In the hurricane that wreaked havoc in Denmark in early January, felling thousands of trees and removing rooftops, the country's 5400 wind turbines stood firm, although a few suffered rotor or nacelle damage. The association of Danish wind turbine owners says Denmark's incentive program for replacing old wind turbines with new, which ran between 2002 and 2004, helped keep damage to a minimum. No fewer than 1480 old machines under 150 kW in size were dismantled during the program and replaced by bigger and fewer turbines. In a similar storm in 1999, about a dozen smaller and older turbines were toppled. Twenty years ago, nearly half the national fleet of turbines suffered major and minor damage in hurricane force winds. DV's Strange Skriver says newer and bigger turbines are built to withstand higher wind speeds than previously -- typically 53-57 m/s, the "100 year storm," wind speeds expected to hit once every century. At the height of the January storm, winds reached 47 m/s. A 660 kW Vestas turbine suffered most, with one lost blade and another damaged along with the nacelle after it ran out of control. Vestas believes the blades might have been struck by lightning. The company has taken the entire machine back to its factory for inspection.
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Senior Renewable Energy Analyst (WindGEMINI Product Lead) DNV GL Bristol (City Centre), City of Bristol