Construction and installation process to deploy a wind turbine "WTG" on a tension leg platform/spar in medium to deep water

Abstract

Method for installation of a wind turbine generator on a tension leg platform/spar (WTG foundation) using gravity anchors or suction anchors. A concrete WTG foundation is built with the ‘slip form’ method, a combination construction/deployment barge (barge) allows the WTG and WTG foundation to be delivered to the installation site as a complete unit and a split hull hydraulic dump scow facilitates the slip form construction and deployment of the gravity anchors. The barge is sunk as a dry dock to a draft that permits the WTG/WTG foundation to be floated off. The free floating WTG foundation is ballasted with sea water to its operating draft with 5 feet of freeboard. The tension legs from the gravity anchors are attached to the WTG foundation and snugged with equal tension. The sea water is then removed from the WTG foundation. This process tightens the tension legs to their design loads. The WTG/WTG foundation maintains a relatively large water plane and a 5 foot freeboard. The gravity anchors are constructed and deployed to the installation site, with tension legs attached, by means of a split hull hydraulic dump scow. Four gravity anchors are deployed for each WTG installation.

We claim: 
     
         1 . Method for installation of a wind turbine generator “WTG” on a tension leg platform/spar, comprising the steps of:
 constructing a WTG foundation on a construction barge at a dock using a slip form method; 
 forming the gravity anchors in the split hull scow using a slip form method and deploying same to the installation site; 
 install the WTG foundation on the barge before it leaves the dock; 
 tow the construction barge to the installation site using tugs delivering WTG and WTG foundation to installation site as a complete unit; 
 sank the construction barge to a selected draft such that the WTG foundation with the WTG thereon floats off of the barge (dry dock mode), wherein the WTG foundation with the WTG thereon floats freely and is stable having a positive GM; 
 refloat the construction barge with its self-contained pumping system for return to dock; 
 ballasting the WTG foundation with sea water until it reaches its operating draft (approximately five feet of freeboard) maintaining stability throughout the process; 
 positioning the spar over the gravity anchors; attaching the tension legs leading from the gravity anchors to the spar; and; 
 and removing the WTG foundation and establishing tension in the tension legs.