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OFFSHORE WIND CAPITAL GRANTS SCHEME
Barrow Offshore Wind Farm 1st Annual Report
JULY 2006 – JUNE 2007
URN NUMBER: 09/P45
Page 2 of 22
EXECUTIVE SUMMARY
The proposal for establishing an offshore wind farm near Barrow originated in 2001
and was made by the then Warwick Offshore Wind Limited, who organised
preliminary permissions, environmental impact statements, draft lease agreements
etc. for an offshore wind farm at Barrow, about 10 km southeast of Barrow-in-
Furness, Cumbria.
In 2003 DONG VE Ltd. took over Warwick Offshore Wind Limited, and a co-
operation agreement was subsequently made with Centrica Plc for establishing
BOW Ltd. on a shared 50%/50% basis with DONG VE Ltd as the lead partner. All
consents and legal obligations for establishment of the wind farm were obtained,
and a £10m capital grant towards the capital costs was obtained from the
Department of Trade and Industry (DTI) Grant reference number
W102/00/00009/00/00.
Tender documents were issued in 2004 for the work under an EPIC contract
including a 5-year O&M phase.
The EPIC contract was awarded to the VKBR Joint Venture with Vestas Celtic and
KBR (Kellogg Brown & Root Ltd.) as the two partners in the joint venture. As major
sub-contractors VKBR used SIF & Smulders Hoboken for steelworks, AREVA for
electrical works and Marine Projects International Ltd. (MPI) for the marine
installation works. Construction works were initiated in May 2005. The original date
for completion of construction was 20 September 2005. However, this was delayed
by 6 months and the actual construction completion date was 30 April 2006.
The original date for commissioning of the wind farm was 20 November 2005 but
the actual commissioning date was 31 May 2006, a delay of 6 months.
It has been agreed that the period of this first annual report should cover July 2006-
June 2007 because sufficient data does not exist for June 2006.
BOW consists of 30 V90 wind turbine generators (WTGs) manufactured by Vestas,
each of 3.0 MW. Then total installed capacity is 90 MW compared with a total
capacity of maximum 108 MW (30 WTGs a 3.6 MW) provided for in the FEPA license
for the construction.
The original eligible project cost was £81.251m, while the current forecast of total
project cost is now £123m. £112.2 million had already been spent by 31 July 2007.
The total DTI Capital Grant obtained for the project was £10million.
The construction cost per MW installed is £1.37 million (forecast) with a grant
contribution of £0.11 million per MW installed. The construction cost per turbine
installed is £4.10 million.
Page 3 of 22
Site plan
A location map of Barrow Offshore Wind (BOW) is shown below. The 30 WTGs are
placed in 4 rows of alternating 7 and 8 WTGs. The wind farm itself covers an offshore
area of c. 4 x 2.5 km southwest of Barrow-in-Furness, with a distance of 8 km from
the shoreline to the first row of turbines. The general water depth in the area is
about 15 m below Chart Datum.
The alignment of the 27 km long offshore high voltage export cable from the
offshore sub-station to Heysham ashore sub-station is also shown on the location
map below.
The geographical coordinates of each WTG are presented in the table overleaf.
Page 4 of 22
WTG id Position (WGS84)
Longitude (°, ‘, ‘’) Latitude (°, ‘, ‘’)
1 D8 3 19 45.167 W 53 59 42.878 N
2 D7 3 19 25.036 W 53 59 32.226 N
3 D6 3 19 4.908 W 53 59 21.570 N
4 D5 3 18 44.780 W 53 59 10.914 N
5 D4 3 18 24.653 W 53 59 0.254 N
6 D3 3 18 4.532 W 53 58 49.598 N
7 D2 3 17 44.412 W 53 58 38.939 N
8 D1 3 17 24.299 W 53 58 28.279 N
9 C7 3 19 6.974 W 53 59 56.004 N 10 C6 3 18 46.840 W 53 59 45.348 N
11 C5 3 18 26.712 W 53 59 34.692 N
12 C4 3 18 6.588 W 53 59 24.032 N
13 C3 3 17 46.460 W 53 59 13.376 N
14 C2 3 17 26.340 W 53 59 2.713 N
15 C1 3 17 6.216 W 53 58 52.054 N
16 B8 3 18 48.899 W 54 0 19.786 N
17 B7 3 18 28.768 W 54 0 9.130 N
18 B6 3 18 8.636 W 53 59 58.470 N
19 B5 3 17 48.509 W 53 59 47.810 N
20 B4 3 17 28.381 W 53 59 37.151 N
21 B3 3 17 8.257 W 53 59 26.491 N
22 B2 3 16 48.140 W 53 59 15.828 N
23 B1 3 16 28.024 W 53 59 5.165 N
24 A7 3 18 10.696 W 54 0 32.908 N
25 A6 3 17 50.557 W 54 0 22.248 N
26 A5 3 17 30.426 W 54 0 11.588 N
27 A4 3 17 10.295 W 54 0 0.929 N
28 A3 3 16 50.171 W 53 59 50.266 N
29 A2 3 16 30.050 W 53 59 39.602 N
30 A1 3 16 9.934 W 53 59 28.939 N
Substation 3 16 12.713 W 53 59 15.104 N
Landfall cable 2 54 42.552 W 54 1 27.840 N
Page 5 of 22
CONSTRUCTION
Overview of the Construction Programme to July 2007
The following table provides an overview of the actual progress of the
procurement and construction works.
