Electricity might not grow on trees, but it is freely available in the air -- provided you know how to catch it. Such is the contention presented by Dr. Francesco Galembeck of Brazil's University of Campinas at the 240th annual American Chemical Society shindig. He and his crew have shown how tiny particles of silica and aluminum phosphate become electrically charged when water vapor is passed over them. This aims to prove two things: firstly, that airborne water droplets do carry an electric charge, and secondly, that metals can be used to collect that charge. Detractors have pointed out that Dr. Galembeck's team may be generating the droplets' electrical charge by the act of pumping the air over the metals -- which might imply you couldn't practice this technique with still, humid air -- while there's also the rather large caveat that the little electricity they were able to collect from vapor was a hundred million times less than what you could obtain from a solar cell of equivalent size. Still, it's another new door unto a potential alternative energy source and we don't ever like having to close those.