Downscaling CMIP6 climate projections to classify the future offshore wind energy resource and calculate the Levelized Cost of Energy of various wind farm designs in the Spanish territorial waters.

Spain has taken a significant stride towards its goal of installing 1 to 3 GW of floating offshore wind capacity by 2030. This was achieved through the implementation of a Maritime Spatial Planning (MSP) covering 19 designated areas, where it is expected the installation of offshore wind farms in the upcoming years. Therefore, it is of interest analysing the impact of climate change on offshore wind resource in these areas. To achieve a sufficiently high spatial resolution for this study, a dynamic downscaling of a multi-model ensemble from the 6th phase of the Coupled Model Intercomparison Project (CMIP6) was conducted using the Weather Research and Forecasting (WRF) model in the Spanish territorial waters, encompassing the Iberian Peninsula, Balearic Islands, and Canary Islands. Thus, wind data were obtained from the latest climate projections, with a 10-km spatial resolution and a 6-hour temporal resolution. The results were compared, for a historical period from 1985 to 2014, with data from the ERA5 reanalysis database and with observational data from buoys. The results of this validation process showed a great accuracy in the dynamical downscaling performed, generally better than when using data from the Coordinated Regional Climate Downscaling Experiment (CORDEX), which performed dynamical downscaling on data from several CMIP5 climate models. Future projections, from 2015 to 2100, were assessed under the Shared Socioeconomic Pathways (SSP) 2-4.5 and 5-8.5 scenarios. The findings of this study indicate a projected growth in Spain's offshore wind energy potential, especially in the Atlantic Ocean and around the Canary Islands.

Using wind speed data from simulations carried out with the WRF atmospheric model, the offshore wind energy resource was classified in the 19 areas involved in de Spanish MSP. This classification considered the wind power density but also factors such as resource stability, environmental risks, and installation costs. The results reveal significant diversity in wind resource classification within potential offshore wind farm areas, ranging from "fair" (3/7) to "outstanding" (6/7). The most promising areas for offshore wind farm development in the future are situated in the northwest of the Iberian Peninsula and the Canary Islands.

The identification of the most cost-effective solutions in each area involves determining the optimal combination of rated power and the number of turbines and comparing them across different locations to pinpoint the most economical sites for offshore wind energy exploitation. This economic analysis was done for a 25-year near-future period under the SSP 2-4.5 scenario, aligning with the expected operational lifespan of wind farms. This study includes the calculation of the Levelized Cost of Energy (LCOE) index, which gives an indication of the minimal price at which the electricity should be sold in order for the project to be profitable. The results highlight that the LCOE is lower for farms with a higher number of wind turbines featuring increased rated power. While the Canary Islands exhibit the most economically advantageous prices overall, other regions such as Galicia and Cataluña also boast promising areas.