Wind Turbine Decommissioning in the UK Offshore Zone

Transcription

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2 Wind Turbine Decommissioning in the UK Offshore Zone BWEA - Annual Conference 2001 Presented by Dan Pearson

3 Presentation Introduction: Why this topic? Life Cycle of an Offshore Wind Turbine Decommissioning

4 Introduction Introduction Why Offshore Decommissioning? Personal Interest Company Interest

5 OFFSHORE TURBINE LIFE CYCLE

6 Life Cycle Turbine Infrastructure Installation Operaton & Maintenance Decommissioning

7 Turbine Turbine 3.5MW+ Capacity 85m tower, 100m rotor diameter Foundation-Site specific Variable speed

8 Infrastructure Infrastructure Port Interface Logistical maneuvers Sub-sea cable Grid connection Scour protection

9 Installation Installation Vessels Cranage Manpower Towage Weather Seabed characteristics

10 Operation & Maintenance O&M Availability Remote Access Access Servicing Environmental

11 OFFSHORE DECOMMISSIONING

12 Decommissioning The Need for Decommissioning UNCLOS OSPAR Crown Estate Affected UK legislation

13 The Study The Scope Identify key areas Simplification of process Cost estimates of decommissioning Companies involved Oceans Engineering Hydrosoil Services, Seacore, Mr Patrick Harvey

14 The Study Assumptions Thirty individual turbines Sand bank Approx. 7km offshore 3.6MW turbines (85m tower, 100m Rotor diameter) 2 Annemometry masts Buried, under water cabling

15 Site Specifics Gunfleet Sands Geotechnical Wind Resource Wave Dynamics Current Flow Bank Dynamics Water Depth

16 Superstructure Decommissioning - 1 Installation reversal

17 Superstructure Decommissioning - 2 Installation reversal

18 Superstructure Decommissioning - 3 Installation reversal

19 Foundation Decommissioning Foundations Gravity 3 types Monopile 2 types Lattice tower with tension legs

20 Gravity Base Findings Re-Floating Heavy lift - Unknown seabed characteristics Pre-design engineering - costly Towing costs Concrete disposal

21 Monopile Findings 2-types -Driven & Bored Can be cut below sea-bed 18m of steel can be relatively easy to handle Cost implications high if pile to be fully removed

22 Lattice tower with Tension Legs Findings Similar decommissioning properties to monopile High fabrication cost Unproven with specific regard to offshore wind

23 Infrastructure Decommissioning Findings Scour protection - Lifting, Dredging Grid connection - Dismantle, Re-instate Sub-sea cabling - similar costs to installation Anemometer Mast - Monopile cutting

24 Cost Implications Findings Monopile Gravity Total Cost 3,544,000 3,973,000 Cost Per WTG 118, ,000 Total Per MW 34,000 38,000 NB - Estimated costs assuming electrical cable left in situ.

25 Conclusions Site and conditions, although specific to Gunfleet ands can translate an order of magnitude of cost for ther sites Conventional techniques have been assessed. No ccount of new developments Clarity required from relative bodies as to what is cceptable In this case, monopile foundations are, cheapest oundations to decommission

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27 Cost Implications Findings Monopile Gravity Total Cost 3,939,000 4,368,000 Cost Per WTG 131, ,000 Total Per MW 37,500 41,600 NB - Estimated costs assuming electrical cable will be extracted.

28 Programme Exec. Summary, Background information Other infrastructure/steakholder integration Updated weather, metocean parameters Detailed decommissioning description Methodology Interested party consultations Licenses and Permits - Project management issues Pre and post-decommissioning monitoring and

29 Health & Safety Currently no specific guidelines for offshore wind Health & Safety Work act will apply for developments within Territorial Sea Limit (HSE will be fully involved) CDM regulations will apply to both construction and decommissioning Contractors - Health & Safety compliance is paramount in offshore industry and will continue to be so.