Experimental Verification of ABS Concrete Design Methodology Applied to the Design of the First Commercial Scale Floating Offshore Wind Turbine in the United States

The abundance of consistent high strength winds off the world’s coastlines and the close proximity to dense population centers has led to development of innovative marine structures to support wind turbines to capture this energy resource. Off the US coast, 60% of the offshore wind lies in deep water (greater than 60m) where the development of Floating Offshore Wind Turbine (FOWT) hull technology will likely be required in lieu of fixed bottom technology such as jacket structures. The United States National Renewable Energy Laboratory (NREL) and the offshore wind community commonly refer to 60m as the transition point between fixed bottom structures and floating structures due to economic reasons. Floating wind turbines deployed in the harsh offshore marine environment require the use of materials that are cost-effective, corrosion resistant, require little maintenance and are highly durable. This has led the University of Maine to develop a concrete hull technology called VolturnUS for full-scale 6MW FOWTs. In this work, experimental testing was conducted to verify the performance of the concrete under operational, serviceability, and extreme loading conditions as required by the American Bureau of Shipping Guide for Building and Classing Floating Offshore Wind Turbines. The testing included structural testing sub-components of the hull and served as experimental verification of American Bureau of Shipping (ABS) concrete design methodology which is currently approved and being used to design the first commercial scale FOWTs in the United States. Two 6MW wind turbines supported on VolturnUS concrete hulls will be used for the New England Aqua Ventus I project. The project is planned to be deployed and connected to the grid by 2019 in the Northeast U.S. and is funded by the US Department of Energy.