© Dr.techn.Olav Olsen AS

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OO-STAR WIND FLOATERAN INNOVATIVE AND ROBUST SEMI-SUBMERSIBLE FOR OFFSHORE FLOATING WIND

INNOVATION DAY 201728.09.2017 MILLENIUM HOTEL, SEOUL

Seoul, September 28th. 2017

Trond LandbøManager Business Area Energy/RenewableDr.techn.Olav Olsen AS

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DR.TECHN.OLAV OLSEN ASINTRODUCTION

3DR.TECHN. OLAV OLSEN –COMPANY PROFILE> Norwegian independent Structural and Marine

consulting company founded in 1962> Offices in Oslo and Trondheim (Norway)> Approximately 90 employees> Contributes in all project phases, from concept

development to decommissioning> Active in research and development projects

OFFSHORE CONCRETE STRUCTURES

> World leading designer of offshore concrete structures> Shallow to deepwater> Gravity Base Structures (GBS)> Floating concrete platforms> Arctic applications

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NORWAY’S ENGINEERING ACHIEVEMENT OF THE CENTURY5

Troll A GBS, height 472 m

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Draugen GBS at 250 m water depth

GUSTAVE MAGNEL GOLD MEDAL AWARDDR.TECHN.OLAV OLSEN – THE DRAUGEN PLATFORM

7BUSINESS AREAS

> Buildings onshore> Offshore Oil & Gas> Renewable energy> Infrastructures> Harbours and Industry> OO «Futurum»

Core business:Structural &

Marine engineering

Adding value to company and clients

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DR.TECHN.OLAV OLSEN ASOFFSHORE WIND

9OLAV OLSEN - OFFSHORE WIND

OLAV OLSEN - CAPABILITIES OFFSHORE WIND

> Fully coupled simulations: – SIMA– 3DFloat– Deeplines– (Orcaflex, Ashes, FEDEM Windpower)

> Substructures – Bottom fixed and floating– Steel and concrete– Concept development– Design and analysis (ShellDesign)– Geotechnics

> Mooring and anchors– System configuration– System design– Geotechnics

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> Installation– Method development– Installation concepts

> Cost models– Fabrication and Installation

• Substructure• Mooring• Anchors

> Third party verification

11BOTTOM FIXED OFFSHORE WIND

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CONCRETE FOUNDATIONS - GBS

Simple and robust• For water depths up to 100 m +• Inshore completion and testing• Self floating, no offshore heavy lifting• Firm or soft soil• Optimal stiffness and dynamic

characteristics• Not fatigue sensitive• Maintenance free• Long design life, 100 years +• Can support new turbines in the future

Marine environment friendly• No piling• No anchors• Not sensitive to boulders below seabed

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OLAV OLSEN – SFT, SPACE FRAME TOWER

> A bottom fixed solution for Multi-MW Offshore Wind Turbines

> Water depth range 15m-60m

> Transition piece standardized for turbine and tower independent of site conditions

> Standardized Design for variable water depths

> Designed for mass production and efficient assembly

> Variable bottom support solutions

14SPACE FRAME TOWER (SFT)

14>Transition structures are standardized for turbine type

>3 main element types:– Vertical legs, constant diameter – X and K nodes with uniform design. Cost effective

fabrication, superior fatigue capacity.– Uniform X-bracing system

>Foundation - different solutions– Gravity base– Suction buckets– Piles

Gravity Base Piled foundation frame Suction buckets Pre installed pilesGravity/Skirt piles

15FLOATING OFFSHORE WIND TURBINES

Hywind

Hydro/StatoilHiPRWind

EU project

OO star

Patented concept

16HYWIND SCOTLAND PROJECT

> Demo park on the east coast of Scotland. > Progression from Hywind DEMO.> 5 units.> 6 MW turbines.> Scheduled construction start-up: Fall 2015> Scheduled installation: Summer 2017

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OO-STAR WIND FLOATER

© Dr.techn.Olav Olsen AS

18 © Copyright Dr.techn.Olav Olsen AS

19THE OO-STAR WIND FLOATER HISTORY

> Few realistic WTG floaters before 2010> Hiprwind (2010) – questions to scalability and fatigue

