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
10
20
30
40
50
60
70
80
90
100
Jul-0
4A
ug-0
4Se
p-04
Oct
-04
Nov
-04
Dec
-04
Jan-
05Fe
b-05
Mar
-05
Apr
-05
May
-05
Jun-
05Ju
l-05
Aug
-05
Sep-
05O
ct-0
5N
ov-0
5D
ec-0
5Ja
n-06
Feb-
06M
ar-0
6A
pr-0
6M
ay-0
6Ju
n-06
Jul-0
6A
ug-0
6Se
p-06
Oct
-06
Nov
-06
Dec
-06
Jan-
07Fe
b-07
Mar
-07
Apr
-07
May
-07
Jun-
07Ju
l-07
Aug
-07
Sep-
07O
ct-0
7N
ov-0
7D
ec-0
7Ja
n-08
Feb-
08M
ar-0
8A
pr-0
8M
ay-0
8Ju
n-08
Jul-0
8A
ug-0
8Se
p-08
Oct
-08
Nov
-08
Dec
-08
Jan-
09Fe
b-09
Mar
-09
Apr
-09
May
-09
Jun-
09Ju
l-09
Aug
-09
Sep-
09O
ct-0
9N
ov-0
9D
ec-0
9
Capa
city F
acto
r (%
)
0
10
20
30
40
50
60
70
80
90
100
Jul-0
4A
ug-0
4Se
p-04
Oct
-04
Nov
-04
Dec
-04
Jan-
05Fe
b-05
Mar
-05
Apr
-05
May
-05
Jun-
05Ju
l-05
Aug
-05
Sep-
05O
ct-0
5N
ov-0
5D
ec-0
5Ja
n-06
Feb-
06M
ar-0
6A
pr-0
6M
ay-0
6Ju
n-06
Jul-0
6A
ug-0
6Se
p-06
Oct
-06
Nov
-06
Dec
-06
Jan-
07Fe
b-07
Mar
-07
Apr
-07
May
-07
Jun-
07Ju
l-07
Aug
-07
Sep-
07O
ct-0
7N
ov-0
7D
ec-0
7Ja
n-08
Feb-
08M
ar-0
8A
pr-0
8M
ay-0
8Ju
n-08
Jul-0
8A
ug-0
8Se
p-08
Oct
-08
Nov
-08
Dec
-08
Jan-
09Fe
b-09
Mar
-09
Apr
-09
May
-09
Jun-
09Ju
l-09
Aug
-09
Sep-
09O
ct-0
9N
ov-0
9D
ec-0
9
Avai
labi
lity
(%)
0
2
4
6
8
10
12
14
16
Jul-0
4A
ug-0
4Se
p-04
Oct
-04
Nov
-04
Dec
-04
Jan-
05Fe
b-05
Mar
-05
Apr
-05
May
-05
Jun-
05Ju
l-05
Aug
-05
Sep-
05O
ct-0
5N
ov-0
5D
ec-0
5Ja
n-06
Feb-
06M
ar-0
6A
pr-0
6M
ay-0
6Ju
n-06
Jul-0
6A
ug-0
6Se
p-06
Oct
-06
Nov
-06
Dec
-06
Jan-
07Fe
b-07
Mar
-07
Apr
-07
May
-07
Jun-
07Ju
l-07
Aug
-07
Sep-
07O
ct-0
7N
ov-0
7D
ec-0
7Ja
n-08
Feb-
08M
ar-0
8A
pr-0
8M
ay-0
8Ju
n-08
Jul-0
8A
ug-0
8Se
p-08
Oct
-08
Nov
-08
Dec
-08
Jan-
09Fe
b-09
Mar
-09
Apr
-09
May
-09
Jun-
09Ju
l-09
Aug
-09
Sep-
09O
ct-0
9N
ov-0
9D
ec-0
9
Win
d Sp
eed
(m/s
)
02468
10121416
Jul-0
4A
ug-0
4Se
p-04
Oct
-04
Nov
-04
Dec
-04
Jan-
05Fe
b-05
Mar
-05
Apr
-05
May
-05
Jun-
05Ju
l-05
Aug
-05
Sep-
05O
ct-0
5N
ov-0
5D
ec-0
5Ja
n-06
Feb-
06M
ar-0
6A
pr-0
6M
ay-0
6Ju
n-06
Jul-0
6A
ug-0
6Se
p-06
Oct
-06
Nov
-06
Dec
-06
Jan-
07Fe
b-07
Mar
-07
Apr
-07
May
-07
Jun-
07Ju
l-07
Aug
-07
Sep-
07O
ct-0
7N
ov-0
7D
ec-0
7Ja
n-08
Feb-
08M
ar-0
8A
pr-0
8M
ay-0
8Ju
n-08
Jul-0
8A
ug-0
8Se
p-08
Oct
-08
Nov
-08
Dec
-08
Jan-
09Fe
b-09
Mar
-09
Apr
-09
May
-09
Jun-
09Ju
l-09
Aug
-09
Sep-
09O
ct-0
9N
ov-0
9D
ec-0
9
Win
d Sp
eed
(m/s
)
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
4A
ug-0
4Se
p-04
Oct
-04
Nov
-04
Dec
-04
Jan-
05Fe
b-05
Mar
-05
Apr
-05
May
-05
Jun-
05Ju
l-05
Aug
-05
Sep-
05O
ct-0
5N
ov-0
5D
ec-0
5Ja
n-06
Feb-
06M
ar-0
6A
pr-0
6M
ay-0
6Ju
n-06
Jul-0
6A
ug-0
6Se
p-06
Oct
-06
Nov
-06
Dec
-06
Jan-
07Fe
b-07
Mar
-07
Apr
-07
May
-07
Jun-
07Ju
l-07
Aug
-07
Sep-
07O
ct-0
7N
ov-0
7D
ec-0
7Ja
n-08
Feb-
08M
ar-0
8A
pr-0
8M
ay-0
8Ju
n-08
Jul-0
8A
ug-0
8Se
p-08
Oct
-08
Nov
-08
Dec
