Does the ocean have better suitability for wind–solar energy complementarity than land? A regional study in East Asia

Land-based wind–solar complementarity is well established, but its marine counterpart remains underexplored as renewable energy development transitions from land to the ocean. In this work, we first examined the differences in resource potential between sea and land based on the concept of power density and determined the optimal complementarity ratio by minimizing power density fluctuations. Building on this, we investigated the differences in post-complementarity power fluctuations at hourly, daily, and monthly scales for both marine and terrestrial settings. In addition, we used ’availability’ and ’persistence’ as indicators to compare the effectiveness of wind - solar complementarity between ocean and land. The results show that, in general, offshore wind resources are significantly more abundant than onshore ones. Wind–solar complementarity is more pronounced offshore on the hourly scale but stronger onshore at the daily scale. Offshore regions consistently support effective complementarity, while onshore, except in wind-rich areas, complementarity mainly involves solar complementing wind. This study highlights the suitability of marine environments for wind–solar complementarity and supports their complementary utilization offshore.