Button-Battery Sized, Propane Fuel Cell for MP3 Players and Beyond
New Propane-Burning Fuel Cell Could Energize a Future Generation of Small Electrical Devices
"PASADENA, Calif.--Engineers have created a propane-burning fuel cell that's almost as small as a watch battery, yet many times higher in power density. Led by Sossina Haile of the California Institute of Technology, the team reports in the June 9 issue of the journal Nature that two of the cells have sufficient power to drive an MP3 player. If commercialized, such a fuel cell would have the advantage of driving the MP3 player for far longer than the best lithium batteries available"."Fuel cells have been done on larger scales with hydrocarbon fuels, but small fuel cells are challenging because it's hard to keep them at the high temperatures required to get the hydrocarbon fuels to react," Haile says. "In a small device, the surface-to-volume ratio is large, and because heat is lost through the surface that is generated in the volume, you have to use a lot of insulation to keep the cell hot. Adding insulation takes away the size advantage."
"The new technology tackles this problem by burning just a bit of the fuel to generate heat to maintain the fuel cell temperature. The device could probably use a variety of hydrocarbon fuels, but propane is just about perfect because it is easily compressible into a liquid and because it instantly becomes a vapor when it is released. That's exactly what makes it ideal for your backyard barbecue grill".
"As for applications, Haile says that the sky is literally the limit. Potential applications could include the tiny flying robots in which the defense funding agency DARPA has shown so much interest in recent years. For everyday uses, the fuel cells could also provide longer-lasting sources of power for laptop computers, television cameras, and pretty much any other device in which batteries are too heavy or too short-lived".
Flying robots? Can't we think of some more TreeHugging sorts of reasons to push forward with this Ms. Haile?