This environmental impact assessment for Kriegers flak ... - Vattenfall

74 PRESENTATION OF THE AREA
The wind forces the water against the shores.
When the wind drops, the water ß ows back creating a
rotation, rather like in a bathtub, when it reaches the
opposite shore.
The greatest variations of the sea level in the Baltic
occur at south-westerly and north-easterly storms.
Observations of the sea level in the area between
Flensburg and Klaipeda, between the years 1901 and
1940, showed that only 15 % of the year high and year
low respectively, exceeded +/-125 cm. In 50 % of cases
the sea level variations were within +/-25 cm.
11.3 Wind conditions
The winds at Kriegers Flak are during summer time
predominantly westerly, whilst during winter, easterly
winds are quite common. The wind direction is between
southwest and northwest just over 50 % of time.
Three different surveys of the wind resource Kriegers
Flak have been carried out at.
Relative frequency
Relativ
frekvens
Wind direction
Figure; Distribution of wind directions at a position 55 deg N/ 13
deg 18 min E of Kriegers Flak
The Þ rst survey made is accounted for in earlier
consultation material, i.e. measurements from a buoy
with a ten metre high measuring mast from the German
meteorological station “Darsser Schwelle”. Based
on this survey, the average wind speed was calculated
to 9.6m/s at 100 metres hub height. Since these
measuring data were relatively uncertain (measuring
height was only 10 metres), two new surveys have been
carried out. One according to the WASP model and one
according to the MIUU model.
Based on wind data from SMHI during 1980-89
from the high mast at Maglarp, the average wind speed
has, with the help of the WASP method, been calculat-
ed to 8.7 m/s at 100 metres hub height. The main wind
direction was 240 – 300 degrees.
The meteorological institution at Uppsala University
has through the use of its MIUU method calculated the
average wind speed in the area to 9.1 m/s.
A comparison between measurements from Maglarp
and the MIUU model for Kriegers Flak can be seen
in the diagram on the right. In the diagram a MIUU
simulation of the wind climate for Maglarp is also
shown. When comparing the measured readings from
Maglarp with the simulated wind climate, it shows that
the MIUU model correlates well with measured series.
Since the MIUU model not yet is veriÞ ed for measurements
at sea, Sweden Offshore will use to the lower
wind speed of 8.7 m/s.
The Þ gure 8.7 m/s can be compared with the main
criteria of the Swedish Energy Agency to recommend
an area as being of national interest for wind power
i.e. the wind energy should be calculated to at least 3
800kWh/m² per year at a height of 80 metres.
This corresponds to an annual average wind
speed of around 7.2 m/s.
Sweden Offshore is planning to erect up
to three 100 metre tall measuring masts to
verify the performance of the farm.
Germany is further more preparing the
building of the meteorological research station
FINO II at Kriegers Flak, which very
accurately will establish the wind resource in
the area.