> What does the optimal floater look like?> OO-Star Wind Floater developed 2010/11, presented at ONS2012> Preferred concept (steel) for EU project Floatgen – Acciona part 3 MW WTG> NFR project 2013-2014: Designed for 6MW, WD 100 m, North Sea> LIFES50+ 2015-2018: Up-scaling to 10 MW, WD 70-130 m, Hs=7.0 -15.6 m

20 OO-STAR WIND FLOATER – GENERAL DESCRIPTION

• The OO-Star Wind Floater is a robust, stable and very simple 3-leg semisubmersible floater

• Water depth potential from 50 m• Concrete, steel or a combination (hybrid). Material selection according to

optimal design, cost, fabrication facilities etc. But concrete/hybrid best suited for large wind turbines.

• The OO-Star Wind Floater consists of a central shaft supporting the WTG, and a tri-star shaped pontoon supporting 3 buoyancy cylinders for optimal stability.

• In principle the permanent buoyancy is in the columns and shaft. The pontoons provide structural support of the bucket cells, weight stability, added mass and temporary buoyancy for inshore assembly.

• The OO-Star Wind Floater can be fabricated in a dock, on a barge or on a quay. The structure is well suited for modular fabrication.

• The full substructure can float with very small draft and the unit can be fully assembled at quay-side before tow to site. No requirements for deep waters.

• Transport to site by towing. No requirements for expensive heavy lifting offshore.

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22CONCRETE OO-STAR WIND FLOATER – SIZING

> SIZING PREMISES– AIR GAP– NATURAL PERIOD– STATIC TILT AT MAXIMUM THRUST– WTG AND TOWER PARAMETERS– CONCRETE DENSITY AND QUALITY– DAMAGE STABILITY REQUIREMENTS

> GEOMETRIC PARAMETERS TO ADAPT– SHAFT AND CORNER COLUMNS HEIGHT– CENTER DISTANCE BETWEEN SHAFT AND CORNER COLUMNS– SHAFT AND CORNER COLUMN DIAMETERS AND SHAPE– PONTOON WIDTH AND HEIGHT – FLOATING DRAFT– BILGE KEEL AREAS

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DESIGN

HYDROSTATIC STABILITY24

Wind heel moment area (0 to 90 deg/0 to -90 deg) 9680 [MNm*deg]Wind heel moment area (0 to 36.4 deg/0 to -36.4 deg) 5133 [MNm*deg]Righting moment area ROLL (0 to 90 deg) 44205 [MNm*deg]Righting moment area PITCH (0 to 90 deg) 66037 [MNm*deg]Righting moment area ROLL (0 to -90 deg) 44205 [MNm*deg]Righting moment area PITCH (0 to -36.4 deg) 9257 [MNm*deg]Utilization 72 [%]

25HYDRODYNAMIC AND STRUCTURAL ANALYSIS

> Fully coupled simulations:– 3DFloat – SIMA– Deeplines

> Structural analysis:– Sectional forces from simulations– Local FEA models– ShellDesign (linear/non-linear design)

> Main challenges:– 3P effects – FLS– Mooring design– Consistent coupling with structural model– WTG controller, tuning

Initial sizing Beam section checks

Check of local models

Final geometry and reinforcement

layout

STRUCTURAL ANALYSES – ANALYSIS APPROACH26

Update of mooring system (loads), geometry etc.

SHELLDESIGNINTRODUCTION

> Design tool and post processor for reinforced concrete shell structures> Based on extensive development and project experience> Performs code checks according to standards > Sectional design based on non-linear sectional response> Sectional design based on user input or results from FE-analysis> Results presented in tables, 2D graphics and 3D graphics> Special developed feature to calculate non-linear structural response

– The Consistent Stiffness method (CSM)

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The conventional design method:Global linear elastic structural FE analysis + Local non-linear sectional analysis/design

