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COWRIE (Collaborative
Offshore Wind Research Into The Environment) is a body set up to look at
the environmental aspects of offshore windfarms. To date it has allocated £450,000
toward research projects, and it is making the results available to the
public. Projects have included effects on birds, effects of underwater
electomagnetic fields on fish, and the effect of noise and vibration caused
by sea bed piling on sea mammals.
The British Wind Energy
Association has a new website covering many aspects of wind power
generation, news and lists of companies supplying products and services
into this sector.
30 turbines have come on stream
at Scroby Sands 3km off the Norfolk coast producing 60MW for an investment
of £75m.
The wind farm was built by E.ON UK. A 90MW windfarm is also running
at North Hoyle close to North Wales and another of the same size is now
on-stream off the coast at Barrow-in-Furness. A fourth operational 90MW
windfarm is running on the Kentish Flats. 7 further similar sized windfarms
have also been approved.
The UK Government's target is by 2015 to generate up to 15.4% of the UK's
energy needs from onshore and offshore wind power using turbines of up
to 1.2Mw each. The UK Government has now settled 15 leases for large scale
wind farms further offshore, mainly in the Thames Estuary and East Coast
and the Irish Sea.
The world's largest offshore windfarm project will be built in the Thames
Estuary. The Thanet Scheme will cover 13.5 sq miles and lies off the North
Kent coast. The larger London
Array covers 90 sq miles with 341 turbines and lies between Margate
and Clacton. It will cost £1.5bn and generate 1000MW.
Modern wind turbines have two or three bladed rotors around 45 metres
in diameter, supported on tubular steel towers up to 40 metres in height.
The blades turn at a constant speed of about 30 revolutions a minute, driving
a generator that feeds the electricity grid. They typically produce 600Kw
each. A computer system turns the nacelle into the wind and changes blade
angle to maximise torque.
Denmark has emerged as an industry leader in this technology and about
15% of its energy needs are now met by wind power. The most recent developments
involve installing offshore monopylons in as little as 6 hours with just
4 pre-constructed components, The base shaft is first driven into the sea
bed as much as 30m, the tower is then assembled on top of it; the nacelle
and two blades are then fitted to the top of the tower and finally the
third blade is mounted on the turbine shaft. To reduce noise the 39m long
blades are wafer thin at the trailing edge. Canada is also a keen contributor
to this technology and the latest schemes use gearless turbines. A large
wind tunnel is being used to study the effects of turbulence on pylon vibrations
and fatigue life of the blades and suporting structure.
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