Introduction  In order to further improve the cruising ability of underwater equipment, the high specific energy electric energy system is the key to the problem. By comparing the impact of different fuel types on the specific energy of the system, the feasibility of underwater application of fuel cells is explored.

  Method  By comparing and analyzing the characteristics of proton exchange membrane fuel cells and solid oxide fuel cells in different hydrogen storage and oxygen storage methods according to the index requirements, it is determined that the cathode side could meet the design requirements by using liquid oxygen supply and the anode side could adopt different supply methods, such as liquid hydrogen, organic liquid, methanol reforming, direct methanol and direct propane.

  Result  Depending on the characteristics of different fuel cells, the relevant parameters of the tail gas treatment device are calculated and the feasible schemes of underwater fuel cell energy systems are comprehensively compared. The solid oxide fuel cell energy system with liquid oxygen and liquefied propane or organic liquid, the proton exchange membrane fuel cell with liquid oxygen and organic liquid could meet the design requirements.

  Conclusion  The fuel cell energy system can significantly improve the specific energy of the energy system, and the fuel supply form is the main factor affecting the specific energy of the electric energy system.