The use of fuel cell technology for portable power systems potentially offers lower weight compared to other portable power sources. However, highly efficient fuel cells offering excellent power density and low-operating temperature such as Polymer Electrolyte Membrane Fuel Cells (PEMFCs) require a hydrogen (H2) fuel source. One promising H2 fuel source is aluminum hydride (alane or AlH3). This chemical offers increased H2 gravimetric density, as well as a H2 feed stream with only trace amounts of contaminants. Unfortunately, conventional PEMFCs using this method of H2 production from alane have a number of drawbacks. For example, after prolonged heating of alane at low temperatures, increasing the temperature does not produce additional H2. Furthermore, conventional PEMFCs, which heat the alane at higher temperatures, consume more energy heating the alane (or hydrogen fuel source), making less energy available for the intended use. In addition, due to the larger thermal mass of conventional PEMFCs, a significant amount of H2 gas is released during shut down as the cartridge cools down, requiring the ability to utilize and store the energy contained in the H2 gas. Finally, the process of replacing used fuel cell cartridges during operation of the PEMFC (called hot swapping) requires users to handle a hot fuel cell cartridge, which is a safety hazard.
Army researchers have developed a method to fabricate a H2 fuel cell consisting of an insulation layer, a heater layer, an alane fuel source layer, and a waste heat exchange layer. These are rolled into a spiral form and packed into a container. In this manner, the fuel source is always adjacent to the heater layer and the waste heat exchange layer. This allows for both consistent heating of the alane and capture of waste heat. The design further facilitates heating of individual segments of the alane fuel source without significantly increasing the temperature of adjacent segments of the alane fuel source. All of the layers are porous and the H2 is desorbed from the fuel source layers into a fuel cell stack.
This US patent 9,461,323 is related to US patent 9,768,459.
- The only products from the reaction are H2 and aluminum
- Alane is heated to a point to optimize H2 production and eliminate waste heat
- A control unit monitors and changes heating, gas production, and delivery to the PEMFC
- Insulation layers provide for easier handling
- US patents 9,461,323 and 9,768,459 available for license
- Potential for collaboration with Army researchers