First Offshore Wind Farm Decommissioning Complete
Wind farm operator Vattenfall has completed the decommissioning and removal of the five-turbine, 10 MW Yttre Stengrund offshore wind farm – the first dismantlement of its type. The announcement brings offshore wind a step closer to the maturity of offshore oil and gas, which has handled legacy obligations and decommissioning for decades (and may decommission significantly more installations in the years ahead).
Vattenfall announced the Yttre Stengrund decision in 2014; at the time, only one turbine of five was still functioning, and the cost of repair or replacement was prohibitive. Dismantlement began in November 2015 and finished in late January.
"The turbines that were installed at Yttre Stengrund were an early model and only about 50 of them in total were actually produced. The difficulty of getting hold of spare parts and the huge cost involved in upgrading the turbines and gearboxes meant that it wasn't financially viable to replace the turbines," said Maria Hassel, project manager for Vattenfall.
To some, the idea of removing a wind farm in an era when public and private entities are pushing to add renewable energy “may seem a bit of a contradiction in terms,” she added. However, “Yttre Stengrund was one of our first wind farms and we've learnt a lot over the almost 10 years that we've been operating it . . . we have locations with better wind conditions in other parts of the country where we can build new wind power and take with us the knowledge we've gained.”
Offshore construction firm Svensk Sjöentreprenad (SSE) handled the task, taking down the five masts and cutting the concrete foundations off level with the sea bed. Bad weather plagued the project, however, delaying its completion by a month.
The underwater cables connecting the installation with shore are still in place and will be removed this summer. Vattenfall intends to restore the site and to remove any significant trace that the wind farm was ever there.
The firm made news earlier in 2016 for its involvement in the discovery of a lost WWI German U-boat in the North Sea during sonar surveys for a new wind installation.