Complementarity and development potential assessment of offshore wind and solar resources in China seas

The intensification of global energy crisis has attracted worldwide attention on the development of offshore renewable resources. An accurate assessment of spatiotemporal distribution and resources feature of offshore wind and solar (OWS) energy helps to facilitate the proper development and utilization of China's offshore renewable resources. The published ERA5 reanalysis database from 2012 to 2021 is employed to comprehensively evaluate the richness and variability of OWS resources in China seas. Subsequently, the complementarity between these two resources is estimated using Kendall's correlation coefficient, and results indicate the complementarity show seasonal changes in most of the China seas. However, in South China Sea, these two offshore renewable resources are complementary throughout the year. Furthermore, by considering various restrictions such as bathymetry and offshore distance, four typical regions in China seas are selected and their power generation characteristics are calculated. Among these regions, the typical region located in South China Sea exhibits the highest annual energy output, with a 100 km2 combined offshore wind-solar system generating 15.29 TWh. In addition, the advantage of joint system in suppressing output fluctuations is confirmed, which encouraging the confidence in combined development of OWS energy.