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Offshore Wind 2004. From Vindeby to Nysted A Manufacturer’s Experience Henrik Stiesdal Bonus Energy A/S. Bonus’ Offshore Wind Farms. 6 Offshore Projects, 1991-2003 128 Turbines, total 245 MW. Long-Term Strategy. The long-term strategy behind offshore activities:
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Offshore Wind 2004 From Vindeby to Nysted A Manufacturer’s Experience Henrik Stiesdal Bonus Energy A/S
Bonus’ Offshore Wind Farms 6 Offshore Projects, 1991-2003 128 Turbines, total 245 MW
Long-Term Strategy The long-term strategy behind offshore activities: • Get one of the first, moderate-size demonstration projects to acquire longest possible experience • Base offshore projects on proven turbine technology to avoid combination of new technology risks with offshore risks • Accept early offshore projects only in shallow and/or less exposed waters and refuse projects in deep and/or exposed waters until complete offshore technology (turbine modifications, installation, service) proven
Vindeby, Main Project Data World’s first offshore wind farm: • 11 x 450 kW, 1991 • Built by ELKRAFT, owned by SEAS for demonstration of potential in offshore wind power • Bonus scope of supply: Turbines, SCADA, installation, 2 years WOM • Total project cost 7.0 M£ (1991) = 9.1 M£ (2003) • Total project cost per MW installed 1.8 M£ (2003) • Cost of Bonus supply 47% of total project cost
Vindeby, Turbine Details Offshore modifications implemented at Vindeby: • Built-in nacelle crane for service works, can install larger crane for main component replacement • Totally enclosed nacelle and tower • Cooling with heat exchanges for gearbox and generator • Climate control with dehumidifiers in nacelle and tower • Transformer in bottom of tower
Vindeby, Infrastructure Details Essentially an onshore wind farm moved offshore: • Water depths 2-5 m • Moderate fetch (10-15 km) in prevailing wind direction • Turbines in two rows, 8.5 D spacing in rows, 8.5 D spacing between rows • Concrete caisson foundations, conical top to act as ice-breaker • 10 kV wind farm grid voltage • 10 kV land connection
Vindeby, Installation Installation by onshore methods moved offshore: • Foundations and electrical infrastructure installed separately by others • Turbines installed with normal onshore mobile crane placed on standard offshore barge • Turbines shipped two at a time, completely assembled with rotors • 11 turbines installed in 12 days
Vindeby, Experiences 12½ years of operation with no major problems: • High turbine availability • Climate control very efficient - turbines as new inside • Higher incidence of lightning strikes than onshore • Moveable crane for main components not used • Conical foundations cause access problems due to standing waves • Useful weather windows sometimes significantly shorter than predicted by statistics • 10 kV voltage level for internal grid and land connection causes substantial grid losses (7%)
Nysted, Main Project Data World’s largest offshore wind farm: • 72 x 2.3 MW, 2003 • Built by E2, owned jointly by E2, DONG and Sydkraft • Bonus scope of supply: Turbines, SCADA, installation, 5 years WOM • Total project cost app. 140 M£ (2003) • Total project cost per MW installed app. 0.85 M£ (2003) • Cost of Bonus supply app. 60% of total project cost
Nysted, Turbine Details Updated offshore modifications based on Vindeby: • Built-in nacelle crane for service works, can install two versions of larger cranes • Totally enclosed nacelle and tower • Cooling with heat exchanges for gearbox and generator, temperature control in narrow range • Climate control with dehumidifiers in nacelle and tower • Transformer in bottom of tower • Automatic lubrication systems with 12+ months capacity • Permanent on-line machine condition monitoring • Dynamic power factor correction system and fault-ride-through capability
Nysted, Infrastructure Details A true offshore wind power plant: • Water depths 5-10 m • Substantial fetch (80-100 km) in prevailing wind direction • Turbines in grid pattern, 5.8 D spacing in rows, 10.3 D spacing between rows • Ballasted concrete pedestal foundations, inverted cone at top to act as ice-breaker • 33 kV wind farm grid voltage • 132 kV land connection
Nysted, Installation A true offshore installation setup: • Foundations and electrical infrastructure installed separately by others • Turbines installed with A2SEA vessel • Turbines shipped four at a time, loaded on vessel as towers in two sections, nacelles, and completely assembled rotors • 72 turbines installed in 81 days
Nysted, Experiences Project still at early operational stage: • Installation and commissioning according to schedule • Taking-Over achieved one month ahead of schedule • Minor teething troubles, mainly electrical and aerial warning lights • Availability since Taking-Over 97%, not corrected for periods with no access • 29 Nysted turbines each produced over 1 M kWh in December 2003, first and only time this level reached in Denmark
And then... So much for past and present - What about the future?
The Next Generation... A next generation offshore is: • Large (because large turbines make cheaper electricity than small turbines) • But not too large (because organic growth provides more safety than big leaps) • Fitted with further developments of the offshore modifications proven in previous projects, including Vindeby and Nysted • Compliant with all grid requirements, providing fault ride-through and fully flexible regulation
Bonus 3.6 MW Main Data: • 107 m rotor diameter • 80-120 m hub height • Rotor weight 80 t • Nacelle weight excl. rotor 120 t • 100 m tower weight 250 t • Variable speed with full converter to provide maximum flexibility and grid compliance
Bonus 3.6 MW Peculiar Data: • At 10 m/s wind speed the amount of air passing through the rotor every second has a weight of 100 t • The B52 blade root design bending moment in flatwise direction is 14.000 kNm • The maximum tip deflection of the B52 blade is 7 m
Bonus 3.6 MW Schedule: • Prototype installed Summer 2004 • 0-series installed late 2004 / early 2005 • First significant commercial projects second half 2005 • Unlimited production early 2006