North Sea Beatrice Platform as OREC
Wind Potential and Power Generated
Wind profile
| Mean 100m wind speed is
| 9.88 m/s
|
| " 50m "
| 8.95m/s
|
| " 10m "
| 7.11m/s
|
Monthly wind roses are shown for the area between 57.7o to 58.7ºN and 02.8o to 03.8ºW (supplied by the Met Office, covering the period from 1923 to 1998). In this area of the North Sea, the predominant wind direction throughout the year is south-westerly. There is, however, seasonal variation; wind direction varies from predominantly south-westerly between September and April, to south-easterly in May and June, and westerly to north-westerly in July and August. For most of the year the wind is most often force 4 or 5, but, during the summer (May to August) the wind is mostly force 1 to 3. Winds are strongest in winter, reaching or exceeding force 7 for about five days a month.
Platforms
There are 4 platforms in this field. 'AP', 'AD', 'B' and 'C'.
Although 'AP' and 'AD' are very close to one another, it may be feasible to put a large wind turbine on both. The maximum separation distance between these two turbines would be 180m, this separation is NW while the prevailing wind blows from the SW.
If we used two smaller turbines (rotor d=33m) then we would only generate half the power of a single 2 MW turbine.
Therefore we propose that 'AP' and 'AD' should be simulated with a 2 MW turbine on each and also with a single turbine on one. This would be done using a computer tool to determine the array efficiencies throughout the year and hence decide whether using 2 large turbines this close together and in this wind profile, is feasible and cost effective.
Both 'B' and 'C' can be re-used without problem.
We could have four turbines in a line roughly NW, two at the centre 180m apart and one on each end of the diagonal, spaced 5 kilometres away.
This would give a wind farm with an installed capacity of 8MW, arranged in a line NNW with the prevailing wind almost perpendicular to this, blowing from the SW.
Wind turbine
2 MW NEG-Micon, NM2000-500/72
| Hub Height
| 78m tower + deck height ~ 100m
|
| Radius
| 66m
|
| Rated Output
| 2MW at 14m/s
|
| Cut-in
| 4m/s
|
| Cut-out
| 25m/s
|
| Asynchronous generator, power factor
| 0.98
|
| Cost per turbine
| £1 000 000
|
| Weight of turbine and 78m tower is 200 metric tonnes
|
Wind loading
Moment at base of tower never exceeds 10 000 KN m under extreme loading (48m/s) and with a 78 m tower.
Electricity generated, per turbine per year
| In winter
| 5 213 000 kWh
|
| In summer
| 3 096 000 kWh
|
| The wind turbine generates leading power
per turbine
| 8 309 000 kWh/year
-1 695 714 kVAr/year
|
| Or 4172.605 hours of full load (2MW)
| Average load = 953 kW
Capacity coefficient = 0.48
|
Estimated yearly power output, 4 turbines:
| 29,081,500 kWh/year
|
| -5,934,999 kVAr/year
|
Income:
Depends on price of kW and kVAr. Assuming power is bought and sold at the grid connection on shore, 5% losses 5pkWh / 2.5pkWh then
| with losses:
| 27,627,425 kWh/year
-6,247,367 kVArh/year
|
To service a loan of £ 5 000 000 at 10 % over 20 years requires
£ 590 000 /year.
So remainder is £ 635 186 per annum from 8MW offshore windfarm.
