Hydrogen by Osmotic Disparity

To mitigate challenges in transporting and storing energy from distributed off-grid small-scale energy harvesters, there is the need for research and development of innovative marine andhydrokinetic systems that produce nonelectric products such as hydrogen and fresh water, which may be unlimitedly stored and easily transported. A novel system, which meets agency requirements, has been developedanddemonstratedinthe Phase I effort and proposed to be productized in Phase II. The system is based on reverse electrodialysis to convert a salinity gradient between river- and seawaters into electrical power, which is applied to the deionization of river water by electrodialysis, resulting in hydrogen production by proton exchange membrane electrolysis and accumulation of this hydrogen in low-pressure, metal-hydride storage. The power conversion balance was analyzed, and the membrane stack power harvesting density of ~1 W/m2 and hydrogen generation rate of 3.37 mg/min (37.7 mL/min) per m2 of membrane stack were experimentally demonstrated, thus confirming the feasibility of the proposed approach and the efficiency of the novel design for the reverse electrodialysis stack. The exploration of the commercial potential for the proposed system revealed a realistic commercial potential for the proposed system with an expected return on investment in 11 years. With all major aspects of the system’s technical feasibility convincingly demonstrated in Phase I, most of the Phase II resources will be invested in the building and demonstration of a real-scale minimal-configuration pilot system to reveal and mitigate technical challenges, minimize the cost of equipment, and demonstrate the productivity of the proposed system for potential users. Commercial Applications and Other Benefits: The improved reverse electrodialysis unit may be used both alone and in complete hydrogen-producing systems to add distributed power sources in multiple locations such as at a river’s estuaries or near desalination plants, which produce significant amounts of concentrated brine. Besides the utilization of additional renewable power resources, the production of concentrated energy (hydrogen) allows for improved power delivery to remote, off-grid locations to feed electrical generators (fuel cells), including those installed in vehicles. Moreover, the distribution of hydrogen-charged storage containers in urban areas allows for a wider use of hydrogen-powered or electric cars, which provide environmental benefits. Because this power is obtained from a renewable source, the cost of hydrogen will be significantly lower than those of current technologies.