2004 2005 2006 2007
3rd qt 4th qt 1st qt nd qt 3rd qt 4th qt 1st qt 2nd qt 3rd qt 4th qt 1st qt 2nd qt 3rd qtID Description J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D J F M A M J J A S
1 Procurement of plant
2 Onshore work
3 Foundation installation
4 Turbine installation
5 Offshore cabling
6 Grid connection
7 Commissioning
8 Wind farm tests9 Outstanding and
remedial EPIC works
Description of Construction Methods
Procurement of plant
The EPIC main contractor VKBR (Vestas Celtic and Kellog Brown) procured and
installed all items necessary for establishment of BOW.
VKBR used SIF & Smulders Hoboken as sub-contractors for the procurement of the
foundation steel works, i.e. for manufacturing of monopiles, transition pieces and J-
tubes and delivery to the load out site at H&W in Belfast. AREVA was engaged as the
sub-contractor for the supply and delivery of all electrical and related components,
i.e. the offshore sub-station at BOW and the onshore sub-station in Heysham.
Vestas Celtic, the one partner of VKBR Joint Venture, supplied the 30 wind turbine
generators.
Onshore preparation
BOW is connected by a high voltage export cable, which includes a 1.5 km long
onshore section, to Heysham electrical sub-station and the national grid. For the
connection of BOW to the national electricity grid a separate onshore sub-station
has been constructed at Heysham sub-station.
Electrical installations for the BOW sub-station in Heysham are all complete, and the
SCADA system is linked up and running.
Page 6 of 22
Foundation installation
The structure used to support the WTGs is a monopole foundation. This type of
foundation has also been used for other large offshore wind farms. A main steel pile
is driven into the seabed by means of a hydraulic hammer, being operated from a
jack-up vessel (“Resolution”). At 9 out of 30 monopiles it was necessary to drill out
the internal soil plug prior to driving the pile to the final level. The monopiles
installed all have a diameter of 4.750 m and a length of between 49 and 61 m – the
actual pile length was determined on the basis of an assessment of the soil
conditions at each WTG position. All monopiles were driven to a final level, so each
monopole has been installed with a top level of +5.0 m CD (corresponding to Mean
Sea Level (MSL)).
The transition pieces (TPs) with a service platform for operation and maintenance
were then grouted onto the monopole. The transition piece also has a flange for
bolting the wind turbine tower to it. The top level of each TP is +20.25 m CD.
In order to connect the WTGs to the grid, the foundations hold internal J-tubes for
installation of submarine cables. The foundation installation was started in May
2005 and completed in November 2005, using the jack-up vessel, “Resolution”, as
installation vessel. The installation of foundations was delayed for various reasons,
for example, design of grout seal connection, the required time for drilling out the
soil plug for 9 monopiles, and weather downtime.
Offshore turbine installation
After completion of the foundations, the WTGs were then installed and this was
completed on 30 April 2006. Four complete WTG sub-assemblies were transported
on “Resolution” from Belfast to BOW. Three lifts were required for each complete
wind turbine:
– The first lift is the complete tower;
– The second lift is the nacelle with 2 turbine blades (“bunny ears”.); and
– The third lift is the final turbine blade, which finalises the mechanical
installation.
The hub height of the WTGs installed is at a level of +80 m CD, and the rotor
diameter is 90 m.
Offshore cabling
The cables from the WTGs interconnect in 4 rows of 7-8 WTGs, each having one
cable connection to the offshore sub-station, from which the export cable was laid
to the shore at Heysham and onwards to the onshore sub-station, also at Heysham,
where it connects to the onshore grid. For the offshore cabling a special purpose
cable installation vessel was used.
Page 7 of 22
The initial cable burial depth achieved was not sufficient to requirements at some
locations . After a survey of exact burial depth during the summer 2006, which was
undertaken as part of the post-construction survey as agreed in the FEPA licence,
supplementary jetting of the offshore transmission cable was carried out in March -
April 2007. To date a few remaining sections are still in need of additional protection.
Evaluation of the solutions including the need for reburial are ongoing within the
project
All infield cables were completed on 30 April 2006. Additional burial works (by
jetting) of the inter-array cables were executed in April – May 2007. About half of the
cable ends are in need of additional uraduct protection, and some have free spans
substantially longer than assumed in project design. Diving work for placing this
supplementary protection will be initiated at the end of July 2007.
Grid connection
The grid connection is available and the WTGs are producing power.
