Cost-effective floating wind turbines producing at least 20MW each: this is the futuristic but feasible vision that is to be explored in an exciting new collaboration between RISØ DTU, DHI and international partners from both industry and research community. DHI contributes to the collaboration with knowledge on hydrodynamic loading on the floating wind turbine.
Highly elegant, the ballerina dances with the wind seemingly without any effort. Nevertheless, the slender swimmer may in fact be the future of offshore wind energy production.
The ballerina is a floating wind turbine for deep offshore or farshore waters, currently being developed by an international project collaboration termed DeepWind. DeepWind explores a technology taking us away from the good old windmill we've known for centuries. Instead, it combines a vertical axis wind turbine (VAWT) with a rotating, floating offshore substructure (see picture).
"The technology behind the proposed concept is very challenging. We need research in a wide area of different technologies - for example the dynamics of the system, blade materials, sub-sea power generators, turbine control and safety. Moreover, shaft loading and also the mooring and torque absorption system need to be investigated," explains Dr. Uwe Schmidt Paulsen from RISØ DTU, who is the overall coordinating manager of the 4-year project supported by EU through the 7th framework programme.
DHI contributes to the project with knowledge on and modelling technologies for the hydrodynamics of the wind turbine. How does the water flow around the rotating and floating shaft? What forces does it need to withstand - from currents and waves and their combined effects? DHI will explore these and other questions by employing composite modelling, an up-to-date combination of physical and numerical models on fluid dynamics (CFD): Laboratory tests help to investigate the underlying physics, while refined models translate the lab results to real-life scale. "DHI has been active for years in composite and hybrid modelling, an area which is rapidly gaining importance. We foresee a number of new applications within green offshore energy in the future, supporting design optimisation and device up-scaling," says Dr. Stefan Carstensen, DHI's project manager in DeepWind.
The elegant ballerina waves her arms and shakes her hips – and thereby hopefully one day helps to cover the world's growing energy demand.