An Integrated Water Electrolyzer with Pervaporation Membrane for Impure Water Feeds

Green hydrogen (H2) via low-temperature electrolysis (LTE) powered by variable renewable electricity is a key part of the plans to stabilize the electricity grid and decarbonize the transportation and manufacturing sectors. The barriers to this compelling vision are cost, transportation and storage, and lack of a hydrogen infrastructure. These may be overcome by developing lower cost electrolyzers for distributed H2 generation that can directly utilize impure water. Currently, since ultrapure water is required for LTE, the cost of balance-of-pant (BOP) can exceed that of the electrolyzer stack.Our Approach: To simultaneously address the twin challenges of using tap, brackish or sea water, while reducing the cost of BOP, we have developed a novel water electrolyzer stack which can function with a direct impure water feed, i.e., without the reverse osmosis (RO) and deionization (DI) steps normally required in feed water treatment. At the heart of this invention is a novel membrane-electrode assembly (MEA) structure which integrates a membrane-based water purifier within the cell. The majority of the efforts so far to develop direct impure water electrolyzers have been focused on developing electrocatalysts and ion-exchange membranes that are resistant to fouling by ions in non-DI water.Planned Work: We propose to validate on the bench-scale in Phase I, the performance and effectiveness of our direct impure water electrolyzer (DIWE) with a unique and efficient energy/mass integrated cell structure. Thereupon, we will optimize the new cell MEA structure, including optimizing precious metal catalyst loading and membrane properties to reduce the stack cost while enhancing performance. Finally, we will test the durability of our cell while operating on tap/sea water, thus advancing from TRL2 to TRL3.Commercialization Plans/Benefits: if this work is advanced to Phase II with DOE support, we will build and test a prototype that can directly use brackish/sea water. In addition, a detailed TEA and LCA will be performed to show that by thus halving the cost of the electrolyzer plant, we can accomplish the DOE cost target of $2 kg-1 for green H2 by 2026. Phase II work will advance our technology to TRL4. It will be followed by Phase III, when we will build/test a pilot plant with private equity to advance to TRL6/7. We expect subsequent commercial implementation to help decarbonize the energy and industrial sectors.