Thermodynamic analysis and optimization design of alkaline water electrolysis hydrogen production system for offshore wind power

Objectives In order to fully leverage electricity and seawater resources, this paper carries out the thermodynamic analysis and optimization design of an alkaline water electrolysis（AWE） hydrogen production system for offshore wind power. The focus comprises the impacts of operating pressure, temperature and lye flow rate on the operational characteristics of the system.

Methods Thermodynamic, kinetic and flux balance analyses are carried out to develop a thermodynamic equilibrium model for hydrogen production by alkaline water electrolysis using Aspen Plus software, which is then validated in comparison with the experimental results.

Results The optimum working pressure and temperature of the alkaline water electrolysis hydrogen production system are 9 bar and 70 °C respectively, and the optimum lye flow rate is 1600 t/h. The system energy loss and exergy loss increase with the increase of input current density. When the alkaline water electrolysis input current density reaches 3000 A/m², the system energy efficiency and exergetic efficiency are 63.58% and 57.27% respectively, and the system energy loss accounts for 26% of the total energy input, of which the exergy loss of the electrolyzer is the highest, accounting for 93.39% of the total exergy loss of the system.

Conclusions Through this parametric optimization method, a suitable range of operating parameters can be obtained, providing useful references for the selection of offshore wind power hydrogen production parameters.