Scientists at Motorola Labs have reached new milestones in their development of miniature fuel cells that may one day be used to power everything from cellular phones and laptop computers to portable cameras and electronic games. They have now demonstrated a prototype of an integrated, ceramic-based miniature direct methanol fuel cell (DMFC) system and have also built several of the key components required for a miniature, ceramic-based reformed methanol to hydrogen fuel cell (RHFC).
The key to successfully miniaturizing a DMFC system for small consumer electronics is scaling down the system components surrounding the actual fuel cell device. Previous DMFC systems have used discrete components to process and deliver methanol to the fuel cell, determine the methanol concentration within the fuel cell, and separate the carbon dioxide generated within the fuel cell from the liquid fuel.
Last year, Motorola (NYSE: MOT) announced a multi-layer ceramic technology for processing and delivering the fuel and air to the fuel cell membrane electrode assembly (MEA). The researchers have now integrated many of these other components, including a methanol concentration sensor and liquid-gas separation for CO2 release, directly in the ceramic device. Miniature pumps and control and conversion electronics were also built into the device. The ceramic DMFC experimental assembly, measuring about two inches (5cm) by four inches (10cm) and less than one-half of an inch (1cm) thick (without electronics or fuel) produces over 100mW net power continuously. In the lab, the fuel cell system has been operated continuously for a week at a time, with little degradation in performance.
Motorola Labs is also doing research on a related fuel cell technology in which methanol is converted to hydrogen as needed and supplied to a more conventional hydrogen fuel cell MEA. The key to successfully miniaturizing an RHFC system is scaling down the system components surrounding the actual fuel cell device and integrating them both structurally and thermally. Previous RHFC systems have used discrete metal components to vaporize the methanol fuel, reform the methanol to hydrogen, clean up the output of the reformer, and house the fuel cell stack. Using its multi-layer ceramic technology, Motorola researchers have demonstrated an integrated vaporizer and miniature methanol steam reformer, and separately a miniature chemical heater -- three of the key components in the RHFC system. The reformer assembly, measuring 38mm x 13mm x 1mm thick, integrates both the fuel vaporizer and methanol steam reformer. The chemical heater, with the same dimensions as the reformer, provides a simple structure for converting a percentage of the methanol fuel into heat to drive the reformer reaction. Eventually Motorola plans to integrate all of these components, along with a fuel cell, into a single device producing 1W or greater power.
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