Hydrogen has been identified as a key clean energy carrier for long-term storage and usage in hard-to-abate sectors with high power requirements. However, it is mainly produced using fossil fuels, diminishing the clean benefits. Proton exchange membrane (PEM) water electrolyzers are a critical technology in development that uses renewable electricity to split water molecules, producing hydrogen at a high capacity and high purity while operating under compact, low-temperature conditions. One drawback of state-of-the-art PEM water electrolyzers is the requirement for highly purified, deionized water for efficient operation. The most abundant source of water on the planet is seawater, which has high salt content and other impurities. Typically, seawater is deionized and purified in a separate process, such as reverse osmosis, before being used for electrolysis, driving up the energy requirement and operational cost. This is a viable option for applications where water purification systems are accessible and affordable, and weight requirements are not a factor. Yet, some remote, lightweight applications, such as unmanned aerial vehicles (UAVs), would benefit from a compact system that can directly convert seawater to hydrogen without additional bulky deionization systems. This work presents a compact system that couples the state-of-the-art PEM water electrolyzer with seawater deionization through pervaporation membrane (PVM) deionization. The perfluorinated sulfonic acid (PFSA) electrolyte membrane typically used for PEM water electrolysis was repurposed as an ion-exchange membrane for PVM deionization. The fabrication, testing, and optimization of a lab-scale system that directly utilizes heat from a PEM electrolyzer for PVM to deionize seawater, which is subsequently used for water electrolysis, will be presented.
