Performance prediction of a tidal in-stream current energy converter and site assessment next to Jindo, South Korea

Abstract

The magnitude of energy, which can be extracted by tidal energy converter devices, has a significant impact on the commercial viability of a project. Therefore, a quantitative characterization of the tidal current at the location of interest and subsequently a reliable prediction of the productivity of a tidal energy converter prior to installation is of high interest. This paper presents the successful deployment of a unique and novel fully symmetric tidal in-stream current energy converter HyTide 110-5.3 in Jindo, South Korea, and a methodology to predict the productivity of a single device based on simulation. The simulation combines a 2D shallow water equation model with turbine performance curves and is validated using real performance data from the prototype under real conditions. In addition, the predicted productivity is compared with actual field measurements during the operation of the Voith demonstrator using two Acoustic Doppler Current Profilers according to the IEC specifications for the performance assessment of Tidal Energy Converters, which is novel at that time. The simulation results show that the productivity of a single device can be predicted accurately and furthermore serves as a proof of concept for the symmetrical turbine layout. The 2D shallow water equation solver based on OpenFOAM® (tidalFoam) captures the rough conditions at the turbine site accurately, where the turbine is facing flood tides with a mean inclined inflow angle of 30°. In addition, the zero-equation turbulence model is shown to successfully capture the influence of a Kármán Vortex street on the turbine unit. High-resolution data of bathymetry, shorelines, and tidal elevations are used to set up the open boundaries of the unstructured mesh used in the model. The sea ground friction as an additional source term in the model is used to calibrate the simulation against Acoustic Doppler Current Profiler measurements on site. The simulation results are shown to be reliable, yielding highly accurate productivity predictions of a single tidal turbine. This is an important step towards a robust commercial evaluation of tidal energy projects prior to installation. Based on the single turbine model, simulations of three tidal current turbine farms as well as the available theoretical and technical power output of the region around Jindo during an entire moon cycle were performed. Possible impacts on average volumetric flow rate changes for neighbouring channels are presented.