SBIR-STTR Award

The objective is the development of a miniature hydrogen generator for small Proton Exchange Membrane (PEM) fuel cells. The energy density of this rechargeable power source is 6 to 8 times higher than that of rechargeable batteries. The hydrogen generator is the key for utilizing the long life PEM fuel cell in External Ventricular Assist Device (EVAD) and other man-portable applications with comparatively small power but significant long-term capacity requirements. The generator development is based on the reaction of alkali or alkali-earth metal hydrides with water forming oxides or hydroxides. The generator operates in a passive mode. Hydride is contained in a replaceable fuel cartridge placed in a generator receptacle. Wicking material distributed throughout the cartridge provides a water transport path to the hydride surface. Water is separated from the hydride by a microporous hydrophilic membrane. It allows water to pass, but once wet is impervious to hydrogen gas owing to its bubble pressure. Hydrogen generation is controlled by the build-up of pressure which prevents additional water from entering the fuel cartridge. The effort provides for:(1) verification of the control concept,(2) fabrication, and(3) evaluation of a breadboard system with an available 2OW PEM fuel cell and design of a preprototype generator.Awardee's statement of the potential commercial applications of the research:The combination of a hydride-based hydrogen generator combined with an oxygen or air-breathing PEM fuel cell offers significantly higher energy densities than conventional rechargeable batteries in man-portable applications.National Heart, Lung and Blood Institute (NHLBI)

A concept has been developed for the generation of hydrogen by reacting selected alkali metal hydrides with water. Hydrogen is consumed in a Proton Exchange Membrane (PEM) fuel cell to generate DC power for operation of a Left Ventricular Assist Device (LVAD and Total artificial heart (TAH). Generator and fuel cell operate safely and reliably at about atmospheric pressure producing potable water and electric power. The Hydride - PEM fuel cell power source operates like a battery but provides 2-3 times the energy density of advanced secondary batteries. Life cycle costs will be significantly lower. Lithium aluminum hydride is used for hydrogen generation. Water insoluble and chemically benign lithium meta aluminate is formed in the reaction. The generator operates in a passive and load responsive mode. Reactants are fully utilized. This is accomplished by the use of a corrugated, perforated sheet metal structure for support and distribution of hydride panicles. Wicking is relied upon for distribution of water. Layers of wicking material placed adjacent to the metal structure preform this function. Water is stored in a bladder. From there it is forced through a hydrophilic microporous membrane into the generator until the pressure is high enough to force excess water back into the bladder. Hydrogen is kept from entering the bladder by virtue of the membrane bubble pressure.National Heart, Lung, and Blood Institute (NHLBI)