First power was produced from WTG D6 on 4 March 2006 and by the end of May
2006 all WTGs were running.
Commissioning & tests
Commissioning and energization of the WTGs was completed by 31 December 2006.
Outstanding and remedial works
A number of outstanding and remedial works related to the EPIC Contract are
currently being undertaken by VKBR and were scheduled for completion in autumn
2007. However, adverse weather over summer 2007 has delayed this work and the
scheduled completion date is now 1 July 2008.
Page 8 of 22
Wind farm annual operation information
PERFORMANCE REPORTING
Availability
Three measures of availability are used to describe the performance of the wind
farm.
• Technical availability of the wind farm is the actual availability - the time that
the wind turbines are available to generate as a percentage, compared to the
theoretical maximum. There is no allowance for routine or breakdown
maintenance activities or for the effects of external influence.
• Commercial Availability is based on the technical availability but includes
alleviation for requested stops, the loss of the external grid connection and for
weather days.
• Planned availability is the technical availability forecasted for the year,
calculated by taking into account all of the planned work and available recourses,
calculated from the annual work plan. The work plan details all of the routine and
planned works and was developed to ensure that all work was fully assessed,
prioritised and completed within the required timescales.
Output and Capacity Factor
The capacity factor is calculated as a percentage, comparing the amount of
generation produced, with the theoretical maximum generation that would have
been produced if the turbines operated at maximum output during a specified time
period.
The annual budgeted capacity factor is calculated as budgeted production divided
by maximum output for 8760 hours in a normal year.
Page 9 of 22
Availability (hours %)
Table 1 shows the monthly the recorded technical availability for each WTG at BOW
over the period July 2006 – June 2007.
Table 1 Monthly availability of WTG’s (% of time) July 2006 - June 2007.
The recorded average availability is 67%, while the planned availability of the WTGs
was 90.25%. Thus, actual availability has been significantly lower than planned.
The lower availability after October 2007 is due to a number of WTG faults, mainly
generator bearings and rotor cable faults combined with low access to the WTG
because of high waves.
Furthermore, the wave climate in the winter season 2006-2007 has been dominated
by persistent westerly winds yielding significantly more adverse weather than
statistically expected for long-term conditions. This has to some extent been
unexpected for the company undertaking the operation and maintenance work.
We have not at this stage completed an analysis of down-time. This is currently
scheduled to take place in spring 2008.
Unit Jul-06 Aug Sep Oct Nov Dec Jan-07 Feb Mar Apr May Jun Avg
A1 87 72 26 88 98 100 76 34 66 94 93 80 76
A2 65 92 90 92 44 16 26 92 95 99 31 68 68
A3 47 95 69 53 52 87 29 92 83 91 87 75 72
A4 97 99 82 43 59 51 99 78 21 85 89 97 75
A5 66 99 99 78 100 92 13 88 64 89 15 47 71
A6 90 92 93 83 83 66 12 55 26 0 0 0 50
A7 96 82 39 48 12 23 1 76 92 98 94 98 63
B1 89 88 94 99 29 0 0 60 63 76 0 0 50
B2 78 75 86 99 6 15 1 66 90 96 91 97 67
B3 91 99 62 70 69 62 44 21 13 74 84 98 65
B4 94 97 70 79 49 37 16 42 96 95 99 85 72
B5 95 77 78 98 97 42 67 23 0 1 0 0 48
B6 95 94 98 93 64 40 43 87 100 95 98 98 84
B7 100 100 99 100 68 67 45 51 38 96 62 93 77
B8 79 71 91 99 96 54 0 65 89 97 97 95 78
C1 98 99 97 83 31 38 78 98 94 64 0 0 65
C2 60 78 97 91 98 100 34 85 6 62 95 93 75
C3 96 96 95 95 5 82 54 79 31 96 91 95 76
C4 58 75 99 79 24 50 0 71 96 60 75 95 65
C5 95 94 97 83 100 100 32 90 98 99 50 71 84
C6 95 62 87 89 6 83 5 60 87 98 96 90 71
C7 93 74 86 99 70 51 60 96 95 17 89 91 77
D1 86 73 53 89 67 68 96 81 41 96 85 91 77
D2 98 98 80 94 91 87 5 48 71 31 0 0 58
D3 80 85 79 71 49 56 46 81 56 62 50 41 63
D4 51 56 83 62 31 26 64 87 84 71 75 76 64
D5 60 52 89 85 50 49 97 94 51 95 16 75 68
D6 90 92 77 94 95 98 0 12 0 0 0 0 46
D7 69 95 84 85 84 64 36 90 85 84 69 26 73
D8 98 84 99 77 95 50 0 0 0 0 0 0 42
Avg 83 85 83 83 61 58 36 67 61 71 58 63 67
Page 10 of 22
Wind speed (m/s)
For the 12-month period, July 2006 – June 2007, the yearly average wind speed was
9.0 m/s at hub height for all turbines. Table 2 also sets out the monthly average wind
speed recorded at each turbine. However, for a number of turbines with limited data
coverage the recorded average wind speed has not been included, because data
communication has been incomplete over long periods due to cable communication
failure and/or WTG repairs.
