As far as the underlying science and technology are concerned, it's pretty well established that at least certain types of electric airplanes are not only feasible but even quite practical. At least one, the German Antares 20E, is already on the market, and a second, the side-by-side two-seat Pipistrel Taurus Electro, made in Slovenia (within yodeling range of Austria and Italy, if your geography momentarily fails you), is due at the end of this year. Both are self-launching sailplanes whose pylon-mounted engines and propellers retract fully into the aft fuselage. The cost of climbing to 6,000 feet under electric power, a Pipistrel engineer reported, is one-sixth that of climbing to the same altitude in the Rotax 503-powered version of the Taurus. Boeing recently demonstrated an electric two-seater, but this seems to be a research project aimed at developing more efficient APUs and garnering a little publicity in the process; Boeing is not going into the LSA business. John Monett, the developer of the popular Sonex homebuilt kit, unveiled an electric version of his 1,100-pound single-seat Waiex at Oshkosh in 2007; as far as I know, it has not yet flown. A number of solar-powered airplanes have been built with the eventual aim of achieving "eternal" flight, and durations of more than two days have already been demonstrated, proving, if it needed to be proved, that enough extra energy can be collected by solar cells during the day to last an airplane through the night. A European project, Solar Impulse, is currently developing an airplane that will do Voyager and GlobalFlyer (but not the Breitling Orbiter 3 balloon) one better by circling the earth nonstop with no fuel at all.