Tidal Current Power Resources and Influence of Sea-Level Rise in the Coastal Waters of Kinmen Island, Taiwan

Abstract

Abstract:The tidal current power (TCP) resource, the impact of TCP extraction on hydrodynamics and the influence of sea-level rise (SLR) on TCP output in the coastal waters of Kinmen Island (Taiwan) are investigated using a state-of-the-art unstructured-grid depth-integrated numerical model. The model was driven by eight tidal constituents extracted from a global tidal prediction model and verified with time series of measured data for tide level and depth-averaged current. The simulations showed reasonable agreement with the observations; the skill index was in the excellent (0.71-0.93) range with regard to simulating tide level and currents. Model predictions indicated that the channel between Kinmen and Lieyu serves as an appropriate site for deploying the tidal turbines because of its higher tidal current and deeper water depth. The bottom friction approach was utilized to compute the average TCP over a spring-neap cycle (i.e., 15 days). Mean TCP reached its maximum to 45.51 kW for a coverage area of 0.036 km 2 when an additional turbine friction coefficient (C t ) increased to 0.08, and a cut-in speed of 0.5 m/s was used. The annual TCP output was estimated to be 1.08 MW. The impact of TCP extraction on the change in current is significant, with a maximum reduction rate of instant current exceeding 60%, and the extent of influence for the average current is 1.26 km in length and 0.30 km in width for the −0.05 m/s contour line. However, the impact of TCP extraction on the change in tide level is insignificant; the maximum change in amplitude is only 0.73 cm for the K 2 tide. The influence of SLR on the TCP output in Kinmen waters was also estimated. Modeling assessments showed that due to SLR produces faster tidal current, the annual TCP output increased to 1.52 MW, 2.01 MW, 2.48 MW and 2.97 MW under the same cut-in speed and coverage area conditions when SLR 0.25 m, SLR 0.5 m, SLR 0.75 m and SLR 1.0 m were imposed on the model.

Investigation of the Possibilities to Improve Hydrodynamic Performances of Micro-Hydrokinetic Turbines

“…Tidal stream turbine performances are investigated numerically and experimentally in [14]. The investigation presented in [15] indicate that there is a limit to available tidal current power output (TCP) due to significant reduction in tidal currents. It is founded that the installation of turbines not only slowed down tidal currents but also affected a certain area near the TCP extraction site.…”

Numerical Simulation of Large Wave Heights from Super Typhoon Nepartak (2016) in the Eastern Waters of Taiwan

“…The introduction of the no-mode-splitting technique in the SCHISM contributes to eliminating numerical errors regarding the splitting between internal and external modes [18]. SCHISM and SELFE have been widely used for simulating the inundation associated with storm surge [19][20][21], assessing the effects of sea-level rise on tidal current energy [22] and predicting flash floods in mountainous areas [23]. Typhoon-induced hydrodynamics can be well mimicked by depth integration, i.e., a 2D model; moreover, a 2D model requires fewer computing resources and less model execution time than a 3D model.…”

On the Sensitivity of Typhoon Wave Simulations to Tidal Elevation and Current

“…The numerical stability constraints are relaxed due to the application of the semi-implicit scheme in SCHISM. SCHISM and SELFE have been used in the simulation of storm surge inundation [15][16][17] and riverine flash flooding [18], in the evaluation of tidal current energy variations resulting from sea-level rise [19], and in investigation of fecal coliform transportation in an estuarine system [20]. A two-dimensional model is preferred over a three-dimensional model for storm surge, storm tide, and wind wave modeling because two-dimensional models require less execution time and computational resource consumption; therefore, SCHISM-2D, a depth-integrated version of SCHISM, was utilized in the present study to simulate the sea-surface elevations and currents.…”