NREL’s Updated Wind Resource Assessment for Offshore California Shows Even Stronger Winds

Abstract:

Floating wind turbine technologies have advanced significantly in recent years, prompting commercial interest in the deep waters of offshore California. Previous wind resource assessments have found abundant hub-height winds in this region, helping offset risks for the emerging industry in the U.S.

We present an updated wind resource assessment, CA20, for offshore California that shows substantially stronger winds than preceding assessments. The previous state-of-the-art wind resource assessment for the region, NREL’s 2013 Wind Integration National Dataset (WIND) Toolkit, stemmed from a seven-year 2007-2013 analysis with the Weather Research and Forecasting (WRF) model. CA20 builds upon this dataset by expanding to a twenty-year analysis 2000-2020 while also incorporating significant updates that have been made to numerical weather prediction since 2013. We analyze factors that drive the large differences between the two datasets, such as the simulated years, an updated reanalysis product (ERA-Interim to ERA5), the planetary boundary layer (PBL) scheme (YSU to MYNN), and the WRF version (3.4.1 to 4.1.2). The change in PBL scheme induces the most impact, which we attribute to predominately stable conditions in offshore California and divergence of YSU and MYNN schemes under such conditions.