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

there are technical and economic limitations. If built
shallower than 10 meters there is a greater conß ict with
the surrounding eco system as the sunlight penetrates
the water causing a more abundant ß ora and fauna.
The latter problem occured when planning the German
project Adlergrund, where the rich ß ora and fauna was
especially important, as the area was protection worthy
for resting birds.
e) Distance to the coast
The wind farm should be placed at a distance that limits
the effects on the landscape picture and reduces the
disturbance of the visual experience. At the same time
the wind farm should be placed at a distance that does
not incur costs that are too high when connecting to the
electrical grid (as mentioned above the costs for 1km
sea cable is approximately Þ ve million SEK). Sweden
Offshore is of the opinion that the optimal distance is
between 20 and 40 km.
f) Seabed conditions
The selected area should be good for grounding the
foundations, such as sand and moraine. Loose sand
deposits can however be inappropriate if they are subjected
to transport and movement through currents and
waves. The seabed substratum is also of importance.
Rocky and uneven seabeds makes the grounding of the
foundation harder. In most cases the seabed conditions
do not cause a hazard to the establishment of
wind farms but can inß uence the method of grounding
which in turn has an effect on the economy.
g) Local wind conditions
The wind energy is proportionate to the cube of the
wind speed. This means that if the wind speed is
doubled the wind energy is increased eightfold. The
local wind condition is for this reason of high importance.
Offshore wind resources generally increase in
proportion to the distance from the coast. According
to STEM, the main criteria for suggesting an area of
national interest for wind power is that the wind energy
content should be at least 3 800 kWh/m2/year at the
height of 80 m above ground/sea (Wind power: Distribution
of the national planning target and criteria for
areas of national interest, STEM, ER 16:2003). This
corresponds to an average wind speed of approximate-
ALTERNATIVE LOCATIONS 45
ly 7,2m/s per year.
h) Conditions for grid connection
Connection points with available capacity must be
located within reasonable distance from the coast. In
the report “Overall conditions for large-scale wind
power development offshore and in mountain regions”,
The Swedish Transmission System Operator, Svenska
Kraftnät, on appointment from the government,
showed the effects of large-scale wind power development
offshore and in mountain regions. In this report
Svenska Kraftnät stated that the conditions for connection
are most favourable in locations where there
has previously been electricity production but that now
are redundant. The table below shows the production
sources that are redundant and where connection of
wind power production was considered relatively easy.
Out of these four locations Barsebäck is the only
remaining redundant production site included in the
report. The other sites are back in production and can
produce electricity when needed. The probable development,
according to Svenska Kraftnät, is that wind
farms with installed capacity of about one hundred
Power plant Capacity [MW]
Barsebäck 600
Stenungsund 820
Marviken 200
Bråvalla 240
MW primarily get connected to the regional grid and
that these then need to be reinforced. The reasons
are that it is generally cheaper to connect to a lower
voltage grid, and that the regional grids are closer to
the coast than the transmission grid, which reduces
distance, and thereby the connection costs, between the
wind farm and the grid. Larger wind farms may need
to be connected directly to the transmission grid when
the regional grid is incapable of accepting the capacity.
i) Environmental restrictions
When choosing alternative locations, the local environment
is important. The wind farm should not inß uence
or encroach areas that are ofÞ cially protected or
ecologically sensitive.