offshore wind risks - issues and mitigations...2011/09/07 · offshore access issue - current...

Ian Chester / Jan Talaśka2011-09-05

Offshore Wind Risks - Issues and Mitigations

Baltexpo 2011 - Offshore Wind presented by DNV

DNV – An Independent Foundation

© Det Norske Veritas AS. All rights reserved.


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9,000employees, of which 76% have a university degree

300offices

100countries

Services to the Wind Industry

Accredited Services

� Project Certification

� Type Certification

� Testing Services- Power Performance Testing- Loads Testing

Advisory Services

� Wind Resource Assessment

� Project Development Support

� Due Diligence

� Marine Advisory Services

� Asset Risk Management 30%

40%360

10 2030

4050310

320330

340 350



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� Wind Turbine Technology

� Health, Safety and Environmental Risk Management

� Training and Educational Programs

0%

10%

20%

50

60

70

80

90

100

110

120

130140

150160170

180190200

210220

230

240

250

260

270

280

290

300

310

% of Time % of Energy

Construction

Wind energyuncertainty

Turbine technology

Major Risks in Offshore Wind Farms



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Marineconditions

Turbine foundations

Offshoreaccess

Subseacables

Regulatory regimeGrid

connection

Offshore Wind - Combining DNV competences

=+



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40+ years of offshore oil & gas experience

Global leader in project risk and certification of offshore

wind projects

25 years of hands-on experience with wind

turbines

40+ years of offshore oil & gas experience

Wind Energy Uncertainty

� Issue- Reliability of kWh generated estimates- Real on-site data are scarce- Wind resource estimates have large

uncertainty- Loss factors are not well understood (e.g.

wakes and turbulence)- Potential large variation in wind resource

across a R3 site



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� Mitigation- Offshore measurement (fixed tower, novel

solutions) over sufficient period of time(> 2 years)

- Layout optimisation and understanding the trade-offs

- Transparency of energy estimates

Site Conditions – Marine Environment

� Issue- The weather and sea conditions- Varying water depths and sea bed conditions

across a site- Weather window for offshore work is small

� Mitigation- Solid, site-specific information

- Measurement campaigns



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- Measurement campaigns- Data mining- Geotechnical investigation - Safety factors in design

- Relevant learning from oil and gas - Development / use of equipment / methods

suitable in adverse conditions

Wind Turbine Technology

� Issue- Large MW turbines required 10 MW?- Component failures difficult to rectify

offshore

� Mitigation- Turbine selection- Strong warranty agreements- Condition monitoring



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- Condition monitoring- Data monitoring, analysis and response- Proactive maintenance- Further research into design loadings- Turbine type certification- Engineered for reliability

Wind Turbine Foundations

� Issue- Costly foundation designs due to:

- Harsher marine conditions- Deeper water- Larger turbines

- Shallow-water solutions may not work

� Mitigation- Standardisation



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- Standardisation - Quality control during manufacture- Research programs (e.g. Carbon Trust OWA)- Information sharing between WTG

manufacturer and foundation designers for benefit

Subsea Cables and Power Transmission

� Issue- Many problems during cable installation, e.g.

improper cable handling- Human introduced hazards (e.g. anchoring)- Natural hazards (seabed mobility)- Unplanned downtime not considered in

energy estimates

� Mitigation



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Deep w

ater channel

� Mitigation- Cabling

- Understand site-specific conditions- Chose appropriate cabling design (e.g. armour, burial

depth, scour protection)- Work with experienced partners- Plan with contingencies

- Substation- Realistic expectations for annual maintenance time- Include unplanned outages- Diligent inspections and maintenance

Grid Connection

� Issue- Load centres are far away from offshore wind

farms- Congestion in certain areas of the grid- Long distance / high power will require (less

proven) offshore HVDC solutions- Uncertainty about ownership / operation of

assets



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� Mitigation- Early dialogue between developer and grid

operator- Careful evaluation of various options

Construction

� Issue- Major project - Contract strategy selection- Managing the interfaces- Supply chain and facilities- Unexpected technical issues

� Mitigation- Previous project experience



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- Previous project experience- Project lifecycle engineering supervision- Installation concept studies - Develop your own team- Plan A, B and C- Project Certification

Construction Vessels

� Issue- Vessels are scarce and expensive

(e.g. +100 k£/day + mob/demob)- Capabilities (crane, deck space, propulsion)

limited- Vessel reliability

� Mitigation- Developers building own vessels



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- Developers building own vessels- Long-term contracts (but uncertainties about

project schedules)

Offshore Access

� Issue- Current access solution (boat fendering)

limited by sea state (e.g. < 1.5 m significant wave height)

- Access to turbines more frequent than expected

- Health and safety issues – reputational risk

� Mitigation



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� Mitigation- Improvement of current solutions (e.g. to 3 m

significant wave height)- New access solutions (e.g. heave-

compensated gangway)- Additional access by helicopter-hoisting- Research programs (e.g. UK Carbon Trust

OWA)

Operations & Maintenance

� Issue- Determining the optimum O&M approach- Lack of deep offshore wind O&M experience

in the market- Limited experienced personnel- Personnel health and safety issues

� Mitigation- Minimise need to access the turbines



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- Minimise need to access the turbines- Turbines designed for easy O&M- O&M considered at the windfarm design

concept stage- Specialist vessels required

Regulatory Regime

� Issue- Investors looking for long-term certainty- UK ROC scheme reasonably successful, but

also discussion about feed-in tariffs- Carbon tax

� Mitigation- Firm statement and action from Government- Long -term agreements



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- Long -term agreements- Know the market

An Opportunity

� The wind industry is moving further offshore

� Need to quantify offshore risk and become comfortab le with it

� Lever oil & gas experience

� Prime movers will have an advantage

� Reliable project outturns – cost, schedule and quali ty



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Safeguarding life, property and the environment

www.dnv.com



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offshore wind risks - issues and mitigations...2011/09/07 · offshore access issue - current...

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