Table 2 Monthly average wind speed at each turbine July 2006 – June 2007 Wind speed [m/s]
Year: 2006 2007
Parkunit Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr
May Jun Average
A1 6,6 8,3 8,1 9,7 12,1 11,3 13,8 8,2 9,9 6,9 7,8 6,5 9,1
A2 6,7 7,9 8,4 9,6 11,6 10,5 13,5 8,7 10,2 7,0 7,0 6,9 9,0
A3 6,5 8,1 8,3 9,9 11,7 10,4 6,2 8,6 10,1 7,0 7,7 6,5 8,4
A4 6,6 8,0 8,1 9,6 11,6 10,8 13,7 8,1 9,9 6,8 7,7 7,1 9,0
A5 6,5 8,2 8,0 9,0 13,0 8,8 10,0 7,5 7,5 7,4 8,6
A6 6,6 8,3 8,2 9,6 11,6 10,1 10,0 9,9 6,9 7,5 5,1 8,5
A7 7,0 8,2 8,0 10,2 12,2 10,8 13,3 8,8 10,4 7,8 8,3 7,5 9,4
B1 6,6 8,3 8,4 9,6 11,3 11,2 13,7 8,8 10,3 6,7 7,9 9,3
B2 6,7 8,0 8,3 8,7 12,0 10,8 14,4 8,8 10,5 7,0 7,9 7,2 9,2
B3 6,5 8,0 8,3 9,8 11,5 11,2 12,3 4,8 6,8 7,4 7,7 6,9 8,4
B4 6,6 8,2 8,1 9,3 11,7 10,9 8,7 10,4 7,0 7,9 7,0 8,7
B5 6,8 8,3 8,3 9,8 11,8 11,2 13,8 9,5 10,0 6,9 7,5 4,9 9,1
B6 6,6 8,3 8,0 9,4 11,6 10,7 11,4 8,2 10,0 7,1 7,8 7,0 8,8
B7 8,2 9,7 11,6 11,0 14,0 8,6 9,9 7,1 7,6 7,1 9,5
B8 6,9 8,4 8,1 9,6 10,7 10,2 8,4 7,6 8,3 7,6 8,6
C1 6,7 8,3 8,6 9,9 11,3 11,3 14,2 9,0 10,5 6,9 7,9 9,5
C2 6,6 8,1 8,4 9,5 12,2 11,1 13,9 8,8 9,7 7,2 8,1 7,2 9,2
C3 6,6 8,1 8,1 9,1 11,7 8,6 8,7 7,0 7,9 7,0 8,3
C4 6,5 8,1 8,2 9,4 11,1 9,2 10,4 6,8 8,0 7,1 8,5
C5 7,1 8,7 8,6 10,0 12,3 11,5 13,8 9,2 10,8 7,7 8,4 7,4 9,6
C6 6,8 8,2 8,2 10,3 11,5 15,0 10,9 8,7 10,6 7,4 8,2 7,3 9,4
C7 6,6 8,3 8,0 9,3 11,4 10,2 13,6 8,5 9,9 6,7 7,6 6,9 8,9
D1 6,8 8,3 8,4 10,0 12,1 14,5 8,9 9,1 7,2 8,0 7,3 9,1
D2 7,5 8,1 8,2 10,3 12,2 12,7 13,0 8,6 9,2 6,6 7,4 9,4
D3 6,6 8,3 8,4 9,9 11,7 13,9 8,8 10,4 7,1 7,5 6,8 9,0
D4 6,8 8,7 8,6 10,0 11,8 11,1 13,9 9,2 10,6 7,5 8,2 7,2 9,5
D5 7,1 8,3 8,5 9,9 12,1 11,1 13,9 9,1 10,0 7,6 8,9 7,4 9,5
D6 6,8 8,4 7,5 9,6 7,9 11,2 7,2 8,4
D7 6,7 8,6 8,5 10,0 12,4 11,3 13,8 9,0 10,5 7,3 8,0 7,5 9,5
D8 7,0 8,8 8,6 9,9 12,1 12,3 10,8 10,2 7,3 8,5 9,6
Average 6,7 8,3 8,3 9,7 11,7 11,3 13,0 8,8 10,0 7,1 7,9 7,0 9,04
The recorded average wind speed for individual turbines varies from 8.3 – 9.6 m/s
with an overall average annual wind speed of 9.0 m/s. These observed variations
from turbine to turbine can be assigned to the influence of data gaps, spikes in the
data time series and effects of instrument calibration. Natural fluctuations from
Page 11 of 22
turbine to turbine, as a result of lee effects and impact of rotors running or not
running, are also expected to have some influence.
A wind study undertaken by Tripod Wind Energy in 2006 showed that the long-term
mean wind speed at Shell Flat (at a height of 75m which is representative of Barrow)
is 9.2 m/s. Thus, the average wind speed in the reporting period has more or less
been at the long term mean level.
