Efficient, Compact Seawater Electrolysis and Product Storage for Medical and Energy Applications

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Renewable Energy Generation and Storage; Advanced Materials OBJECTIVE: To develop a dual-function seawater electrolyzer capable of generating both medical-grade oxygen and high purity hydrogen. DESCRIPTION: The products of water electrolysis, molecular oxygen and hydrogen, are attractive for a variety of military capabilities, ranging from life-support to alternative fuels. Recently, a surge in research activity has led to opportunities towards harnessing these valuable resources from direct electrolysis of natural sources including ocean water. The ability to generate contaminant-free hydrogen and oxygen from the raw and complex matrix of natural seawater would enable production and use at the point-of-need and as-needed. A highly efficient, integrated systems approach for the production and capture of oxygen and hydrogen with minimal power input is desired. Ideal system features include the ability to operate with minimal user intervention, regenerable/rechargeable catalyst after use, with the optional ability to operate hybridized with renewable energy sources. Target systems should produce medical-grade oxygen and ultra-high purity hydrogen continuously for at least 10 hours before catalyst regeneration is required. Optimal designs should generate more energy than that required to power the electrocatalysis. PHASE I: Develop a concept for a seawater electrolyzer that efficiently produces pure oxygen and hydrogen. Demonstrate feasibility through analysis and limited laboratory and/or brassboard demonstrations. Provide energy estimates for variable output levels of pure oxygen and hydrogen with a target to match metabolic oxygen demands, power requirements and power source, pressurized gas storage in a standard size scuba tank and reliability estimates, including lifetime expectancy. The required Phase I deliverables will include: 1) a research plan for the engineering the design of the seawater electrolyzer; 2) a preliminary prototype, either a physical a highly detailed virtual prototype, capable of demonstrating the requirements of the design; 3) test and evaluation plan including data collection methodologies and identification of proper controls and 4) a hazards analysis for safe generation and storage of hydrogen and oxygen. Important considerations should include ability to resist corrosion and fouling in harsh seawater environments. Phase I will provide key information about the uses and limitations of the system and could include rapid prototyping and/or modeling and simulation. PHASE II: Fabricate, demonstrate, and validate the seawater electrolyzer prototype based on the Phase I design concept. The system should be tested under expected operational environmental conditions (e.g. temperatures, pressures; potential contaminants). Ideal features for the final product form factor would be portable, low or no power requirements (not to exceed 2 kg Li-ion battery); and include appropriate sensors and control systems that quantify and partition the hydrogen and oxygen gas products. Conduct a cost analysis to estimate the cost to fabricate a limited number of systems (1-10 units) as well as a lifetime cost estimate based on updated system reliability estimates from Phase I. Update the hazards analysis from Phase I for the Phase II system. Delivery of up to 2 prototypes to the program office for further testing is desired. PHASE III DUAL USE APPLICATIONS: Develop prototypes into functional systems optimized for a specific use application as agreed to by an appropriate sponsor. Operationally relevant conditions (e.g., portable, life support application) may necessitate and inform additional development. Scalable systems approaches that demonstrate value beyond medical use of oxygen to energy at the tactical edge, underwater life support systems and/or unmanned vehicles are preferred. REFERENCES: 1. Jin, Huanyu, et al. "Emerging materials and technologies for electrocatalytic seawater splitting." Science Advances 9.42 (2023): eadi7755. 2. Zhang, Ran, et al. "Recent Advances in High Performance Direct Seawater Electrolysis for Green Hydrogen." Advanced Energy and Sustainability Research 5.9 (2024): 2400085. KEYWORDS: seawater electrolysis, medical grade oxygen, high purity hydrogen