operational and reliability analysis of offshore wind farms

Operational and Reliability Analysis of Offshore Wind Farms

Has availability gone with the wind?

Christopher J. Crabtree, Durham University, UK

EWEA 2012

17th April 2012

Wind in the UK

• Operational Capacity– Onshore: 4.25 GW– Offshore: 1.52 GW

• Under Construction or Consented– Onshore: 5.37 GW– Offshore: 3.92 GW

• Planned– Onshore: 7.66 GW– Offshore: 2.28 GW

• Round 3 Offshore: up to 25 GW

Capacity Factor and Cost of Energy

• Average capacity factor:– Onshore (DECC) = 27.3%– Round 1 offshore = 29.5%– Expected offshore = 35.0%

• Average cost of energy:– Onshore (2006) = £47 per MWh– Round 1 offshore = £69 per MWh

• What might be affecting capacity factor and cost of energy?

Availability0

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(m/s

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02468

10121416

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(m/s

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Scroby Sands (30 x V80-2MW - UK Offshore) North Hoyle (30 x V80-2MW - UK Offshore)

Kentish Flats (30 x V90-3MW - UK Offshore) Barrow (30 × V90-3MW - UK Offshore)

Egmond aan Zee (36 × V90-3MW - NL Offshore)

Capacity Factor

02468

10121416

Jul-0

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Scroby Sands (30 x V80-2MW - UK Offshore) North Hoyle (30 x V80-2MW - UK Offshore)

Kentish Flats (30 x V90-3MW - UK Offshore) Barrow (30 × V90-3MW - UK Offshore)

Egmond aan Zee (36 × V90-3MW - NL Offshore)

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Availability and Capacity Factor

• Capacity factor depends upon availability

• Large variations in availability

• What is causing availability to vary?– ‘Seasonal’ variations are not consistent– What about the wind conditions?

• What is the result?

Kentish Flats (V90)Scroby Sands (30 x V80)

Egmond aan Zee (36 x V90)North Hoyle (30 x V80)

0102030405060708090

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Monthly Availability with Wind Speed

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Availability and Wind Speed

Energy and Wind SpeedKentish Flats (30 x V90-3MW)Scroby Sands (30 x V80-2MW)

Egmond aan Zee (36 x V90-3MW)North Hoyle (30 x V80-2MW)

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Scroby Sands: Energy Generated and Theoretically Lost due to Unavailability per Turbine over 3 years

Energy Generated Theoretical Lost Energy due to Unavailability

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Series1 Series2

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Kentish Flats (30 x V90-3MW)Scroby Sands (30 x V80-2MW)

Egmond aan Zee (36 x V90-3MW)North Hoyle (30 x V80-2MW)

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Unworkable Days



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No relationshipWater depth = 3.6m



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Decreasing availabilityWater depth = 9.8m



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Unworkable Days




Significantly decreasing availabilityWater depth = 12.8m

Decreasing availabilityWater depth = 9.8m

Conclusions

• Offshore wind is achieving higher capacity factors than onshore– Highly variable availability– Season and wind speed dependent

• Large energy losses at certain wind speeds– Wind speed, water depth and unworkable days are linked

• Stops must be occurring at higher wind speeds– A reliability problem

• Unable to access turbines for repair– An operations problem

Why Worry?

Location Water Depth

(m) Distance to Shore (km)

Reported Wind Farms

North Hoyle, UK 7-11 6

Scroby Sands, UK 5-10 2.3

Kentish Flats, UK 5 8.5

Barrow, UK 15-20 7.5

Egmond aan Zee, NL 19-22 10

Why Worry?

Location Water Depth

(m)

Distance to Shore (km)

Reported Wind Farms

North Hoyle, UK 7-11 6

Scroby Sands, UK 5-10 2.3

Kentish Flats, UK 5 8.5

Barrow, UK 15-20 7.5

Egmond aan Zee, NL 19-22 10

UK Round 3

Firth of Forth 31-62 37-77

Dogger Bank 18-63 125-290

Irish Sea 26-74 15-40

Operational and Reliability Analysis of Offshore Wind Farms

Thank you for listening

Dr Christopher J. Crabtree

[email protected]

operational and reliability analysis of offshore wind farms

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