Modelling challenges of floating offshore wind turbines
TU Delft Wind Energy Institute (DUWIND) invited alumnus Dr. Po Wen Cheng to present a review of the floating offshore wind turbine (FOWT) sector at the Aerospace Engineering faculty on November 2.
"Floating offshore wind energy is currently not a major research area at TU Delft, but was started here by a former researcher, Andrew Henderson, who identified many of the challenges we are now tackling," said Cheng, who currently works at Stuttgart Wind Energy and Institute of Aircraft Design (University of Stuttgart).
Cheng obtained his PhD at TU Delft in offshore wind turbines in 2002. He spoke of his experience doing collaborative research with the offshore and wind turbine industries, aiming to scale up the technology with cost effective solutions. "The technology has been shown to be technically feasible," he said, showing slides of prototype floating wind turbines on the sea. "But it remains a niche area. We researchers have a role in helping industry to gain a better understanding of the complex behaviour of floating wind turbines to achieve cost efficient designs."
In a floating situation at sea everything is dynamic, so his research focuses on more sophisticated modelling of the complex interplay of aerodynamic, hydrodynamic, control and mooring systems. This aims to reduce risk and uncertainty in simulations for industry and streamline the industrial design process. Currently there are several floater types being researched and prototyped and more than a dozen numerical simulation software tools used for modelling.
"Of the many variants, no single one meets all the criteria for optimal design. Technology convergence has to happen. For industrial production we need one or two types to prevail to provide the necessary economies of scale," he said.
If standardized, low cost structural floater solutions can be reached for FOWT technology. It may displace part of the bottom fixed types in deeper water, as this is the volume market at feasible water depths of 40-80m at an optimal distance from shore. Then the cost advantages in more straightforward transport and installation of FOWT solutions become relevant and economies of scale can drive costs further down.
He recommends seeking a maximum synergy between the cost effective production approach of already optimised three-blade onshore wind turbine towers and floater designs and control technologies as the most effective development path.