Seawater Membrane Distillation Coupled with Alkaline Water Electrolysis for Hydrogen Production: Parameter Influence and Techno-Economic Analysis

The production of green hydrogen requires renewable electricity and a supply of sustainable water. Due to global water scarcity, using seawater to produce green hydrogen is particularly important in areas where freshwater resources are scarce. This study establishes a system model to simulate and optimize the integrated technology of seawater desalination by membrane distillation and hydrogen production by alkaline water electrolysis. Technical economics is also performed to evaluate the key factors affecting the economic benefits of the coupling system. The results show that an increase in electrolyzer power and energy efficiency will reduce the amount of pure water. An increase in the heat transfer efficiency of the membrane distillation can cause the breaking of water consumption and production equilibrium, requiring a higher electrolyzer power to consume the water produced by membrane distillation. The levelized costs of pure water and hydrogen are US$1.28 per tonne and $1.37/kg H2, respectively. The most important factors affecting the production costs of pure water and hydrogen are electrolyzer power and energy efficiency. When the price of hydrogen rises, the project’s revenue increases significantly. The integrated system offers excellent energy efficiency compared to conventional desalination and hydrogen production processes, and advantages in terms of environmental protection and resource conservation.