In California offshore waters, sustained northwesterly winds have been identified as a key energy resource which could contribute substantially to California’s renewable energy mandate (Senate Bill 100). However, the development of large-scale offshore wind energy projects has the potential to reduce the wind stress at the sea surface, which could have local and/or regional implications on California wind-driven upwelling, nutrient delivery, and ecosystem dynamics. Under a current project funded by the California Energy Commission (CEC) (EPC-19-009), Integral Consulting Inc. (Integral) is evaluating potential changes in California coastal upwelling from offshore wind project development over a variety of environmental conditions, device characteristics, and wind farm configurations.
The work described here under Ocean Protection Council (OPC) funding accelerated the timeline upon which results from the CEC project are reported for the existing coupled numerical atmospheric-ocean circulation models, without (baseline) and with simulated turbines. Described in this report is a comparison of upwelling effects resulting from the installation of wind turbines offshore of Morro Bay, Diablo Canyon and Humboldt using operational upwelling metrics for physical transport and nutrient delivery. Modest changes to wind speeds are found in the lee of wind farms, which leads to a decrease in upwelled physical volume transport and resulting nutrient supply to the coastal zone in the vicinity of the Morro Bay and Diablo Canyon call areas. While changes are also observed near the Humboldt call area, they are substantially smaller than those seen near Morro Bay. Since the effect of this decrease on the ecosystem was not evaluated in this study, no conclusions on ecosystem effects can be drawn from the modeled physical changes.