Environmental Engineering Reference
In-Depth Information
Figure 8.1
Artist ' s
impression
of
the
ICORASS
10 MW wind turbine. (Reproduced from
Polymarin)
Figure 8.1 shows an artist's impression of a radical design for a 10 MW wind turbine pro-
posed by a consortium led by Dutch rotor blade maker Polymarin Composites. This turbine
known as ICORASS, which stands for integral composite offshore rotor active speed
stall-control has a 160 m two-blade rotor and is intended for offshore applications where
foundation and installation costs do not scale linearly with turbine power, providing
cost savings for larger unit sizes. The design is highly robust to provide exceptional reliability
and availability as required for offshore application where access and maintenance is diffi cult.
Key features of this particular design are the integration of a direct drive alternator into
the hub, a fi xed blade angle with stall power control and the use of a permanent magnet
alternator for speed reduction (braking) above rated wind speed to ensure fi xed power
delivery, and lastly a downwind free yawing rotor to remove the need for an active yaw drive
system.
It is too early to say whether such advanced design concepts are likely to be commercially
successful, but it is clear that future turbines will be signifi cantly larger than today's, espe-
cially where offshore application is concerned, and that wider use will be made of advanced
composites. Alongside innovations in construction, increased use will be made of sophisti-
cated condition monitoring and preventative maintenance systems.
8.2.2 Offshore Wind Farm Development
An offshore installation has advantages over and above the reduction in turbine costs from
the resulting economies of scale. The marine environment is windier resulting in an increased
energy yield, and the winds are more persistent and less turbulent making system-wide inte-
gration easier. Very large wind turbines that might cause an unacceptable visual intrusion
onshore may well be acceptable if sited away from the shore. Additionally, the transportation
of exceptionally large or heavy items is easier over water than over land where roads may
