Land-sea integrated grid architecture based on electric power-hydrogen coupling and its efficacy for offshore wind power systems: A case study of the coastal grid in Guangdong Province

[Objective] Guangdong is a leading province in offshore wind power development in China. By the end of 2024, its installed nearshore wind capacity ranked first nationwide, with a long-term near-shore development plan exceeding 30 GW. However, challenges such as insufficient power transmission capacity, grid stability issues caused by large-scale integration, and the ongoing reform of market-based pricing for renewable energy have posed significant obstacles to the future consumption of nearshore wind power. Hence, this study designs an integrated land-sea energy system based on electricity-hydrogen coupling, and verifies its performance through simulation. [Methods] By analyzing the actual operational data from three offshore wind farms in Guangdong Province, we identified three typical power output curves (low, medium, high) corresponding to different stages of renewable energy development through cluster analysis. An optimization model was established to simulate the integrated land-sea system, defining three dimensions to describe the system's nearshore wind power consumption efficacy: the electro-hydrogen conversion index, wind power effective utilization rate, the share of total system cost attributed to renewable energy. [Results] (1) The low, medium, and high output scenarios mainly occur in summer, spring, and winter respectively, indicating a significant correlation between nearshore wind power output and climate in the region; (2) Under different scenarios, the constructed electric power-hydrogen coupling system can essentially achieve complete absorption of nearshore wind power. Under the high-output and low-demand scenario, the total system cost is approximately 71.7% of that under the low-output and high-demand scenario; (3) The consumption efficacies of the coupled system vary with different offshore wind power penetration rates and hydrogen system capacity configurations. When both the power-to-hydrogen configuration capacity and hydrogen storage tank capacity increase, the power-to-hydrogen conversion ratio and overall system efficacy significantly improve. [Conclusion] The electricity-hydrogen coupling system can effectively improve the consumption of nearshore wind power, and increasing the configured capacity of the hydrogen energy system contributes to enhancing the overall system effectiveness.