Sandia and Partners Complete Phase I of a Vertical-Axis Deep-Water Offshore Turbine Study

Sandia and partners from the University of Maine, Technical University of Delft, Iowa State University, TPI Composites, and Texas A&M University have completed the first phase of a project to explore the feasibility of large-scale vertical-axis wind turbines (VAWTs) for deep-water offshore locations. The results of this conceptual study show the potential for significant cost of energy (COE) reduction in the deep-water offshore environment for VAWTs. Component cost models were developed to perform a levelized COE (LCOE) analysis. The LCOE analy­sis was employ­ed to gain a better under­standing of op­portunities for cost reduction and tradeoffs in the design space for offshore VAWTs. Major project accomplishments include:

• developing design codes for floating offshore VAWT systems,
• identifying driving wind and wave design conditions & standards,
• completing design studies for floating VAWT system design concepts, and
• new innovations & analysis to mitigate technical challenges.

The Sandia design studies for VAWT rotors include an assessment of different rotor architectures, numbers of blades, and different material choices. A few of the configurations are shown here.

The initial phase also produced new developments for large-scale deep-water offshore VAWT technology in the form of

• an updated set of VAWT design codes (structural, aerodynamic, aeroelastic, and hydrodynamic/mooring);
• rotor structural dynamics & platform design studies;
• a novel VAWT airfoil design;
• aeroelastic stability tool development & stability estimates;
• balance-of-station cost reductions; and
• new approaches for storm survival & load alleviation.

Currently, plans are being made for the next phase, including enhancements to the suite of VAWT codes that have been developed in Phase I as well as detailed design studies and up-scaling of rotor & platform concepts. In addition, promising LCOE reduction pathways identified in the initial phase will be explored in the design studies. The project was funded by the DOE under the US Offshore Wind Technology Development program (DE-FOA-415).