The wind direction on the wind turbines and at the meteorological station has been
recorded, but unfortunately not been calibrated with respect to recording wind
direction in comparison to the north direction. Therefore, wind roses from the
various turbines are not consistent. For two selected turbines, B6 and C5, the below
figure shows recorded wind roses, illustrating the distribution on wind direction.
The wind roses from the corresponding turbines illustrate that their lack of
calibration has affected the data.
Output (MWh)
Monthly power production July 2006 to June 2007
The annual power production generated at all 30 WTGs during the 12-month period
was 193,784 MWh, which was less than the expected budget of 301.910 MWh. This
represents 64.2% of the actual annual production target.
However, during May 2007 there was a problem with data availability for calculation
of production at each WTG. Table 3 shows that the total production for May 2007
was less than the exported production - 11,795MWh versus 12,793 MWh. It is likely
Page 12 of 22
that the actual total production was about 13,100 MWh (instead of 11,795 MWh),
which would mean the the total annual production was 195,089 MWh or 64.6% of
budgeted production.
Table 3: The production in MWh for each turbine per month and year WTG 2006 2007 12-month
id Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Period
A1 476 555 131 811 1480 1169 1269 137 768 591 706 413 8.506
A2 179 446 670 838 510 13 284 826 1141 611 170 344 6.032
A3 154 754 492 334 688 731 497 810 938 556 664 399 7.016
A4 511 820 663 390 710 252 1593 519 157 528 662 604 7.412
A5 354 819 776 436 0 136 150 666 534 553 69 193 4.686
A6 427 741 709 966 1073 199 230 601 369 -6 -8 0 5.302
A7 538 460 -2 305 43 79 3 544 1094 678 125 583 4.449
B1 417 647 756 983 226 -5 -8 578 649 439 0 0 4.680
B2 371 506 594 299 -1 0 -2 727 1125 591 709 604 5.523
B3 475 814 385 565 957 483 627 48 91 398 560 586 5.988
B4 497 773 454 701 538 200 301 417 1145 578 758 482 6.844
B5 512 536 547 1035 1450 231 1147 202 -1 -4 0 0 5.655
B6 507 842 787 867 901 226 795 779 1148 616 748 564 8.779
B7 432 429 786 1074 941 197 699 441 274 618 451 600 6.941
B8 481 561 698 1084 715 -1 -3 704 884 681 796 600 7.201
C1 519 833 851 868 252 226 1199 881 1159 330 0 0 7.119
C2 202 534 807 701 1458 1206 488 716 19 361 737 585 7.814
C3 522 823 776 873 -5 -1 63 564 236 600 734 574 5.759
C4 259 666 810 719 220 -2 0 748 1133 337 501 583 5.974
C5 514 826 746 797 1522 1213 461 799 1189 630 349 301 9.348
C6 519 447 608 422 -11 0 84 463 1060 648 765 574 5.580
C7 531 645 633 1082 999 49 963 847 1168 77 744 589 8.327
D1 514 521 189 852 992 231 1527 687 359 662 694 608 7.836
D2 528 573 369 976 1404 961 -11 515 799 163 -2 0 6.275
D3 391 624 468 680 603 32 618 660 501 463 262 257 5.558
D4 219 485 614 674 346 35 978 765 1058 386 601 405 6.568
D5 217 339 687 987 673 335 1640 861 440 632 0 543 7.355
D6 463 782 601 1026 238 0 0 33 -1 -3 0 0 3.139
D7 330 824 715 847 1317 503 449 764 1050 549 0 247 7.595
D8 550 714 853 742 1515 153 -1 -1 0 -3 -1 0 4.521
Sum at WTG 12.610 19.337 18.171 22.935 21.756 8.850 16.041 17.303 20.486 13.261 11.795 11.239 193.783
Exported 12.263 18.843 17.705 22.411 21.195 8.537 15.560 16.892 19.912 12.921 12.793 11.077 190.109
Imported 131 66 69 22 22 64 18 83 31 76 77 91 750
Budget 21.170 20.560 23.120 27.100 26.110 27.350 29.600 31.100 28.500 22.800 22.000 22.500 301.910
The annual exported power production of 190,109 MWh is 2.6% less than the power
that is produced 195,089 MWh. This is mainly due to cable and transformer losses.
Load factor (Capacity factor, %)
Table 4 sets out an overview of the observed capacity factors for the wind farm as a
whole, calculated on the basis of theoretical production as well as the budgeted
production. It is seen below that the actual capacity factor is 24% compared to
budget 37%, which at this stage is only to be assumed to be due to the lower
availability.
