holes
• Poor definition of environmental risks
leading to tight permitting windows
• Poor appreciation of the wave/tidal
environment leading to tight operational
windows
• Poor understanding of marine
environment leading to excessive
weather delays
EXAMPLE
• Lack of consultation with cable
manufacturers / marine contractors
regarding the practicalities of
installation
• Lack of quality in cable route survey
definition and data interpretation for
the cable route
• Developers accepted consent
conditions that are unrealistic or
impractical
• Poor understanding of impacts of
construction
• Unrealistic permit conditions being
passed on to contractors to implement
• Risk of a high-voltage subsea cable
shortage in the next few years as
well as a possible shortage of trained
workers
• The supply base is currently limited
to a number of companies and time
to establish new production facilities
is significant depending on
competition from other energy
infrastructure projects
Risk of shortage of high-voltage subsea
cables and possibly trained workers
Poor planning regarding cable installationPoor understanding of environmental
conditions

10. The major offshore wind expansion plans on the horizon drives the demand for cable
cost and insurance claims reduction
Page 10
DEMAND FOR CABLE COST REDUCTIONS
Source: MEC Intelligence analysis
EXAMPLES
• With major industry expansion plans on the horizon, there has never been a greater
need for the industry to come together and develop a coordinated approach to the
challenges it faces going forward.
Major offshore wind expansion plans
• The installation and burial processes currently being used have resulted in many
insurance claims being made by offshore developers to cover the costs of damage to
cables.
Substantial insurance claims due to cable damage

11. Key innovations in order to drive cost down on cables include cable installation and
maintenance robots, alternative HVDC cable technologies, AC/DC rectifier technology
development and new types of submarine cables
Page 11
KEY INNOVATIONS
Source: MEC Intelligence analysis
EXAMPLES
• Underwater robot developed for subsea cable burial
• Provides more scheduling flexibility
• Inter-array cables can be installed more quickly
• Less need for expensive diving activities
• Cable maintenance robot
• More cost-efficient measure of maintenance
Cable installation
• HVDC Plus (Siemens technology)
• Modular multilevel voltage-sourced converters
• Preferred solution where shortage of space is a criterion
• Improves the performance of the transmission grid with
regard to system security
• Will be used for the world’s longest HVDC submarine grid
connecting England and Scotland (420 km)
• HVDC Light (ABB technology)
• Increases the reliability of power grids
• Upper range: 1,200 MW and ±500 kV.
Cable technology
• Mercury arc valves
• Thyristor converters
AC/DC rectifier technology development
• Mass-impregnated cables
• Self-contained fluid-filled cables
• Extruded insulation cables
Types of submarine cables used

12. Findings
Page 12
REMARKS
VII
VIII
VI
IIII
V
III
I
II
Medium voltage array cables interconnect the turbines and the substation, high voltage export cables connect the
offshore substation to onshore and subsea cable burial is the current best practice to ensure cable protection
A number of different methods for cable installation exist but the most common is to simultaneously lay and bury the
cable using a plough
The offshore wind cable industry is dominated by a limited number of players on the cable and equipment side and 4-
5 key players on the cable installation side
Cables account for ~14% of the balance of plant with export cables accounting for ~75% and array cables accounting
for ~25%, and cables account for ~33% of installation and commissioning costs which is a significant share
The primary economic and technological drivers are related to the installation and burial of subsea cables and ~70%
of insurance claims from offshore wind farm operations relate to cable damage
Poor understanding of environmental conditions, poor planning regarding cable installation and risk of shortage of
high-voltage cables and trained workers pose the primary cable challenges
The major offshore wind expansion plans on the horizon and the many economic and technical challenges currently
facing the offshore wind cable industry drives the demand for cable cost reductions
Key innovations in order to drive cost down on cables include cable installation and maintenance robots, alternative
HVDC cable technologies, AC/DC rectifier technology development and new types of submarine cables
Source: MEC Intelligence Analysis

13. Perspectives
Page 13
REMARKS
Source: MEC Intelligence Analysis
Considering the ambition to reduce the cost of offshore wind energy – would innovations in logistics and supply chain,
be able to stand up to the requirements? Which areas are likely to become bottlenecks?
With the value split in the offshore wind changing rapidly, which are the key stakeholders who are positioned to win
and lose market share in the future offshore wind energy market?
What does the emergence of markets and industries across the globe mean, in the context of the contemporary
suppliers?
Considering supply constraints, and the need to build operational excellence and flexibility - are there business models
and/or innovative port infrastructure configurations, which yield competitive advantage?
With the offshore wind market rapidly becoming global - which local rules, policies, and various stakeholder decision
making criteria, are essential to know to grow and sustain markets?
Considering the requirement of local content in the markets, how should companies organize to branch-out
internationally?

14. About MEC Intelligence
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Please visit Catalyst Strategy Consulting for more information.
Page 14
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15. Sample Publications in Offshore Wind
MEC Intelligence has conducted a vast range of bespoke researched studies for
leading international companies in the areas of Maritime, Energy and Cleantech
– along with authoring a range of free and commercial insights and reports
within our focal domains
Publications and Credentials
Offshore Wind Foundation
October 2011
Offshore Wind Cables
June 2012
Offshore Wind Logistics
July 2012
Offshore wind market in China
August 2012
Sample Publications in Marine and Cleantech
LNG as Propulsion Fuel
October 2011
Electric Vehicles
December 2011
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within market forecasting and analysis, project cost
benchmarking in e.g. sourcing, best practice studies etc.
We leverage an extensive network of experts and
professionals, to provide bespoke research and analysis,
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