Temporal complementarity analysis of solar photovoltaic, onshore, and offshore wind resources in the Iberian Peninsula

The integration of renewable energies into the electricity systems of European countries plays a key role in the European Union's ambitious goal of achieving a neutral climate by 2050. The geostrategic position of the Iberian Peninsula (IP) makes Spain and Portugal a benchmark in renewable energies, where their share exceeds the European average (around 50% in Spain and 60% in Portugal). Currently, solar photovoltaic (PV) and onshore wind power are the main sources of renewable energies in these countries. However, the offshore wind resource, which is set to play an important role in future energy systems, has great potential for exploitation in the IP. In this context, the Spanish and Portuguese governments have provided a legislative framework to encourage the development of offshore wind farms in the coming years. Furthermore, the annual cycle of energy demand in the IP peaks during the winter and summer. Yet, neither the annual cycle of onshore wind nor solar PV energy generation adjust alone with this demand curve. Previous studies agree that spatial and/or temporal complementarity between these resources can be used to increase renewable energy production and smooth the temporal variability of the combined energy supply. Although in the IP only a few studies analyzing these issues, they conclude that this region presents a great potential in terms of complementarity between these sources. Thus, the objective of this work is to determine whether offshore wind energy presents substantial temporal complementarity with onshore wind and solar PV energies in the IP in winter and summer. For this, hourly solar PV and onshore wind real time generation were obtained from Spanish and Portuguese electrical networks and normalized by the installed capacity. With respect to the offshore wind resource, hourly wind speed at 150 meters hub height was extracted for different locations marked as suitable zones by the Spanish and Portuguese governments from the COSMO-REA6 high-resolution reanalysis for 2015-2019. Once the wind speed was translated into capacity factor, we established a capacity factor threshold representing an appropriate efficient resource. We then analyzed the availability and length of generation/non-generation episodes for each resource based on that threshold. Finally, we analyzed the complementarity and synergy between resources, i.e., cases in which the generation of one resource complements the non-generation of another resource and cases in which any of the resources complements the rest. Some of the initial results show that offshore wind complements solar photovoltaic in winter and onshore wind in summer. This indicates that the exploitation of the offshore wind resource can contribute to diversify and improve the integration of renewable generation in the energy mix of the Iberian electricity system.