A Tidal Hydrodynamic Model for Cook Inlet, Alaska, to Support Tidal Energy Resource Characterization

Abstract

Cook Inlet in Alaska has been identified as a prime site in the U.S. for potential tidal energy development, because of its enormous tidal power potential that accounts for nearly one-third of the national total. As one important step to facilitate tidal energy development, a tidal hydrodynamic model based on the unstructured-grid, finite-volume community ocean model (FVCOM) was developed for Cook Inlet to characterize the tidal stream energy resource. The model has a grid resolution that varies from about 1000 m at the open boundary to 100–300 m inside the Inlet. Extensive model validation was achieved by comparing model predictions with field observations for tidal elevation and velocity at various locations in Cook Inlet. The error statistics confirmed the model performs reasonably well in capturing the tidal dynamics in the system, e.g., R2 > 0.98 for tidal elevation and generally > 0.9 for velocity. Model results suggest that tides in Cook Inlet evolve from progressive waves at the entrance to standing waves at the upper Inlet, and that semi-diurnal tidal constituents are amplified more rapidly than diurnal constituents. The model output was used to identify hotspots that have high energy potential and warrant additional velocity and turbulence measurements such as East Foreland, where averaged power density exceeds 5 kw/m2. Lastly, a tidal energy extraction simulation was conducted for a hypothetical turbine farm configuration at the Forelands cross section to evaluate tidal energy extraction and resulting changes in far-field hydrodynamics.

Evaluating the Potential for Tidal Phase Diversity to Produce Smoother Power Profiles

“…Data from [16] were verified with measurements and other modeled data in the Salish Sea [15,16] and also compared to modeled data from [17] in Alaska. Practical considerations for the phenomenon to be realized in practice were outlined, and it was established that while the concept of tidal phase diversity has limited potential to feasibly benefit the grid around Washington and Alaska, site-specific analyses would be required to determine the practicality of developing the resources in any identified locations for this purpose.…”

“…This indicates that non-tidal residuals are present, but results show the same behavior (Table 4). The large time lags in M 2 water level propagation [17,26] can be seen from the cross-correlation analysis of the complete time series as well ( Figure 4a). Correlations are taken from a point in the deepest part of the offshore boundary condition.…”

“…Results from two refined models in the Salish Sea [15,16] (YW14 hereafter) and Cook Inlet, AK [17] (WY19 hereafter), are used to complement the results from H11. These are numerical models based on the Finite-Volume, Community Ocean Model (FVCOM) [18,19].…”

“…Thus, only seven points are selected for analyzing this region as shown in Figure 5. As confirmation of the correlations, data from Wang and Yang [17] (WY19) are used. The model extent and correlations are shown in Figure 4.…”

Optimal experiment design for bottom friction parameter estimation

“…Marshall et al (2017), Whomersley et al (2018)) and marine renewable energy (e.g. Adcock et al (2015), Neill et al (2018), Mackie et al (2020a), Wang and Yang (2020)), as well as underpinning the modelling of coastal hazards including storm surges (Flather, 2000). Accurate tidal models are therefore of significant value, yet any model output is subject to a variety of sources of uncertainty.…”