Page 13 of 22
Table 4 Overview of observed capacity factors for BOW
Year Month Period
length
Theoretical
production at
Maximum
rated output
Budget
Production
Exported
Power
Import Gross
Power
Exported
Capacity
factor
(actual)
Capacity
factor
(budget)
Days MWh MWh MWh MWh MWh % %
2006 July 31 66,960 21,170 12,263 131 12,132 18.1% 42.7%
August 31 66,960 20,560 18,843 66 18,777 28.0% 8.7%
September 30 64,800 23,120 17,705 69 17,636 27.2% 23.7%
October 31 66,960 27,100 22,411 22 22,389 33.4% 17.4%
November 30 64,800 26,110 21,195 22 21,173 32.7% 18.9%
December 31 66,960 27,350 8,537 64 8,473 12.7% 69.0%
2007 January 31 66,960 29,600 15,560 18 15,542 23.2% 47.5%
February 28 60,480 31,100 16,892 83 16,809 27.8% 46.0%
March 31 66,960 28,500 19,912 31 19,881 29.7% 30.2%
April 30 64,800 22,800 12,921 76 12,845 19.8% 43.7%
May 31 66,960 22,000 12,793 77 12,716 19.0% 42.2%
June 30 64,800 22,500 11,077 91 10,986 17.0% 51.2%
Total 365 788,400 301,910 190,109 750 189,359 24.0% 37.3%
Operation and maintenance costs
BOW has been operated since 1 January 2007 by Vestas on a 5-year operation and
maintenance contract and so any costs are mainly covered by the O&M Contract
with Vestas. Items such as management, lease payments to Crown Estate, post-
construction monitoring and insurances are paid by BOW outside the contract with
Vestas. A breakdown with approximate figures for the 6 months is presented in
Table 5.
Table 5 Breakdown of approximate O&M Costs in 6-month period (£k)
Jan 2007 – June 2007
O&M offshore facilities incl. service contract
Vestas 1,558
O&M lease and license 102
Environmental Management 297
Other 35
Total O&M Costs 1,992
The accounted costs are somewhat higher but due to an incentive mechanism with
VKBR, some of the costs have been kept out of the above in order to show relevant
O&M costs. The reported costs are only for the last 6 months as this is the only O&M
period in the reported 12 months.
For the 6-month period, January – June 2007, with a total export production of
89,155 MWh this gives an O&M cost of:
• £22,133 per MW installed (for half-year)
• £66,400 per wind turbine (for half-year)
Page 14 of 22
• £22.34 per MWh produced / exported
Operational issues
Work performed on the wind farm is categorized as planned or unplanned
maintenance.
Planned work
• 3-month Service
– The 3-monthly turbine service started on 14th June 2006 and was completed
on 28th July 2006 as planned.
• 12-month Service
– The 12-monthly turbine service started in June 2007, but has not yet been
completed due to bad weather. It will be finished within 3 months from June
2007.
• Monthly inspections of HV systems on offshore and onshore substation
– The monthly inspections are carried out according to manufacturer’s
recommendation.
• Annual turbine transformer inspection
– During the transformer inspections a fault on a transformer was detected.
The turbine was shut down and the transformer will be replaced in August
2007.
• The annual offshore safety rescue exercise “Cumbrian Breeze” in cooperation
with MCA and RNLI was postponed due to bad weather twice. The exercise will
be undertaken in September 2007.
• Annual inspections of firefighting equipment
• Environmental Surveys as agreed in the site consent Unplanned work
Unplanned work on the turbines in the reporting period has been substantial. Some
of the issues have been minor technical problems, which have been solved by a local
reset or minor work to the turbine.
Other larger issues, which have been dealt with, are:
Page 15 of 22
• Generator bearings have failed and replaced with a new type.
• Generator rotor cables have been replaced with a new type
• Pitch system has been modified.
In late August 2006 problems with the bearings and rotor cables on the generators
started. Due to bad weather, a lack of spare parts and a lack of certified technicians
to do the repair works the turbines have since had long periods of downtime.
At the same time, problems began on the pitch system and adverse weather has
contributed to some of the turbines having long periods of downtime.
Due to gearbox problems seen on other turbines of the same type, an inspection
process was begun at the start of 2007. These inspections showed that a few
gearboxes were beginning to have similar problems. The EPIC contractor, VKBR,
decided on their own to proactively replace gearboxes before failure.
The replacement schedule started in July 2007 and was completed in early-October
2007. Furthermore, the replacement of gearboxes will have an impact on the
schedule for completion of the outstanding and remedial works under the EPIC
Contract, which has also been delayed by adverse weather during the summer 2007.
Access arrangements
Access to the wind farm is via transfer vessels.
A maximum significant wave height (Hs) limit of 1.5m was enforced in the summer
and autumn 2007 but due to extreme bad weather, BOW tried to work above this
limit by using different vessels for the transfer and can under some circumstances
transfer safely up to a significant wave height of 2m. By autumn 2007 one of the
service vessels was able to operate in significant wave heights of up to 2m.
Page 16 of 22
The wind farm is situated in an exposed area as demonstrated by the accessibility
figure of 51%. This limited access to the wind farm contributed to the lower
availability of the WTGs.
