http://running_on_alcohol.tripod.com/id30.html A fuel cell is a device that can obtain 40 to 50% efficiency in conversion of a fuel into useable power (as opposed to approximately 18% efficiency for the average internal combustion engine). This technology is a by-product of the NASA space program, developed to provide a lightweight and efficient power source for use on manned space missions. Some fuel cells use specialized molecular sieves made of complex polymers with some type of anode/cathode properties , and others use expensive platinum catalysts. There are four main types available. Some use pure hydrogen as a fuel source to make electricity. Some are designed to run on propane, but may only have a membrane life expectancy of 3,000 hours (125 days). One of the main problems with any fuel cell is contamination of the membrane. So it seems like a great advantage, then, to use a fuel source which has been distilled and is 99.9999 % pure. The ideal fuel for a fuel cell is ethanol. Plus, this is a biologically derived fuel with no horrible byproducts.