Floating wind weight estimating for installation

Abstract

Weight control of floating offshore wind turbines which is a growing market within the marine renewable energy sector. The floating offshore wind turbines give access to deeper water sites, with minimal visual impact from land, once operational. The paper includes the weight control requirements for Spars, barges, semi submersibles and Tension Leg Platforms (TLPs) as floating wind platforms and in addition for various new arrangements such as turret mooring and suspended ballast keel.

Discussion is included on heavy maintenance the implication for accurate weight control during operations. There are weight control challenges for the various substructure types during the temporary phases of construction and offshore installation. An accurate assessment of the buoyancy of the floating wind turbine for different drafts and trims is required. Allowances need to be included in the weight calculation for temporary buoyancy, sea-fastenings and grillage.

Weight control for installation has an influence on the weather window for the floating substructures during transportation to the offshore site, and for their mooring and electrical connection. The paper will cover weight calculation methods during early design, detailed design, construction, installation, operation and demolition. The installation process for a floating wind turbine varies with substructure type and this paper will give an overview of the weight control requirements for loadout, ocean transport and mooring connection. The floating offshore wind turbine weight and centre of gravity has a direct bearing on draft, intact stability and motions. As part of the weight control process the centre of gravity and radii of gyration need to be accurately determined for each stage of the installation.