Assessment of offshore wind-solar energy potentials and spatial layout optimization in mainland China

Developing offshore wind and solar energy presents a promising solution to reduce carbon emissions. Yet, there has been little focus on the co-location of offshore wind and solar energy, and an absence of methods for optimizing their spatial layout for regional integration. To this end, this study introduces a framework to assess both the technical and economic potential using geographic information system technology, and to seek the optimal spatial layout by combining electricity dispatch simulation and multi-objective optimization. Our results reveal that China's offshore wind-solar generation potential amounts to similar to 15.7 x 10(3) TWh/year, half of which is accessible at a cost of less than <euro>86/MWh. This potential could satisfy 100% of the coastal electricity demands, but the proportion of offshore generation delivered to the grid and the share of load addressed are contingent on specific constraints. We demonstrate that co-located wind-solar farms diminish generation variability and that energy storage markedly reduces PV curtailment during dispatch. Our study underscores the importance of site selection in distant offshore and decentralized placement among locations with varying characteristics. Our study serves as a foundation for offshore wind-solar energy endeavors and offer crucial considerations for the spatial layout optimization of ocean renewable energy utilization.