Portable electronic devices (PEDs) such as cell phones and laptop computers have ever-growing needs for electrical power, yet the batteries they use provide only 1 to 2% energy per pound as hydrocarbon fuels. Because hydrocarbon fuels pack high energy densities, they are the fuel of choice for power generation at large scales. However, this is not done at small scales since engineers have been unable to scale internal combustion or steam engines down to the sizes required to generate electricity for PEDs. Tiny fuel cells (which convert fuel directly into electricity) have been used to power PEDs, but have only succeeded by using fuels such as hydrogen or methanol which have safety issues and/or very low energy per pound when the weight of the storage tank is included. The present work proposes to use propane and butane, the same easily-stored, high energy density fuels used in disposable lighters, for generating power for PEDs and provides a very simple, versatile system for supplying air to the device. The results of this work could have a significant impact on PEDs with electrical energy storage densities exceeding batteries by a factor of 10. Moreover, disposal of empty fuel cartridges in landfills is preferable to disposal of used batteries containing toxic metals. This work will involve undergraduate and graduate engineering students and also educate K-12 students through programs at Syracuse and USC.
Portable electronic devices have ever-growing needs for electrical power, yet batteries provide only 1 to 2% of the energy density of hydrocarbon fuels. Scale-down of internal combustion engines and electrical generators to MEMS scales has been unsuccessful due to issues with heat losses, friction and the difficulty of manufacturing parts at small scales with sufficient precision. The PIs propose to generate electrical power from hydrocarbon fuels at small scales using (1) thermal transpiration in nanoporous materials for fuel and air pumping; (2) combustion on Pt- and Au- catalysts with room-temperature ignition; and (3) single-chamber solid oxide fuel cells requiring no seals or separation between fuel and oxidant for power generation within the thermal transpiration pump. Reactors of arbitrary shape will be constructed using parts built using a unique 3-dimensional printing technology for porous sintered stainless steel. The activity of supported Au nanoparticles for low-temperature ignition of hydrocarbon oxidation will be measured using in-situ FTIR/Gas Chromatography analysis. To determine what property has the most impact on low-temperature oxidation, their surface structure modifications will be assessed via Scanning Electron Microscopy and their chemical modifications via X-ray Photoelectron Spectroscopy. The effects of ion substitution on the properties of double-perovskite structures will be investigated and the catalytic behavior of several precious-metal, oxide-supported electrocatalysts will also be examined. A high purity source of gadolinia-doped-ceria is expected to increase the electrolyte conductivity, yet retain the processability for thin-film electrolyte fuel cell fabrication. The envisioned system is self-contained, has pumping and power generation integrated into one device, has no moving parts and operates only on thermal and electrochemical energy supplied by hydrocarbon fuels (i.e., it has no parasitic electrical energy losses). This research could also enable spin-off applications to other systems requiring gas pressurization or vacuum pumping, e.g. micro gas chromatographs or toxic chemical agent sensors.