Impact of Tidal Currents and Model Fidelity on Wave Energy Resource Assessments

Abstract Numerous studies have identified wave energy as a valuable renewable energy option in the international effort to decarbonize energy systems. For North America’s Pacific Northwest region, most of previous efforts to characterize the wave climate had limited nearshore spatial resolution, were driven by simplistic wave boundary conditions, and/or did not include the effect of wave-current interactions. This work identifies the impact of model fidelity on the wave resource characterization and develops an understanding of the impact of tidal currents on the region’s wave energy resource. A comparison of the outputs from two wave models, identical except for the influence of tidal currents, indicated that tidal current induced differences in the energy period that could exceed ±5s, while the significant wave height and wave power density were consistently decreased across the model domain by up to 4% and 9%, respectively. Beyond differences in these wave parameters, there were significant differences in the spectral and directional distribution of waves. The peakedness of the wave spectrum exhibited reductions of up to about 2.5 (on typical peakedness between 1 and 5), mean wave direction changed at some locations by 180° (the maximum possible), and directional spreading changed by up to ±40°. Given sensitivities of wave energy converters to wave direction and frequency, the results suggest that including tidal currents in a wave assessment could significantly influence subsequent recommendations on wave farm planning.