Objective Deep-sea wind power offers abundant resources with fewer marine space constraints, making it a key focus for future offshore wind power development. Offshore electro-hydrogen coupling (EHC) technology serves as a major approach to improve the economic efficiency of power transmission for deep-sea wind power and solve the difficulty of wind power accommodation.

Methods The high salinity and humidity of the marine environment, combined with wind power fluctuations, create significant differences in technology, operational efficiency, and reliability between offshore and onshore EHC systems. A combination of literature review, comparative analysis and logical deduction was adopted to analyze the characteristics and challenges of offshore EHC technology, propose various engineering application modes, and identify the technical bottlenecks under each scenario.

Results Five typical EHC modes for deep-sea wind power were identified: onshore centralized electro-hydrogen conversion, offshore centralized electro-hydrogen conversion, offshore decentralized electro-hydrogen conversion, electro-hydrogen conversion integrated with oil and gas systems, and electro-hydrogen conversion integrated with comprehensive energy islands. The onshore centralized electro-hydrogen conversion mode was technologically mature but required transmitting deep-sea wind power to onshore terminals, necessitating further technical and economic evaluation. The other four modes involved offshore electro-hydrogen conversion, where technologies remained underdeveloped. A phased development path was proposed: 1) Demonstrate EHC at fixed wind farms with oil and gas pipelines near shallow offshore oil and gas fields. 2) Expand to EHC at floating wind farms with oil and gas pipelines near deep-water oil and gas fields. 3) Develop offshore decentralized electro-hydrogen conversion and electro-hydrogen conversion integrated with comprehensive energy islands.

Conclusion For the offshore centralized electro-hydrogen conversion, fixed facilities in shallow waters are preferred for housing electro-hydrogen conversion equipment. If floating facilities are used, special attention must be given to the voltage class, current capacity, and heat dissipation of dynamic cables and slip rings. In the offshore decentralized electro-hydrogen conversion, key challenges include the mechanical strength of electrolyzers mounted on floating wind turbines, hydrogen embrittlement of pipelines, and the safety and integration of flexible risers or dynamic connectors. These findings offer theoretical guidance and practical references for the planning, layout, and large-scale development of deep-sea wind power resources.