-08
Jan-
09Fe
b-09
Mar
-09
Apr
-09
May
-09
Jun-
09Ju
l-09
Aug
-09
Sep-
09O
ct-0
9N
ov-0
9D
ec-0
9
Win
d Sp
eed
(m/s
)
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)
0
10
20
30
40
50
60
70
80
90
100
Jul-0
4A
ug-0
4Se
p-04
Oct
-04
Nov
-04
Dec
-04
Jan-
05Fe
b-05
Mar
-05
Apr
-05
May
-05
Jun-
05Ju
l-05
Aug
-05
Sep-
05O
ct-0
5N
ov-0
5D
ec-0
5Ja
n-06
Feb-
06M
ar-0
6A
pr-0
6M
ay-0
6Ju
n-06
Jul-0
6A
ug-0
6Se
p-06
Oct
-06
Nov
-06
Dec
-06
Jan-
07Fe
b-07
Mar
-07
Apr
-07
May
-07
Jun-
07Ju
l-07
Aug
-07
Sep-
07O
ct-0
7N
ov-0
7D
ec-0
7Ja
n-08
Feb-
08M
ar-0
8A
pr-0
8M
ay-0
8Ju
n-08
Jul-0
8A
ug-0
8Se
p-08
Oct
-08
Nov
-08
Dec
-08
Jan-
09Fe
b-09
Mar
-09
Apr
-09
May
-09
Jun-
09Ju
l-09
Aug
-09
Sep-
09O
ct-0
9N
ov-0
9D
ec-0
9
Capa
city F
acto
r (%
)
0
10
20
30
40
50
60
70
80
90
100
Jul-0
4A
ug-0
4Se
p-04
Oct
-04
Nov
-04
Dec
-04
Jan-
05Fe
b-05
Mar
-05
Apr
-05
May
-05
Jun-
05Ju
l-05
Aug
-05
Sep-
05O
ct-0
5N
ov-0
5D
ec-0
5Ja
n-06
Feb-
06M
ar-0
6A
pr-0
6M
ay-0
6Ju
n-06
Jul-0
6A
ug-0
6Se
p-06
Oct
-06
Nov
-06
Dec
-06
Jan-
07Fe
b-07
Mar
-07
Apr
-07
May
-07
Jun-
07Ju
l-07
Aug
-07
Sep-
07O
ct-0
7N
ov-0
7D
ec-0
7Ja
n-08
Feb-
08M
ar-0
8A
pr-0
8M
ay-0
8Ju
n-08
Jul-0
8A
ug-0
8Se
p-08
Oct
-08
Nov
-08
Dec
-08
Jan-
09Fe
b-09
Mar
-09
Apr
-09
May
-09
Jun-
09Ju
l-09
Aug
-09
Sep-
09O
ct-0
9N
ov-0
9D
ec-0
9
Avai
labi
lity
(%)
0
2
4
6
8
10
12
14
16
Jul-0
4A
ug-0
4Se
p-04
Oct
-04
Nov
-04
Dec
-04
Jan-
05Fe
b-05
Mar
-05
Apr
-05
May
-05
Jun-
05Ju
l-05
Aug
-05
Sep-
05O
ct-0
5N
ov-0
5D
ec-0
5Ja
n-06
Feb-
06M
ar-0
6A
pr-0
6M
ay-0
6Ju
n-06
Jul-0
6A
ug-0
6Se
p-06
Oct
-06
Nov
-06
Dec
-06
Jan-
07Fe
b-07
Mar
-07
Apr
-07
May
-07
Jun-
07Ju
l-07
Aug
-07
Sep-
07O
ct-0
7N
ov-0
7D
ec-0
7Ja
n-08
Feb-
08M
ar-0
8A
pr-0
8M
ay-0
8Ju
n-08
Jul-0
8A
ug-0
8Se
p-08
Oct
-08
Nov
-08
Dec
-08
Jan-
09Fe
b-09
Mar
-09
Apr
-09
May
-09
Jun-
09Ju
l-09
Aug
-09
Sep-
09O
ct-0
9N
ov-0
9D
ec-0
9
Win
d Sp
eed
(m/s
)
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
100
0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0
Avai
labi
lity
(%)
Wind Speed (m/s)
Monthly Availability with Wind Speed
0102030405060708090
100
0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0
Avai
labi
lity
(%)
Wind Speed (m/s)
Monthly Availability with Wind Speed
0102030405060708090
100
0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0
Avai
labi
lity
(%)
Wind Speed (m/s)
Monthly Availability with Wind Speed
0102030405060708090
100
0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0
Avai
labi
lity
(%)
Wind Speed (m/s)
Monthly Availability with Wind Speed
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)
0
500
1000
1500
2000
5 6 7 8 9 10 11 12 13
Ener
gy (M
Wh)
Scroby Sands: Energy Generated and Theoretically Lost due to Unavailability per Turbine over 3 years
