Using Coupled Atmosphere / Ocean Simulations to Evaluate Wind Resource off the U.S. West Coast

Offshore wind turbines can be a vital component of the U.S. renewable energy portfolio, due to the wind resource typically being stronger and more dependable there than on land. Thus the U.S. DOE has an objective of establishing 30 gigawatts of offshore wind capacity by 2030. Wind energy lease sales were held for the U.S. West Coast for the first time in 2022. Compared to the U.S. East Coast, however, the West Coast offshore environment exhibits steeper topography, seasonal upwelling, deeper waters, multi-modal sea states, and very different currents and meteorological regimes. Few modeling systems incorporate the mutual dynamical interaction between ocean, waves, and the atmosphere on timescale relevant for wind energy applications. The general paucity of offshore observations, especially around wind turbine hub height (100-200 m), makes it difficult to evaluate the fidelity of all numerical models in this region. Observationally Driven Resource Assessment with Coupled Models (ORACLE) is a multi-institutional project that aims to increase the trust in novel observational algorithms and ocean-wave-atmosphere coupled modeling techniques to reduce wind resource uncertainty quantification along the U.S. West Coast. In this study, we perform year-long simulations of the region using the Coupled-Ocean-Atmosphere-Wave-Sediment-Transport (COAWST) modeling framework. In our particular configuration we make use of atmospheric (WRF), wave (WAVEWATCH III), and oceanic (ROMS) models at kilometer-scale grid spacing, all of which mutually interact with each other. To evaluate the model performance, we make use of an observational database including buoy and coastal observations. We also leverage data from deployments of lidar-equipped DOE buoys near the Humboldt and Morro Bay wind energy lease areas from 2020-2022. We will present results from this evaluation, as well as sensitivity studies to determine the impact of modes of coupling (e.g., air / sea heat and momentum fluxes, wave / current interactions) on hub-height wind fields.