Tiny charges gathered directly from humid air could be harnessed to generate electricity, researchers say.
Dr Fernando Galembeck told the American Chemical Society meeting in Boston that the technique exploited a little-known atmospheric effect.
Tests had shown that metals could be used to gather the charges, he said, opening up a potential energy source in humid climates.
However, experts disagree about the mechanism and the scale of the effect.
"The basic idea is that when you have any solid or liquid in a humid environment, you have absorption of water at the surface," Dr Galembeck, from the University of Campinas in Brazil, told BBC News.