The monthly number of days with weather downtime, with corresponding
percentage, in the period July 2006 – June 2007 is presented in Table 6. Total
weather days in the reporting period was 178 days giving an average accessibility of
51%. Table 6 Monthly number of days with weather downtime
2006 2007
July Aug Sep Oct Nov Dec Jan Feb Mar April May June
5 17 14 19 25 21 23 15 16 5 8 10
16.1% 54.8% 46.6% 61.3% 83.3% 67.8% 74.2% 53.6% 51.6% 16.6% 25.8% 33.3%
Remote monitoring
The production of the wind farm is monitored round the clock through the SCADA
system. The site operator monitors the wind farm in the daytime, and the operator’s
24h surveillance center in Denmark takes over the monitoring outside normal
working hours. Stopped turbines can be restarted through the SCADA system. BOW
has direct access to Vestas’ SCADA system.
Health and safety
The health and safety standards at BOW are considered to be good and the site has
experienced a low number of accidents although the incidents that have occurred
are considered to be serious.
Through the year the health and safety managers and the BOW site manager have
been working proactively to develop a rigorous approach to health and safety to
prevent accidents.
Accidents and incidents over the reporting period
13 October 2006
Whilst lifting hoses for a generator gear box oil change from the vessel
Amstelestroom up to the nacelle on WTG D5, the deck winch blocked. The chain
failed and dropped, 80% landed in the sea and 20% landed on the deck of the vessel.
There were no injuries to personnel, no damage to any assets and no environmental
releases. All items that landed in the sea have been recovered.
Page 17 of 22
24 January 2007
Whilst using the davit on the transition piece the shackle pin (50g) on the davit itself
came loose and fell approximately 10m on to the vessel below.
14 February 2007
A Vestas technician badly twisted his right ankle, whilst disembarking from the
offshore provider service vessel. He was treated at hospital and the accident was
reported to RIDDOR (Reporting of Injuries, Diseases and Dangerous Occurrences
Regulations 1995).
12 April 2007
During work on a WTG about 100 litres of oil leaked out and down the outside of the
tower from the nacelle. Some of the oil ran all the way down the tower and dripped
into the sea. Cleaning up was carried out immediately to minimise pollution.
23 May 2007.
An employee sprained his ankle, when he lost his balance stepping down from a
storage locker, resulting in a lost time injury (8 days).
Proactive safety initiatives
Due to the severity of the accidents, a system of issuing awards to personnel
reporting HSE (Health, Safety, Environment) incidents, near miss events and/or HSE
hazard observations has been established by the O&M Contractor, Vestas, in order
to improve the employees’ way of thinking about safety. Initially, the award was
issued as a team award, which had no impact. Then awards were issued to
individuals, and 18 safety observations were made in June 2007, and in July 2007
another 6 observations have been filed to BOW.
Examples of observations:
• Railing on the service boat too low
• Slippery area on the service boat
• Suggestion to install electrical hoist on davit on transition peice • Non-certified
lifting equipments
The observations give the Vestas HSE manager a good platform for identifying
initiatives aiming at improving the HSE environment at BOW.
Alcohol and drug test
Vestas has introduced random drug and alcohol tests on site to ensure that all
employees are fit for work at all times.
Other proactive safety initiatives
• HSE is a priority agenda item at each O&M meeting.
Page 18 of 22
• No work is executed without method statements and risk assessments being
reviewed and approved by BOW beforehand.
• Regular internal inspections/audits from Vestas HSE manager.
Emergency exercises
On 5 April 2007 Vestas carried out two internal emergency exercises with good
results. The objective of each exercise was to test the communication links between
site personnel and the crew vessel skippers and to highlight potential issues with
regards to lowering a casualty from the nacelle to the vessel using a stretcher. The
two photographs overleaf are from these exercises. During each exercise notes on
the actions of each participant was made together with a time log. Then, the
exercise was concluded with a debriefing session with comments for further
improvement.
Similar exercises will be carried out on a regular basis.
Page 19 of 22
Future events
An emergency response exercise called Cumbria Breeze is scheduled in September
2007, subject to weather conditions. The HSE Manager of Vestas arranged a
meeting with MCA (Maritime and Coastguard Agency) in July 2007 to plan the
exercise. The emergency response exercise is a real time, Search and Rescue
Exercise. This includes HM Coastguard, Royal National Lifeboat Institution and
Cumbria Ambulance Service.
Page 20 of 22
Documentation
For each operation to be executed in BOW it is necessary that BOW prior to the start
of the operation has commented and approved the method statement and risk
assessment. It is desirable that the contractor would be more proactive in revising
and presenting risk assessments and method statements when introducing new
operations and this issue is on the agenda at every quarterly HSE meeting.
Environmental monitoring
Seabed and Scour monitoring
Monitoring of scour around turbines and along the export cable takes place in
accordance with the FEPA Licence requirement, and is undertaken at six-monthly
intervals.
