Simple and sustainable electric power generation by free evaporation of liquids from the surface of a conventional thermoelectric generator†

Liquid evaporation, or water vapor generation, is a spontaneous natural process and is always accompanied by evaporation cooling. However, evaporation cooling that can directly produce electricity based on the Seebeck effect and even supply power for electronic devices has not yet been reported. Here, liquid evaporation generators (LEGs), with cheap and practical thermoelectric generators (TEGs), are demonstrated to generate electric power based on the combination of the Seebeck effect and evaporation cooling. We systematically explored the LEG based on water evaporation (w-LEG) in a real environment, and five tandem w-LEGs can produce a maximum voltage of 4.4 V and achieve a maximum power density of 5.4 mW cm⁻², which can successfully supply power for common electronic devices. Our concepts demonstrate a new supplement of green energy technology and a new direction for the applications of low temperature thermoelectric conversion (below 50 °C).