TOWER DESIGN

> Design principle: Avoid resonance with 1P and 3P> 3P range for DTU 10 MW turbine is 0.30–0.48 Hz> Natural frequency of 1st bending mode with DTU

tower with turbine on floater is 0.43 Hz> Updated tower has increased stiffness to avoid

resonant response in tower

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DTU tower

Updated towerGdF GoM WoB

Tower weight [t] 875 1220 1250 1310

RESPONSE COMPARISON

> Response spectrum for fore-aft moment at tower base> Wind = 17.9 m/s => 3P = 0.48 Hz

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PitchWaves

DTU

tow

er m

ode

Upd

ated

tow

er m

ode

3P

MOORING - BASIC CONFIGURATION

> 3 line system

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WoB: Pure chain catenary

GoF and GoM: Chain catenary with Clump weight

Fast screening

Simplified verification

Full verification

DESIGN APPROACH

> Sufficient ULS capacity > Sufficient fatigue life> Maximum offset, typical % of water

depth (due to power cable flexibility)> Redundancy (mooring line failure)

> Initial design by in-house spreadsheet and SIMO

> Analysed by fully coupled analysis> Dynamic representation of mooring

lines

31Conceptual design

Optimization with simplified analysis

Design criteria fulfilled?

No(change input)

YesVerification with limited amount of DLCs

(full dynamic analysis)

Design criteria fulfilled?

Yes

Verification with all DLCs (full dynamic analysis)

Optimal design?

Yes

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FABRICATION/ASSEMBLY

33FABRICATION SET-UP

34FABRICATION 25 UNITS/YEAR – TYPICAL SCHEDULE

35ASSEMBLY AT QUAYSIDE

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TRANSPORT AND INSTALLATION

OVERVIEW37

Marine Operations

Minor Port Activities

Installation of OO-Star Wind Floater

Pre-lay of Mooring

Pre-lay of Cables

Preparation

Tow to site

Positioning at site

Flooding of pontoons

Connect to mooring legs

Connect to array cable

Install clump weights

Adjust corner column ballast

Transit back to fab site

Installation of OO-Star Wind Floater

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TRANSPORT/INSTALLATION – KEY FIGURES> Installation floaters

– Two AHTS per unit + one tug assisting on site– Minimum 150 t bollard pull required (WoB) – reference tugs 230 t BP– Towing speed 2 knots, transit speed 13 knots– Installation in different campaigns – durations depending on distance to

shore and environment

> Installation mooring/anchors– Two and two AHTS working side by side, number of spreads depending on

site

> Installation inter-array cables, dynamic and static– 2 vessels used, one for dynamic cable and one for static cable– Dynamic and static cables installed in campaigns – duration depending on

distance from shore and environment

INSTALLATION OF OO STAR WIND FLOATERTOWING

> Towed by two AHT vessels in parallel> Third vessel assisting on site – star formation> Connection points on columns of OO Star Wind Floater> Retrieval system for emergency connection (pick up line and buoy)> First tug connects to column dependant on weather direction> Second tug connects pick up line and buoy before connection to second

column

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FABRICATION/INSTALLATION - SCHEDULEWeek No

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 # 101 # # # # # # # # 110 111112

123456789

1011121314151617181920212223242526272829303132333435363738394041424344454647484950

72 84 96 10812 24 36 48 60

Installation Campaign 125 units, 2 units per weekTotal duration 12 weeks (84 days)Mob/demob included

Installation Campaign 225 units, 2 units per weekTotal duration 12 weeks (84 days)Mob/demob included

Fabrication for Storage18 units, one unit per two weeks36 + 12 weeks duration

Fabrication for Storage18 units, one unit per two weeks36 weeks duration

PRE-LAY OF MOORING

> Anchors and mooring lines installed in first phase of project

> Retrieval system for hook up of OO Star Wind Floater

> Chains and anchors delivered onshore and the installation vessels carry maximum load before approaching offshore site

> Chains transported in chain lockers, anchors stored on deck

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SWL

PRE-LAY OF CABLES

> Installed in early phase of the project, and wet stored with buoyancy elements

> Construction/Flex-Lay vessel with DP III assumed for static cables

> Feasible to use MPSV with DP III and offshore crane capacity for dynamic cables

> Below- and on deck flex storage on carousels

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OPERATION AND DECOMMISSIONG

OPERATION – KEY ASPECTS> Floater has ample stability and is passively moored during operation.> Passive ballast system in corner nodes. Minor water ballast used for initial

trimming.> Pontoons are flooded during operation. No hydrostatic loading in

combination with large bending moments. > Fixed mooring points at 2 columns, fairlead/chain stopper at 3rd column.

