Offshore, Wind Power

Largest Offshore Windfarm Opens in Denmark

The largest offshore windfarm in the world has opened off the harbour in Denmark’s capital city.

COPENHAGEN, Denmark, DK, 2001-05-07 <SolarAccess.com> Twenty turbines are located in depths of 5 to 10 metres at the entrance of the Copenhagen harbour. The 40 MW capacity of the Middelgrunden facility is four times greater than the second largest offshore site in Sweden, and will supply 3 percent of the electricity for the city. The consortium that installed the windfarm includes K¿benhavns Energi distribution company and 8,500 members of the Middelgrundens Vindm¿llelaug cooperative, both of which own ten of the 2 MW turbines. The Bonus units are placed 180 m apart in a curve, to produce a total windfarm length of 3.4 km. They have modified corrosion protection, internal climate control and built-in service cranes. Annual generation will be 99,000 Mwh, with guarantied output of 89,000 MWh and an efficiency of 93.3 percent. Technical requirements for offshore units are more demanding due to the climate and the higher risk of structural corrosion. Other problems include access during adverse weather and a greater cost to replace large components. Corrosion is reduced inside the machine by keeping the unit sealed, and gear and generator are cooled by heat exchangers which recycle air used in the air-cooling system. Dehumidification units are located in the tower and nacelle, with standby heating systems for the main electric components to prevent condensation during sudden variations in temperature. Each turbine is equipped with two nacelle-mounted hydraulic cranes, which allow parts to be lifted from sea level. If the built-in cranes lack lifting capacity, they can install a large transportable crane, capable of lifting heavy blades, gearbox and generator. A computer in each turbine has its own e-mail address to allow communication via Internet. The Middelgrunden co-operative was formed in 1997 to sell shares in the development. The turbines cost DKK 200 million to purchase and install, with another 74 million for foundations, 34 million for connection to the grid, 16 million for planning, 8 million to establish the co-operative, and 6 million for contingency, for a total of DKK 172 million. Annual income the first six years include 300 DKK per share for the sale price of electricity, 270 for the green RE certificate and tax reimbursement, minus 70 for operation, in order to yield a net income of 530 DKK per share. The Danish Parliament will provide a minimum price of 0.6 DKK/kWh for the first 12,000 full-load-hours, equivalent to six years of operation. The electricity reform guarantees a minimum sales price of 0.43 DKK/kWh for ten years. Wind generation in Denmark is expected to double by 2005, up from the current contribution of 10 percent of the country’s electrical power. More than 5,600 turbines are operating in the country, with a price per kWh of 4c. Two larger offshore facilities are due to start operation next year in Denmark, and more are planned off the coast of Sweden and the Netherlands.