Energy Generated Theoretical Lost Energy due to Unavailability
0
500
1000
1500
2000
5 6 7 8 9 10 11 12 13
Ener
gy (M
Wh)
Kentish Flats: Energy Generated and Theoretically Lost due to Unavailability per Turbine over 3 years
Energy Generated Theoretical Lost Energy due to Unavailability
0
500
1000
1500
2000
5 6 7 8 9 10 11 12 13
Ener
gy (M
Wh)
North Hoyle: Energy Generated and Theoretically Lost due to Unavailability per Turbine over 3 years
Energy Generated Theoretical Lost Energy due to Unavailability
0
500
1000
1500
2000
5 6 7 8 9 10 11 12 13
Ener
gy (M
Wh)
Egmond aan Zee: Energy Generated and Theoretically Lost due to Unavailability per Turbine over 3 years
Energy Generated Theoretical Lost Energy due to Unavailability
0
500
1000
1500
2000
5 6 7 8 9 10 11 12 13
Ener
gy (M
Wh)
Egmond aan Zee: Energy Generated and Theoretically Lost due to Unavailability per Turbine over 3 years
Energy Generated Theoretical Lost Energy due to Unavailability
Energy and Wind Speed
0%
20%
40%
60%
80%
100%
5 6 7 8 9 10 11 12 13
Ener
gy (M
Wh)
Egmond aan Zee: Energy Generated and Theoretically Lost due to Unavailability per Turbine over 3 years
Energy Generated Theoretical Lost Energy due to Unavailability
0%
20%
40%
60%
80%
100%
5 6 7 8 9 10 11 12 13
Ener
gy (M
Wh)
Scroby Sands: Energy Generated and Theoretically Lost due to Unavailability over 3 years
Energy Generated Theoretical Lost Energy due to Unavailability
0%
20%
40%
60%
80%
100%
5 6 7 8 9 10 11 12 13
Ener
gy (M
Wh)
Kentish Flats: Energy Generated and Theoretically Lost due to Unavailability over 3 years
Series1 Series2
0%
20%
40%
60%
80%
100%
5 6 7 8 9 10 11 12 13
Ener
gy (M
Wh)
North Hoyle: Energy Generated and Theoretically Lost due to Unavailability over 3 years
Energy Generated Theoretical Lost Energy due to Unavailability
0
500
1000
1500
2000
5 6 7 8 9 10 11 12 13
Ener
gy (M
Wh)
Egmond aan Zee: Energy Generated and Theoretically Lost due to Unavailability per Turbine over 3 years
Energy Generated Theoretical Lost Energy due to Unavailability
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)
0%
20%
40%
60%
80%
100%
5 6 7 8 9 10 11 12 13
Ener
gy (%
)
Kentish Flats: Energy Generated and Theoretically Lost due to Unavailability over 3 years
Series1 Series2
0%
20%
40%
60%
80%
100%
5 6 7 8 9 10 11 12 13
Ener
gy (%
)
Kentish Flats: Energy Generated and Theoretically Lost due to Unavailability over 3 years
Series1 Series2
0%
20%
40%
60%
80%
100%
5 6 7 8 9 10 11 12 13
Ener
gy (%
)
Kentish Flats: Energy Generated and Theoretically Lost due to Unavailability over 3 years
Series1 Series2
0%
20%
40%
60%
80%
100%
5 6 7 8 9 10 11 12 13
Ener
gy (%
)
Kentish Flats: Energy Generated and Theoretically Lost due to Unavailability over 3 years
Series1 Series2
0
5
10
15
20
25
30
0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0