The first post-construction scour monitoring survey was undertaken in September
/October 2006 and covered all 30 turbines foundations and the export cable. This
survey indicated that scour was present around the turbines to varying extent. The
extension of the scour was not larger than expected. Furthermore, depressions
created from the jack-up vessel could be identified at some of locations. The survey
of the export cable identified that it was exposed in some sections.
The second post-construction seabed and scour monitoring survey was undertaken
in April 2007. This survey included 9 turbines and the export cable. This survey
indicated that the scour at some locations has been partially in-filled by natural
sedimentation processes and that the area of scour is dynamic in extent.
Furthermore, the data indicated that the sea bed depressions created by the jack-up
vessels used for installation of the wind turbines were backfilled by natural
sedimentation processes.
The April 2007 survey of the export cable identified some exposed sections of the
export cable. Further work has been undertaken in May 2007 at exposed sections
along the export cable in order to bury these sections. The collected data is now
evaluated and the need for further work on the cable will be considered.
Fishery monitoring
The first post-construction fishery survey was carried out in December 2006, and the
second post-construction fishery survey was carried out in March 2007. A third post-
construction fishery survey is planned for October 2007. The survey results were
analysed and reported and will be included in the annual report to the Licence
Authority in November 2007. A comparative analysis between pre-construction and
post-construction data will be included in the annual report to the Licence Authority
in autumn 2008.
Page 21 of 22
Benthic monitoring
An inter-tidal and sub-tidal benthic survey was undertaken in March 2007 as a part
of the post-construction monitoring programme required in the FEPA Licence. Grab
samples collected from the sea bed at the development site (wind farm and cable
route) and reference sites have been analysed and reported in June 2007. A
comparative analysis between pre-construction and post-construction data is to be
undertaken in August 2007 and will be reported in the first year post-construction
monitoring report.
Noise monitoring
An underwater operational noise survey was undertaken in January - February 2007.
The main conclusions of the report were that:
• The levels of underwater noise measured throughout the survey were
sufficiently low that damage to marine species will not occur. The underwater
noise from the operational wind farm is unlikely to cause a behavioural
(avoidance) response in marine animals in the region.
• The marginal increase in very low frequency noise around individual turbines is
likely to be due to tidal flow around turbine structure. An increase in noise in and
around the turbine array is likely to be due to increased wind and wave noise
interacting with the turbine structures.
• The increase in noise is within the typical variation that would be expected in
shallow water regions due to weather, sea state and tidal flow conditions.
The survey results were included in the annual report to the Licence Authority in
November 2007.
Ornithology
Boat-based and aerial bird survey data was collected at the wind farm and in a
reference area during the period July 2006 - July 2007. In January 2007 BOW and
Natural England agreed on a post-construction monitoring programme including
boat-based and aerial surveys.
Boat-based surveys have been undertaken in August 2006, October 2006, May 2007
and July 2007. Aerial surveys have been undertaken in October 2006 and March
2007. Data will be analysed and reported in the annual report to Licence Authority in
November 2007 in relation to the monitoring objectives set up in the FEPA Licence
and as agreed with Natural England.
Current measurements
According to the FEPA Licence a post-construction survey of the current profile
around a monopile shall be undertaken and used to verify the numerical modelling
used in the Environmental Statement. The current measurements were undertaken
with an ADCP (Acoustic Doppler Current Profiler) around 3 monopiles. The main
Page 22 of 22
conclusions of the survey indicated that the suggestions based on the numerical
modelling were not unreasonable. The survey results will be included in the annual
report to licence Authority in November 2007.
Annual reporting of monitoring results
The annual report covering monitoring during construction was submitted to the
Licence Authority in November 2006. The first year post-construction monitoring
was be summarised in a report and submitted to the Licence Authority in November
2007. The report will include the technical reports.
Public relations
As Barrow was completed journalists and the Secretary of State for Trade &
Industry, Alistair Darling, visited the wind farm on 14 July 2006. To coincide with this
visit, DONG Energy and Centrica issued a press release announcing the event and an
explanation of the importance of the wind farm. In the press release, Alistair Darling
said, "... The Barrow wind farm is a further signal of the energy industry continuing
to invest in green projects, which can enhance future security of supply, as well as
helping reduce carbon emissions."
On 25 September Centrica and DONG Energy declared the wind farm officially open
and celebrated this by sponsoring the local Walney School in their efforts to win
specialist engineering status. The sponsorship and the official opening of the wind
farm were also announced through a press event, where journalists from the UK and
Denmark were invited to visit the school as well as the wind farm. This event was
also marked by a press release issued by BOW.
This report was prepared by Dong Energy A/S.
For further information on the project contact: [email protected]
For further information on the Capital Grant Scheme contact:
Nick Beale at [email protected]
Tel 0870 190 6042
Printed in the UK on recycled paper containing a minimum of 75% post consumer waste.
First published May 2008. Department of Business Enterprise and Regulatory Reform. www.berr.gov.uk
©Crown Copyright. URN 09/P45
