Session: 09-01-13 Novel and Hybrid Offshore Wind Concepts

Paper Number: 79827

79827 - Assessment of the Power Obtained by a Multi Wind Turbine Floating Platform 

In order to reduce the LCOE (Levelized Cost of Energy) of floating wind energy, the installed power capacity per floating platform tends to increase. Typically, this is achieved by increasing the size of the wind turbine. However, up-scaling wind turbines, may reach an economically viability limit, mainly due to the increase in production costs of massive components. For example, the blade mass increases exponentially with respect to the blade radius. For this reason, several multi wind turbine floating platform configurations, that potentially could reduce the energy cost, have being proposed and are currently in development. Moreover, multi wind turbine onshore configurations have been found to produce a combined blockage effect on the incoming flow that allows a greater extraction of power than single-rotor.

The main objective of this study is to assess the power obtained by a multi wind turbine configuration with respect to a single turbine on a floating platform under wind and wave loading using the Multi wind tUrbine Simulation Tool (MUST). This software is a CENER’s in-house development, based on NREL's OpenFAST code, that allows the simulation of more than one wind turbine (tower, nacelle, rotor) installed on the same floating platform. MUST has been coupled to CENER’s in-house aerodynamic module AeroVIEW (Aerodynamic Vortex fIlamEnt Wake) that captures the aerodynamic interaction between nearby rotors in aeroelastic simulations.

In this study, two operational cases from the OC4 project with the NREL 5MW OC4 semi-submersible floating wind turbine have been simulated with MUST and AeroVIEW to obtain the reference performance for the single rotor floating wind turbine configuration. The motions of the platform obtained from these two reference cases have been imposed into a sub-structure that support two wind turbine in side-side arrangement in order to compare the power obtained by the two different configurations in similar operational conditions. Finally, a turbulent wind and irregular wave case has been simulated in floating condition, using a modified version of the OC4 platform able to support two NREL 5MW wind turbines. The resulting power has been compared also with the reference obtained for the single wind turbine OC4 configuration.

The analysis of the results shows a possitive effect of having two side to side rotors on the same floating platform in the generated power besides the potentially saves in the costs of massive components.

Presenting Author: Raquel Martín-San-Román CENER

Authors:

Raquel Martín-San-Román CENER
José Azcona-Armendáriz CENER
Mikel Iribas-Latour CENER
Alvaro Cuerva-Tejero Universidad Politécnica de Madrid