A Danish company says it has developed an unusual offshore turbine mount it calls a Bucket Foundation that pulls or sucks itself into a seabed for a solid turbine foundation. Its development company, Universal Foundation (universalfoundations.dk), says the invention will significantly reduce offshore installation costs.
The foundation is essentially a large steel bucket inverted (open side down) with a ribbed supports holding a turbine-tower base to the closed or top end. The firm says no special equipment is needed to position the foundation. When in place, large suction pumps pull water and sea-bed material out of the bucket while differential pressure pushes the foundation into the sea floor. Prototypes have included a 2-m dia. by 2-m deep version and another 4 by 4 m. The latest prototype, a 10 by 10-m unit, supports a 3-MW Vestas V90 in Frederikshavn, Denmark.
The firm says the design combines the advantages of a gravity-base foundation, a monopole, and a suction bucket into one unit. “The design has been in development for nearly a decade,” says Universal Foundation CTO Søren Nielsen. “Successful prototypes have worked well for met masts and turbine foundations. It’s now entering full-scale production for the offshore wind market.” The design includes installation controls for vertical alignment as it sucks itself into the seabed, thereby reducing total installation time.
The company points to several advantages.
• It accommodates a broad range of site conditions, loadings, and operational performance requirements.
• Installation does not depend on jack-up vessels, the seabed needs no preparation, it needs no diver operations, and there is no need for a transition piece which eliminates a grouted connection.
• Pile driving is eliminated, which also eliminates environmental concerns regarding noise. Hence, it avoids ‘no pile driving’ periods in the year.
• The design reduces or eliminates need for scour protection.
• The suction operation is reversible allowing for complete removal of the foundation. This allows re-deployment of met masts and equipment.
• The foundation weighs less than traditional undersea foundations.
Filed Under: Offshore wind