The developer has replaced the nacelles and blades of the five 20-year-old, 550kW Wind World turbines at its Bockstigen project with components from used V47-660kW Vestas units increasing the site's nameplate capacity from 2.75MW to 3.3MW.
The turbines’ towers, foundations and cabling remained untouched, however.
The developer initially wanted to decommission Bockstigen, which has been online since 1998, and replace it with a new wind farm consisting of twelve 4MW turbines.
But transmission system operator (TSO) Svenska kraftnät’s plans for a 400kV DC connection between Gotland and mainland Sweden that could have helped integrate 500MW of wind power — including that generated by Momentum’s new project — were cancelled due to cost concerns.
Unable to distribute power from its planned 48MW site, Momentum decided to repower instead, company CEO Kim Madsen explained.
Despite Baltic Sea waves, wind speeds of more than 20m/s, and the challenges created by replacing the hardware using a mobile crane installed on a jack-up platform secured by cables, the upgrade was completed in November.
Repowering was completed less than a year after the option was first proposed and at a cost of less than €5 million, Madsen claimed. Repowering also did not require a new permit.
Crucially, Madsen added the upgrade will extend the project’s life by 15 years and double its output from 5.5GWh/year to 11GWh/year, but will not place much extra burden on connections between Gotland and Sweden.