Generating Electricity from Rain

A surprisingly high voltage can be generated from raindrops using a field-effect, transistor-style structure, reports a new study from the City University of Hong Kong in the journal Nature. A single drop can muster 140 volts, enough to briefly light up 100 small LED bulbs. The new design couples an aluminum electrode with an indium-tin oxide electrode layered with polytetrafluoroethylene (PTFE), a material with a quasi-permanent electric charge. When a raindrop hits the PTFE/tin surface, it bridges the two electrodes and creates a closed-loop circuit that helps fully release any stored charges. The technology could handle sustained rainfall, as well. If there are continuous drops, the charge accumulates and eventually hits a saturation point. Building rooftops could supplement some of the electricity used inside, and electric boats could extend their range.