Tensioning from vessel, no winch.> Main access at central tower. Simlified access to corner columns.> Designed for accidental filling of central tower and corner nodes.> Designed for ship impact ULS/ALS.> All main structural parts are designed for minimum 25 yr design life, with

no requirements for inspection (concrete designed for 50 yrs).> Secondary steel will be inspected regularly in parallel with WTG parts.

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DECOMMISSIONING – KEY ASPECTS> Removal of floater, mooring system, anchors and cable will basically be

reverse installation. > No offshore heavy lifting is required. AHTS and cable laying vessels used.> Floater released from cable and mooring lines, towed to shore for

upgrade/reuse/resale.> Mooring lines, anchors removed by similar vessels as used for installation.> Depending on further life of windfarm the cables can be removed as

reverse installation.> WTG/steel tower removed inshore, as reverse assembly.> Upgrade/repair of secondary steel prior to reuse of substructure.> Scrap-sale of steel tower, chains, anchors and cables (depending on

windfarm decision).> Anchors removed, or left in place depending on type and regulations

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KEY CHALLENGES AND ADVANTAGES

47OFFSHORE WIND CHALLENGES> The main and overall challenge is to reduce cost of energy (LCOE) – cannot rely

on subsidies in the future> Requirements:> Consistent frame conditions (political, consenting, tendering process, environment etc.)

> Development of consistent rules and regulations> Development of business tools (financing, insurance etc.)

> Development of supplier industry (competition, effectivity, market stability)

> Development of new and better technology– Economy of scale, larger turbines– Increase effectivity, robustness and operation life– Reduce CAPEX, OPEX

> Development of fabrication and installation methods (reduce CAPEX, risk)

IMPROVED TECHNOLOGY - SUBSTRUCTURES> Robust and cost effective design

– Not overdesign, but implement reserves to allow for unknowns– Standardisation will reduce cost – floaters have higher potential

for this– Integrated design – WTGs, substructures and mooring (not sub-

optimize)– Advanced design tools – coupled analyses and non-linear

material behaviour

> Concrete can increase the operational life of substructure

– Long term thinking wrt. consenting and operability– Other elements should also focus on increased operation life

(WTGs, mooring, cables etc.)– Develop a market for reuse of substructures, replacement of

WTGs, 2nd hand market for elements which can be reused.

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OO-STAR WIND FLOATER - ADVANTAGES

– OO-Star WF is a simple and robust floater concept with favourable motions for WTG and cable

– Concrete less sensitive to fatigue than steel (WTGs are fatigue machines)– Concrete substructure with long design life, 50 yrs for L50+, 100+ years with

minor adjustments (concrete cover, cathodic protection and outfitting)– Adaptive to all environmental conditions and WTG sizes– Can be completed on land and fully assembled at quayside at <10 m WD– Concrete can be fabricated in all countries, limited number of skilled workers

required– Very good «scalability» factor for increase of WTG size– Possible to improve cost and durability by lifting interface between concrete

shaft and steel tower (sensitivity check in L50+, but not used as Base Case)

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DISCLAIMER & COPYRIGHT50

DisclaimerDr.techn.Olav Olsen provides no warranty, expressed or implied, as to the accuracy, reliability or completeness of the presentation. and neither Dr.techn.Olav Olsen nor any of its directors or employees will have any liability to you or any other persons resulting from your use.

CopyrightCopyright of all published material including photographs, drawings and images in this presentation remains vested in Dr.techn.Olav Olsen and third party contributors as appropriate. Accordingly, neither the whole nor any part of this document shall be reproduced in any form nor used in any manner without prior permission and applicable acknowledgements. No trademark, copyright or other notice shall be altered or removed from any reproduction.