Introduction of offshore electrolysis:Electrolysis of seawater to produce hydrogen can be achieved in two ways. One is to desalinate seawater and remove impurities to form fresh water before electrolysis. The other is direct electrolysis of seawater. At present, seawater electrolysis is the most mature technology for hydrogen production directly from seawater. It is found that the direct hydrogen production technology from seawater is still in the stage of technological development and verification, and still faces great challenges. Indirect hydrogen production from seawater still needs demonstration to solve the problems existing in the complex production process. Its future development depends on three factors: the demand for hydrogen production for hydrogen energy development, the cost and feasibility of electricity sources, and the technical feasibility.