Abstract
There is increasing interest in harvesting tidal stream energy because it is clean and renewable, highly predictable and stable and abundant locations close to coastal communities. Many efforts have been carried out to assess and characterize tidal stream resource at high tidal energy sites around the world. The International Electrotechnical Commission (IEC) Technical Specifications (IEC TS 62600-201) provides standards and guidelines for tidal energy resource assessment and characterization, based on tidal hydrodynamic and turbulence characteristics. Numerical models, combined with field measurements, are regularly used to assess, and characterize tidal energy resource at potential tidal energy project sites. However, most of the previous modeling studies on tidal energy resource assessment only focused on the tidal hydrodynamic characteristics, and turbulence parameters are often not simulated and reported, because of lack of high-quality turbulence measurement data and the challenge of model ability for simulating turbulence. The turbulence statistics can be used to help test device performance and predict fatigue loads and for design stage assessments. The Western Passage is an energetic tidal channel between New Brunswick, Canada, and the state of Maine in the United States. It is identified as one of the top sites for tidal stream energy development in the U.S. In this study, we developed a tidal hydrodynamic model for the Western Passage using the Finite Volume Community Ocean Model (FVCOM) to characterize the resource and simulate the turbulence parameters, such as turbulent intensity and kinetic energy. IEC technical specifications were considered in the model configurations and simulations. The model was validated with field measurements for water level, tidal current and turbulence. Comparisons of model results with observed data showed a good agreement throughout the entire data collection period. This study demonstrated the good model performance of FVCOM model in simulating turbulence intensity and kinetic energy using the Mellow-Yamada turbulence length-scale model (MY2.5) in the context of tidal energy development in Western Passage, which has not been reported before. Tidal current, power density, turbulent intensity and kinetic energy along selected cross sections were calculated to evaluate the feasibility of the tidal energy development at several locations that feature strong currents in the Western Passage. Sensitivity analysis was conducted to investigate the role of channel geometry and bathymetry, such as headlands and underwater sills, on turbulence production in the Western Passage. While coastal models based on Reynolds-averaged Navier–Stokes (RANS) equations do not resolve the inertial subrange turbulence to directly guide device design, the validated model results of turbulence kinetic energy and turbulence intensity can be used to support site selections. This study demonstrated that simulated turbulent properties can provide a new perspective in project site siting, which should be included in the modeling effort as part of the tidal energy resource assessment.