Unw
orka
ble
Day
s
Wind Speed (m/s)
Monthly Unworkable Days with Wind Speed
0
5
10
15
20
25
30
0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0
Unw
orka
ble
Day
s
Wind Speed (m/s)
Monthly Unworkable Days with Wind Speed
0
5
10
15
20
25
30
0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0
Unw
orka
ble
Day
s
Wind Speed (m/s)
Monthly Unworkable Days with Wind Speed
Kentish Flats (30 x V90-3MW)Scroby Sands (30 x V80-2MW)
Egmond aan Zee (36 x V90-3MW)
Unworkable Days
Kentish Flats (30 x V90-3MW)Scroby Sands (30 x V80-2MW)
Egmond aan Zee (36 x V90-3MW)
0
20
40
60
80
100
0.0 5.0 10.0 15.0 20.0 25.0 30.0
Avai
labi
lity
(%)
Unworkable Days
Monthly Availability with Unworkable Days
0
20
40
60
80
100
0.0 5.0 10.0 15.0 20.0 25.0 30.0
Avai
labi
lity
(%)
Unworkable Days
Monthly Availability with Unworkable Days
0
20
40
60
80
100
0.0 5.0 10.0 15.0 20.0 25.0 30.0
Avai
labi
lity
(%)
Unworkable Days
Monthly Availability with Unworkable Days
Availability and Unworkable Days
Kentish Flats (30 x V90-3MW)Scroby Sands (30 x V80-2MW)
Egmond aan Zee (36 x V90-3MW)
0
20
40
60
80
100
0.0 5.0 10.0 15.0 20.0 25.0 30.0
Avai
labi
lity
(%)
Unworkable Days
Monthly Availability with Unworkable Days
0
20
40
60
80
100
0.0 5.0 10.0 15.0 20.0 25.0 30.0
Avai
labi
lity
(%)
Unworkable Days
Monthly Availability with Unworkable Days
0
20
40
60
80
100
0.0 5.0 10.0 15.0 20.0 25.0 30.0
Avai
labi
lity
(%)
Unworkable Days
Monthly Availability with Unworkable Days
Availability and Unworkable Days
No relationshipWater depth = 3.6m
Kentish Flats (30 x V90-3MW)Scroby Sands (30 x V80-2MW)
Egmond aan Zee (36 x V90-3MW)
0
20
40
60
80
100
0.0 5.0 10.0 15.0 20.0 25.0 30.0
Avai
labi
lity
(%)
Unworkable Days
Monthly Availability with Unworkable Days
0
20
40
60
80
100
0.0 5.0 10.0 15.0 20.0 25.0 30.0
Avai
labi
lity
(%)
Unworkable Days
Monthly Availability with Unworkable Days
0
20
40
60
80
100
0.0 5.0 10.0 15.0 20.0 25.0 30.0
Avai
labi
lity
(%)
Unworkable Days
Monthly Availability with Unworkable Days
Availability and Unworkable Days
No relationshipWater depth = 3.6m
Decreasing availabilityWater depth = 9.8m
Kentish Flats (30 x V90-3MW)Scroby Sands (30 x V80-2MW)
Egmond aan Zee (36 x V90-3MW)
0
20
40
60
80
100
0.0 5.0 10.0 15.0 20.0 25.0 30.0
Avai
labi
lity
(%)
Unworkable Days
Monthly Availability with Unworkable Days
0
20
40
60
80
100
0.0 5.0 10.0 15.0 20.0 25.0 30.0
Avai
labi
lity
(%)
Unworkable Days
Monthly Availability with Unworkable Days
0
20
40
60
80
100
0.0 5.0 10.0 15.0 20.0 25.0 30.0
Avai
labi
lity
(%)
Unworkable Days
Monthly Availability with Unworkable Days
Availability and Unworkable Days
No relationshipWater depth = 3.6m
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
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